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Apr 1982

Volume 20, Issue 4, pp. 925-1417


Initial stages of high‐temperature metal oxidation

C. Y. Yang and W. E. O’Grady

J. Vac. Sci. Technol. 20, 925 (1982); http://dx.doi.org/10.1116/1.571644 (5 pages) | Cited 2 times

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In this paper we will discuss the application of XPS and UPS to the study of the initial stages of high‐temperature (≳350 °C) electrochemical oxidation of iron and nickel. In the high‐temperature experiments, we have electrochemically oxidized iron and nickel electrodes in contact with a solid oxide electrolyte in the UHV system. The great advantages of this technique are that the oxygen activity at the interface may be precisely controlled and the ability to run the reactions in UHV allows the simultaneous observation of the reactions by XPS.
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81.05.Bx Metals, semimetals, and alloys
79.60.Bm Clean metal, semiconductor, and insulator surfaces
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
82.45.-h Electrochemistry and electrophoresis

An Auger electron spectroscopy (AES) study of the initial stages of oxidation of the single crystal Be (0001) surface

D. E. Fowler and J. M. Blakely

J. Vac. Sci. Technol. 20, 930 (1982); http://dx.doi.org/10.1116/1.571645 (4 pages) | Cited 5 times

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The oxidation of Be(0001), in particular the early stages of the reaction, was tracked dynamically by AES using a computer controlled single pass CMA. The reaction was followed by monitoring the three Auger transitions, Be(KVV), BeO(KVV), and O(KVV) in dN/dE mode. Because the Be(KVV) and the BeO(KVV) signals overlap, a multiple linear regression analysis based on a linear combination of the spectra of clean, cleaved Be and a BeO crystal was done to separate them. Results have been obtained for oxygen partial pressures ranging from 4.7×10−7 Pa (3.6×10−9 Torr) to 1.3×10−4 Pa. Considerable structure is seen in the uptake curves suggesting the occurrence of multiple stages of growth. The oxidation process appears to be linearly dependent on pressure for high pressures. Further conclusions are made difficult due to the strong enhancement of the oxidation by the AES incident electron beam. Finally, at all pressures studied, an excess of oxygen signal compared to that expected from stoichiometric BeO exists in the very early stage of the oxidation.
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81.05.Bx Metals, semimetals, and alloys
79.20.Fv Electron impact: Auger emission
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

In situ Mössbauer studies of passive films on iron

J. Eldridge, M. E. Kordesch, and R. W. Hoffman

J. Vac. Sci. Technol. 20, 934 (1982); http://dx.doi.org/10.1116/1.571646 (5 pages) | Cited 3 times

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Mössbauer effect spectroscopy is applied to the analysis of the passive film on iron with the aim of supplying local site information. High count rate transmission experiments have been performed to examine the passive film in situ under a variety of potentials. When electroplated, Fe‐57 enriched iron films are cathodically reduced at −350 mV RHE for over 1 h and then passivated at a potential of 1350 mV in a buffered borate solution pH 8.4, an isomer shift of 0.64±0.01 mm/s vs SNP and a quadrupole splitting of 1.14±0.09 mm/s for the passive layer are obtained. The isomer shift indicates iron present in the Fe+3 valence state. The quadrupole splitting is larger than for bulk crystalline iron oxides, suggesting a disordered structure. MES data of cathodically reduced passive films show only pure iron, demonstrating complete reduction of the passive film. Spectra taken of a natural iron film passivated in an Fe‐57 containing borate solution indicate no contribution from iron precipitated from the solution. The resonant area associated with the passive film is observed to depend on specimen preparation, in particular, the amount of time spent during cathodic reduction prior to passivation. The isomer shift and quadrupole splitting are not greatly affected by changes in the passivating potential in the range from 1050 to 1550 mV RHE.
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68.55.-a Thin film structure and morphology
76.80.+y Mössbauer effect; other γ-ray spectroscopy

Surface composition of a tin–lead alloy

G. C. Nelson and J. A. Borders

J. Vac. Sci. Technol. 20, 939 (1982); http://dx.doi.org/10.1116/1.571647 (4 pages) | Cited 1 time

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The surface and near surface composition of a single phase tin–lead alloy whose bulk composition was 99.83 at.% tin and 0.17 at.% lead has been measured as a function of temperature in vacuum and in an oxidizing ambient. In vacuum, the outer monolayer of the surface is enriched in lead at all temperatures studied (≊65% at.% Pb at 23 °C). From the measured lead surface composition as a function of temperature, a heat of segregation of 4.7 kcal/mole is calculated. The data obtained in an oxidizing ambient indicate that the near surface composition is dependent on the oxygen partial pressure as well as the temperature at which the sample is annealed.
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68.35.Md Surface thermodynamics, surface energies
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
81.05.Bx Metals, semimetals, and alloys

Electron loss study of the native oxide of tin

A. J. Bevolo, J. D. Verhoeven, and M. Noack

J. Vac. Sci. Technol. 20, 943 (1982); http://dx.doi.org/10.1116/1.571648 (3 pages) | Cited 4 times

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Using electron loss spectroscopy in combination with ion beam depth profiling, it has been established that the oxide of tin formed by electropolishing followed by room temperature aging is metal free and composed of a mixture of SnO2 and SnO. In a fresh oxide layer, the SnO2 is confined to the outer portion of the predominantly SnO oxide. In an aged oxide layer, SnO2 is present up to the oxide/metal interface with an ever decreasing concentration as the interface is approached.
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81.05.Bx Metals, semimetals, and alloys
79.20.Kz Other electron-impact emission phenomena
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
79.20.Fv Electron impact: Auger emission

Summary Abstract: Raman spectroscopy combined with ion bombardment to depth profile oxide films

J. C. Hamilton, R. E. Benner, and B. E. Mills

J. Vac. Sci. Technol. 20, 946 (1982); http://dx.doi.org/10.1116/1.571649 (2 pages) | Cited 1 time

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Abstract Unavailable
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82.80.Dx Analytical methods involving electronic spectroscopy
82.80.Ej X-ray, Mössbauer, and other γ-ray spectroscopic analysis methods

A review of surface spectroscopies for semiconductor characterization

C. R. Helms

J. Vac. Sci. Technol. 20, 948 (1982); http://dx.doi.org/10.1116/1.571650 (5 pages) | Cited 2 times

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Semiconductor technology requires probably more sophisticated characterization techniques than any other modern technology. For example, many applications require atomic sensitivities of 1 ppb or less, and we may be interested in analyzing a volume smaller than 10−16 cm3 (hopefully not at the same time). In addition to elemental analysis of very small volumes, determination of the chemical state (oxidation state, etc.) of the constituents is many times critical. Of equal importance, especially for the high density of devices contemplated for very large‐scale integration, is the detection and characterization of defects present in wafer starting materials. Many techniques have been applied to these problems including Auger electron spectroscopy, x‐ray photoelectron spectroscopy, Rutherford backscattering, and secondary ion mass spectrometry. In this paper, I will describe the capabilities and limitations of these techniques for studies of important systems in semiconductor technology. The goal of this paper will be to provide the reader with the information necessary to choose among these techniques for a particular analysis application and to show how each can be applied in a complimentary fashion for a specific problem.
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82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
82.80.Dx Analytical methods involving electronic spectroscopy
82.80.Ej X-ray, Mössbauer, and other γ-ray spectroscopic analysis methods

Quantitative Auger microanalysis of the silicon–oxygen–nitrogen system

A. van Oostrom, L. Augustus, F. H. P. M. Habraken, and A. E. T. Kuiper

J. Vac. Sci. Technol. 20, 953 (1982); http://dx.doi.org/10.1116/1.571651 (4 pages) | Cited 7 times

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Auger depth profiling data are presented for thin films of silicon oxide grown by thermal oxidation and for thin films of silicon nitride and silicon oxynitride deposited by low pressure chemical vapor deposition. Samples are bombarded by 500 eV argon ions, and Auger data is collected in either the N(E) or the dN/dE mode of operation. By probing the N, O, and Si(KLL) peaks a quantitative analysis of these films has been made.
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68.55.-a Thin film structure and morphology
79.20.Fv Electron impact: Auger emission
68.60.-p Physical properties of thin films, nonelectronic
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Comparison of AES and XPS analysis of thin passive films

D. R. Baer, D. A. Petersen, L. R. Pederson, and M. T. Thomas

J. Vac. Sci. Technol. 20, 957 (1982); http://dx.doi.org/10.1116/1.571652 (5 pages) | Cited 4 times

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The surface composition and elemental depth profiles of native oxide films formed on amorphous FeCrNiPB alloys have been studied using both Auger electron spectroscopy (AES) and x‐ray photoelectron spectroscopy (XPS). Although both AES and XPS are surface sensitive techniques, differences in electron escape depths for various Auger and photoelectron peaks result in different sample volumes being analyzed by the two methods. This is found to be significant for specimens that have thin surface films with a varying elemental depth composition such as passive layers. Standard XPS and AES analysis of the data from the surface films using either published or bulk normalized sensitivity factors gave different results for the film composition from the two techniques. In addition, AES and XPS sputter profiles were dissimilar. A ’’true’’ depth profile was constructed using an iterative method, considering escape depth broadening effects and the measured profiles. Model calculations of XPS and AES film compositions based on this profile reproduce the differences observed in the experimental XPS and AES data, showing that it is difficult to determine the content of a complex film without some type of depth analysis.
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81.05.Bx Metals, semimetals, and alloys
79.20.Fv Electron impact: Auger emission
79.60.Bm Clean metal, semiconductor, and insulator surfaces

Composition and electron stress effects in silicon nitride thin films made by thermal growth and chemical etching of LPCVD MNOS structures as studied by x‐ray photoelectron spectroscopy (XPS)

J. A. Wurzbach, F. J. Grunthaner, and J. Maserjian

J. Vac. Sci. Technol. 20, 962 (1982); http://dx.doi.org/10.1116/1.571653 (4 pages) | Cited 1 time

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XPS has been used in conjunction with stopped‐flow chemical etching and angular resolution to obtain depth profies and interface structures of native oxide LPCVD MNOS structures and thermally‐grown silicon nitride films. Depth profiling of LPCVD samples required stopped‐flow etching with HF/H3PO4/ethanol (15:10:60). A uniform composition of nearly stoichiometric Si3N4 was found throughout the bulk; SiO2 was found intact at the interface along with a sharp Si3N4/SiO2 interface width of 8–10 Å. Another LPCVD sample was etched to ∠30 Å and subjected to a low‐energy electron flux in an XPS investigation of degradation mechanisms of MNOS devices; cleavage of Si–H bonds was observed. Angle‐resolved XPS on thin, thermally grown films showed a compositional gradient ranging from a high concentration of oxide at the surface to nearly pure Si3N4 at the interface. The results are related to interface state formation and mechanisms of MNOS memory degradation and film growth.
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73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
81.65.-b Surface treatments
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.55.-a Thin film structure and morphology

The preparation and characterization of transition metal nitride films

P. T. Dawson and S. A. J. Stazyk

J. Vac. Sci. Technol. 20, 966 (1982); http://dx.doi.org/10.1116/1.571654 (2 pages) | Cited 1 time

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Nitride surface films of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W have been prepared by reaction with NH3 gas at high temperature. The films have been characterized by x‐ray diffraction, Auger electron spectroscopy, depth profiling, and scanning electron microscopy.
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68.55.-a Thin film structure and morphology
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
81.05.Bx Metals, semimetals, and alloys
68.60.-p Physical properties of thin films, nonelectronic

Artifacts observed during Auger profiling of Ta, Ti, and W metals, nitrides and oxynitrides

S. Ingrey, M. B. Johnson, R. W. Streater, and G. I. Sproule

J. Vac. Sci. Technol. 20, 968 (1982); http://dx.doi.org/10.1116/1.571655 (3 pages) | Cited 6 times

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Studies of CKVV Auger spectra indicate carbide formation in certain metals and compounds resulting from ion beam bombardment of contaminated (air exposed) surfaces. Carbide buildup on W, Ta, and Ti surfaces after ’’static’’ sputter cleaning in an AES system, occurred in the presence of small partial pressures of CH4 generated from the speciman chamber walls and ion pump well. This carbide buildup was greatly accelerated by electron beam irradiation.
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81.05.Bx Metals, semimetals, and alloys
79.20.Fv Electron impact: Auger emission
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

Thermal desorption measurements for estimating bakeout characteristics of vacuum devices

L. Beavis

J. Vac. Sci. Technol. 20, 972 (1982); http://dx.doi.org/10.1116/1.571656 (6 pages) | Cited 1 time

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The present paper deals with experiments which indicate that vacuum devices with proper bakeout will remain at vacuum for several year periods when isolated from pumps and pumping.(AIP)
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68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics
81.40.Gh Other heat and thermomechanical treatments
68.43.-h Chemisorption/physisorption: adsorbates on surfaces
66.30.J- Diffusion of impurities

Behavior of small leaks in the presence of liquid or gaseous helium at 4.2 K

S. Sinharoy and W. J. Lange

J. Vac. Sci. Technol. 20, 978 (1982); http://dx.doi.org/10.1116/1.571657 (4 pages) | Cited 1 time

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Increased present day use of cryogenics necessitates an understanding of the behavior of small leaks at liquid helium temperatures. Little is to be found in the literature except that related to super‐fluid effects in the range 1.4 to 2.9 K. We report the results of an investigation on the behavior of two small leaks (leak rates in the vicinity of 2×10−7 atm cc air/s at room temperature) at 4.2 K in contact with gaseous as well as liquid helium. In both cases, a significant increase in the leak rate was found when the leaks were in contact with liquid helium at 4.2 K. The observed behavior is explained using a model based on the changes in the physical properties of helium with temperature.
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07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment
47.45.Dt Free molecular flows
47.55.Kf Particle-laden flows

Methods for calibration of standard leaks

M. V. Iverson and J. L. Hartley

J. Vac. Sci. Technol. 20, 982 (1982); http://dx.doi.org/10.1116/1.571658 (4 pages) | Cited 1 time

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The Sandia Laboratories Standards Department is currently using the comparison, PΔV, and accumulate‐dump methods to calibrate standard leaks. The comparison method may be used in the range from 10−5 to 10−8 atm cm3/s with a maximum uncertainty of 10%. The PΔV method can be used for fundamental calibration of faster leaks in the range from 10−3 to 10−5 atm cm3/s with a maximum uncertainty of 5%. Finally the accumulate‐dump method can be used to fundamentally calibrate leaks in the range from 10−4 to 10−10 atm cm3/s with uncertainties ranging from 5 to 20%. The purpose of this paper is to introduce these three calibration methods with an analysis of the errors involved. These methods are reviewed and compared with other leak calibration methods.
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07.30.Hd Vacuum testing methods; leak detectors

A 26‐cm electron‐cyclotron‐resonance ion source for reactive ion beam etching of SiO2 and Si

M. Miyamura, O. Tsukakoshi, and S. Komiya

J. Vac. Sci. Technol. 20, 986 (1982); http://dx.doi.org/10.1116/1.571659 (3 pages) | Cited 12 times

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A 26 cm ECR ion source for reactive ion beam etching has been developed for precise processing of semiconductor devices in sub‐micron range. Such fine patterns of SiO2 films on Si substrates as 0.6‐ μm width are produced precisely and anisotropically without etching residues or redeposition with c‐C4F8 as etching gas. The ECR ion source can be operated continuously for more than 40 h with C4F8 plasma, as it has no hot filament. Etch rate ratio of SiO2 to Si increases with increasing C4F8 pressure. A selectivity of about 30:1 is obtained at 2×10−4 Torr. Monitoring methods such as secondary ion mass spectrometry, emission spectroscopy, and Auger electron spectroscopy were used to study the ion source characteristics and etching processes. Reactive ion beam etching using ECR ion source operates with less metal contamination than Ar ion beam etching.
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81.05.Bx Metals, semimetals, and alloys
79.20.Fv Electron impact: Auger emission
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
85.40.Bh Computer-aided design of microcircuits; layout and modeling

Technology and applications of pumping fluids

L. Laurenson

J. Vac. Sci. Technol. 20, 989 (1982); http://dx.doi.org/10.1116/1.571660 (7 pages)

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The chemical and physical properties of the fluids employed in vacuum are given and the suitability of these fluids for various vacuum applications in relation to their properties are discussed. Techniques used for determining the suitability of fluids for vacuum use are indicated. Aspects of the above are illustrated by chemical formulas, mass spectra, and other experimental data such as oxidation resistance. The choice of fluids is discussed for the three applications of plasma processes (both deposition and etching), large pumping systems, and physical electronic applications such as electron microscopy, mass analysis, and spectroscopy. Finally, general aspects of vacuum fluids, their associated pumps, and auxiliary equipment are considered, for example: traps, pump maintenance, changing fluids, and the measurement of characteristics such as backstreaming.
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07.30.Cy Vacuum pumps

Factors influencing the ultimate vacuum of single structure vapor pumping groups

N. T. M. Dennis, L. Laurenson, A. Devaney, and B. H. Colwell

J. Vac. Sci. Technol. 20, 996 (1982); http://dx.doi.org/10.1116/1.571661 (4 pages)

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The single structure vapor pumping group consists of a vapor pump, watercooled baffle, and a quarter swing valve mounted in a single casing. Ten years of experience with such pumping groups using polyphenyl ether has shown that they can give a virtually contamination‐free vacuum. Potential sources of contamination such as vacuum sealing, pump design, high vacuum valves (their sealing gaskets and mode of operation), and the fore vacuum conditions have been studied using both mass spectrometers and quartz crystal microbalances to determine the low levels of organic contamination that arise in the system from the above sources. It is shown that the precautions taken to ensure a ’’clean’’ vacuum must be more stringent than were previously appreciated.
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07.30.Cy Vacuum pumps

On cryosorption pumping of hydrogen with the ZDB–150 type cryopump cooled by a two‐stage closed‐cycle refrigerator

Bing‐kun Liu, Jia‐sheng Ren, and Xiu‐hua Cui

J. Vac. Sci. Technol. 20, 1000 (1982); http://dx.doi.org/10.1116/1.571527 (5 pages)

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The ZDB–150 type cryopump with a 150‐mm i.d. flange, cooled by a two‐stage refrigerator, has been developed for pumping hydrogen, which is the major outgassing product of most metals and the main gas load to be removed in some special applications, such as nuclear fusion. In order to improve the pumping performance of this cryopump for hydrogen, several different configurations and geometries of cryosorption panels were designed and tested. On the other hand, the favorable distribution of the refrigeration capacity and temperature at two cold heads of the refrigerator were also considered and tested. This paper presents the test results on pumping speed and pump capacity for hydrogen with forenamed various considerations. In the selected optimum configuration and condition, the maximum pumping speed and capacity, 2400 l/s and 11 000 Torr⋅l, respectively, were reached. It was concluded that enhancing the pumping capability of cryopump for hydrogen is potentially feasible.
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07.30.Cy Vacuum pumps

A comparison of cryopump and diffusion pump performance on MMA 29×45 ft vacuum chamber

R. C. Muhlenhaupt

J. Vac. Sci. Technol. 20, 1005 (1982); http://dx.doi.org/10.1116/1.571528 (5 pages)

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Four, 48‐in., 95 000 l/s diffusion pumps have been replaced by four, similar sized, 40 000 l/s cryopumps on the Martin Marietta Aerospace, Space Simulation Laboratory, 29×45 ft thermal vacuum chamber. The pumping speeds of both systems were initially calculated to provide a theoretical comparison of their performances. Then the pumpdown times, the ultimate pressures, and effective pumping speeds were measured for both systems. The performance data obtained in the calculations and the tests along with a description of the test methods employed in their determination are presented.
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07.30.Cy Vacuum pumps

Calculation of sputtering ion pump speed

W. Ho, R. K. Wang, T. P. Keng, and K. H. Hu

J. Vac. Sci. Technol. 20, 1010 (1982); http://dx.doi.org/10.1116/1.571529 (4 pages) | Cited 2 times

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Until now, a semiempirical formula S = K(I/P) is widely used to express the pumping speed of a sputtering ion pump. The constant K is decided by experiments. An attempt is made to find this constant by the Schuurman’s theory of magnetic confined gas discharge, the theory of sputtering, and the Langmuir’s theory of adsorption. It is found that K may be expressed as K = 4.9×10−3Cfu1/4a [g+2−(g2+4g)1/2], for nitrogen at room temperature in a diode pump, where C is a configuration factor, f is a pressure dependent factor, ua is the anode potential, g = 2.45×10−3Cfu1/4a I/PA, and A is the area of the inner surface of the anode. This relation is in fairly good agreement with experimental results.
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07.30.Cy Vacuum pumps

Computation of the performance of mechanical boosters with various fore pumps

R. G. Livesey and L. J. Budgen

J. Vac. Sci. Technol. 20, 1014 (1982); http://dx.doi.org/10.1116/1.571530 (4 pages)

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The large number of possible combinations of mechanical boosters and fore pumps makes it desirable to be able to quickly compute the performance of various combinations using previously measured data. Accurate calculation is important in order to ensure that the combination size and therefore cost and energy usage are kept to a minimum. This paper describes the computation, using a microcomputer, of the speed curves of combinations from data on the zero flow compression ratio characteristics. It is shown that taking the booster inlet impedances into account gives calculated values which are in good agreement with experimental results.
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07.30.Cy Vacuum pumps
07.30.Hd Vacuum testing methods; leak detectors
07.30.Kf Vacuum chambers, auxiliary apparatus, and materials

Summary Abstract: Fingerprinting silicone diffusion pump fluids

D. Petraitis

J. Vac. Sci. Technol. 20, 1018 (1982); http://dx.doi.org/10.1116/1.571531 (1 page)

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Abstract Unavailable
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07.30.Cy Vacuum pumps

Mechanical vacuum pumping equipment for applications involving corrosive and aggressive materials

I. Currington, A. Devaney, and P. Connock

J. Vac. Sci. Technol. 20, 1019 (1982); http://dx.doi.org/10.1116/1.571532 (4 pages)

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In chemical environments such as those encountered in the semiconductor industry it is important to specify a complete pumping system including pumps, accessories, oils, and an operating procedure. The paper discusses certain features of the pump design that are important in ensuring reliability when pumping aggressive materials. Further the accessories designed to augment the performance of the pump in aggressive situations are discussed with specific data on their performance under controlled conditions. Special attention is given to a range of oils and oil filtration methods, as in most cases it is the results of oil degradation and contamination that cause operating difficulties in aggressive atmospheres.
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07.30.Cy Vacuum pumps
07.30.Kf Vacuum chambers, auxiliary apparatus, and materials
06.60.Wa Laboratory safety procedures

High throughput pumping of dangerous gases with a multistage roots vacuum pump

J. Henning, E. Rossmanith, and J. Steinmüller

J. Vac. Sci. Technol. 20, 1023 (1982); http://dx.doi.org/10.1116/1.571533 (4 pages)

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The pumping of critical gases—high‐purity, expensive, or dangerous gases—in the vacuum range from 10−3 mbar (1 micron) to atmospheric pressure at specified temperatures and with a minimum of contamination is discussed. A reasonable solution to the problems arising in this field is a positive displacement vacuum pump—a special roots vacuum pump—which requires no lubrication in the working chamber and no mechanical contact between rotors and housing, but which, due to a cooling process free of foreign media, can pump with high compression ratios. A specially designed multistage roots vacuum pump, to pump UF6 from a centrifuge uranium‐separating installation is described. This pump has a maximum pumping speed for nitrogen of 220 m3/h (130 cfm) and can compress directly from below 10 mbar to atmospheric pressure.
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07.30.Cy Vacuum pumps
06.60.Wa Laboratory safety procedures

Implementation of adaptive process control to a dry etching process

F. J. Bresnock and Th. Stumpf

J. Vac. Sci. Technol. 20, 1027 (1982); http://dx.doi.org/10.1116/1.571534 (4 pages)

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The implementation of a minicomputer for adaptive process control in a reactive ion etching tool is described. Improved process control was demonstrated including the ability to adapt to nonlinear, time‐varying processes. The system provides an extremely flexible process development environment.
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81.05.Bx Metals, semimetals, and alloys
07.05.Hd Data acquisition: hardware and software
07.05.Kf Data analysis: algorithms and implementation; data management
07.05.Rm Data presentation and visualization: algorithms and implementation
07.07.Tw Servo and control equipment; robots
89.20.Ff Computer science and technology

Fragment ion pattern coefficients of quadrupole mass spectrometers

Bing‐Sen Hu, Rong‐Zong Wang, and Shi‐Xiang Zhou

J. Vac. Sci. Technol. 20, 1031 (1982); http://dx.doi.org/10.1116/1.571535 (3 pages) | Cited 1 time

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When measuring the partial pressure of residual gases with a QMS, every gas component in the system must be calibrated. The calibration contains two items: the fragment pattern coefficients and sensitivity. We have measured the fragment pattern coefficients of several samples, such as H2, N2, air, NH3, CO, CO2, O2, Ar, ethylene, propylene, alcohol, acetone, etc. The coefficients are the average value of five data points measured over a long period (from several months to one year). Several factors which limit the accuracy of fragment pattern coefficients of the QMS are discussed. It has been shown that contamination and the geometric accuracy of the analyzer are two most important factors. Under controlled conditions, the reproducibility of fragment pattern coefficients of QMS is better than ±15%.
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07.75.+h Mass spectrometers

Failure mechanism of TV tubes

Chong‐ruo Wu, Yu‐hua Zhu, and Zhang‐qi Chen

J. Vac. Sci. Technol. 20, 1034 (1982); http://dx.doi.org/10.1116/1.571536 (5 pages) | Cited 2 times

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In an attempt to extend the life of TV tubes, several factors causing the failure of TV tubes have been studied. The residual gas composition in TV tubes operating for more than 5000 h, and the residual gas in many TV tubes after failure has been analyzed with an omegatron. With the aid of AES, SEM, and SIMS the coating and the base metal of the oxide‐coated cathodes have also been studied. It has been found that the main source of gas release is the EID of the fluorescent screen. The rate of desorption decreases with time. The influences of the coating materials and technology on EID have been measured. The method of reducing EID is discussed. A barium film getter is able to sorb a large number of oxy‐gases, but it also introduces some argon into the tubes. The getter containing the argon, the sorption mechanism of argon, and a way to lower the argon pressure have been studied in some detail.
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84.47.+w Vacuum tubes

Vacuum process in drying of power transformer insulation

J. F. Lennon

J. Vac. Sci. Technol. 20, 1039 (1982); http://dx.doi.org/10.1116/1.571537 (4 pages)

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The drying of transformer insulation to remove absorbed water spans the spectrum of vacuum pumping systems from mechanical rotary piston pumps and mechanical boosters, to liquid ring pumps down to vapor booster and vapor diffusion pumps. Power transformers can weigh 500 000 lb and contain 30 000 lb of insulation. A primary dry of the cellulosic insulation using narrow boiling hydrocarbons as a boiling heat transfer medium occurs in large‐volume tanks of varying capacity from 7000–21 000 ft3. Internal assemblies containing the insulation are first dried to water contents of 0.1% by weight. The pressure and temperature in these tanks range from 25 to 120 °C with pressure levels as low as 0.3 Torr at cycle completion. Secondary transformer drying takes place after internal assemblies are installed within steel transformer tanks. These tanks range in free volume to 3500 ft3. Drying may take place at ambient or elevated temperatures (depending on atmospheric exposure history) at pressures approaching 0.001 Torr.
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84.30.-r Electronic circuits

Compressive strength and outgassing characteristics of concrete for large vacuum‐system construction

H. S. Cullingford, M. D. Keller, and R. W. Higgins

J. Vac. Sci. Technol. 20, 1043 (1982); http://dx.doi.org/10.1116/1.571538 (5 pages)

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Concrete enclosures can be used for vacuum‐system construction. However, limited information exists on the behavior of concrete in vacuum. For this reason, concrete testing was performed recently at the Los Alamos National Laboratory to obtain data on outgassing and compressive strength of concrete in vacuum. The results of the experimental program will be presented to support the major conclusion that concrete is suitable for high‐vacuum systems without degradation of strength and should be considered for large vacuum‐system construction.
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07.30.Kf Vacuum chambers, auxiliary apparatus, and materials
28.52.-s Fusion reactors
81.70.-q Methods of materials testing and analysis

Deuterium trapping by impurities in copper

D. J. Mitchell

J. Vac. Sci. Technol. 20, 1048 (1982); http://dx.doi.org/10.1116/1.571539 (4 pages) | Cited 2 times

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The addition of Er, Zr, or Ti to copper provides trapping sites for hydrogen isotopes, which causes the apparent diffusivity of hydrogen to take on values that are smaller than its normal diffusivity in pure copper. This apparent diffusivity can be described in terms of the dopant concentration and the binding energy of the hydrogen isotope to the traps. Criteria are met that enable the results of permeation breakthrough measurements, which were made between 300° and 700 °C, to be extrapolated to room temperature. The resultant lag‐time for deuterium breakthrough for a 0.25‐mm‐thick membrane of Cu containing 0.88 at.% Er, for example, exceeds 1000 years at 25 °C. Therefore, this alloy is suitable for use in vacuum enclosures where it is necessary to restrict hydrogen permeation for long periods of time. Thermodesorption measurements for samples that were exposed to deuterium reveal that there are two types of traps in these alloys, and demonstrate that deuterium‐to‐dopant atomic ratios approaching two can be obtained.
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82.39.Wj Ion exchange, dialysis, osmosis, electro-osmosis, membrane processes
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
66.30.-h Diffusion in solids

Automobile flywheel energy storage: Practical vacuum requirements

N. Milleron and D. N. Frank

J. Vac. Sci. Technol. 20, 1052 (1982); http://dx.doi.org/10.1116/1.571540 (4 pages)

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For passenger automobiles with 1367 kg curb weight during typical driving conditions in city traffic, fuel efficiency improvements between 50 –100% (5–7 km/h) can be realized by proper utilization of a flywheel‐energy storage unit (0.2 kW h) and a heat engine. A brief introduction is given concerning the pros and cons of flywheels compared to other energy storage options. How to provide a cost effective, quality vacuum environment and system for rotating, composite flywheels is discussed. To be practical, a vacuum system for such an environment must be reliable, safe, and economical (in energy resources and dollars) to manufacture, monitor, maintain, and repair. Each embodiment of flywheel energy storage may be sufficiently unique to require a vacuum environment tailored to suit it. A general discussion of the important vacuum parameters and practical vacuum systems is followed by an example of a candidate design which includes a fiber array pump.
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07.30.Hd Vacuum testing methods; leak detectors
07.30.Cy Vacuum pumps
89.30.-g Fossil fuels and nuclear power

Novel oxygen source for ultrahigh vacuum studies

C. Y. Yang and W. E. O’Grady

J. Vac. Sci. Technol. 20, 1056 (1982); http://dx.doi.org/10.1116/1.571541 (4 pages)

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High‐temperature solid oxide electrolyte (e.g., yttria‐stabilized zirconia) cells are compatible with ultrahigh vacuum systems. Since the oxygen activity at the electrode/electrolyte interface is controlled precisely by the applied potential, the cells are ideal as oxygen sources for UHV studies. A three‐electrode oxide electrolyte cell has been constructed and incorporated into a UHV surface analysis chamber. The control of the cell is extremely sensitive, and it can be used either to maintain a constant oxygen pressure or to pulse oxygen similar to a molecular beam source in the UHV chamber.
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07.30.Kf Vacuum chambers, auxiliary apparatus, and materials

Surface analysis of severely corroded coal liquefaction vessel components and model laboratory films

R. B. Shalvoy, B. H. Davis, G. B. Freeman, and A. A. Sagüés

J. Vac. Sci. Technol. 20, 1060 (1982); http://dx.doi.org/10.1116/1.571542 (4 pages)

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When a high chloride content coal was run in the Wilsonville, Alabama Solvent Refined Coal (SRC) pilot plant, an unusually high rate of corrosion was observed in parts of a distillation tower. Appreciable corrosion was not observed during prior operation with lower chloride content coals. Corroded components were examined with ESCA with a goal of understanding the source and mechanism of the rapid corrosion. Process conditions were modeled in the IMMR laboratory with the goal of isolating the critical factors responsible for the severe corrosion. The addition of NH4Cl to low corrosivity SRC liquids resulted in severe corrosion of test samples. Films forming on the test samples and the surfaces of components taken from the corroded areas of the SRC vessel had similar spectra suggesting that the laboratory experiment had duplicated the conditions leading to severe corrosion in the SRC tower. The consequences of a low level of chlorine in the components and the film are discussed. Depth profiles revelaed a surface depletion of Fe and Cr in the samples. Possible corrosion mechanisms are considered.
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81.05.Bx Metals, semimetals, and alloys

Comparison of the theoretical detection capabilities of SIMS and AES for microanalysis

D. G. Welkie and R. L. Gerlach

J. Vac. Sci. Technol. 20, 1064 (1982); http://dx.doi.org/10.1116/1.571543 (4 pages)

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The theoretical detection capabilities of scanning‐probe SIMS and AES for surface chemical imaging and depth profiling are examined. The tradeoff between chemical spatial resolution and detection sensitivity arises from the relationship between the probe diameter d and current I. This relationship depends on characteristics of the source and the probe‐forming optics. The theoretical relationship between d and I was calculated for ion probes using either a liquid‐metal field ion emitter (LMI) source or a conventional gas‐phase source. These results are used to evaluate practical spatial resolution and detection sensitivity limits for obtaining images and depth profiles with a quadrupole‐based SIMS instrument using either type of source. It is demonstrated that an LMI source should result in up to several orders of magnitude better performance than that of a gas‐phase source. Results are also presented for a SAM instrument using a thermionic LaB6 cathode and a W (100) field emission cathode. The superiority of AES over SIMS is evident for high spatial resolution analysis of the outer several atomic layers, while SIMS wins out at lower spatial resolution and for thicker film analysis. These results further demonstrate the complementarity of these microanalytical techniques.
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82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)

Summary Abstract: High‐performance molecular secondary ion mass spectrometry (SIMS)

J. E. Campana, T. M. Barlak, J. R. Wyatt, J. J. DeCorpo, and R. J. Colton

J. Vac. Sci. Technol. 20, 1068 (1982); http://dx.doi.org/10.1116/1.571544 (2 pages) | Cited 1 time

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Abstract Unavailable
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79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
07.75.+h Mass spectrometers
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)

Summary Abstract: Apparatus for studying photochemical degradation of polymeric coatings on mirrors using FT‐IR reflection absorbance spectroscopy

J. D. Webb, P. Schissel, A. W. Czanderna, D. M. Smith, and A. R. Chughtai

J. Vac. Sci. Technol. 20, 1069 (1982); http://dx.doi.org/10.1116/1.571545 (2 pages)

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42.79.Wc Optical coatings
75.20.Ck Nonmetals
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
81.65.-b Surface treatments

Automated computer analysis of x‐ray radiographs greatly facilitates measurement of coating thickness variations in laser fusion targets

D. M. Stupin, K. R. Moore, G. D. Thomas, and R. L. Whitman

J. Vac. Sci. Technol. 20, 1071 (1982); http://dx.doi.org/10.1116/1.571546 (4 pages)

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We have built an automated system to analyze x‐ray radiographs of laser fusion targets which greatly facilitates the detection of coating thickness variations. Many laser fusion targets require opaque coatings 1 to 20 μm thick which have been deposited on small glass balloons 100 to 500 μm in diameter. These coatings must be uniformly thick to 1% for the targets to perform optimally. Our system is designed to detect variations as small as 100 Å in 1‐μm‐thick coatings by converting the optical density variations of contact x‐ray radiographs into coating thickness variations. Radiographic images are recorded in HRP emulsions and magnified by an optical microscope, imaged onto television camera, digitized and processed on a Data General S/230 computer with a code by Whitman. After an initial set‐up by the operator, as many as 200 targets will be automatically characterized.
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68.55.-a Thin film structure and morphology
67.25.bh Films and restricted geometries
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)

A phase modulation interferometer for ICF target characterization

David E. Cooper

J. Vac. Sci. Technol. 20, 1075 (1982); http://dx.doi.org/10.1116/1.571547 (4 pages)

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Characterization requirements for high gain laser fusion targets are severe. We are required to detect defects on the surfaces of opaque and transparent shells with an amplitude resolution of ±5 nm and a spatial resolution of 1–10 μm. To achieve this we have developed a laser‐illuminated phase‐modulation interferometer. This instrument is based on a photoelastic polarization modulation technique which allows one to convert phase information into an intensity modulation which can be easily and sensitively measured using ac signal processing techniques. This interferometer has detected path length changes as small as 1 nm and the required spatial resolution is assured by using a microscope objective to focus the probe laser beam down to a small (∠1 μm) spot on the surface of a microballoon. The interferometer will soon be coupled to an LSI–11 controlled 4π sphere manipulator which will allow us to automatically inspect the entire surface area of a target sphere.
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07.60.Ly Interferometers
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
81.70.-q Methods of materials testing and analysis

Capillary gas filling of inertial fusion targets

B. A. Brinker and J. R. Miller

J. Vac. Sci. Technol. 20, 1079 (1982); http://dx.doi.org/10.1116/1.571548 (3 pages)

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High‐Z gases are often added to the DT fuel in inertial fusion targets to provide a means for diagnosing target implosion conditions. Various techniques have been used to incorporate some nonfuel gases into fusion targets including permeation, drill‐fill‐plug, and vertical drop‐oven filling. We have developed a new fabrication technique which permits filling fusion targets with most high‐Z gases but which does not add geometric perturbations to the stalk‐mounted target. The first step of this new technique is to mount a glass microballoon on a thin drawn glass capillary in the usual manner. A few micrometer diameter hole is drilled through the shell at the capillary location with a focused 1.05 μm wavelength laser. Pusher and ablator layers are then coated onto the capillary mounted shell. The desired gas mixture is introduced into the target through the capillary which is then sealed closed. The gas fill capillary, equivalent in dimensions to the normal target mounting stalk, supports the target during the implosion experiment. In addition, the gas‐filled volume in the capillary acts as a reservoir, replenishing gas that permeates out of the target. We have also used this fabrication technique to produce a target which serves as a calibration standard for interferometric characterization.
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52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)

Target fabrication using laser and spark erosion machining

X. Clement, A. Coudeville, P. Eyharts, J. P. Perrine, and R. Rouillard

J. Vac. Sci. Technol. 20, 1082 (1982); http://dx.doi.org/10.1116/1.571571 (3 pages)

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Fabrication of laser fusion targets requires a number of special techniques. We have developed both laser and spark erosion machining to produce minute parts of complex targets. A high repetition rate YAG laser at double frequency is used to etch various materials. For example, marks or patterns are often necessary on structured or advanced targets. The laser is also used to thin down plastic coated stalks. A spark erosion system has proved to be a versatile tool and we describe current fabrication processes like cutting, drilling, and ultra precise machining. Spark erosion has interesting features for target fabrication: it is a highly controllable and reproducible technique as well as relatively inexpensive.
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81.65.-b Surface treatments
42.60.-v Laser optical systems: design and operation

The fabrication of laser‐seal‐welded targets for particle beam fusion experiments

S. Armstrong, F. F. Flick, and F. Perry

J. Vac. Sci. Technol. 20, 1085 (1982); http://dx.doi.org/10.1116/1.571572 (2 pages)

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Proposed Sandia particle beam fusion targets require seamless spheres filled with high pressure deuterium‐tritium gas. Conventional fill techniques utilizing small diameter fill tubes produce perturbations upon implosion. These perturbations may cause instabilities and jetting of target material into the fuel core, resulting in a low target yield. At Los Alamos, a fabrication technique was developed to eliminate the need for fill tubes. This technique uses a laser to seal‐weld a small fill hole in the target wall, while in a high pressure gas environment. This paper will discuss in detail the fabrication parameters for processing simulated laser‐seal‐welded targets. These steps include electroplating, micromachining and laser welding. The fabricated laser‐ seal‐welded cylindrical targets will be subjected to hydrodynamic experiments at Sandia to determine the effect of the laser seal weld upon implosion.
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06.60.Vz Workshop procedures (welding, machining, lubrication, bearings, etc.)
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
79.20.Ds Laser-beam impact phenomena

Fabrication of thin‐wall, freestanding inertial confinement fusion targets by chemical vapor deposition

D. W. Carroll and W. J. McCreary

J. Vac. Sci. Technol. 20, 1087 (1982); http://dx.doi.org/10.1116/1.571573 (4 pages) | Cited 3 times

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To meet the requirements for plasma physics experiments in the inertial confinement fusion (ICF) program, chemical vapor deposition (CVD) in fluid beds was used to fabricate freestanding tungsten spheres and cylinders with wall thicknesses less than 5.0 μm. Molybdenum and molybdenum alloy (TZM) mandrels of the desired geometry were suspended in a carrier bed of dense microspheres contained in an induction‐heated fluid‐bed reactor. The mandrels were free to float randomly through the bed, and using the reaction WF6+3H2→723 KW +6HF, very fine‐grained tungsten was deposited onto the surface at a rate and in a grain size determined by temperature, gas flow rate, system pressure, and duration of the reaction. After coating, a portion of each mandrel was exposed by hole drilling or grinding. The mandrel was then removed by acid leaching, leaving a freestanding tungsten shape. Experimental procedures, mandrel preparation, and results obtained are discussed.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)

Metal shell technology based upon hollow jet instability

J. M. Kendall, M. C. Lee, and T. G. Wang

J. Vac. Sci. Technol. 20, 1091 (1982); http://dx.doi.org/10.1116/1.571574 (3 pages) | Cited 5 times

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Spherical shells of submillimeter size are sought as ICF targets. Such shells must be dimensionally precise, smooth, of high strength, and composed of a high atomic number material. We describe a technology for the production of shells based upon the hydrodynamic instability of an annular jet of molten metal. We have produced shells in the 0.7–2.0 mm size range using tin as a test material. Specimens exhibit good sphericity, fair concentricity, and excellent finish over most of the surface. Work involving a gold–lead–antimony alloy is in progress. Droplets of this are amorphous and possess superior surface finish. The flow of tin models that of the alloy well; experiments on both metals show that the technique holds considerable promise.
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52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
47.27.wg Turbulent jets

Preparation of multishell ICF target plastic foam cushion materials by thermally induced phase inversion processes

A. T. Young, D. K. Moreno, and R. G. Marsters

J. Vac. Sci. Technol. 20, 1094 (1982); http://dx.doi.org/10.1116/1.571575 (4 pages) | Cited 4 times

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Homogeneous, low‐density plastic foams for ICF targets have been prepared by thermally induced phase inversion processes. Uniform, open cell foams have been obtained by the rapid freezing of water solutions of modified cellulose polymers with densities in the range of 50–7 mg/cm3 and respective average cell sizes of 2 to 40 μm. In addition, low‐density, microcellular foams have been prepared from the hydrocarbon polymer poly(4‐methyl‐l‐pentene) via a similar phase inversion process using homogeneous solutions in organic solvents. These foams have densities from 20 to 50 mg/cm3 and average cell sizes of 20 μm.
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82.70.Rr Aerosols and foams
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials

A new method for the batch production of micro‐Fresnel zone plates

D. Glocker and R. Wiseman

J. Vac. Sci. Technol. 20, 1098 (1982); http://dx.doi.org/10.1116/1.571576 (3 pages)

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A new method has been developed for making micro‐Fresnel zone plates used in the coded imaging of x rays and α particles produced from laser fusion target implosions. The method allows the fabrication of numerous plating molds from a single master mold, which is particularly useful in α‐particle imaging since each target shot requires a new zone plate. A master mold was made in polyimide using reactive ion etching, and a number of silicone rubber replicas were made of the mold. Each replica was then used to produce a number of photoresist final molds into which gold was electroplated. This microfabrication technique has produced high quality 10‐μm‐thick zone plates having 100 zones and a 5‐μm‐wide outer zone.
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42.79.Ci Filters, zone plates, and polarizers
52.70.Nc Particle measurements
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces

The statistical theory of turbomolecular pumps

J. G. Chu and Z. Y. Hua

J. Vac. Sci. Technol. 20, 1101 (1982); http://dx.doi.org/10.1116/1.571577 (4 pages) | Cited 4 times

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The working principle of a modern turbomolecular pump is analyzed from the point of view of statistical mechanics. The pumping action is mainly due to the collision probabilities of the gas molecules with the upper and lower blade surfaces caused by the high‐speed relative motion between the rotating blades and the gas molecules. In turbomolecular pumps the molecular drag action only serves as an approximate mathematical description when the rotating speed of the blades is not very high, and both the pumping speed and the compression ratio will saturate as the blade speed approaches the average thermal velocity of the gas molecules, i.e., they cannot increase limitlessly with increasing blade speed as suggested by the molecular drag principle. Finally, the compression ratio of a multistage pump with blades of finite lengths under different rotating speeds are calculated and compared with the experimental results.
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07.30.Cy Vacuum pumps
05.20.-y Classical statistical mechanics

Influence of magnetic fields on a large‐sized turbomolecular pump

A. Nishidé, S. Kanéto, T. Ikégami, and Y. Sakamoto

J. Vac. Sci. Technol. 20, 1105 (1982); http://dx.doi.org/10.1116/1.571578 (4 pages)

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Application of turbomolecular pumps in the field of nuclear fusion research and accelerators requires knowledge concerning the temperature rise and the decrease of rotation frequency due to leakage magnetic field. We measured them for pumps OV–TH 5000 (pumping speed: 5000 l/s) and OV–TH500 (500 l/s), set in a leakage magnetic field of mirror field coils used for plasma research. The allowable magnetic field is about 100 G for both types, if we take 120 °C to be tolerable rotor temperature. An effective magnetic shield can be realized by the use of simple permalloy cylinders.
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07.30.Cy Vacuum pumps

Theoretical determination of electron density distribution in an orbitron device correlated with results concerning its ionization efficiency

B. Petit and M. L. Feidt

J. Vac. Sci. Technol. 20, 1109 (1982); http://dx.doi.org/10.1116/1.571579 (5 pages)

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Boltzmann’s equation has been integrated for electrons describing trajectories in a radial electrostatic field (electron–electron and electron–residual‐gas interactions are neglected). One‐particle distribution functions are deduced for electrons describing, respectively, stable and unstable trajectories. Evolution of ionization efficiency of the device with various parameters is calculated using the preceding distributions. Experiments allow us to determine the integration constants and to validate theoretical predictions.
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52.20.Dq Particle orbits
52.20.Fs Electron collisions
52.25.Kn Thermodynamics of plasmas
05.20.Dd Kinetic theory

Temperature‐controlled vacuum cell and two‐stage pumping system for laser‐induced fluorescence and absorption studies of UF6

R. N. Shelton, W. W. Rice, F. B. Wampler, and J. J. Tiee

J. Vac. Sci. Technol. 20, 1114 (1982); http://dx.doi.org/10.1116/1.571580 (4 pages)

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One of the commonly used compounds in uranium processing is gaseous UF6. Laser methods for monitoring UF6 density and pressure have been under investigation at Los Alamos. In order to calibrate these laser probe techniques, an evacuable, temperature‐controlled cell was needed for laser‐induced fluorescence (LIF) and ultraviolet absorption studies of UF6. It was necessary to construct the optical cell from materials compatible with UF6 and to thermally control the cell. The pumping system had to evacuate the cell and the complete gas‐handling system to 5×10−5 Torr and also be corrosion resistant. A cell and system were constructed that met and exceeded our requirements. Constant, repeatable LIF results have been obtained at temperatures of −30 to 80 °C and over the pressure range of 0.005 to 80 Torr with this cell. This repeatability is due to the temperature stability of the system (i.e., ±0.1 °C from −30 to 0 °C and ±0.05 °C from 0 to 100 °C). The well‐controlled temperature of the UF6 has also allowed us to successfully determine ultraviolet absorption cross sections as functions of temperature over the 0 to 100 °C range. By judicious choice of materials and working fluid, the temperature range of this cell may be extended beyond the −30 to 100 °C range of our present work. E;82 33.50.Dq
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33.50.Dq Fluorescence and phosphorescence spectra

Summary Abstract: A technique for calculating DT content in glass microballoons from x‐ray counts

B. S. Jorgensen

J. Vac. Sci. Technol. 20, 1118 (1982); http://dx.doi.org/10.1116/1.571581 (2 pages)

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Abstract Unavailable
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82.80.Dx Analytical methods involving electronic spectroscopy
82.80.Ej X-ray, Mössbauer, and other γ-ray spectroscopic analysis methods

Summary Abstract: Air desorption from a water film

D. Edwards

J. Vac. Sci. Technol. 20, 1120 (1982); http://dx.doi.org/10.1116/1.571582 (2 pages)

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Abstract Unavailable
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68.43.-h Chemisorption/physisorption: adsorbates on surfaces

Summary Abstract: Fabrication of inertial fusion target components through utilization of organometallic polymers

L. B. Kool, R. L. Nolen, and P. J. Evans

J. Vac. Sci. Technol. 20, 1121 (1982); http://dx.doi.org/10.1116/1.571583 (2 pages)

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Abstract Unavailable
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81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials

Summary Abstract: Coating of glass microballoons using an acoustic technique

M. C. Lee, I. Feng, D. D. Elleman, T. G. Wang, and A. T. Young

J. Vac. Sci. Technol. 20, 1123 (1982); http://dx.doi.org/10.1116/1.571584 (2 pages)

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Abstract Unavailable
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81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)
43.35.Ty Other physical effects of sound

Summary Abstract: Positioning and freezing of DT‐filled ICF target using combination of cold molecular beam and quadrupole electric fields

J. Fanning and K. Kim

J. Vac. Sci. Technol. 20, 1124 (1982); http://dx.doi.org/10.1116/1.571585 (2 pages) | Cited 1 time

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Abstract Unavailable
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52.55.Pi Fusion products effects (e.g., alpha-particles, etc.), fast particle effects
79.20.Kz Other electron-impact emission phenomena
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces

A tritium‐compatible high‐vacuum pumping system

Don O. Coffin

J. Vac. Sci. Technol. 20, 1126 (1982); http://dx.doi.org/10.1116/1.571586 (6 pages) | Cited 1 time

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Large magnetic‐fusion power reactors will require vacuum pumps with greater speeds and capacities for hydrogen and helium isotopes than any now available. Present fusion engineering efforts concentrate on DT‐burning tokamaks, so pumps for these systems must perform reliably during prolonged exposure to radioactive tritium gas. A mechanical pumping train that exposes only tritium‐compatible metals to the vacuum medium has been assembled. The system comprises a reciprocating metal‐bellows compressor, a bellows‐sealed, spiral‐cavity, positive‐displacement blower, and a canned‐motor, magnetic‐bearing turbopump. These pumps feature hermetic drives, and their pumping chambers contain no liquid metals, plastics, elastomers, or lubricants. The pumping system achieves vacuums as low as 1 mPa without cryogenics, and its pumping speed increases from 5 L/s at atmospheric pressure to 500 L/s below 100 mPa. Systems with ultimate pumping speeds of 5000 L/s can be assembled using larger pumps of the same design as those tested.
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07.30.Cy Vacuum pumps
28.52.-s Fusion reactors

Organic getter for tritium

P. C. Souers, E. R. Bissell, G. D. Honoré, L. C. Kang, R. T. Tsugawa, and H. H. Miller

J. Vac. Sci. Technol. 20, 1132 (1982); http://dx.doi.org/10.1116/1.571587 (3 pages)

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Liquid and solid acetylenes on supported platinum catalysts have been studied in an effort to getter 1 ppm T2 from 1 at. air and nitrogen gas at room temperature. The results have not been successful, as only 0% to 15% of the tritium ends up in the organic phase, and there is no guarantee that hydrogenation takes place. Tritiated water is formed as the major product either by direct reaction with oxygen or exchange with background water.
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82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
28.41.Te Protection systems, safety, radiation monitoring, accidents, and dismantling

Measurement of H2, D2 solubilities in Zr–Al

R. J. Knize, J. L. Cecchi, and H. F. Dylla

J. Vac. Sci. Technol. 20, 1135 (1982); http://dx.doi.org/10.1116/1.571588 (3 pages) | Cited 3 times

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We have measured solubility constants for hydrogen and deuterium in the Zr–Al alloy to be: KH = exp [11.1(5)−16900(600)/T] [Torr/(Torr⋅1/g)2] and KD = exp [12.2(8)−16800(600)/T] [Torr/(Torr⋅1/g)2], respectively, where K is defined implicitly by P = Kq2 with P the equilibrium pressure (in Torr) and q the bulk concentration (in Torr⋅l/g). These values, in conjunction with a model for the solubility, predict that the constant for tritium, KT ∠4KH. Consequently, the regeneration of tritium will be faster by a factor of 4 over that for hydrogen at the same temperature, or the tritium regeneration temperature can be reduced∠50 K compared to hydrogen for the same regeneration time.
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64.75.-g Phase equilibria

Summary Abstract: Polyimide and polyamide–imide in a tritium atmosphere

K. F. Wylie, J. E. Hockett, and T. L. Buxton

J. Vac. Sci. Technol. 20, 1138 (1982); http://dx.doi.org/10.1116/1.571589 (2 pages)

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Abstract Unavailable
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81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
62.20.M- Structural failure of materials
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

Performance characteristics of a broad range ionization gage tube

C. R. Tilford, K. E. McCulloh, and Han Seung Woong

J. Vac. Sci. Technol. 20, 1140 (1982); http://dx.doi.org/10.1116/1.571590 (4 pages)

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Seven commercial ’’broad‐range’’ Bayard–Alpert ionization gage tubes were calibrated for N2, Ar, H2, D2, and He. Between 10−4 and 10−1 Pa N2 sensitivities varied between 3.2 and 4×10−2 Pa−1 (4.3 and 5.4 Torr−1), as low as 52% of the specified sensitivity of 8 Torr−1. Relative sensitivities of 0.16±0.016 were obtained for He, and 0.37±0.04 for H2 and D2. Sensitivities were determined at reduced emission for N2 up to 1.4 Pa and 3 Pa for Ar. Argon sensitivities increased by up to 50% over this range. Voltage dependences were determined for changes in both the filament and grid bias voltages. These data showed an inexplicable grouping of the gage tubes into two distinct groups, one with small voltage coefficient typical of Bayard–Alpert gages, the other with much larger coefficients, such as expected from conventional triode gages.
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07.50.-e Electrical and electronic instruments and components
07.30.Kf Vacuum chambers, auxiliary apparatus, and materials

A group of terminal‐flow UHV gauges

Z. Y. Hua, X. L. Yang, S. Y. Qiu, J. Z. Chen, J. Y. Tang, and Q. D. Sun

J. Vac. Sci. Technol. 20, 1144 (1982); http://dx.doi.org/10.1116/1.571591 (4 pages)

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An ionization gauge structure, designated as the ’’terminal‐flow’’ type, with the filament and collector plate located on opposite ends of a helical grid, has been designed for a group of nonmagnetic UHV gauges with good sensitivity. Four typical designs, a high sensitivity gauge, a shunt gauge, a suppressor gauge, and a shielding gauge, the characteristics of which have been studied experimentally, are described. The electrodes in each gauge are quite simple; therefore the gauges are easy to degas and can be used on general purpose UHV systems.
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07.30.Dz Vacuum gauges

Spinning rotor viscosity gauge: A transfer standard for the laboratory or an accurate gauge for vacuum process control

G. Reich

J. Vac. Sci. Technol. 20, 1148 (1982); http://dx.doi.org/10.1116/1.571592 (5 pages) | Cited 4 times

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A new gauge has been developed that appears to be the ideal tool for measuring low pressures in both research and industrial vacuum processes where reliability and accuracy of measurement are of importance. In particular, it will be emphasized that the spinning rotor viscosity gauge (licensed by Kernforschungsanlage Jülich GmbH, Germany) is in fact a fundamental vacuum gauge because its ’’sensitivity’’ depends only on the mass and diameter of the ball. These quantities do not change and can be determined accurately by well‐known fundamental methods. The new gauge excels the common vacuum gauges by the following features: long‐term stability, instantly operational; high accuracy and repeatability; no hysteresis; no temperature stabilizing required. The new gauge is rugged and will perform well under both working and transfer conditions. The spinning rotor viscosity guage has inherent long‐term reproducibility that will serve well should it be used as a transfer standard. The simplicity and accuracy of operation should offer applications in the area of process control.
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07.30.Dz Vacuum gauges

A new wide‐range B–A gauge from UHV to 10−1 Torr

N. Ohsako

J. Vac. Sci. Technol. 20, 1153 (1982); http://dx.doi.org/10.1116/1.571506 (3 pages) | Cited 1 time

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In a conventional B–A gauge, the ion collector current shows a strong nonlinearity with increasing pressure above about 10−3 Torr. This is considered to be due to the ion current to the filament becoming comparable to the electron emission from the filament. In this new gauge, an auxiliary electrode whose potential is kept lower than that of filament, is placed near the filament to eliminate such an undesirable ion current. By this modification, the linear region is extended up to 10−1 Torr N2 without sacrificing the sensitivity. Through the optimization study of electrode design parameters such as structure and potential, a gauge with a semicylindrical electrode kept at ground potential gives the best result. This new B–A gauge can cover the pressure range from 10−10 to 2×10−1 Torr with linear ion current–pressure characteristics.
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07.30.Dz Vacuum gauges

Vacuum instrumentation on the Daresbury synchrotron radiation source

R. J. Reid

J. Vac. Sci. Technol. 20, 1156 (1982); http://dx.doi.org/10.1116/1.571507 (3 pages)

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The vacuum instrumentation for the ultrahigh vacuum system of the electron storage ring of the SRS is part of a complex, interlinked system under the control and supervision of a hierarchy of computers. The vacuum system has been in operation for over one year and has attained average base pressures of better than 5×10−8 Pa. The main pressure measurement devices are Bayard–Alpert ionization gauges and the operational precautions required in using such devices will be discussed. Quadrupole residual gas analyzers are used for partial pressure measurements and their use, particularly in the areas of leak detection and in the monitoring of the progress of bakeout of the ring, will be described. Projected data analysis facilities for residual gas analysis will also be discussed.
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07.30.Kf Vacuum chambers, auxiliary apparatus, and materials
07.30.Bx Degasification, residual gas

Calibration of secondary standard ionization gauges

M. Hirata, M. Ono, H. Hojo, and K. Nakayama

J. Vac. Sci. Technol. 20, 1159 (1982); http://dx.doi.org/10.1116/1.571508 (3 pages) | Cited 2 times

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A McLeod gauge, designed, built and maintained by us, serves as the primary vacuum standard of Japan. We measure the sensitivities for nitrogen of the secondary standard ionization gauges (VS–1) with an accuracy of ±3% with the McLeod gauge in the pressure range from 0.01 to 0.3 Pa. The VS–1 gauge is a triode type that shows constant sensitivity from 1×10−4 to 0.3 Pa. 258 VS–1 gauges were calibrated since 1964. The average value of the sensitivities is 0.137 Pa−1. About 85% of the gauges have sensitivities with less than ±10% deviation from the average. The main reason for the spread of sensitivities was the electrode displacement. We discuss the technical problems connected with the use of the VS–1 gauge as a transfer gauge for international comparison of vacuum standards.
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07.30.Hd Vacuum testing methods; leak detectors

He leak detection in the presence of deuterium background in tokamak vacuum systems

W. R. Blanchard, R. B. Krawchuk, and H. F. Dylla

J. Vac. Sci. Technol. 20, 1162 (1982); http://dx.doi.org/10.1116/1.571509 (4 pages) | Cited 2 times

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Helium leak detection systems for magnetic fusion devices present several unique design problems because of the large dynamic range required and the high partial pressures of D2 encountered. We describe the design and operation of a He leak detector system for the PDX tokamak. The system consists of a differentially‐pumped, low resolution, He mass spectrometer which is interfaced to the foreline of one of the torus turbomolecular pump lines. The He detector has a minimum throughput sensitivity of 10−10 Torr⋅l/s, and the torus‐integrated system has been designed for detection of torus leaks over the range of 10−7 to 10 Torr⋅l/s. Minimum leak‐rates on the 38 m3 PDX vessel which have been quantified using this system are ∠3×10−8 Torr⋅l/s. When PDX is operated with D2 plasmas it is necessary to reduce the partial pressure of D2 by a factor of 100 within the mass spectrometer to maintain this sensitivity in the presence of the torus D2 outgassing. We have designed and incorporated a D2 filter which employs a Zr–Al getter assembly to affect the required D2 pressure reduction.
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07.30.Kf Vacuum chambers, auxiliary apparatus, and materials
52.55.Fa Tokamaks, spherical tokamaks
52.55.Hc Stellarators, torsatrons, heliacs, bumpy tori, and other toroidal confinement devices

Summary Abstract: Pressure measurements in magnetic fusion devices

H. F. Dylla

J. Vac. Sci. Technol. 20, 1166 (1982); http://dx.doi.org/10.1116/1.571510 (2 pages)

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Abstract Unavailable
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52.55.Pi Fusion products effects (e.g., alpha-particles, etc.), fast particle effects
52.70.Nc Particle measurements
52.25.Kn Thermodynamics of plasmas

Unique design of Doublet and Big Dee vacuum vessels

J. E. Miller

J. Vac. Sci. Technol. 20, 1168 (1982); http://dx.doi.org/10.1116/1.571511 (5 pages)

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The Doublet III tokamak now in its fourth year of operation at General Atomic Company, has its plasma contained in a kidney‐shaped toroidal vacuum vessel, a configuration that presented unique design challenges. Most tokamak vacuum vessels are constructed of solid walled sections separated by either thin walled bellows (to increase the toroidal resistance) or by poloidal insulation breaks. Such control of the toroidal resistance is crucial in minimizing magnetic error fields in the plasma region caused by currents induced in the vessel by the changing fields. The Doublet III vessel is unique in its all‐welded construction consisting of thin skins over a corrugated center. Such a construction results in a low cross sectional area of material to increase the toroidal resistance, while maintaining adequate strength. The design process for such a vessel is reviewed with a description of its design. In order to more closely address the design issues of next generation devices, plans are being formulated to modify Doublet III to a large Dee‐shaped plasma facility. This would be accomplished by disassembling the device and replacing the Doublet vessel with a large Dee vessel. The design approach for the new vessel will be similar to that of the present vessel, but because of different operating requirements and experience gained in the operation of Doublet III and other large tokamaks, the specific design criteria are different. These differences and their implications are reviewed.
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07.30.Kf Vacuum chambers, auxiliary apparatus, and materials
52.55.Fa Tokamaks, spherical tokamaks
52.55.Hc Stellarators, torsatrons, heliacs, bumpy tori, and other toroidal confinement devices
28.52.-s Fusion reactors

Design and fabrication of the vacuum vessel for the tokamak fusion test reactor

W. G. Reddan

J. Vac. Sci. Technol. 20, 1173 (1982); http://dx.doi.org/10.1116/1.571512 (4 pages) | Cited 1 time

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The design parameters, special features, and certain fabrication and test aspects of the TFTR vacuum vessel are described. The vessel is a single walled, stainless steel toroidal shell, designed for a base pressure of 10−8 Torr. The design basis includes the electromagnetic loads resulting from the disruption of a 3 MA plasma in a 5.2 T magnetic field. The vessel is configured to permit maximum access for neutral beam injection and diagnostic equipment. In addition, it is designed so that a segment of the machine can be removed and replaced using remote maintenance techniques. During the fabrication special processes were used to ensure cleanliness, achieve dimensional control, and perform in‐process vacuum tests.
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07.30.Hd Vacuum testing methods; leak detectors
28.52.-s Fusion reactors
52.55.Fa Tokamaks, spherical tokamaks
52.55.Hc Stellarators, torsatrons, heliacs, bumpy tori, and other toroidal confinement devices

The LLNL tandem mirror experiment (TMX) upgrade vacuum system

W. L. Pickles, A. K. Chargin, R. P. Drake, A. L. Hunt, D. D. Lang, J. J. Murphy, P. Poulsen, T. C. Simonen, T. H. Batzer, T. P. Stack, and R. L. Wong

J. Vac. Sci. Technol. 20, 1177 (1982); http://dx.doi.org/10.1116/1.571513 (5 pages) | Cited 1 time

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The tandem mirror experiment (TMX) upgrade is a large, tandem, magnetic‐mirror fusion experiment with stringent requirements on base pressure (10−8 Torr), low H reflux from the first walls, and peak gas pressure (5×10−7 Torr) due to neutral beam gas during plasma operation. The 225 m3 vacuum vessel is initially evacuated by turbopumps. Cryopumps provide a continuous sink for gases other than helium, deuterium, and hydrogen. The neutral beam system introduces up to 480 l/s of H or D. The hydrogen isotopes are pumped at very high speed by titanium sublimed onto two cylindrical radially separated stainless steel quilted liners with a total surface area of 540 m2. These surfaces (when cooled to about 80 K) provide a pumping speed of 6×107 l/s for hydrogen. The titanium getter system is programmable and is used for heating as well as gettering. The inner plasma liner can be operated at elevated temperatures to enhance migration of gases away from the surfaces close to the plasma. Glow discharge cleaning is part of the pumpdown procedure. The design features are discussed in conjunction with the operating procedures developed to manage the dynamic vacuum conditions.
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52.55.Jd Magnetic mirrors, gas dynamic traps
07.30.Bx Degasification, residual gas
07.30.Cy Vacuum pumps
07.30.Kf Vacuum chambers, auxiliary apparatus, and materials

The leak testing program of the doublet III project

G. L. Jackson

J. Vac. Sci. Technol. 20, 1182 (1982); http://dx.doi.org/10.1116/1.571514 (6 pages)

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Vacuum integrity of large fusion tokamaks has become increasingly important as the complexity and requirements for cleanliness have increased. Doublet III is a large noncircular tokamak (R = 1.43 m, V = 27 m3) designed for a base pressure of 2×10−8 T and a leak rate of 5×10−6 T⋅l/s. Initial leak testing of the vacuum chamber used conventional techniques. After final assembly, leak testing became more difficult as diagnostic systems, coil systems, and heating blankets enveloped the vacuum vessel. Methods were developed to locate and quantify vacuum leaks in this difficult environment. A residual gas analyzer was used for temporal response to gases flowed at various points outside the vessel. Leaks occurring in the primary vessel wall were measured by pumping on gas cooling channels adjacent to the primary vacuum wall. Air in these channels was also displaced by other gases at a constant rate to give location of leaks to within 50 cm. Vacuum leaks occurred during machine operations due to applied stresses, plasma‐material interactions, and diagnostic equipment failures. Machine vents to fix these leaks involve a significant loss of time, particularly in returning to clean wall conditions. Methods other than venting the vessel have been used, such as helium ’’patches,’’ if these leaks are sufficiently small.
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07.30.Hd Vacuum testing methods; leak detectors
07.30.Bx Degasification, residual gas

Summary Abstract: Vacuum system problems of EBT—a steady‐state fusion experiment

R. L. Livesey

J. Vac. Sci. Technol. 20, 1188 (1982); http://dx.doi.org/10.1116/1.571515 (2 pages)

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Abstract Unavailable
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07.30.Kf Vacuum chambers, auxiliary apparatus, and materials
52.55.Fa Tokamaks, spherical tokamaks
52.55.Hc Stellarators, torsatrons, heliacs, bumpy tori, and other toroidal confinement devices

Neutral‐beam systems for magnetic fusion reactors

Joel H. Fink

J. Vac. Sci. Technol. 20, 1191 (1982); http://dx.doi.org/10.1116/1.571516 (6 pages) | Cited 2 times

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Neutral beams for magnetic fusion reactors are at an early stage of development, and require considerable effort to make them into the large, reliable, and efficient systems needed for future power plants. To optimize their performance and establish specific goals for component development, systematic analysis of the beamlines is essential. Three ion source characteristics are discussed: arc‐cathode life, gas efficiency, and beam divergence, and their significance in a high‐energy neutral‐beam system is evaluated.
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07.77.-n Atomic, molecular, and charged-particle sources and detectors
52.55.Fa Tokamaks, spherical tokamaks
52.55.Hc Stellarators, torsatrons, heliacs, bumpy tori, and other toroidal confinement devices
52.55.Jd Magnetic mirrors, gas dynamic traps
28.52.-s Fusion reactors

PDX neutral beam reionization losses

H. W. Kugel, H. F. Dylla, H. P. Eubank, T. A. Kozub, R. Moore, G. Schilling, L. D. Stuart, A. Von Halle, and M. D. Williams

J. Vac. Sci. Technol. 20, 1197 (1982); http://dx.doi.org/10.1116/1.571517 (4 pages)

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Reionization losses for 1.5 MW H ° and 2 MW D ° neutral beams injected into the PDX tokamak were studied using pressure gauges, phototransistors, thermocouples, surface shielding, and surface sample analysis. Considerable outgassing of conventionally prepared 304 SS ducts occurred during initial injections and gradually decreased with the cumulative absorption of beam power. Reionization power losses are presently about 5% in the ducts and about 12% total for a beamline including the duct. Present duct pressures are attributed primarily to gas from the ion source and neutralizer with much smaller contributions from residual wall desorption. Physical mechanisms for the observed duct outgassing are discussed.
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52.55.Fa Tokamaks, spherical tokamaks
52.55.Hc Stellarators, torsatrons, heliacs, bumpy tori, and other toroidal confinement devices
52.40.Hf Plasma-material interactions; boundary layer effects
52.50.Gj Plasma heating by particle beams
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics

Feasibility of multi‐Mev neutral beams of light atoms for heating and current drive in magnetically confined plasmas

L. R. Grisham, D. E. Post, and D. R. Mikkelsen

J. Vac. Sci. Technol. 20, 1201 (1982); http://dx.doi.org/10.1116/1.571518 (4 pages)

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We explore the advantages and problems of using neutral beams formed from negative ions A<30 that have been accelerated to 1–2 MeV/amu. Due to the very high energies, the required ion currents are small. We discuss possible production methods to yield adequate (0.1−1.0 A/source) currents of Li−, C−, O−, or Si−, which would be accelerated by electric‐quadrupole‐focused rf accelerators such as the LASL RFQ or the BNL MEQALAC. We investigate system design questions, including vacuum pumping, pressure restrictions in the accelerator, different possible neutralization methods, and efficiency. Compared to D° injection at 150–200 keV, this technique allows greatly reduced vacuum pumping requirements, much higher beam density (which should permit small cross section beam ducts through the blanket), and better plasma penetration, but at the expense of lower accelerator power efficiency because the required combination of current, voltage, and location near the confinement device render electrostatic acceleration impractical.
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52.50.Gj Plasma heating by particle beams
52.40.Mj Particle beam interactions in plasmas
07.77.-n Atomic, molecular, and charged-particle sources and detectors
29.25.Lg Ion sources: polarized
29.25.Ni Ion sources: positive and negative

Summary Abstract: Technique to determine impurities in neutral beams

D. J. Markevich and J. A. Tanis

J. Vac. Sci. Technol. 20, 1205 (1982); http://dx.doi.org/10.1116/1.571519 (2 pages) | Cited 1 time

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Abstract Unavailable
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07.77.-n Atomic, molecular, and charged-particle sources and detectors

Summary Abstract: Deuterium beam species measured by fusion reactions in the neutralizer

R. R. Smith and M. D. Strathman

J. Vac. Sci. Technol. 20, 1206 (1982); http://dx.doi.org/10.1116/1.571520 (2 pages)

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Abstract Unavailable
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25.45.-z 2H-induced reactions
25.55.-e 3H-, 3He-, and 4He-induced reactions

Summary Abstract: Steady‐state gas efficiency of ion sources for neutral beams

M. C. Vella, K. H. Berkner, D. J. Massoletti, H. M. Owren, and J. E. Willis

J. Vac. Sci. Technol. 20, 1208 (1982); http://dx.doi.org/10.1116/1.571521 (2 pages) | Cited 1 time

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29.25.Lg Ion sources: polarized
29.25.Ni Ion sources: positive and negative
52.50.Dg Plasma sources
07.77.-n Atomic, molecular, and charged-particle sources and detectors

Summary Abstract: Excitation cross sections of hydrogen relevant to neutral beam diagnostics

Y. K. Bae, C. F. Burrell, and R. H. McFarland

J. Vac. Sci. Technol. 20, 1209 (1982); http://dx.doi.org/10.1116/1.571522 (2 pages)

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Abstract Unavailable
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34.50.Fa Electronic excitation and ionization of atoms (including beam-foil excitation and ionization)

Neutral particle diagnostics for ohmically and auxiliary heated tokamaks

F. Wagner

J. Vac. Sci. Technol. 20, 1211 (1982); http://dx.doi.org/10.1116/1.571523 (7 pages) | Cited 8 times

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Protons and hydrogen atoms in a plasma undergo charge‐exchange collisions which give rise to an energetic charge‐exchange flux emerging from the plasma. The intensity and energy distribution of the charge‐exchange flux is measured separately for hydrogen or deuterium. Besides discussing the basic principles and the experimental techniques, this report concentrates on plasma characteristics accessible to neutral particle diagnostics. From the energy distribution of the charge exchange flux, the ion energy distribution can be inferred. In the case of a thermal plasma the measurement of the ion temperature profile allows the analysis of the ion energy transport, and with auxiliary heating the ion heating efficiency can be estimated. From the absolute intensity of the charge‐exchange flux the hydrogen atom density can be determined; strong toroidal variation, with sharp increases at limiter and gas input valve, is observed. The atom flux which leaves the plasma hits the wall and forms one branch of plasma wall interaction which can be investigated by measuring the backscattering of neutrals from the wall and by analyzing the wall sputtering due to charge‐exchange atoms. Neutral particle diagnostics carried out in the divertor chamber of a divertor tokamak reveal strong plasma wall interaction at the neutralizer plate.
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52.70.Nc Particle measurements
28.52.-s Fusion reactors

The fast ion diagnostic’s neutral beam injector on the poloidal divertor experiment

A. Nudelman, R. Goldston, and R. Kaita

J. Vac. Sci. Technol. 20, 1218 (1982); http://dx.doi.org/10.1116/1.571524 (4 pages) | Cited 2 times

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Neutral beams, in conjunction with charge‐exchange analyzers, have proved to be valuable diagnostic tools for studying high temperature tokamak plasmas. The PDX Fast Ion Diagnostic Experiment (FIDE) consists of a Diagnostic Neutral Beam (DNB) and spatially imaging charge‐exchange analyzer. The DNB is built around a Lawrence–Berkeley Laboratory 40‐kV, 10‐A, 4‐grid ion source. The power requirements are 0.5 MW in up to 10‐ms‐long pulse bursts. The accelerating grid is supplied from a 125‐kJ, 50‐kV capacitor bank with a hard‐tube modulator for switching and pulse burst generation at up to 3 kHz. The filament and arc power is drawn directly from a 480‐V ac line through multiphase controlled rectifiers, which provide a soft start for the filament and fast switching for the arc. Special attention was paid to the H–V transmission line, since the power supplies could not be located close to the ion source. The DNB has been tested under actual operating conditions and is now being used in experiments with the charge‐exchange analyzer.
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52.70.Nc Particle measurements
52.55.Fa Tokamaks, spherical tokamaks
52.55.Hc Stellarators, torsatrons, heliacs, bumpy tori, and other toroidal confinement devices

Neutral density measurements in doublet III

J. S. deGrassie, J. C. DeBoo, M. A. Mahdavi, N. Ohyabu, and M. Shimada

J. Vac. Sci. Technol. 20, 1222 (1982); http://dx.doi.org/10.1116/1.571525 (4 pages)

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