An experimental technique is described for obtaining reproducible sorption measurements in high-density discharges. Data are given for the sorption of argon, neon, and helium at the quartz walls of an electrodeless discharge for a surface temperature range of −35 ° to 750 °C. The complex dependence of sorption on temperature and discharge power is described in terms of sticking times, depth of ion penetration, diffusion coefficients, and flux rates. A theory is presented which gives good agreement with experiment. Maximum diffusion of gas into the walls occurs when the product of sticking time and ion flux is equal to the number of available trapping sites at the surface. The average depth of ion penetration in quartz was calculated from the theory and data to be in the range of 3 to 7×10−8 cm for helium, neon, and argon ions with bombarding energies of 12 to 17 eV.