Modeling of collisional effects in RF plasma sources

Abstract

Summary form only given, as follows. Collisions are an important factor for power absorption in most radio-frequency (RF) plasma sources. Our chief interest in this work is the effect of collisional damping in helicon-type plasma sources. We consider sources with the frequency of operation on the order of 10 MHz and neutral background pressures ranging from a few mTorr to atmospheric. The characteristic collision frequency varies greatly over this pressure range. We consider three different regimes: /spl nu//spl Lt//spl omega/, /spl nu//spl ap//spl omega/ and /spl nu//spl Gt//spl omega/, where /spl nu/ is the characteristic collision frequency and /spl omega/ is the frequency of the RF source. We present results which show the differences of the radial power deposition for these three regimes using the ANTENA2 code, which employs a Krook-type model to calculate collisional damping. We discuss limitations of and possible improvements to this collision model. We also discuss the use of these results for improving the design of sources which will operate at neutral pressures.