Three dimensional microwave heating power distribution in an electron cyclotron resonance processing plasma

Abstract

Summary form only given. We are currently investigating the mechanisms of microwave power absorption in an ECR plasma. Relative microwave power measurements are made in the vicinity of the quartz window where 2.45 GHz heating power enters the plasma chamber. One dimensional measurements along the axis have been reported in which Faraday rotation of the incident electric field has been observed. Here, 3-D profiles of the microwave heating power distribution will be presented, as well as profiles of each electric field component. The purpose of this study is to explain how microwave power is absorbed in the plasma, especially the electric field component that is not resonant with electron cyclotron motion. We also try to clarify the transition between the low and high density mode. The low mode is characterized by an E field configuration with peaks and nodes throughout the plasma chamber. This is like a standing wave in a circular cavity with a weak plasma dielectric. In the high mode there is no detectable power beyond the resonance zone. The microwave field intensity is greatest in front of the waveguide opening, 2 to 5 cm from the quartz plate. Finally, the 3-D power distribution will be used in a computer simulation of this ECR reactor to accurately model the electron heat source.