Paper PS2-WeA11
Plasma-Surface Interactions, Erosion, and Impact on Plasma Distribution Functions

Wednesday, October 31, 2012, 5:20 pm, Room 25

Plasma-surface interactions can play a large role in changing characteristic plasma distribution functions. To improve our fundamental understanding of these effects, we leverage several plasma characterization techniques (Langmuir probe, ion energy/mass analyzer, optical emission spectroscopy) with real-time characterization by in situ ellipsometry of the eroding plasma-facing surface. Using these methods, we qualitatively and quantitatively studied the time evolution of gaseous and surface derived plasma impurities. High-density inert plasmas (Ar) and low-density reactive plasmas (H₂, D₂) respond differently to molecular impurities in the plasma. When H₂/D₂ or surface/gaseous derived CH_X -related impurities are introduced into Ar plasma, large changes in plasma properties are observed. We report on changes to the ion energy/mass distributions, electron temperature/distribution functions, and plasma density for different conditions . CH_X effects on H₂ and D₂ plasmas, and H₂/D₂ plasma mixtures were also investigated. We also explore the effects of changing the relative C:H fluxes into the plasma from eroding surfaces using graphitic (high C:H ratio) and polymeric (lower C:H ratio) films. In steady-state contact with plasmas, hydrocarbons are eroded as C, H, and CH_X impurities into the plasma reflective of their initial C:H ratios. Along with these studies, we have compared how varying the gap distance between the plasma generation coil and hydrocarbon substrate electrode affects impurity fluxes and plasma properties. A comparison of plasma properties for two different inductively coupled plasma reactors has also been completed and sheds light on how plasma properties and observed trends change for different geometries and plasma sources.