ON THE INFLUENCE OF COULOMB COLLISIONS ON THE ELECTRON-ENERGY DISTRIBUTION FUNCTION OF SURFACE-WAVE PRODUCED ARGON PLASMAS

The effect of Coulomb collisions on the electron energy distribution function (EEDF) in surface-wave produced argon plasmas in the RF and microwave regime is studied via solution of the Boltzmann equation, including a Fokker-Planck term, in the well known Lorentz approximation. The maintenance field strength is determined self-consistently by simultaneously solving a particle balance equation subjected to a boundary condition, which accounts for the sheath formation at the wall. The modifications to the EEDF and some derived parameters introduced by the Coulomb collisions will be discussed. The theoretical predictions are compared to experimental results, which have been obtained by a Langmuir probe technique on a surface-wave produced argon discharge at 60 MHz.