Ion and neutral energies in a multipolar electron cyclotron resonance plasma source

Abstract

Discharge species energies have been measured in a multipolar electron cyclotron resonance (ECR) plasma source excited in the TE211 mode at 2.45 GHz. Diagnostic measurements were performed in argon gas discharge with a 12.5-cm-diam multipolar ECR reactor operating in the 0.5–7-mTorr pressure regime. The experimental diagnostic techniques of (1) laser induced fluorescence, (2) emission spectroscopy, (3) Langmuir probes, and (4) multigrid energy analyzer measurements were employed. The ion and neutral energies versus pressure, input power, and position were measured for two static magnetic field configurations: (1) 8 pole/8 magnet and (2) 4 pole/8 magnet. In both configurations the ion energies are (1) low (<30 eV) and relatively monoenergetic, and (2) decrease with increasing pressure, and (3) increase slightly with increasing power. The 4 pole/8 magnet configuration exhibits the lowest average ion energy, approximately 11 eV, and has less neutral gas heating (<0.07 eV) as the input power is increased to 700 W.