Time- and space-resolved electron-impact excitation rates in an rf glow discharge

Electron-impact excitation rates in a capacitively coupled 13.6-MHz rf argon discharge were derived from optical emission measurements with high time and space resolution. A propagating excitation wave form is shown to exist at gas pressures as high as 1.0 Torr. The observed features---including temporal broadening of the wave form---are in agreement with recent simulation results, and can explain apparent transitions in electron energy distributions previously reported.