Time-resolved optical emission and electron energy distribution function measurements in rf plasmas

Abstract

Comparisons between experimentally measured time-dependent electron energy distribution functions and optical emission intensities are reported for low-frequency (100 and 400 kHz) radio-frequency driven discharges in argon. The electron energy distribution functions were measured with a time-resolved Langmuir probe system. Time-resolved optical emissions of argon resonance lines at 687.1 and 750.4 nm were determined by photon-counting methods. Known ground-state and metastable-state excitation cross sections were used along with the measured electron energy distribution functions to calculate the time dependence of the optical emission intensity. It was found that a calculation using only the ground-state cross sections gave the best agreement with the time dependence of the measured optical emission. Time-dependent electron density, electron temperature, and plasma potential measurements are also reported.

Time and space-resolved experimental investigation of the electron energy distribution function of a helium capacitive discharge at atmospheric pressure

“…This is not the case for the generalized distribution which describes the highenergy electron portion in accordance with T hot . In addition, the overall shape of the EEDF is similar to those reported in low pres sure RF plasmas [28,29] which is consistent with the fact that electrons with energy below 5 eV play an important role in the discharge kinetics (excitation and ionization from collision with metastable atoms), hence the rise in the population of the low energy electrons of the EEDF. In the case of the discharge in the γ mode, the deviation from the Maxwell-Boltzmann distribution is less pronounced and the EEDF tends towards a Druyvesteyn distribution as expected when the pressure is increased in typical low pressure CCRF discharges [30].…”

Application of excitation cross sections to optical plasma diagnostics

“…The high signal rates and short lifetimes of atomic states allow OES techniques also to be useful in monitoring fast transient signals from pulsed plasmas. Temporal and phase resolved measurements have been used to study electron temperatures and electron densities [68,90,91]. For example, Behle et al [92] have studied the 794.8 nm Ar(2p 4 ) and 480.0 nm Ar + emission lines for a pulsed slot-antenna microwave discharge.…”