Capacitively coupled hydrogen plasmas sustained by tailored voltage waveforms: excitation dynamics and ion flux asymmetry

TY - JOUR

T1 - Capacitively coupled hydrogen plasmas sustained by tailored voltage waveforms:

T2 - excitation dynamics and ion flux asymmetry

AU - Bruneau, Bastien

AU - Diomede, P

AU - Economou, DJ

AU - Longo, S

AU - Gans, Timo

AU - O'Connell, Deborah

AU - Greb, Arthur

AU - Johnson, Erik V.

AU - Booth, Jean-Paul

N1 - © 2016, IOP Publishing Ltd.

PY - 2016/7/8

Y1 - 2016/7/8

N2 - Parallel plate capacitively coupled plasmas in hydrogen at relatively high pressure (~1 Torr) are excited with tailored voltage waveforms containing up to five frequencies. Predictions of a hybrid model combining a particle-in-cell simulation with Monte Carlo collisions and a fluid model are compared to phase resolved optical emission spectroscopy measurements, yielding information on the dynamics of the excitation rate in these discharges. When the discharge is excited with amplitude asymmetric waveforms, the discharge becomes electrically asymmetric, with different ion energies at each of the two electrodes. Unexpectedly, large differences in the $\text{H}_{2}^{+}$ fluxes to each of the two electrodes are caused by the different $\text{H}_{3}^{+}$ energies. When the discharge is excited with slope asymmetric waveforms, only weak electrical asymmetry of the discharge is observed. In this case, electron power absorption due to fast sheath expansion at one electrode is balanced by electron power absorption at the opposite electrode due to a strong electric field reversal.

AB - Parallel plate capacitively coupled plasmas in hydrogen at relatively high pressure (~1 Torr) are excited with tailored voltage waveforms containing up to five frequencies. Predictions of a hybrid model combining a particle-in-cell simulation with Monte Carlo collisions and a fluid model are compared to phase resolved optical emission spectroscopy measurements, yielding information on the dynamics of the excitation rate in these discharges. When the discharge is excited with amplitude asymmetric waveforms, the discharge becomes electrically asymmetric, with different ion energies at each of the two electrodes. Unexpectedly, large differences in the $\text{H}_{2}^{+}$ fluxes to each of the two electrodes are caused by the different $\text{H}_{3}^{+}$ energies. When the discharge is excited with slope asymmetric waveforms, only weak electrical asymmetry of the discharge is observed. In this case, electron power absorption due to fast sheath expansion at one electrode is balanced by electron power absorption at the opposite electrode due to a strong electric field reversal.

U2 - 10.1088/0963-0252/25/4/045019

DO - 10.1088/0963-0252/25/4/045019

M3 - Article

SN - 0963-0252

VL - 25

SP - 1

EP - 9

JO - Plasma sources science & technology

JF - Plasma sources science & technology

IS - 4

M1 - 045019

ER -