Measurements of Nonlocal Electron Energy Distribution Functions in the Afterglow of an RF ICP Discharge

In previous work [1], it was shown that even a small number of nonlocal fast electron, which do not significantly affect the overall mean electron energy, can dramatically change the plasma and near-wall sheath properties. In this work, Langmuir probe measurements of electron density, temperature and energy distribution functions (EEDF) in the afterglow of low-pressure (30-50 mTorr) noble-gas rf ICP discharges have been carried out. The experimental setup is described in [2]. The primary focus of this work was the investigation of the high energy portion of the EEDF which shows peaks corresponding to electrons with energies 5-20 eV, depending on the gas mixture. These peaks arise from electrons produced in Penning ionization with metastable noble gas atoms. ~This fast component of the EEDF can be controlled independently on the slow electrons, a direct consequence of the nonlocality. \newline \newline [1] V. Demidov et al. \textit{PRL} \textbf{95}, 215002 (2005). \newline [2] W. Guo et al., \textit{PSST} \textbf{10}, 43 (2002).