Fast, hot electron production and ion acceleration in a helicon inductive plasma

作者：Sung Yung Ta^*; Li Yan; Scharer John E

来源：Physics of Plasmas, 2016, 23(9): 092113.

DOI：10.1063/1.4962758

A large, time-averaged, double layer-like plasma potential drop of 80V over several hundred Debye lengths has been observed in the magnetic expansion region on the Madison Helicon eXperiment. It is operated in an inductive mode at 900W and low argon operating pressures (0.12-0.20 mTorr) in the collisionless regime. The plasma space potential drop is due to the formation of a double layer-like structure in the magnetic expansion region and is much higher than the potential drop caused by a Boltzmann expansion. With the plasma potential drop, a locally negative potential ion hole region at lower pressures with a higher electron density than ion density has been observed just the downstream of the potential drop region. Two-temperature Maxwellian electron distributions with a warm (T-e approximate to 15 eV) and bulk (T-e approximate to 5 eV) components are observed just upstream of the double layer validated through a RF compensated Langmuir probe and an optical emission spectroscopy (OES) diagnostics. In the expansion chamber downstream of the double layer-like potential drop, a single warm (T-e approximate to 15 eV) Maxwellian electron distribution is observed via both the Langmuir probe and OES diagnostics. Ion beam energies of 65 eV are also observed downstream of the potential drop. Published by AIP Publishing.

• 出版日期2016-9