Electron energy distribution function and plasma potential in a planar inductive argon discharge without electrostatic screen

Abstract

Studies on electron heating are done during the power coupling change in the discharge mode transition (E–H mode transition) in a planar inductive argon discharge without electrostatic screen (Faraday shield). The electron energy distribution function (EEDF) evolution is measured by the alternating current superposition method with a radio frequency (rf) compensated Langmuir probe. The trend of its integrals, electron density and effective electron temperature, and especially the plasma potential against rf power are presented. It is demonstrated that the plasma potential is governed primarily by the high-energy electron tail in a plasma with bi-Maxwellian EEDF. The interdependence of the EEDF and the plasma potential is discussed. The experimental results show that the plasma potential against rf power reflects a change in the relative contribution of capacitive power coupling to electron heating.

Parametric study on excitation temperature and electron temperature in low pressure plasmas

“…(6) showed stronger pressure dependence but a weaker power dependence. Similar observations were previously reported in argon ICPs [18,19].…”

Global model analysis of negative ion generation in low-pressure inductively coupled hydrogen plasmas with bi-Maxwellian electron energy distributions

“…For the low pressure inductively coupled plasmas (ICPs), observations of the biMaxwellian EEDs and analyses on their formation mechanisms have been reported by several research groups. [6][7][8][9][10][11][12] McNeely et al observed a distinct bi-Maxwellian EED in the RF-driven negative ion source of a low-pressure and high-power (0.27 Pa and 79 kW) hydrogen ICP. They analyzed the competition between two main factors, i.e., the electron-electron collisions and the collisionless heating (or stochastic heating), that determines whether to Maxwellize or bi-Maxwellize EED.…”

The radio frequency magnetic field effect on electron heating in a low frequency inductively coupled plasma

“…The decrease of plasma potential is consistent with the well-known fact that the electron temperature of high energy electrons determines the plasma potential. 13 The radial distributions of the rf magnetic field, B z , are given in Fig. 4.…”

“…10 For the acquisition of the electron energy distribution function ͑EEDF͒, the ac signal superposition method 11,12 is used as described in our other papers. 13,14 To simplify the measurement circuit and to reduce the distortion owing to other harmonic components, the second-harmonic method is used. The amplitude of the second-harmonic component is related to the second derivative of the probe current through Taylor expansion as follows:…”