RF power absorption by plasma of low pressure low power inductive discharge located in the external magnetic field

E A Kralkina,A A Rukhadze,K V Vavilin,P A Nekliudova,A K Petrov,V B Pavlov

doi:10.1063/1.5023631

Abstract

Present paper is aimed to reveal experimentally and theoretically the influence of magnetic field strength, antenna shape, pressure, operating frequency and geometrical size of plasma sources on the ability of plasma to absorb the RF power characterized by the equivalent plasma resistance for the case of low pressure RF inductive discharge located in the external magnetic field. The distinguishing feature of the present paper is the consideration of the antennas that generate not only current but charge on the external surface of plasma sources. It is shown that in the limited plasma source two linked waves can be excited. In case of antennas generating only azimuthal current the waves can be attributed as helicon and TG waves. In the case of an antenna with the longitudinal current there is a surface charge on the side surface of the plasma source, which gives rise to a significant increase of the longitudinal and radial components of the RF electric field as compared with the case of the azimuthal antenna current.

Highlights

Nowadays inductive RF discharge became an inseparable part of a number of plasma technologies such as surface modification, etching, deposition of coatings with ion assistance, etc
Experimental results show the non-monotonous variation of equivalent plasma resistance with increase of magnetic field strength at pressures below 10mTorr independently on the antenna shape and kind of the working gas
The data obtained with antennas generating both azimuthal and longitudinal currents show that the curves Rpl(B) exhibit a series of local maxima and do not decrease with B in the considered range of magnetic fields

Summary

Introduction

Nowadays inductive RF discharge became an inseparable part of a number of plasma technologies such as surface modification, etching, deposition of coatings with ion assistance, etc. The expression for the penetration depth of the cyclotron waves into the bulk plasma in the collisionless limit coincides with the expression for the anomalous skin layer:[6] In a collisional plasma, the penetration depth changes and it is determined by the expression for the normal skin layer. It was shown[6] that in case of weak damping cyclotron waves could propagate in plasma only in the frequency range ω < Ωe. It means that the resonance frequency is shifted to the frequencies

Methods

Results

Conclusion