Helicon waves in a non-uniform plasma
- 1 February 1994
- journal article
- Published by IOP Publishing in Plasma Sources Science and Technology
- Vol. 3 (1) , 49-57
- https://doi.org/10.1088/0963-0252/3/1/006
Abstract
The dispersion relation for helicon waves in a cold plasma of radially varying density has been reduced to compact form, and the radial eigenmodes have been computed for different density profiles. The results show a marked asymmetry between the left- and right-hand circularly polarized modes: the m=-1 (left) mode has a centrally peaked wave intensity and resonates with a much higher central density than the m=+1 mode. Positive feedback is therefore possible, leading to nonlinear channelling of the discharge. At a radius where the density falls to a certain value, a singularity arises in the coefficients of the wave equation; care must be taken in integrating through this point. This singularity has no physical significance. The marked difference between the m=+1 and -1 modes in a non-uniform plasma is caused by a difference in sign of the electron drift along the density gradient. Energy deposition is peaked near the radius of the peak in Bz, so that broad, uniform density profiles can be obtained by using the m=+1 mode and narrow, dense columns by using the m=-1 mode. These results explain many features observed by various groups over the past two years.Keywords
This publication has 14 references indexed in Scilit:
- Experimental modeling of inductive dischargesJournal of Vacuum Science & Technology A, 1993
- Plasma production by helicon wavesPlasma Sources Science and Technology, 1993
- Etching characteristics in helicon wave plasmaPlasma Sources Science and Technology, 1993
- Electron acceleration in helicon sourcesPlasma Physics and Controlled Fusion, 1992
- Plasma production in a toroidal heliac by helicon wavesPhysical Review Letters, 1991
- Observation of nonthermal electron tails in an rf excited argon magnetoplasmaPhysics of Fluids B: Plasma Physics, 1991
- Plasma ionization by helicon wavesPlasma Physics and Controlled Fusion, 1991
- Ar ii laser generated by Landau damping of whistler waves at the lower hybrid frequencyPhysical Review Letters, 1989
- Fast anisotropic etching of silicon in an inductively coupled plasma reactorApplied Physics Letters, 1989
- Plasma production with rotating ion cyclotron waves excited by Nagoya Type-III antennas in RFC-XXNuclear Fusion, 1986