Guided‐Wave‐Produced Plasmas

Abstract

A review on recent development in self-consistent description of high-frequency discharges is presented. The discussions are based on fluid models of travelling-wave-sustained plasmas and results for the axial structure of discharges in different gases.

Travelling-wave-sustained discharges

“…The same holds also for sustaining the discharge along its total length, i.e.n(z) and |E(z)| 2 are related to each other at each position z along the discharge [15,82,[99][100][101][102]. Since the wave field intensity |E(z)| 2 is present in the maintenance field intensity E 2 (z) and the latter is related to [17,25], the relation between plasma densityn(z) and |E(z)| 2 is in fact the (n-)-relation present in (2.3). Thus, the (n-)-relation necessary for the self-consistent description of the discharge represents the relation n(|E| 2 ) between plasma density and field intensity which is the expression of the ionization nonlinearity.…”

“…The step ionization (the first term in the right-hand side of (3.3)) and the recombination (the second term therein) are responsible for the discharge self-consistency in the cw regime of maintenance of discharges in atomic gases without and in a weak external magnetic field [16][17][18][24][25][26][27]30]. The step ionization is the process which ensures the n(|E| 2 )-dependence in almost the total pressure range of diffusion-controlled discharges.…”

“…This problem arose because of the necessity of involving the dispersion law [1,4,5,10,11,[13][14][15][16][17][18]65,66,[69][70][71][75][76][77]81,82] both in the description of these discharges and their diagnostics. The dispersion law of SWs in axially homogeneous plasmas was used as a local dispersion law from the very beginning of their study.…”

“…Discovered in 1974 by Moisan et al [1,2] as new plasma sources, the travelling-wave-sustained discharges [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] have generated since then an increasing interest in the gas-discharge physics, both theoretically and experimentally and also regarding the gas-discharge applications.…”

“…Operation of stationary and pulsed discharges, discharge maintenance without and in an external magnetic field as well as discharge production in different gases (argon, helium, helium-argon gas mixtures and hydrogen) are covered [16][17][18][24][25][26][27][28][29][30][31][32][33]. In all the cases, the basis of the discharge maintenance-the discharge self-consistency and the electron heating in the high-frequency field-are stressed.…”