Wave propagation and diagnostics in argon surface-wave discharges up to 100 Torr

Abstract

Deals with the study of argon surface-wave produced discharges as the effective collision frequency nu becomes larger than the excitation pulsation omega (either at low frequency or at high pressure). Both conditions have been studied in the experiment reported. Discharges have been produced in the 1-100 Torr range in capillary tubes with 210 MHz and 2450 MHz excitation frequency. First, the set of Maxwell equations and boundary conditions is solved taking into account the attenuation due to collisions. Then the nu / omega influence is discussed. Secondly a diagnostic method providing the axial density profile ne(z) and the collision frequency nu is reported. Finally the authors find scaling laws for these discharges.

Travelling-wave-sustained discharges

“…The work on TWSDs stimulated analysis of the SW dispersion behaviour in homogenous-plasma waveguides with different configuration under the conditions of weak and strong collisions as well as studies of the wave properties in the different regions of their phase diagrams [65][66][67][68][69][70][71].…”

“…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.…”

“…They involve measurements of the wave characteristics (wavenumber and its variation along the discharge length) for determination of the plasma parameters (plasma density and its axial profile) by using knowledge for the wave dispersion properties. The interferogram method and the field radial decay method are the radiophysics methods [4,65,76,[121][122][123][124][125][126][127][128] first invented, the former-the interferogram method-has been very widely used in the diagnostics of the SWSDs. A lot of results [4,5,65,76,[121][122][123][124][125][126][127][128] have been accumulated, by using this method, for the axial density profile-the most remarkable characteristic of the SWSDs, which is a consequence of the self-consistent interdependence between the parameters of the guided wave and of the generated plasma.…”

“…6 and 7, for ea / = 0. 65. Collisions in the plasma volume control both the wave dispersion properties in the plasma-density range of interest for the discharge maintenance (the range with < in Fig.…”

Spectroscopic characterization of a neon surface-wave sustained (2.45 GHz) discharge at atmospheric pressure

“…3, the difference in slope shown by the n e axial profiles for each one of the three gases can be explained in terms of the direct relation of this slope to electron-atom collision frequency for the momentum transfer ν (characteristic parameter of the discharge that depends only on the pressure and gas temperature) and of the inverse dependence of the slope on the discharge tube radius [49]. In Fig.…”