Untersuchung des negativen Glimmlichts von abnormalen Edelgas-Glimmentladungen mit und ohne Hochfrequenz-Zusatzheizung
Holtkamp, M. (Corresponding author)
Publikationen vor 2000; PRE-2000; Retrocat
Jülich Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag 1997
II, 145 p.
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Berichte des Forschungszentrums Jülich 3369
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Please use the identifier: http://hdl.handle.net/2128/21851 in citations.


The negative glow of an abnormal glow discharge with a large-area cold magnesium cathode was investigated. In this kind of dis charge an electron beam is formed in the cathode fall region, the energy ranging between 1keV and 2keV. This beam produces a cold, nearly field-free plasma at a high density. A Langmuir probe was applied in order to measure the electron density, the electron temperature, and the plasma potential. In all cases when noble gases are used two groups of electrons are found. The cold group in helium exhibits a temperature of 0.06eV at densities between 10$^{16}$m$^{-3}$ and 10$^{17}$ m$^{-3}$. The density of the fast electrons falls about three orders below that of the cold group; the temperature is about 3 eV. The electric field strength was obtained from the plasma potential. It does not exceed 50 V/m in the negative glow and increases to 400 V/m towards the cathode fall. The ion and also the electron beam current could be determined from the electron density gradient at the edge of the negative glow and from the current to the cathode. By solving the diffusion equation having incorporated the production by the beam electrons the density distribution of the cold group was obtained and agreement was found with the experimental results. Neither can the temperature of the cold electrons be controlled by variation of the current density and the gas pressure nor by a variation of the discharge voltage. Actually, thetemperature of the fast electrons depends weakly on the energy of the electron beam. The temperature of the cold electrons is mainly influenced by the energy transfer by the fast electrons and by elastic processes. In order to raise the temperature of the cold group electrons, additional rf-power was coupled into the negative glow at a frequency of 13.56 MHz. With an rf-power of 280 mW the temperature of the cold electrons is increased up to 2.5 e V in the negative glow of the discharge in neon. In helium only a temperature of 0.8 eV is reached because of the high collisional losses with neutrals. As the electron temperature increases the density of the electrons decreases. This tendency is stopped due to additional ionisation by electrons which are heated up in the rf-field. [...]