Resonances, Absorption and Linear Excitation of Cyclotron Harmonic Waves in a Discharge Plasma

Autor: H. Prinzler
Rok vydání: 1974
Předmět:
Zdroj: Beiträge aus der Plasmaphysik. 14:225-241
ISSN: 1521-3986
0005-8025
DOI: 10.1002/ctpp.19740140604
Popis: Standing cyclotron harmonic waves below the second harmonic are observed using the noise radiation of a mercury discharge tube at 1465 MHz. From the positions of the Buchsbaum-Hasegawa resonances the density profile and the electron temperature are derived, these parameters agree quite well with the behaviour of the collision-free, magnetized plasma column. A onedimensional model applicable to our waveguide geometry is developed taking into account linear excitation of cyclotron harmonic waves by a quasistationary external field in a bounded plasma. Absorption and excitation are controlled by the scale length L1 at the hybrid point and a coupling length lc, introduced by Eq. (20); the electron gyration radius rc, scale length L1, coupling length lc, and slab thickness 2a obeying the relation rc≪lc≪L1≪2a. The main absorption is caused by enhanced collisional damping at the upper hybrid region and only a small fraction being dissipated in the wave mode, though its field strength is large compared with that at the plasma boundary (EW/E(a) ≈ 6). An estimation of the mean field strength within the coupling region shows, that such a low power as 1 mW/cm2 absorbed in the hybrid region may produce fieldstrength exceeding the typical threshold values for non-linear excitation mechanism.
Databáze: OpenAIRE
Externí odkaz: