摘要:

AbstractOn étudie le couplage des ondes magnétoacoustiques dans un plasma nonidéale pour une situation physique qui modéle la magnétosphère terrestre. On a calculé la forme générale de la matrice de couplage dont les éléments permettent déterminer la manière dans laquelle une certaine onde peut être réfléchie sur les nonhomogénéités du plasma ont peut générer une onde

ISSN:0005-8025    

DOI:10.1002/ctpp.19740140602

出版商:WILEY‐VCH Verlag    

年代:1974

数据来源: WILEY

摘要:

AbstractThe neutral gas flux from the wall into the column ‐ connected with the ion flux to the wall ‐ and the anisotropy of the velocity distribution of the neutral gas are included into the theory of the steady‐state positive column.d/lnandvn0/v0occur as characteristic parameters.ddenotes the radius of the column,lnthe mean free path of the neutral atoms for ionization,vn0the mean velocity of the neutral atoms re‐emitted from the wall,v0= (2kTe/M)1/2,Mthe ion mass,Tethe electron temperature. On the axis the neutral gas densityNnis decreasing, ifd/lnis rising. At the wallNnis increasing forvn0≪v0, but it is almost constant or decreasing forvn0≫v0at the same time. In the plasma the total number of the atoms and the ions is taken as constant. In the case of smallvn0the degree of ionization is high only ford≫ln. However, it is already high ford≈lnin the case of highvn0. Therefore, the radial profiles of the neutral gas densities of different gases in a column can differ from each other. Almost full ionization can be reached near the axis. These results hold, too, if the initial velocity of the ions and a magnetic field are taken into account.d/ln, the degree of ionization, and the electron temperature are given as functions of the electric power input and of the total number of the neutrals and the ions. The velocities of the re‐emitted atoms depend on the accomodation coefficient of the ions recombining at the wall. With risingd/lnan increasing number of the neutral atoms is re‐emitted with superthermal velocities and the total number of the neutrals and the ions can be decreased. The anisotropy of the velocity distribution of the neutral atoms and the ions must be taken into account for the interpretations of spectrosc

ISSN:0005-8025    

DOI:10.1002/ctpp.19740140603

出版商:WILEY‐VCH Verlag    

年代:1974

数据来源: WILEY

摘要:

AbstractStanding 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 L1at the hybrid point and a coupling lengthlc, introduced by Eq. (20); the electron gyration radiusrc, scale lengthL1, coupling lengthlc, and slab thickness 2a obeying the relationrc≪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/cm2absorbed in the hybrid region may produce fieldstrength exceeding the typical threshold values for non‐linear excitat

ISSN:0005-8025    

DOI:10.1002/ctpp.19740140604

出版商:WILEY‐VCH Verlag    

年代:1974

数据来源: WILEY

ISSN:0005-8025    

DOI:10.1002/ctpp.19740140601

出版商:WILEY‐VCH Verlag    

年代:1974

数据来源: WILEY