Competitive effects of an axial magnetic field and of neutral gas depletion in a positive column

2009 ◽  
Vol 16 (5) ◽  
pp. 053507 ◽  
Author(s):  
L. Liard ◽  
J.-L. Raimbault ◽  
P. Chabert
Keyword(s):  
Magnetic Field ◽  
Positive Column ◽  
Axial Magnetic Field ◽  
Competitive Effects ◽  
Neutral Gas

Stability of a positive column in the presence of an axial magnetic field

1982 ◽  
Vol 28 (1) ◽  
pp. 113-124 ◽  
Author(s):  
Mahinder S. Uberoi ◽  
Chuen-Yen Chow
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Electron Density ◽  
Electric Fields ◽  
Positive Column ◽  
Axial Magnetic Field ◽  
Previous Analysis ◽  
Self Consistent ◽  
The Stability ◽  
Axisymmetric Perturbations

Self-consistent infinitesimal perturbations of electron density and electric field are used to analyse the stability of the plasma. The axisymmetric perturbations are stable for any magnetic and electric field strengths. The non-axisymmetric perturbations with azimuthal modes m ≥ 1 and less than a certain integer are unstable for certain ranges of magnetic and electric fields. The mode m = 2 can be more unstable than the mode m = 1. Previous analysis by other authors was confined to the case m = 1 and the perturbations were not self-consistent. Our results differ significantly from the earlier results.

Effect of neutral gas motion on the rotation of dust clusters in an axial magnetic field

2009 ◽  
Vol 16 (1) ◽  
pp. 013702 ◽  
Author(s):  
Jan Carstensen ◽  
Franko Greiner ◽  
Lu-Jing Hou ◽  
Horst Maurer ◽  
Alexander Piel
Keyword(s):  
Magnetic Field ◽  
Axial Magnetic Field ◽  
Neutral Gas

Radial variation of excited atom densities in an argon plasma column produced by a microwave surface wave

1982 ◽  
Vol 60 (3) ◽  
pp. 379-382 ◽  
Author(s):  
M. Moisan ◽  
R. Pantel ◽  
A. Ricard
Keyword(s):  
Magnetic Field ◽  
Surface Wave ◽  
Plasma Column ◽  
Positive Column ◽  
Excited Atom ◽  
Axial Magnetic Field ◽  
Argon Plasma ◽  
Gas Pressure ◽  
Radial Variation ◽  
Radial Profiles

The radial variations of radiative and metastable atom densities in an argon plasma column produced by a microwave surface wave are obtained. A large variety of radial profiles is observed as a function of wave frequency (300–1000 MHz), gas pressure (50–200 mTorr), tube diameter (17.5–34 mm) and axial magnetic field. The results differ significantly from those reported for the dc positive column, where the radial distributions keep approximately the same J0 Bessel-like profile.

Resonanzverschiebungen in HF-Entladungen bei axialem Magnetfeld/Resonance Shifts in High Frequency Discharges in Axial Magnetic Field Configurations

1976 ◽  
Vol 31 (9) ◽  
pp. 1122-1130 ◽  
Author(s):  
B. Lammers ◽  
U. Oberlack ◽  
H. Schlüter
Keyword(s):  
Magnetic Field ◽  
High Frequency ◽  
Axial Magnetic Field ◽  
Hydrogen Plasma ◽  
Electron Density Profile ◽  
Field Configuration ◽  
Lower Hybrid ◽  
Neutral Gas ◽  
Apparent Shift ◽  
Lower Hybrid Resonance

AbstractThe pressure dependence of the lower hybrid resonance is investigated in a hydrogen plasma generated by a high frequency discharge. Appreciable shifts of the absorption peak with the neutral gas pressure are observed only in a mirror like magnetic field configuration. The measurements show that this shift cannot be explained by a change of the ion composition of the plasma, but must be attributed to two other mechanisms: The composition of the spectrum of the kn-components is influenced by the axial electron density profile so that at low pressure the higher modes of the spectrum are dominant.With higher pressure the formation of radial modes is favoured which leads to an additional apparent shift of the resonance.

Das toroidale schwachionisierte Magnetoplasma II

1967 ◽  
Vol 22 (12) ◽  
pp. 1904-1919
Author(s):  
F. Karger
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Charge Carrier ◽  
Electric Field ◽  
Magnetic Field Strength ◽  
Positive Column ◽  
Substantial Reduction ◽  
Field Method ◽  
Critical Magnetic Field ◽  
Neutral Gas

A special alternating field method was used to eliminate the influence of the concentration effect (described in Part I1) on the measurements of interest and to increase by more than an order of magnitude the critical magnetic field strength for the onset of the helical instability of the positive column. This made it possible to check in detail the theory — formulated in Parts I and II — of a stable, weakly ionized toroidal magnetoplasma (potential profile, density profile, charge carrier losses).The theoretically predicted transverse electric field strength leading to the torus drift was observed, while the outward density displacement due to the torus drift did not occur. It was proved that the reason for this was an effect which results from a transverse gradient in the rate of ionization (grad ξ effect) and which causes a substantial reduction of the charge carrier losses. In the decaying plasma with vanishing longitudinal electric field, on the other hand, the outward density displacement was reeorded in accordance with the theory.The influence of the toroidal curvature on the magnetic field strength at which the helical instability sets in and on the turbulent state of the positive column was also investigated. It was also possible to verify the influence of the grad ξ effect on the helical oscillation.The grad ξ effect may be important for the early heating phase in projected toroidal fusion machines with neutral gas stabilization.

EXPANSION OF LASER-PRODUCED ION BEAMS IN AN AXIAL MAGNETIC FIELD

2002 ◽  
Vol 6 (4) ◽  
pp. 8
Author(s):  
J. Wolowski ◽  
J. Badziak ◽  
P. Parys ◽  
E. Woryna ◽  
J. Krasa ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Axial Magnetic Field ◽  
Ion Beams
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