Self-compression of a plasma column of finite electrical conductivity in an external axial magnetic field

1975 ◽  
Vol 15 (5) ◽  
pp. 901-908
Author(s):  
D. Zoler ◽  
I. Grosu ◽  
F. Laur ◽  
D. Ruscanu ◽  
R. Gazi
Keyword(s):  
Magnetic Field ◽  
Electrical Conductivity ◽  
Plasma Column ◽  
Axial Magnetic Field ◽  
Finite Electrical Conductivity

Anomalous skin effect for a plasma column in a magnetic field

1973 ◽  
Vol 10 (3) ◽  
pp. 349-358 ◽  
Author(s):  
R. G. Storer ◽  
C. Meaney
Keyword(s):  
Magnetic Field ◽  
Plasma Column ◽  
Electron Density Distribution ◽  
Skin Effect ◽  
Axial Magnetic Field ◽  
Complete Solution ◽  
Low Frequency ◽  
Anomalous Skin Effect ◽  
Plasma Radius ◽  
Cylindrical Plasma Column

The influence of a steady axial magnetic field on the anomalous penetration of low frequency electromagnetic fields into a cylindrical plasma column is investigated by considering a plasma with a Gaussian electron density distribution. For this model, a complete solution is obtained for Boltzmann's equation coupled to Maxwell's equations, and the fields calculated exactly. The results show dramatic changes of the internal fields for small changes of the applied magnetic field when the average Lamour radius of the electrons is of the order of the plasma radius.

scholarly journals Measurement of Some Argon Plasma Parameters Glow Discharge Under Axial Magnetic Field

2019 ◽  
Vol 7 (4) ◽  
pp. 158-166
Author(s):  
Pshtiwan M.A. Karim ◽  
Diyar S. Mayi ◽  
Shamo Kh. Al-Hakary
Keyword(s):  
Magnetic Field ◽  
Electrical Conductivity ◽  
Glow Discharge ◽  
Electron Temperature ◽  
Breakdown Voltage ◽  
Axial Magnetic Field ◽  
Argon Plasma ◽  
Emission Lines ◽  
Plasma Parameters ◽  
Gas Pressures

This paper investigates the characteristics some of argon plasma parameters of glow discharge under axial magnetic field. The DC power supply of range (0-6000) V is used as a breakdown voltage to obtain the discharge of argon gas. The discharge voltage-current (V-I) characteristic curves and Paschen’s curves as well as the electrical conductivity were studied with the presents of magnetic field confinement at different gas pressures. The magnetic field up to 25 mT was obtained using four coils of radius 6 cm and 320 turn by passing A.C current up to 5 Amperes. Spectroscopic measurements are employed for purpose of estimating two main plasma parameters electron temperature (Te) and electron density (ne). Emission spectra from positive column (PC) zone of the discharge have been studies at different values of magnetic field and pressures at constant discharge currents of 1.5 mA. Electron temperature (Te) and its density are calculated from the ratio of the intensity of two emission lines of the same lower energy levels. Experimental results show the abnormal glow region characteristics (positive resistance). Breakdown voltage versus pressure curves near the curves of paschen and decrease as magnetic field increases due to magnetic field confinement of plasma charged particles. Also the electrical conductivity increases due to enhancing magnetic field at different gas pressures. Both temperature density of electron and the intensities of two selected emission lines decrease with increasing pressure due decreasing of mean free path of electron. Electron density increase according to enhancing magnetic field, while the intensity of emitting lines tends to decrease.

Zur Rayleigh-Taylor-Instabilität eines rotierenden Wasserstofflichtbogens im axialen Magnetfeld

1970 ◽  
Vol 25 (2) ◽  
pp. 273-282 ◽  
Author(s):  
H. F. Döbele
Keyword(s):  
Magnetic Field ◽  
Growth Rate ◽  
Heat Conduction ◽  
Dispersion Relation ◽  
Electrical Conduction ◽  
Growth Rates ◽  
Plasma Column ◽  
Qualitative Agreement ◽  
Axial Magnetic Field ◽  
Rayleigh Taylor Instability

Abstract The Rayleigh-Taylor instability of a rotating hydrogen arc in an axial magnetic field is investigated with allowance for electrical conduction, heat conduction and viscosity. The r-depending part of the perturbation was assumed to be in the form of a half-period of a standing wave. The corresponding dispersion relation is derived in the WKB-approximation and is solved numerically. In contrast with the case without dissipation, the frequencies and growth rates of the different modes depend on the parameters of the unperturbed plasma column. The calculation shows, in qualitative agreement with the experiment, that with increasing magnetic field the highest growth rate passes successively to the next higher mode.

On the re-connexion of magnetic field lines in conducting fluids

1970 ◽  
Vol 4 (2) ◽  
pp. 207-229 ◽  
Author(s):  
Tyan Yeh ◽  
W. Ian Axford
Keyword(s):  
Magnetic Field ◽  
Electrical Conductivity ◽  
Two Dimensions ◽  
Neutral Point ◽  
Inviscid Fluid ◽  
Hydromagnetic Flow ◽  
Finite Electrical Conductivity ◽  
Field Lines ◽  
Two Sides ◽  
Special Case

The reconnexion of magnetic field lines is described for a special case of steady, incompressible hydromagnetic flow in two dimensions. A similarity solution is obtained which corresponds to the flow of a perfectly conducting, inviscid fluid such that magnetic field lines are carried from two sides toward, then on the other two sides away from, the centre of an X-configuration. The effects of viscosity are important in shocks which form in the vicinity of the X-lines of the configuration. The effects of finite electrical conductivity must be taken into account near the centre of the configuration which, in the symmetrical case discussed, is an X-type neutral point. From an approximate solution valid in this region it is found that the fluid must flow from the larger to the smaller wedges of the X-configuration. Hence, the reconnexion process is such that oppositely directed magnetic field lines move towards the neutral point in the larger wedges, become reconnected at the neutral point, and move away in the smaller wedges. Since the solution in the vicinity of the neutral point appears to be no more than a response to the external flow, which is in turn controlled by conditions far from the neutral point and is essentially unaffected by viscosity and finite electrical conductivity, it is tentatively concluded that the rate of re-connexion of magnetic field lines does not depend on these quantities, and that, in general, re-connexion can be expected to take place rapidly if circumstances are favourable.

Druckerhöhung und Wärmeleitfähigkeit in einem zylindersymmetrischen Wasserstoffplasma im axialen Magnetfeld unter Berücksichtigung von Thermokräften

1968 ◽  
Vol 23 (11) ◽  
pp. 1695-1706
Author(s):  
J. Raeder ◽  
S. Wirtz
Keyword(s):  
Magnetic Field ◽  
Thermal Conductivity ◽  
Plasma Column ◽  
Thermal Equilibrium ◽  
Axial Magnetic Field ◽  
Hydrogen Plasma ◽  
Local Thermal Equilibrium ◽  
Total Thermal Conductivity ◽  
Boltzmann Equations ◽  
External Pressures

The pressure increase and total thermal conductivity are calculated for an infinitely long hydrogen plasma column in an axial magnetic field. The calculations, which are based on the first and third moments of the Boltzmann equations for atoms, ions and electrons, are carried out under the assumption of local thermal equilibrium. Numerical results are given for magnetic fields up to 150 kG, temperatures to 106°K and external pressures ranging from 103 to 105 dyne/cm2. Comparison of these results with previous calculations, which neglect thermal forces, shows that they cause an increase of pressure also in the completely ionized plasma and therefore modify the thermal conductivity indirectly.

Melt motion in a Czochralski crystal puller with an axial magnetic field: isothermal motion

1986 ◽  
Vol 164 ◽  
pp. 237-273 ◽  
Author(s):  
L. N. Hjellming ◽  
J. S. Walker
Keyword(s):  
Magnetic Field ◽  
Electrical Conductivity ◽  
Crystal Growth ◽  
Field Strength ◽  
Axial Magnetic Field ◽  
Molten Silicon ◽  
Crystal Face ◽  
Rotation Rates ◽  
Crucible Rotation ◽  
The Magnetic Field

A magnetic field suppresses turbulence and thermal convection in a Czochralski crystal puller. The amounts and distributions of dopants and oxygen in the crystal are determined by the motion of the molten silicon during crystal growth. This paper presents analytical solutions for the melt motion in a Czochralski puller with a strong, uniform, axial magnetic field. The relatively small electrical conductivity of the crystal plays a key role in determining the flow. Certain combinations of crystal and crucible rotation rates lead to flow patterns with a large volume of almost stagnant fluid under most of the crystal face. The values of these rotation rates depend on the magnetic field strength.

Stability of a stratified partially ionized plasma in a vertical magnetic field

1978 ◽  
Vol 19 (1) ◽  
pp. 183-191 ◽  
Author(s):  
S. L. Maheshwari ◽  
P. K. Bhatia
Keyword(s):  
Magnetic Field ◽  
Electrical Conductivity ◽  
Growth Rate ◽  
The Other ◽  
Conducting System ◽  
Vertical Magnetic Field ◽  
One Dimensional ◽  
Finite Electrical Conductivity ◽  
Partially Ionized ◽  
The Stability

The dynamic stability of a stratified layer of partially ionized compressible plasma is discussed to investigate the effects of finite electrical conductivity and ion viscosity. The prevailing magnetic field is assumed to be uniform and vertical. For a semi-infinite plasma having a one-dimensional exponential density gradient along the vertical, the dispersion relation has been obtained by variational methods. It is found that the ion viscosity and ion–neutral collisions, whether included jointly or separately, do not change the stability criterion of the perfectly conducting system. Their inclusion, however, has a tendency to reduce the growth rate of the unstable perturbations showing that they have a stabilizing influence. On the other hand the inclusion of the effects of finite resistivity and compressibility of the medium is found to be destabilizing as the wavenumber range over which the plasma would otherwise be stable, becomes unstable.

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