Zur Begrenzung der radial en Ausdehnung des Li chtbogenstromes durch ein axiales Magnetfeld. II. Skalengesetze und Vergleich mit Experimenten / On Limitation of the Radial Extent of the Arc Current by Means of an Axial Magnetic Field. II. Scaling Laws and Comparison with Experimental Results

1972 ◽  
Vol 27 (4) ◽  
pp. 652-670
Author(s):  
O. Klüber
Keyword(s):  
Magnetic Field ◽  
Cross Sections ◽  
Scaling Laws ◽  
Axial Magnetic Field ◽  
Angular Frequency ◽  
Model Calculations ◽  
Simple Geometry ◽  
Radial Extent ◽  
Arc Current ◽  
Field Lines

Abstract In an arc with superimposed axial magnetic field, radial current components cause a rotational motion of the plasma column and produce azimuthal Hall currents and hence electromotive forces such that the arc current is guided by the magnetic field lines. In the first part of this paper the steady-state plasma equations have been solved for a homogeneous plasma in simple geometry, allowance being made for finite viscosity. Here, scaling laws giving the radial extent of the arc current are obtained. In addition, electrodes with finite cross sections are treated. The results of model calculations agree well with experimental data. Generally, the model is applicable, if the angular frequency of the plasma is small compared with the ion gyration frequency.

scholarly journals Zur Begrenzung der radialen Ausdehnung des Lichtbogenstromes durch ein axiales Magnetfeld

1970 ◽  
Vol 25 (11) ◽  
pp. 1583-1600
Author(s):  
O. Klüber
Keyword(s):  
Magnetic Field ◽  
Hall Current ◽  
Axial Magnetic Field ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Plasma Radius ◽  
Arc Current ◽  
Field Lines ◽  
The Magnetic Field ◽  
Generally True

Abstract In an arc without external magnetic field the current carrying region is identical with the conducting plasma column. This is no longer generally true if the arc is in an axial magnetic field and if the electrode radius is much smaller than the plasma radius. Radial current components then produce a rotational motion of the plasma and an azimuthal Hall current, and hence electromotive forces which try to suppress the current perpendicular to the magnetic field. In a plasma with finite viscosity the rotation is determined by the Navier-Stokes equation, which is solved here for a homogeneous plasma simultaneously with generalized Ohm's law. The results show that the plasma rotation is always an essential, and often the dominant, mechanism for guiding the arc current parallel to the magnetic field lines.

scholarly journals Evolution of the Cathode Spot Distribution in an Axial Magnetic Field Controlled Vacuum Arc at Long Contact Gap

2017 ◽  
Vol 4 (1) ◽  
pp. 99-103
Author(s):  
B. Tezenas du Montcel ◽  
P. Chapelle ◽  
A. Jardy ◽  
C. Creusot
Keyword(s):  
Magnetic Field ◽  
High Speed ◽  
Cathode Spot ◽  
Axial Magnetic Field ◽  
Processing Method ◽  
Vacuum Arc ◽  
Single Spot ◽  
High Speed Video ◽  
Video Images ◽  
Arc Current

The distribution of cathode spots in a CuCr25 vacuum arc controlled by an axial magnetic field and ignited on the lateral surface of the cathode is investigated for long gap distances, from the processing of high-speed video images. The processing method includes also estimating the current carried by a single spot and reconstructing the distribution of the current density at the cathode. Various distributions depending partly on the arc current are described.

scholarly journals Gas–puff Z pinches with strong axial magnetic fields

1987 ◽  
Vol 5 (4) ◽  
pp. 699-706 ◽  
Author(s):  
F. S. Felber ◽  
F. J. Wessel ◽  
N. C. Wild ◽  
H. U. Rahman ◽  
A. Fisher ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Inertial Confinement Fusion ◽  
Scaling Laws ◽  
Axial Magnetic Field ◽  
Argon Laser ◽  
Nitrogen Laser ◽  
Inertial Confinement ◽  
X Ray ◽  
Confinement Fusion

Ultrahigh axial magnetic fields have been compressed and measured in a gas-puff Z pinch. A 0·5-MA, 2–cm-radius annular gas-puff Z pinch with a 3-minute repetition rate was imploded radially onto an axial seed field, causing the field to compress. Axial magnetic field compressions up to 180 and peak magnetic fields up to 1·6 MG were measured. Faraday rotation of an argon laser (515·4 nm) in a quartz fiber on axis was the principal magnetic field diagnostic. Other diagnostics included a nitrogen laser interferometer, x-ray diodes, and magnetic field probes.The magnetic field compression results are consistent with simple snowplow and self-similar analytic models, which are presented. The axial magnetic fields strongly affect the Z pinch dynamics. Even small axial fields help stabilize the pinches, some of which exhibit several stable radial bounces during a current pulse.The method of compressing axial fields in a gas-puff Z pinch is extrapolable to the order of 100 MG. Scaling laws are presented. Potential applications of ultrahigh axial fields in Z pinches are discussed for x-ray lasers, inertial confinement fusion, and collimated sources of gamma radiation.

scholarly journals Electron Outflow in Axisymmetric Pulsar Magnetospheres. II

1987 ◽  
Vol 40 (5) ◽  
pp. 687
Author(s):  
RR Burman
Keyword(s):  
Magnetic Field ◽  
Axial Magnetic Field ◽  
Lorentz Factor ◽  
Surface Flow ◽  
Stellar Surface ◽  
Extended Version ◽  
Pulsar Magnetosphere ◽  
Poloidal Magnetic Field ◽  
Field Lines ◽  
Limiting Surface

Tn the axisymmetric pulsar magnetosphere model of Mestel et al. (1985), electrons, following injection with non-negligible speeds from the stellar surface, flow with moderate acceleration, and with poloidal motion that is closely tied to poloidal magnetic field lines, before reaching a limiting surface, near which rapid acceleration occurs. The present paper continues an analysis of flows which either encounter the limiting surface beyond the light cylinder (between the cones of zero axial magnetic field), or do not meet it at all. The formalism introduced by Mestel et aL for the description of the outflow is applied in an extended version which fully incorporates Yo, the emission Lorentz factor of the particles. This treatment removes the singularity of Yo at the stellar poles that occurred in the earlier work: because of a nonuniformity in taking the limit of nonrelativistic injection, full incorporation of Yo acts to keep it finite.

Effect of an axial magnetic field and arc current on the anode current density in diffuse vacuum arcs

2016 ◽  
Vol 23 (9) ◽  
pp. 093507 ◽  
Author(s):  
Hui Ma ◽  
Yingsan Geng ◽  
Zhiyuan Liu ◽  
Jianhua Wang ◽  
Zhenxing Wang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Current Density ◽  
Axial Magnetic Field ◽  
Anode Current Density ◽  
Anode Current ◽  
Arc Current

scholarly journals Collimation of laser-produced plasmas using axial magnetic field

2015 ◽  
Vol 33 (2) ◽  
pp. 175-182 ◽  
Author(s):  
Amitava Roy ◽  
Sivanandan S. Harilal ◽  
Syed M. Hassan ◽  
Akira Endo ◽  
Tomas Mocek ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Axial Magnetic Field ◽  
Laser Pulses ◽  
Plume Expansion ◽  
Charge Coupled Device ◽  
Particle In Cell ◽  
Cell Modeling ◽  
Plasma Plumes ◽  
Intensified Charge Coupled Device ◽  
Field Lines

AbstractWe investigated the expansion dynamics of laser-produced plasmas expanding into an axial magnetic field. Plasmas were generated by focusing 1.064 μm Nd:YAG laser pulses onto a planar tin target in vacuum and allowed to expand into a 0.5 T magnetic field where the field lines were aligned along the plume expansion direction. Gated images employing an intensified charge-coupled device showed focusing of the plasma plume, which were also compared with results, obtained using particle-in-cell modeling methods. The estimated density and temperature of the plasma plumes employing emission spectroscopy revealed significant changes in the presence and absence of the 0.5 T magnetic field. In the presence of the field, the electron temperature is increased with distance from the target, while the density showed opposite effects.

scholarly journals Dynamic Arc Current Distribution of Parallel Vacuum Arcs Subjected to Bipolar Axial Magnetic Field

IEEE Access ◽  
2020 ◽  
Vol 8 ◽  
pp. 58290-58299
Author(s):  
Haomin Li ◽  
Zihan Wang ◽  
Yingsan Geng ◽  
Zhiyuan Liu ◽  
Jianhua Wang
Keyword(s):  
Magnetic Field ◽  
Current Distribution ◽  
Axial Magnetic Field ◽  
Arc Current

Scaling laws for a self-generated axial magnetic field in laser-produced plasma

1988 ◽  
Vol 31 (5) ◽  
pp. 1303 ◽  
Author(s):  
B. Chakraborty ◽  
Manoranjan Khan ◽  
B. Bhattacharyya ◽  
Sukanta Deb ◽  
H. C. Pant
Keyword(s):  
Magnetic Field ◽  
Scaling Laws ◽  
Axial Magnetic Field ◽  
Laser Produced Plasma

Models of Structure and Dynamics of Prominences

1979 ◽  
Vol 44 ◽  
pp. 322-330 ◽  
Author(s):  
U. Anzer
Keyword(s):  
Magnetic Field ◽  
Cross Sections ◽  
Theoretical Models ◽  
Opposite Polarity ◽  
The Sun ◽  
Structure And Dynamics ◽  
Common Basis ◽  
Field Lines ◽  
Physical Phenomena ◽  
Helical Field

The discussion in Working Group1was centered around 3 theoretical models. The participants were well aware of the fact that these idealized models have only limited value towards our goal of understanding the complex physical phenomena of quiescent prominences. We used these models mainly as a common basis for our discussion. The models, shown in Figure 1 are all 2-dimensional and only cross-sections normal to the long axis of the prominence are drawn. They are based on different magnetic field configurations. In all 3 models currents flow inside the prominence giving rise to a Lorentz-force which keeps the material from falling freely towards the surface of the Sun. Due to horizontal motion parallel to the prominence of the foot points of opposite polarity a magnetic field normal to the plane drawn will be induced. This then implies additional currents in the corona surrounding the prominence. Note that those field lines in the Kuperus and Raadu model which are open cannot maintain any shear and therefore must lie in the plane. The circular lines in the model of Malville result from a projection of helical field structures.

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