Physics issues associated with low- beta plasma generators

Borovsky, Joseph E.

doi:10.1109/27.199506

Cited by 5 publications

(4 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The plasma‐β is a measure of how strongly distorted the magnetic field can be owing to diamagnetic currents in the plasma. β can be defined two ways: a thermal β defined as β th = 8πnk B (T i + T e )/B 2 or a ram β defined as β ram = 4πnm i v 2 /B 2 where v is the plasma flow velocity [ Parsons and Jellison , 1983; Borovsky , 1992]. β th is a measure of the currents when a warm plasma is confined by a magnetic field; β ram is a measure of the currents when a plasma flow is deflected or slowed.…”

Section: Differencesmentioning

confidence: 99%

Differences between CME‐driven storms and CIR‐driven storms

2006

View full text Add to dashboard Cite

[1] Twenty one differences between CME-driven geomagnetic storms and CIR-driven geomagnetic storms are tabulated. (CME-driven includes driving by CME sheaths, by magnetic clouds, and by ejecta; CIR-driven includes driving by the associated recurring high-speed streams.) These differences involve the bow shock, the magnetosheath, the radiation belts, the ring current, the aurora, the Earth's plasma sheet, magnetospheric convection, ULF pulsations, spacecraft charging in the magnetosphere, and the saturation of the polar cap potential. CME-driven storms are brief, have denser plasma sheets, have strong ring currents and Dst, have solar energetic particle events, and can produce great auroras and dangerous geomagnetically induced currents; CIR-driven storms are of longer duration, have hotter plasmas and stronger spacecraft charging, and produce high fluxes of relativistic electrons. Further, the magnetosphere is more likely to be preconditioned with dense plasmas prior to CIR-driven storms than it is prior to CME-driven storms. CME-driven storms pose more of a problem for Earth-based electrical systems; CIR-driven storms pose more of a problem for space-based assets.Citation: Borovsky, J. E., and M. H. Denton (2006), Differences between CME-driven storms and CIR-driven storms,

show abstract

Section: Differencesmentioning

confidence: 99%

Differences between CME‐driven storms and CIR‐driven storms

2006

View full text Add to dashboard Cite

show abstract

“…There must be a mechanism that stops the drift, i.e. an effect allowing for transverse currents which reduce vertical polarization [24,25]. One of the possible mechanisms, the so called Alfvén-or wave conductance [61] , was proposed by Parks et al [23] and Rozhansky et al [62].…”

Section: Drift Motion Of the Ablated Substance: Particle Deposition Pmentioning

confidence: 99%

“…The complete stopping of the drift motion is due to various effects: the short circuiting of the currents through the background plasma, the presence of rotational transform and shear in the magnetic field geometry [21,24,25]. In the model described in [63], it is assumed that drift ceases to exist when the cloud expands along the magnetic field lines and reaches a length of the order of a single passage along the large radius and, du to the presence of rotational transform, currents are induced in the cloud analogous to the Pfirsch-Schlüter equilibrium currents.…”

Section: Drift Motion Of the Ablated Substance: Particle Deposition Pmentioning

confidence: 99%

See 1 more Smart Citation

Pellet – Plasma Interaction: an Analysis of Pellet Injection Experiments by Means of a Multi‐Dimensional MHD Pellet Code

Lengyel

Schneider

Kardaun

et al. 2008

Contrib. Plasma Phys.

View full text Add to dashboard Cite

This work is aimed at the analysis of pellet injection experiments by means of a magnetohydrodynamic code that computes the processes of pellet ablation, expansion, ionization, and magnetic confinement of the ablated substance. In particular, experimental pellet injection scenarios stemming from the tokamak ASDEX-Upgrade (D2 pellets) and the stellarator W7-AS (carbon pellets) are analyzed by means of this time-dependent quasithree-dimensional MHD pellet code. Pellet penetration depths measured in ASDEX-Upgrade at LFS (lowfield-side) and HFS (high-field-side) pellet injection, are compared with computational results.It was found that the penetration depths of deuterium pellets observed in about twenty randomly selected LFS and HFS injection scenarios could accurately be reproduced by a single code in which drift effects were intentionally ignored. This may be understood as an indication of the negligible effect drift exerts on the ablation process. At the same time, the distribution of the ablated and partially ionized substance may very well be affected by the drift of the ionized particles in the direction of the decreasing magnetic field.With the help of the Dα radiation patterns observed, the magnitudes of the heat fluxes affecting the pellet and the ablation cloud were estimated. The calculations show that the thermal heat fluxes (electron and ion) acting along the magnetic field lines are not sufficient to explain the size of the radiating filaments observed.The effect of extra-thermal electrons on the ablation history of pellets injected in W7-AS is demonstrated: the particle end energy fluxes causing measured pellet ablation profiles are determined.Based on a statistically well-designed computational data set, an empirical scaling of the penetration depths in terms of the background plasma parameters was attempted. It is shown that the form of the temperature profile of the background plasma cannot be ignored while deriving scaling laws; the specification of the central or the bulk temperature alone is insufficient.Quantitative data are provided for the magnitudes of various additional processes such as the anomalous thermal conduction across the field lines or the grad(B)-induced drift of the shielding cloud surrounding the pellet.The modelling of supersonic gas jets, a fuelling method that appears to be an alternative to pellet injection, is also considered. Since the massive stream of a cold gas represents a disturbance for the recipient plasma similar to that of a pellet, its dynamics can be described by the same means as the evolution of pellet clouds.

show abstract

The dc electrical coupling of flow vortices and flow channels in the magnetosphere to the resistive ionosphere

Borovsky¹,

Bonnell²

2001

J. Geophys. Res.

View full text Add to dashboard Cite

Abstract. The dc electrical coupling of magnetospheric flow vortices and magnetospheric flow channels to the ionosphere is numerically calculated. The equations governing the coupling are derived from current continuity plus Ohm's laws taken for the regions of field-aligned current between the ionosphere and magnetosphere and for the Pedersen layer of the ionosphere. For vortices the strength of the coupling (as measured by fractional penetration of the magnetospheric electric fields down to the ionosphere and by the amount of power dissipation) varies, as expected, with the size of the vortex footprint in the ionosphere. However, because of the diode-like nature of the field-aligned currents, the coupling also varies with sign of the vorticity' Positive center vortices (vorticity antiparallel to B) couple much more strongly than do negative center vortices (vorticity parallel to B). Negative center vortices tend to dissipate most of their energy in parallel currents, whereas positive center vortices dissipate most of their energy in Pedersen currents. The electric fields of positive center vortices spread across B as they connect to the ionosphere, whereas the electric fields of negative center vortices stay confined to their magnetic footprints. Consequently, positive center vortices in the magnetosphere produce quasi-circular vortices of flow in the ionosphere whereas negative center vortices in the magnetosphere produce narrow east-west-elongated vortices of flow in the ionosphere. Negative center vortices in the magnetosphere could produce east-west-aligned bright arclike features, and positive center vortices could produce east-west-aligned black-arc features imbedded in large circular patches of aurora. Flow channels in the magnetosphere drive field-aligned currents into the ionosphere' The upward field-aligned current on the negative-charged edge of the channel tends to spread across B, whereas downward current on the positive charge edge tends to stay confined. In the magnetosphere the current spreading results in a back emf that produces a backward flow outside the flow channel on the negative-charged edge.

show abstract

Physics issues associated with low- beta plasma generators

Cited by 5 publications

References 33 publications

Differences between CME‐driven storms and CIR‐driven storms

Differences between CME‐driven storms and CIR‐driven storms

Pellet – Plasma Interaction: an Analysis of Pellet Injection Experiments by Means of a Multi‐Dimensional MHD Pellet Code

The dc electrical coupling of flow vortices and flow channels in the magnetosphere to the resistive ionosphere

Contact Info

Product

Resources

About