scholarly journals Current neutralization of ion beam rotating and propagating in plasma

1987 ◽  
Vol 5 (3) ◽  
pp. 481-493 ◽  
Author(s):  
Takayuki Aoki ◽  
Keishiro Niu
Keyword(s):  
Magnetic Field ◽  
Plasma Frequency ◽  
Ion Beam ◽  
Electron Plasma ◽  
Background Plasma ◽  
Plasma Current ◽  
Time Duration ◽  
Low Density Plasma ◽  
The Magnetic Field ◽  
Uniform Plasma

The current-neutralization fraction of a rotating and propagating light ion beam (LIB) injected into a low density plasma is investigated numerically. The beam space charge is essentially neutralized by a redistribution of the background plasma electrons in a time duration equal to the inverse of electron plasma frequency. When the density of the background plasma is comparable with that of the beam, incomplete current neutralization occurs because the strong magnetic field induced by the intense ion beam restricts the return plasma current.In the simulation, the ion beam and the background plasma are treated as the fluids coupled with Maxwell's equations and Ohm's law, including the effect of the magnetic field on electrical conductivity. The calculations assume that the ion beam is injected in an unsteady fashion into the uniform plasma. It is found that the return current strongly depends on the density of the background plasma. The beam deceleration and the acceleration of the beam head and tail are also considered.

Magnetic stabilization of transverse plasma instabilitiest

1971 ◽  
Vol 5 (3) ◽  
pp. 467-474 ◽  
Author(s):  
B. Buti ◽  
G. S. Lakhina
Keyword(s):  
Magnetic Field ◽  
Growth Rate ◽  
Cyclotron Frequency ◽  
Plasma Frequency ◽  
Electron Plasma ◽  
Wave Number ◽  
Uniform External Magnetic Field ◽  
Magnetic Stabilization ◽  
Streaming Velocity ◽  
The Magnetic Field

Waves, propagating transverse to the direction of the streaming of a plasma in the presence of a uniform external magnetic field, are unstable if the streaming exceeds a certain minimum value. The magnetic field reduces the growth rate of this instability, and also increases the value of the minimum streaming velocity, above which the system is unstable. The thermal motions in the plasma, however, tend to stabilize the system if the magnetic field is weak (i.e. , Ω being the electron cyclotron frequency, k the characteristic wave-number, and Vt the thermal velocity); but, in case of strong magnetic field (i.e. ), they increase the growth rate, provided (ωp being the electron plasma frequency).

Wave propagation in a moving plasma. Part 1. Wave propagation normal to the magnetic field and motion of the plasma along the magnetic field

1974 ◽  
Vol 11 (3) ◽  
pp. 389-395 ◽  
Author(s):  
D. N. Srivastava
Keyword(s):  
Magnetic Field ◽  
Wave Propagation ◽  
Dispersion Relation ◽  
Magnetic Fields ◽  
Plasma Frequency ◽  
Electron Plasma ◽  
Ordinary Wave ◽  
Moving Plasma ◽  
The Magnetic Field

The dispersion relation for a collisionless moving electron plasma, when the direction of motion is along the magnetic field, and that of the wave propagation normal to the magnetic field, is analysed. It is shown that in small magnetic fields the ordinary wave develops a new band of backward waves below the plasma frequency. When the frequency of the wave is higher than the plasma frequency, the effect of the motion of the plasma is identical to a deviation of the direction of propagation.

scholarly journals Stability properties of the electron return current for intense ion beam propagation through background plasma

2011 ◽  
Vol 29 (2) ◽  
pp. 269-273 ◽  
Author(s):  
V.N. Khudik ◽  
E.A. Startsev ◽  
R.C. Davidson
Keyword(s):  
Magnetic Field ◽  
Ion Beam ◽  
Longitudinal Velocity ◽  
Electron Plasma ◽  
Background Plasma ◽  
Surface Mode ◽  
Return Current ◽  
Stability Properties ◽  
New Feature ◽  
The Stability

AbstractWhen an intense ion beam propagates through a dense background plasma, its current is partially neutralized by the electron plasma return current. Due to the non-uniformity of the background plasma electrons longitudinal velocity profile ${\bar v}$(r), the flow can be unstable. The instability is similar to the Kelvin-Helmholz instability for the non-uniform flow of an incompressible neutral fluid, with the electrostatic potential playing the role of pressure. For the case of electron return current flow, the significant new feature is the presence of the partially self-neutralized magnetic field of the ion beam, which significantly affects the evolution of small-amplitude excitations. In this paper the stability properties of the flow of electrons making up the plasma return current is investigated using the macroscopic cold-fluid-Maxwell equations. It is shown that this flow may become unstable, but the instability growth rates are exponentially small. This unstable body mode is qualitatively different from previously studied surface-mode excitations of the electron plasma return current for an intense ion beam with a sharp radial boundary, which is found to be stable due to the stabilizing influence of the partially neutralized magnetic field of the ion beam.

Nonlinear evolution of a wave packet propagating along a hot magnetoplasma column

1987 ◽  
Vol 37 (1) ◽  
pp. 107-115
Author(s):  
B. Ghosh ◽  
K. P. Das
Keyword(s):  
Magnetic Field ◽  
Multiple Scales ◽  
Nonlinear Evolution ◽  
Axial Magnetic Field ◽  
Modulational Instability ◽  
Wave Train ◽  
Dielectric Medium ◽  
Ion Effects ◽  
The Magnetic Field ◽  
Uniform Plasma

The method of multiple scales is used to derive a nonlinear Schrödinger equation, which describes the nonlinear evolution of electron plasma ‘slow waves’ propagating along a hot cylindrical plasma column, surrounded by a dielectric medium and immersed in an essentially infinite axial magnetic field. The temperature is included as well as mobile ion effects for ail possible modes of propagation along the magnetic field. From this equation the condition for modulational instability for a uniform plasma wave train is determined.

The interface of a uniform plasma enveloped by the magnetic field of a system of line currents

1969 ◽  
Vol 3 (4) ◽  
pp. 651-660 ◽  
Author(s):  
C. Sozou
Keyword(s):  
Magnetic Field ◽  
Inverse Problem ◽  
Complex Variable ◽  
Field Boundary ◽  
Equilibrium Configurations ◽  
Minimum Number ◽  
The Magnetic Field ◽  
Uniform Plasma

It is shown that complex variable transformations, suitable for obtaining the solution for the field boundary of a system of line currents confined in one cavity by a perfectly conducting uniform plasma, can be used for obtaining the solution to the inverse problem where a perfectly conducting uniform plasma is confined in one cavity by a system of line currents. It is deduced that the minimum number of line currents for confining (not stably) a plasma is two. The equilibrium configurations for several special but simple cases are investigated and discussed.

Fast magnetic field penetration into low resistivity plasma

2017 ◽  
Vol 83 (1) ◽  
Author(s):  
Amnon Fruchtman
Keyword(s):  
Magnetic Field ◽  
Energy Dissipation ◽  
Electric Field ◽  
Density Gradient ◽  
Magnetic Energy ◽  
Measured Velocity ◽  
Magnetic Field Penetration ◽  
The Magnetic Field ◽  
Uniform Plasma ◽  
Field Penetration

Penetration of a magnetic field into plasma that is faster than resistive diffusion can be induced by the Hall electric field in a non-uniform plasma. This mechanism explained successfully the measured velocity of the magnetic field penetration into pulsed plasmas. Major related issues have not yet been resolved. Such is the theoretically predicted, but so far not verified experimentally, high magnetic energy dissipation, as well as the correlation between the directions of the density gradient and of the field penetration.

THE ADMITTANCE OF AN INFINITE CYLINDRICAL ANTENNA IN A LOSSY INCOMPRESSIBLE, ANISOTROPIC PLASMA

1967 ◽  
Vol 45 (12) ◽  
pp. 4019-4038 ◽  
Author(s):  
Edmund K. Miller
Keyword(s):  
Magnetic Field ◽  
Free Space ◽  
Cyclotron Frequency ◽  
Plasma Frequency ◽  
Floating Potential ◽  
Space Layer ◽  
Cylindrical Antenna ◽  
Warm Plasma ◽  
Positive Ion ◽  
Uniform Plasma

A numerical investigation of the admittance of an infinite, circular cylindrical antenna excited at a circumferential gap of nonzero thickness, and immersed in a lossy incompressible magnetoplasma with the antenna parallel to the static magnetic field is described. A concentric free-space layer (the vacuum sheath) which separates the antenna from the external uniform plasma is included in the analysis to approximate the positive ion sheath which may form about a body at floating potential in a warm plasma. The numerical results for the antenna admittance show that: (1) in the absence of a sheath, a sharp admittance maximum is found at the electron cyclotron frequency, with the maximum more pronounced when the plasma frequency exceeds the cyclotron frequency than for the converse case; (2) the vacuum sheath shifts upward in frequency and reduces in amplitude the admittance maximum which occurs for the sheathless case at the cyclotron frequency; (3) a kink or minimum in the admittance is found at the plasma frequency.

Ion beam excitation of ion-cyclotron waves and ion heating in plasmas with drifting ions

1978 ◽  
Vol 19 (2) ◽  
pp. 237-252 ◽  
Author(s):  
J. P. Hauck ◽  
H. Böhmer ◽  
N. Rynn ◽  
Gregory Benford
Keyword(s):  
Magnetic Field ◽  
Ion Beam ◽  
Ion Beams ◽  
Ion Heating ◽  
Ion Cyclotron Waves ◽  
Diffusion Effects ◽  
Ion Cyclotron ◽  
Cyclotron Mode ◽  
The Magnetic Field ◽  
Beam Excitation

Ion-cyclotron waves are excited by cesium and potassium ion beams in cesium and potassium Q-machine plasmas. The ion beams are injected along the magnetic field with care to avoid beam transverse velocities. The observed ion-cyclotron mode frequencies are below those driven by electron currents. These resonant instabilities are convective in character with small spatial growth rates ki/kr ≃ 0.05. Plasma ion heating is observed and is consistent with a model in which mode amplitudes are saturated by diffusion effects.

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