The effect of a steady azimuthal field on rotating magnetic field current drive

1987 ◽  
Vol 37 (3) ◽  
pp. 423-433 ◽  
Author(s):  
W. K. Bertram
Keyword(s):  
Magnetic Field ◽  
Plasma Column ◽  
Substantial Reduction ◽  
Current Drive ◽  
Rotating Magnetic Field ◽  
Azimuthal Magnetic Field ◽  
Low Resistivity ◽  
Cylindrical Plasma ◽  
Resistive Plasma ◽  
Cylindrical Plasma Column

The method of generating steady azimuthal currents in a cylindrical plasma column by means of a rotating magnetic field is investigated numerically and analytically for the case where an external steady azimuthal magnetic field is applied to the plasma. For a plasma of low resistivity, the effect of imposing a strong azimuthal field is a substantial reduction in the amount of current that can be driven. For a resistive plasma the effect is more complicated. In some cases the azimuthal field enhances current drive as has been observed in recent experiments.

Analytical solutions for the current driven by a rotating magnetic field in a cylindrical plasma with azimuthal field

1988 ◽  
Vol 40 (1) ◽  
pp. 109-126 ◽  
Author(s):  
Peter A. Watterson
Keyword(s):  
Magnetic Field ◽  
Skin Depth ◽  
Current Drive ◽  
Rotating Magnetic Field ◽  
Toroidal Field ◽  
High Resistivity ◽  
Axial Field ◽  
Low Resistivity ◽  
Cylindrical Plasma ◽  
Synchronous Rotation

The generation of steady currents by a rotating magnetic field (RMF) in a cylindrical plasma permeated by a steady azimuthal (or toroidal) magnetic field is studied analytically. Solutions are presented for the following limiting cases:(1) high resistivity, when the penetration of the RMF and current drive are confined to a skin depth layer;(2) low resistivity and weak toroidal field (small compared with the RMF), when the RMF fully penetrates the plasma and the toroidal current is that due to nearly synchronous rotation of the electron fluid with the RMF;(3) low resistivity and intermediate toroidal field (comparable to the axial field associated with synchronous current), when the toroidal current is a significant fraction of its synchronous value, but large oscillating fields are generated; and(4) strong toroidal field, when the RMF fully penetrates the plasma but current is only driven in a boundary layer at the plasma edge.The applicability of these solutions is governed by the relative sizes of three dimensionless parameters.

Steady-state solutions for the penetration of a rotating magnetic field into a plasma column

1981 ◽  
Vol 26 (3) ◽  
pp. 441-453 ◽  
Author(s):  
Ieuan R. Jones ◽  
Waheed N. Hugrass
Keyword(s):  
Magnetic Field ◽  
Steady State ◽  
Plasma Column ◽  
Skin Effect ◽  
Rotation Frequency ◽  
Rotating Magnetic Field ◽  
Electron Current ◽  
Plasma Cylinder ◽  
Resistive Plasma ◽  
Steady State Solutions

The penetration of an externally applied rotating magnetic field into a plasma cylinder is examined. Steady-state solutions of an appropriate set of magneto-fluid equations show that, provided the amplitude and rotation frequency of the field are suitably chosen, the penetration is not limited by the usual classical skin effect. The enhanced penetration of the rotating field is accompanied by the generation of a unidirectional azimuthal electron current which is totally absent in a purely resistive plasma cylinder.

Radial distribution of the plasma potential in a cylindrical plasma column with a longitudinal magnetic field

2021 ◽  
Vol 87 (4) ◽  
Author(s):  
G. Liziakin ◽  
A. Oiler ◽  
A. Gavrikov ◽  
N. Antonov ◽  
V. Smirnov
Keyword(s):  
Magnetic Field ◽  
Electric Fields ◽  
Radial Distribution ◽  
Plasma Column ◽  
Radial Profile ◽  
Plasma Potential ◽  
Symmetric System ◽  
Axially Symmetric ◽  
Cylindrical Plasma ◽  
Cylindrical Plasma Column

The possibility of controlling the electrostatic field distribution in plasma has yielded wide prospects for modern technologies. As a magnetic field primarily allows for creating electric fields in plasma, it serves as an additional obstacle for the current flow through a medium. In the present paper, an axially symmetric system is considered in which the magnetic field is directed along the axis and concentric electrodes are located at the ends. The electrodes are negatively biased. A model which solves the problem of the radial distribution of the plasma potential inside the cylindrical plasma column supported by the end electrodes is proposed. The most commonly encountered configurations of the electrical connection for the end electrodes are considered, and the particular solutions to the problem of the radial distribution are presented. The contribution of ions and electrons to the transverse conductivity is evaluated in detail. The influence of a thermionic element on the radial profile of the plasma potential is considered. To verify the proposed model, an experimental study of the reflex discharge is carried out with both cold electrodes and a thermionic element on the axis. A comparison of the computational model results with experimental data is given. The presented model makes it possible to solve the problem concerning the plasma potential distribution in the case of an arbitrary number of end electrodes, and also to take into account the inhomogeneity of the distribution of plasma density, neutral gas pressure and electron temperature along the radius.

Helicon waves in a cylindrical plasma column

1994 ◽  
Vol 52 (3) ◽  
pp. 465-470 ◽  
Author(s):  
M. Shoucri
Keyword(s):  
Plasma Column ◽  
Body Wave ◽  
Low Frequency ◽  
Transverse Magnetic ◽  
Current Drive ◽  
Cylindrical Plasma ◽  
Helicon Wave ◽  
Collisional Damping ◽  
Helicon Waves ◽  
Cylindrical Plasma Column

Helicon waves have been used for efficiently coupling radio-frequency power to plasmas, and are studied for their potential application for low-frequency current drive in tokamks. In this paper the electromagnetic field components and the dispersion relation for azimuthally independent helicon-wave oscillations in a cylindrical plasma column are derived. The coupling of transverse electric TE and transverse magnetic TM modes associated with these oscillations is discussed. The effect of the collisional damping on determining the nature of the TM mode (either surface wave or body wave) is analysed.

scholarly journals Effect of the Motion of Ions on the Penetration of a Rotating Magnetic Field into a Plasma Cylinder

1998 ◽  
Vol 51 (5) ◽  
pp. 859 ◽  
Author(s):  
W. N. Hugrass
Keyword(s):  
Magnetic Field ◽  
Equations Of Motion ◽  
Current Drive ◽  
Rotating Magnetic Field ◽  
Simplified Model ◽  
Plasma Cylinder ◽  
Cylindrical Plasma ◽  
Nonlinear Mechanism

A simplified model for the rotating magnetic field (RMF) current drive in an infinitely long cylindrical plasma is considered. The model allows for motion of both the electron and ion fluids in the z and θ directions. It is assumed that equilibrium is satisfied on the average and hence the r components of the equations of motion are not considered. It is shown that the motion of the ion fluid does not introduce any significant modifications to the nonlinear mechanism for the penetration of the RMF into the plasma.

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