Islandinduced bootstrap current on the saturation of a thin magnetic island in tokamaks
Abstract
It is shown that islandinduced bootstrap current density, which results from the symmetry breaking of the vertical bar B vertical bar when an island is embedded in the equilibrium magnetic field B, modifies the evolution equation and the saturation level for a thin magnetic island in tokamaks. This modification is independent of the fraction of the equilibrium bootstrap current density. It is found that islandinduced bootstrap current density increases the saturation level for modes with positive values of {delta}{sup '}. Here, {delta}{sup '} is the stability parameter for the linear tearing modes.
 Authors:
 Engineering Physics Department, University of Wisconsin, Madison, Wisconsin 53706 (United States)
 Publication Date:
 OSTI Identifier:
 20974936
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Physics of Plasmas; Journal Volume: 14; Journal Issue: 4; Other Information: DOI: 10.1063/1.2730500; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; BOOTSTRAP CURRENT; EQUILIBRIUM; ISLANDS; MAGNETIC FIELDS; MAGNETIC ISLANDS; MAGNETOHYDRODYNAMICS; PLASMA; PLASMA CONFINEMENT; TEARING INSTABILITY; TOKAMAK DEVICES
Citation Formats
Shaing, K. C. Islandinduced bootstrap current on the saturation of a thin magnetic island in tokamaks. United States: N. p., 2007.
Web. doi:10.1063/1.2730500.
Shaing, K. C. Islandinduced bootstrap current on the saturation of a thin magnetic island in tokamaks. United States. doi:10.1063/1.2730500.
Shaing, K. C. Sun .
"Islandinduced bootstrap current on the saturation of a thin magnetic island in tokamaks". United States.
doi:10.1063/1.2730500.
@article{osti_20974936,
title = {Islandinduced bootstrap current on the saturation of a thin magnetic island in tokamaks},
author = {Shaing, K. C.},
abstractNote = {It is shown that islandinduced bootstrap current density, which results from the symmetry breaking of the vertical bar B vertical bar when an island is embedded in the equilibrium magnetic field B, modifies the evolution equation and the saturation level for a thin magnetic island in tokamaks. This modification is independent of the fraction of the equilibrium bootstrap current density. It is found that islandinduced bootstrap current density increases the saturation level for modes with positive values of {delta}{sup '}. Here, {delta}{sup '} is the stability parameter for the linear tearing modes.},
doi = {10.1063/1.2730500},
journal = {Physics of Plasmas},
number = 4,
volume = 14,
place = {United States},
year = {Sun Apr 15 00:00:00 EDT 2007},
month = {Sun Apr 15 00:00:00 EDT 2007}
}
DOI: 10.1063/1.2730500
Other availability
Save to My Library
You must Sign In or Create an Account in order to save documents to your library.

Magnetic Island Induced Bootstrap Current on Island Dynamics in Tokamaks
When a magnetic island is embedded in toroidally symmetric tokamaks, the toroidal symmetry in B is broken [K. C. Shaing, Phys. Rev. Lett. 87, 245003 (2001)] . Here, B is the magnetic field. This broken symmetry induces an additional bootstrap current density in the vicinity of the island. It is illustrated that this island induced bootstrap current density modifies the island evolution equation and imposes a lower limit on the absolute value of the tearing mode stability parameter {Delta}{prime} for the island to be unstable. This lower limit depends on the local poloidal plasma beta {beta}{sub p}, the ratio ofmore » 
Magnetic island induced bootstrap current on island dynamics in tokamaks
When a magnetic island is embedded in toroidally symmetric tokamaks, the toroidal symmetry in B is broken [K. C. Shaing, Phys. Rev. Lett. 87, 245003 (2001)]. Here, B is the magnetic field. This broken symmetry induces an additional bootstrap current density in the vicinity of the island. It is illustrated that this island induced bootstrap current density modifies the island evolution equation and imposes a lower limit on the absolute value of the tearing mode stability parameter {delta}{sup '} for the island to be unstable. This lower limit depends on the local poloidal plasma beta {beta}{sub p}, the ratio ofmore » 
Combined RF current drive and bootstrap current in tokamaks
By calculating radio frequency current drive (RFCD) and the bootstrap current in a consistent kinetic manner, we find synergistic effects in the total noninductive current density in tokamaks [1]. We include quasilinear diffusion in the Drift Kinetic Equation (DKE) in order to generalize neoclassical theory to highly nonMaxwellian electron distributions due to RFCD. The parallel plasma current is evaluated numerically with the help of the FASTEP FokkerPlanck code [2]. Current drive efficiency is found to be significantly affected by neoclassical effects, even in cases where only circulating electrons interact with the waves. Predictions of the current drive efficiency are mademore » 
Finiteaspectratio effects on the bootstrap current in tokamaks
The bootstrap current in tokamaks is determined in the low collision frequency regime for arbitrary values of the aspect ratio and effect charge. The resulting expression should be useful for a quantitative analysis of currents in tokamaks.