Enhanced pinch effect due to the electrostatic potential

Journal Article · Mon Oct 01 00:00:00 EDT 1990 · Physics of Fluids B; (USA)

DOI:https://doi.org/10.1063/1.859500· OSTI ID:6477869

Shaing, K C ^[1]; Hazeltine, R D ^[2]

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1. Oak Ridge National Laboratory, Oak Ridge, TN (USA)
2. Institute for Fusion Studies, The University of Texas at Austin, Austin, TX (USA) Department of Physics, The University of Texas at Austin, Austin, TX (USA)

An inward particle pinch appears necessary to explain experimental results in tokamaks. Neither the neoclassical pinch effect, which is too small, nor the off-diagonal quasilinear term, which is usually outward in the trapped particle regime, can account for the observations. A mechanism for an enhanced inward pinch is proposed, based on results for an asymmetric magnetic field bump (Phys. Fluids {bold 15}, 2211 (1972)). Because turbulent fluctuations also break toroidal symmetry, an enhanced inward pinch driven by the fluctuations and the Ohmic inductive field {ital E} is expected. To demonstrate this effect, an inward particle flux is calculated for a model tokamak configuration that has an electrostatic potential bump {Phi}{sub 0} at toroidal angle {zeta}=2{pi}. For the parameter regime {ital r}/{ital R}{lt}{ital e}{Phi}{sub 0}/{ital T}{sub {ital e}}{lt}1, the flux is found to be {Gamma}={minus}4.47{ital K}({ital q})({ital r}/{ital R}){ital L}({Phi}{sub 0})({ital v}{sub {ital te}}/{ital R}{nu}{ital e}) {sup 1/2}{ital cNE}/{ital B}, where {ital r}({ital R}) is minor (major) radius, {ital B} is the magnetic field strength, {ital v}{sub {ital te}} is the electron thermal speed, {nu}{sub {ital e}} is the electron--ion collision frequency, {ital q} is the safety factor, and {ital K}({ital q}) and {ital L}({Phi}{sub 0}) are functions of {ital q} and {Phi}{sub 0}, respectively. The results are also applicable to an asymmetric potential bump created externally to enhance the inward pinch flux of high energy, collisionless particles.

• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6477869
• Journal Information: Physics of Fluids B; (USA), Vol. 2:10; ISSN 0899-8221
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
COLLISIONAL PLASMA
PINCH EFFECT
TOKAMAK DEVICES
PLASMA CONFINEMENT
ASYMMETRY
COULOMB FIELD
ELECTRON-ION COLLISIONS
FLUCTUATIONS
MAGNETIC FIELDS
TOROIDAL CONFIGURATION
TRAPPING
TURBULENCE
ANNULAR SPACE
CLOSED CONFIGURATIONS
CLOSED PLASMA DEVICES
COLLISIONS
CONFIGURATION
CONFINEMENT
ELECTRIC FIELDS
ELECTRON COLLISIONS
ION COLLISIONS
MAGNETIC FIELD CONFIGURATIONS
PLASMA
SPACE
THERMONUCLEAR DEVICES
VARIATIONS
700107* - Fusion Energy- Plasma Research- Instabilities