Magnetic diagnostics for equilibrium reconstructions in the presence of nonaxisymmetric eddy current distributions in tokamaks (invited)

Journal Article · Fri Oct 15 04:00:00 EDT 2010 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.3484488· OSTI ID:22055843

Berzak, L; Jones, A D; Kaita, R; Kozub, T; Logan, N; Majeski, R; Menard, J; Zakharov, L ^[1]

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1. Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States)

The lithium tokamak experiment (LTX) is a modest-sized spherical tokamak (R{sub 0}=0.4 m and a=0.26 m) designed to investigate the low-recycling lithium wall operating regime for magnetically confined plasmas. LTX will reach this regime through a lithium-coated shell internal to the vacuum vessel, conformal to the plasma last-closed-flux surface, and heated to 300-400 deg. C. This structure is highly conductive and not axisymmetric. The three-dimensional nature of the shell causes the eddy currents and magnetic fields to be three-dimensional as well. In order to analyze the plasma equilibrium in the presence of three-dimensional eddy currents, an extensive array of unique magnetic diagnostics has been implemented. Sensors are designed to survive high temperatures and incidental contact with lithium and provide data on toroidal asymmetries as well as full coverage of the poloidal cross-section. The magnetic array has been utilized to determine the effects of nonaxisymmetric eddy currents and to model the start-up phase of LTX. Measurements from the magnetic array, coupled with two-dimensional field component modeling, have allowed a suitable field null and initial plasma current to be produced. For full magnetic reconstructions, a three-dimensional electromagnetic model of the vacuum vessel and shell is under development.

• OSTI ID: 22055843
• Journal Information: Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 10 Vol. 81; ISSN 0034-6748; ISSN RSINAK
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ASYMMETRY
COMPUTERIZED SIMULATION
EDDY CURRENTS
LITHIUM
MAGNETIC FIELDS
MAGNETIC SURFACES
PLASMA CONFINEMENT
SPATIAL DISTRIBUTION
SPHERICAL CONFIGURATION
START-UP
TEMPERATURE RANGE 0400-1000 K
THREE-DIMENSIONAL CALCULATIONS
TOKAMAK DEVICES
TOROIDAL CONFIGURATION
TWO-DIMENSIONAL CALCULATIONS
WALL EFFECTS