Resistive wall stabilized operation in rotating high beta NSTX plasmas
Artikel i vetenskaplig tidskrift, 2006

The National Spherical Torus Experiment (NSTX) has demonstrated the advantages of low aspect ratio geometry in accessing high toroidal and normalized plasma beta, and βN ≡ 10 8〈βt〉 aB0/Ip. Experiments have reached βt = 39% and βN = 7.2 through boundary and profile optimization. High βN plasmas can exceed the ideal no-wall stability limit, βNno-wall, for periods much greater than the wall eddy current decay time. Resistive wall mode (RWM) physics is studied to understand mode stabilization in these plasmas. The toroidal mode spectrum of unstable RWMs has been measured with mode number n up to 3. The critical rotation frequency of Bondeson-Chu, Ωcrit = ωA/(4q2), describes well the RWM stability of NSTX plasmas when applied over the entire rotation profile and in conjunction with the ideal stability criterion. Rotation damping and global rotation collapse observed in plasmas exceeding βNno-wall differs from the damping observed during tearing mode activity and can be described qualitatively by drag due to neoclassical toroidal viscosity in the helically perturbed field of an ideal displacement. Resonant field amplification of an applied n = 1 field perturbation has been measured and increases with increasing βN. Equilibria are reconstructed including measured ion and electron pressure, toroidal rotation and flux isotherm constraint in plasmas with core rotation ω/ωA up to 0.48. Peak pressure shifts of 18% of the minor radius from the magnetic axis have been reconstructed.

Författare

S. A. Sabbagh

Columbia University in the City of New York

A. C. Sontag

Columbia University in the City of New York

J. Bialek

Columbia University in the City of New York

D. A. Gates

Princeton Plasma Physics Laboratory

A. H. Glasser

Los Alamos National Laboratory

J. Menard

Princeton Plasma Physics Laboratory

W. Zhu

Columbia University in the City of New York

M. G. Bell

Princeton Plasma Physics Laboratory

R. E. Bell

Princeton Plasma Physics Laboratory

Anders Bondeson

Chalmers, Tillämpad mekanik, Beräkningsteknik

C. E. Bush

Oak Ridge National Laboratory

J. D. Callen

University of Wisconsin Madison

M. S. Chu

General Atomics

C. C. Hegna

University of Wisconsin Madison

S. M. Kaye

Princeton Plasma Physics Laboratory

L. L. Lao

General Atomics

B. P. LeBlanc

Princeton Plasma Physics Laboratory

Yueqiang Liu

Chalmers University of Technology

R. Maingi

Oak Ridge National Laboratory

D. Mueller

Princeton Plasma Physics Laboratory

K. C. Shaing

University of Wisconsin Madison

D. Stutman

Johns Hopkins University

K. Tritz

Johns Hopkins University

C. Zhang

Institute of Plasma Physics Chinese Academy of Sciences

Nuclear Fusion

0029-5515 (ISSN)

Vol. 46 635-644

Ämneskategorier

Maskinteknik

DOI

10.1088/0029-5515/46/5/014