Wall stabilization effects in DIII-D high beta discharges

Conference · Fri Jul 01 04:00:00 EDT 1994

OSTI ID:10176750

Strait, E J; Taylor, T S; Turnbull, A D; Ferron, J R; Lao, L L; Thompson, S J ^[1]; Rice, B; Wroblewski, D ^[2]; Sauter, O ^[3]

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1. General Atomics, San Diego, CA (United States)
2. Lawrence Livermore National Lab., CA (United States)
3. Centre de Recherches en Physique des Plasmas, Lausanne (Switzerland)

Recent high beta discharges in DIII-D, reaching values up to {beta} = 12.5%, demonstrate that a resistive wall can stabilize low-n MHD modes in a rotating plasma. The maximum beta values reached in discharges with broad current profiles (internal inductance {ell}{sub i} {approx} 0.7) are up to 40% greater than the limit predicted by ideal MHD stability calculations in the absence of a wall, but are consistent with predicted limits assuming a perfectly conducting wall at the position of the vacuum vessel. This wall stabilization is observed for time scales long compared with the resistive penetration time of the wall. Plasma rotation is essential to the stabilization, and instabilities with characteristics of the predicted ``resistive wall`` mode are observed only when the rotation velocity approaches zero at the mode rational surface.

• Research Organization: General Atomics, San Diego, CA (United States); Lawrence Livermore National Lab., CA (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC03-89ER51114; W-7405-ENG-48
• OSTI ID: 10176750
• Report Number(s): GA-A--21754; CONF-940635--9; ON: DE94017509; BR: 35AT10020/35KC07000
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700340
700420
DOUBLET-3 DEVICE
FIRST WALL
HIGH-BETA PLASMA
IMPEDANCE
KINK INSTABILITY
MHD EQUILIBRIUM
PLASMA WAVES, OSCILLATIONS, AND INSTABILITIES
PLASMA-FACING COMPONENTS
ROTATING PLASMA
STABILIZATION