Investigation of global Alfven instabilities in the Tokamak Fusion Test Reactor

Journal Article · Wed Jul 01 04:00:00 EDT 1992 · Physics of Fluids B; (United States)

DOI:https://doi.org/10.1063/1.860462· OSTI ID:7285230

Wong, K L; Durst, R; Fonck, R J; Paul, S F; Roberts, D R; Fredrickson, E D; Nazikian, R; Park, H K; Bell, M; Bretz, N L; Budny, R; Cheng, C Z; Cohen, S; Hammett, G W; Jobes, F C; Johnson, L; Meade, D M; Medley, S S; Mueller, D; Nagayama, Y ; Owens, D K; Sabbagh, S; Synakowski, E J ^[1]

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1. Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States)

Toroidal Alfven eigenmodes (TAE) were excited by the energetic neutral beam ions tangentially injected into plasmas at low magnetic field in the Tokamak Fusion Test Reactor (TFTR) ({ital Proceedings} {ital of} {ital the} 11{ital th} {ital International} {ital Conference} {ital on} {ital Plasma} {ital Physics} {ital and} {ital Controlled} {ital Fusion} {ital Research} (IAEA, Vienna, 1987), Vol. 1, p. 51). The injection velocities were comparable to the Alfven speed. The modes were identified by measurements from Mirnov coils and beam emission spectroscopy (BES). TAE modes appear in bursts whose repetition rate increases with beam power. The neutron emission rate exhibits sawtoothlike behavior and the crashes always coincide with TAE bursts. This indicates ejection of fast ions from the plasma until these modes are stabilized. The dynamics of growth and stabilization were investigated at various plasma currents and magnetic fields. The results indicate that the instability can effectively clamp the number of energetic ions in the plasmas. The observed instability threshold is discussed in light of recent theories. In addition to these TAE modes, intermittent oscillations at three times the fundamental TAE frequency were observed by Mirnov coils, but no corresponding signal was found in BES. It appears that these high-frequency oscillations do not have a direct effect on the plasma neutron source strength.

• DOE Contract Number: AC02-76CH03073
• OSTI ID: 7285230
• Journal Information: Physics of Fluids B; (United States), Journal Name: Physics of Fluids B; (United States) Vol. 4:7; ISSN 0899-8221; ISSN PFBPE
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700310 -- Plasma Confinement-- (1992-)
700340* -- Plasma Waves
Oscillations
& Instabilities-- (1992-)
ALFVEN WAVES
ALPHA PARTICLES
BEAMS
CHARGED PARTICLES
CLOSED PLASMA DEVICES
EMISSION SPECTRA
HYDROMAGNETIC WAVES
ION BEAMS
PLASMA DENSITY
SPECTRA
TFTR TOKAMAK
THERMONUCLEAR DEVICES
TOKAMAK DEVICES