Experimental aspects of effects of high-energy particles on Alfven modes

Conference · Sat Oct 01 04:00:00 EDT 1994

OSTI ID:10103050

Heidbrink, W W

Global Alfven modes are observed in a number of tokamaks, including DIII-D and TFTR. Instabilities occur during neutral-beam injection and during fast-wave ICRF heating, and may recently have been observed during alpha-particle heating. Identification of toroidicity-induced Alfven eigenmodes (TAE) is based primarily on the scaling of the real frequency of the mode. Other modes, including the beta-induced Alfven eigenmode (BAE), are also observed. The stability threshold of TAE modes agree (to within a factor of two) with theoretical predictions. Toroidal mode numbers of n = 2-6 are usually most unstable, as theoretically expected. Measurements of the poloidal and radial mode structure are consistent with theoretical predictions, but the uncertainties are large. Both TAE and BAE modes can cause large, concentrated losses of fast ions. Phenomenologically, beam-driven Alfven modes usually {open_quotes}saturate{close_quotes} through bursts that expel beam ions, while modes observed during ICPF heating approach a steady saturation amplitude.

• Research Organization: General Atomics, San Diego, CA (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC03-89ER51114
• OSTI ID: 10103050
• Report Number(s): GA-A--21811; CONF-9408176--3; ON: DE95003383
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700340
ALFVEN WAVES
ICR HEATING
NEUTRAL ATOM BEAM INJECTION
PARTICLE LOSSES
PLASMA INSTABILITY
PLASMA WAVES, OSCILLATIONS, AND INSTABILITIES
TOKAMAK DEVICES