Charge-exchange measurements of MHD activity during neutral beam injection in the Princeton Large Torus and the Poloidal Divertor Experiment
The horizontally scanning, multiangle charge-exchange analyzers on the Princeton Large Torus (PLT) and the Poloidal Divertor Experiment (PDX) were used to study the effects of MHD activity on the background ion distribution function and on the beam ion slowing-down process during high-power neutral injection. Sawtooth oscillations were observed in the fast ion flux on PLT and PDX, and measurements with neutral beams providing local neutral density enhancement indicate that ions are transported radially when these events occur. With near-perpendicular injection in PDX, at the lower toroidal fields necessary to maximize beta, rapid, repetitive bursts of greatly enhanced charge-exchange flux were observed. These are associated with the ''fishbone'' MHD instability, and a substantial depletion of the perpendicular slowing-down spectrum below the injection energy was seen. A simple phenomenological model for this loss mechanism was developed, and its use in simulation codes has been successful in providing good agreement with the data. The behavior and characteristics of this model are well matched by the direct theoretical calculations.
- Research Organization:
- Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
- DOE Contract Number:
- AC02-76CH03073
- OSTI ID:
- 5317045
- Report Number(s):
- PPPL-2359; ON: DE86015511
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PDX DEVICES
CHARGE EXCHANGE
NEUTRAL ATOM BEAM INJECTION
PLASMA MACROINSTABILITIES
PLT DEVICES
DISTRIBUTION FUNCTIONS
ION BEAMS
BEAM INJECTION
BEAMS
CLOSED PLASMA DEVICES
FUNCTIONS
INSTABILITY
PLASMA INSTABILITY
THERMONUCLEAR DEVICES
THERMONUCLEAR REACTORS
TOKAMAK DEVICES
TOKAMAK TYPE REACTORS
700104* - Fusion Energy- Plasma Research- Plasma Kinetics-Experimental- (-1987)