High beta and second stability region transport and stability analysis
This report describes ideal and resistive studies of high-beta plasmas and of the second stability region. Emphasis is focused on supershot'' plasmas in TFIR where MHD instabilities are frequently observed and which spoil their confinement properties. Substantial results are described from the analysis of these high beta poloidal plasmas. During these studies, initial pressure and safety factor profiles were obtained from the TRANSP code, which is used extensively to analyze experimental data. Resistive MBD stability studies of supershot equilibria show that finite pressure stabilization of tearing modes is very strong in these high {beta}p plasmas. This has prompted a detailed re-examination of linear tearing mode theory in which we participated in collaboration with Columbia University and General Atomics. This finite pressure effect is shown to be highly sensitive to small scale details of the pressure profile. Even when an ad hoc method of removing this stabilizing mechanism is implemented, however, it is shown that there is only superficial agreement between resistive MBD stability computation and the experimental data. While the mode structures observed experimentally can be found computationally, there is no convincing correlation with the experimental observations when the computed results are compared with a large set of supershot data. We also describe both the ideal and resistive stability properties of TFIR equilibria near the transition to the second region. It is shown that the highest {beta} plasmas, although stable to infinite-n ideal ballooning modes, can be unstable to the so called infernal'' modes associated with small shear. The sensitivity of these results to the assumed pressure and current density profiles is discussed. Finally, we describe results from two collaborative studies with PPPL. The first involves exploratory studies of the role of the 1/1 mode in tokamaks and, secondly, a study of sawtooth stabilization using ICRF.
- Research Organization:
- Grumman Corp., Princeton, NJ (United States)
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG02-89ER51124
- OSTI ID:
- 7192576
- Report Number(s):
- DOE/ER/51124-7; ON: DE93000886
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
MHD EQUILIBRIUM
STABILITY
PLASMA INSTABILITY
CHARGED-PARTICLE TRANSPORT
COMPUTERIZED SIMULATION
CURRENT DENSITY
HIGH-BETA PLASMA
ICR HEATING
PROGRESS REPORT
SAWTOOTH OSCILLATIONS
TFTR TOKAMAK
CLOSED PLASMA DEVICES
DOCUMENT TYPES
EQUILIBRIUM
HEATING
HIGH-FREQUENCY HEATING
INSTABILITY
OSCILLATIONS
PLASMA
PLASMA HEATING
RADIATION TRANSPORT
SIMULATION
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
700370* - Plasma Fluid & MHD Properties- (1992-)
700340 - Plasma Waves
Oscillations
& Instabilities- (1992-)