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Motivation
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tarix | 28.07.2018 | ölçüsü | 3,69 Mb. | | #59471 |
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Motivation Motivation - The relationship between plasma rotation and RWM stability in NSTX is more complex than simple models suggest, and kinetic theory has the potential to explain it.
Outline - The MISK code is used to calculate RWM stability.
- Kinetic theory matches NSTX experimental results of instability at moderate rotation.
- Kinetic theory can match the evolution of a shot.
- DIII-D results suggest the importance of hot ions.
Written by Bo Hu, University of Rochester - Hu, Betti, PRL, 2004 and Hu, Betti, and Manickam, POP, 2005
Uses a perturbative calculation, with marginal stability eigenfunction from the PEST code. Calculation of δWK includes the effects of: - Trapped Ions
- Trapped Electrons
- Circulating Ions
- Alfven Layers
- Hot Ions
Density and temperature profiles are self-similarly scaled while keeping β constant (ie, n*2 and T/2 or n/2 and T*2). - Density and temperature profiles are self-similarly scaled while keeping β constant (ie, n*2 and T/2 or n/2 and T*2).
- We find a low rotation “critical” threshold.
- However, there is also a band of marginally stable moderate rotation, and it is here that the experiment goes unstable.
Examining the evolution of a shot - For NSTX shot 121083, β and ωφ are relatively constant leading up the the RWM collapse.
- Calculation of the RWM kinetic growth rate for multiple equilibria shows a turn towards instability just before the RWM.
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