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Local Ion Velocity Measurements in the MST Saturated Single Helical Axis State
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| 자료유형 | 학위논문 |
|---|---|
| 서명/저자사항 | Local Ion Velocity Measurements in the MST Saturated Single Helical Axis State. |
| 개인저자 | Boguski, John . |
| 단체저자명 | The University of Wisconsin - Madison. Physics. |
| 발행사항 | [S.l.]: The University of Wisconsin - Madison., 2019. |
| 발행사항 | Ann Arbor: ProQuest Dissertations & Theses, 2019. |
| 형태사항 | 176 p. |
| 기본자료 저록 | Dissertations Abstracts International 81-03B. Dissertation Abstract International |
| ISBN | 9781085674249 |
| 학위논문주기 | Thesis (Ph.D.)--The University of Wisconsin - Madison, 2019. |
| 일반주기 |
Source: Dissertations Abstracts International, Volume: 81-03, Section: B.
Advisor: Nornberg, Mark |
| 이용제한사항 | This item must not be sold to any third party vendors. |
| 요약 | The first local velocity measurements of helical equilibrium plasmas in the RFP are made to characterize the equilibrium flow profile. In high current, low density MST plasmas, the island associated with the innermost resonant tearing mode can grow and envelop the magnetic axis, resulting in a saturated Single Helical Axis (SHAx) equilibrium. The process by which this self-organized transition occurs is not fully understood. Theory and modeling suggest that viscous dissipation or large flow or magnetic shear might stimulate the transition. Local, toroidally resolved non-axisymmetric velocity measurements are obtained with a CHERS diagnostic while using a resonant magnetic perturbation to control the orientation of the helical plasma. The axisymmetric part of the flow is a rigid-rotor-like poloidal flow and relatively flat toroidal flow. Outside of the core, r/a > 0.5, the non-axisymmetric flow shows variations of order 10 km/s and more structure than a simple sinusoidal variation matching the helical variation of the magnetic axis. The toroidally resolved helical flow shear measured by CHERS may be comparable to strength of the critical shear necessary to mute nonlinear coupling of tearing modes. Flow measurements are compared with preliminary NIMROD simulations of visco-resistive, single-fluid MHD in toroidal and cylindrical geometry with full and limited axial periodicity. Both measurements and toroidal simulations show stronger inboard flows relative to the outboard. In the experiment, the n = 5 component of the poloidal flow is phase shifted by ~0.7 rad from the reconnection-like flow observed in the simulations, possibly due to decoupling of the ion and electron fluids over much of the plasma. |
| 일반주제명 | Plasma physics. Physics. |
| 언어 | 영어 |
| 바로가기 | 
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