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The Influence of Boundary Conditions on Vertical Displacement Event Calculations
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| 자료유형 | 학위논문 |
|---|---|
| 서명/저자사항 | The Influence of Boundary Conditions on Vertical Displacement Event Calculations. |
| 개인저자 | Bunkers, Kyle J. |
| 단체저자명 | The University of Wisconsin - Madison. Physics. |
| 발행사항 | [S.l.]: The University of Wisconsin - Madison., 2019. |
| 발행사항 | Ann Arbor: ProQuest Dissertations & Theses, 2019. |
| 형태사항 | 239 p. |
| 기본자료 저록 | Dissertations Abstracts International 81-02B. Dissertation Abstract International |
| ISBN | 9781085633949 |
| 학위논문주기 | Thesis (Ph.D.)--The University of Wisconsin - Madison, 2019. |
| 일반주기 |
Source: Dissertations Abstracts International, Volume: 81-02, Section: B.
Advisor: Sovinec, Carl R. |
| 이용제한사항 | This item must not be sold to any third party vendors. |
| 요약 | Vertical Displacement Events (VDEs) are of concern for reactor grade-tokamaks due to the possibility of large horizontal and vertical forces. In order to investigate these events from a theoretical standpoint, numerical simulations are necessary. Plasma interacts with the wall during VDEs, so boundary conditions directly affect their simulated evolution. This work enhances and applies fluid-based numerical modeling of VDEs. Newly implemented boundary conditions are adapted from a previous analysis [J. Loizu, et. al. Phys. Plasmas 19, 122307 (2012)] and represent conditions at the magnetic presheath (MPS) entrance. At lowest order in the ratio of normal and tangential length scales, they impose outward parallel flow at the Chodura-Bohm speed [R. Chodura, Phys. Fluids, 25(9) (1982)] and thermally insulating conditions on electron temperature evolution. Axisymmetric calculations of a forced VDE with varying boundary conditions and thermal transport models are presented. The most comprehensive computation uses the full Braginskii thermal conduction model [S. Braginskii, Reviews of plasma physics 1 (1965)]. with a realistic perpendicular heat conduction cutoff and the MPS boundary modeling. When altering the thermal conduction model, the plasma termination time varies with larger perpendicular heat conduction, leading to longer current quench (CQ) times as the area around the main plasma heats and becomes electrically conductive. The current and internal energy decay leading to plasma termination is much slower when substituting flow boundary conditions that are based on ExB drive for the Chodura-Bohm condition in computations with insulated electrons. Computations that impose low electron temperature values at the wall terminate the simulated plasma most rapidly, and are unaffected by the Chodura-Bohm condition on flow. Relative to cases with simplified thermal transport modeling, computations with Braginskii thermal transport show superior numerical properties and are able to run to complete plasma termination, which may be important for future 3D calculations. Computations also show that the wall resistivity strongly affects the forced VDE evolution, with more resistive walls producing faster CQs and larger peak vertical forces. The vertical forces found in this study are not large, even when extrapolated to reactor-grade experiments. However, applying the Chodura-Bohm outflow condition with insulating temperature conditions produces peak forces that are about double those of the Dirichlet temperature calculations. The distribution of the net force is strongly peaked where the plasma is in contact with the resistive wall. |
| 일반주제명 | Plasma physics. Computational physics. |
| 언어 | 영어 |
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: 이 자료의 원문은 한국교육학술정보원에서 제공합니다. |
