| LDR | | 00000nam u2200205 4500 |
| 001 | | 000000431768 |
| 005 | | 20200224104926 |
| 008 | | 200131s2019 ||||||||||||||||| ||eng d |
| 020 | |
▼a 9781392286432 |
| 035 | |
▼a (MiAaPQ)AAI13899562 |
| 035 | |
▼a (MiAaPQ)wisc:16269 |
| 040 | |
▼a MiAaPQ
▼c MiAaPQ
▼d 247004 |
| 082 | 0 |
▼a 530 |
| 100 | 1 |
▼a Whelan, Garth G. |
| 245 | 10 |
▼a Details of Ion-Temperature-Gradient-Driven Instability Saturation. |
| 260 | |
▼a [S.l.]:
▼b The University of Wisconsin - Madison.,
▼c 2019. |
| 260 | 1 |
▼a Ann Arbor:
▼b ProQuest Dissertations & Theses,
▼c 2019. |
| 300 | |
▼a 119 p. |
| 500 | |
▼a Source: Dissertations Abstracts International, Volume: 80-12, Section: B. |
| 500 | |
▼a Publisher info.: Dissertation/Thesis. |
| 500 | |
▼a Advisor: Terry, Paul W. |
| 502 | 1 |
▼a Thesis (Ph.D.)--The University of Wisconsin - Madison, 2019. |
| 506 | |
▼a This item must not be sold to any third party vendors. |
| 520 | |
▼a Heat and particle transport due to plasma microturbulence represents a challenge in the development of commercial fusion power. Microturbulence is caused by gyroradius-scale instabilities, of which the Ion-Temperature-Gradient-Driven (ITG) instability is one. This thesis uses gyrokinetic simulations to characterize how the linear ITG instability saturates, as well as to study the turbulent state that arises.In all of the ITG parameter cases investigated here, zonal flows, which are flows constant along a flux surface, are prominent. Zonal flows are linearly damped and thus must be driven nonlinearly. Some nonlinear energy transfer from the instability sustains the flows, but the majority of the energy injected by the instability is balanced by nonlinear transfer to smaller radial-scale stable and unstable eigenmodes. Unlike Kolmogorov turbulence, the dissipation scale overlaps with the injection scale, so there is no inertial range.This thesis investigates two phenomena relating to ITG in particular, the nonlinear critical temperature-gradient upshift (the Dimits shift) and the nonlinearly enhanced transport reduction which occurs when the normalized plasma pressure 棺 is increased. It is found that, while stable modes are the primary saturation mechanism, the Dimits shift cannot be attributed to a direct reduction of the heat flux by stable modes, or to their effects on the energy injection rate. It has been suggested that energy transfer out of zonal flows, in a manner like tertiary instability, could limit their amplitude and set the nonlinear critical gradient. We find that this is not possible directly, as transfer of flow energy is into the zonal flows for all wavenumber couplings.We apply these same techniques to the nonlinearly enhanced reduction of transport with 棺. Qualitatively, the saturation process is similar throughout the range of 棺. Stable mode effects only slightly increased with 棺. Instead, the majority of the reduction is explained by better frequency matching between interacting modes, which causes energy transfer to be more efficient. This effect can be included in quasilinear mixing-length transport models, and we show that it explains 50% to 100% of the enhanced transport reduction with 棺 in five out of six test cases. |
| 590 | |
▼a School code: 0262. |
| 650 | 4 |
▼a Physics. |
| 690 | |
▼a 0605 |
| 710 | 20 |
▼a The University of Wisconsin - Madison.
▼b Physics. |
| 773 | 0 |
▼t Dissertations Abstracts International
▼g 80-12B. |
| 773 | |
▼t Dissertation Abstract International |
| 790 | |
▼a 0262 |
| 791 | |
▼a Ph.D. |
| 792 | |
▼a 2019 |
| 793 | |
▼a English |
| 856 | 40 |
▼u http://www.riss.kr/pdu/ddodLink.do?id=T15492073
▼n KERIS
▼z 이 자료의 원문은 한국교육학술정보원에서 제공합니다. |
| 980 | |
▼a 202002
▼f 2020 |
| 990 | |
▼a ***1008102 |
| 991 | |
▼a E-BOOK |