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Simultaneous Measurement of the Pedestal Magnetic Pitch and Toroidal Velocity at ELM-Relevant Timescales via a Novel Dual-MSE/CER Spectrometer During Type-1 ELMs at DIII-D
Simultaneous Measurement of the Pedestal Magnetic Pitch and Toroidal Velocity at ELM-Relevant Timescales via a Novel Dual-MSE/CER Spectrometer During Type-1 ELMs at DIII-D
상세정보
- 자료유형
- 학위논문 서양
- 최종처리일시
- 20260202105123
- ISBN
- 9798291547229
- DDC
- 530
- 저자명
- Albosta, Ryan.
- 서명/저자
- Simultaneous Measurement of the Pedestal Magnetic Pitch and Toroidal Velocity at ELM-Relevant Timescales via a Novel Dual-MSE/CER Spectrometer During Type-1 ELMs at DIII-D
- 발행사항
- [Sl] : The University of Wisconsin - Madison, 2025
- 발행사항
- Ann Arbor : ProQuest Dissertations & Theses, 2025
- 형태사항
- 155 p
- 주기사항
- Source: Dissertations Abstracts International, Volume: 87-02, Section: B.
- 주기사항
- Advisor: Geiger, Benedikt.
- 학위논문주기
- Thesis (Ph.D.)--The University of Wisconsin - Madison, 2025.
- 초록/해제
- 요약Fusion power represents a unique opportunity to meet the world's growing energy needs without exacerbating climate change via clean, carbon-free power generation from readily available hydrogen and lithium isotopes. One of the most promising approaches for achieving selfsustained fusion is by magnetically confining high temperature plasmas in so called tokamak devices, operated in the H-mode regime. This involves a doughnut shaped plasma with a self-generated barrier just inside its outer layer which keeps the heat and particles from leaving the confined region. However, this layer, deemed the "pedestal", is not fully understood. The goal of this thesis is to shed new light on the sub-millisecond dynamics occurring in the pedestal by developing a new diagnostic for the measurement of two key pedestal parameters: the local magnetic field and the toroidal plasma rotation velocity.To that end, two novel single-channel Czerny-Turner spectrometers (1) have been deployed at the DIII-D tokamak for simultaneous and co-located measurements of the full spectrally resolved Motional Stark Effect (MSE) Split Deuterium Beam Emission and the Carbon CVI charge exchange emission at high spectral (∆λ = 0.13 nm) and temporal resolution (1-5 kHz). High throughput optics (f/#=2.8) allow for good signal-to-noise at high time resolution using fast EMCCD detectors. Initial results from our 2024 DIII-D H-mode experiment show clear toroidal rotation collapse during ELM crashes from the CER channels, accompanied by Sigma/Pi ratio changes over a similar timescale from the MSE channels. Non-equilibrium neutral beam excited state populations appear to play a large role in pedestal MSE line ratios, as qualitatively predicted by the NOMAD quantum collisional model. Complex neutral beam physics have also been observed in beam-into-gas calibrations, and for the first time have been fully reproduced with a physics forward model, revealing a continuum of beam energies that further complicate the MSE spectrum. Taking all of these factors into consideration: simultaneous measurements of the magnetic pitch, local neutral beam non-equilibrium populations, and toroidal rotation velocity have been obtained for H-mode plasmas within the pedestal during type-1 ELMs at 5 kHz. Rotation and magnetic pitch changes seem to evolve on a similar timescale, agreeing qualitatively with recent nonlinear simulation work (2). The development of this technique, as well as the data produced by this thesis, will contribute towards future diagnosis and understanding of the formation and behavior of the H-mode pedestal. This will allow for better predictive modeling of future fusion power plants, and will also improve our ability to develop more advanced confinement regimes which have the potential to reduce the size and cost of fusion reactors moving forward.
- 일반주제명
- Plasma physics
- 일반주제명
- Nuclear physics
- 일반주제명
- Physics
- 키워드
- Diagnostic
- 키워드
- DIII-D tokamak
- 키워드
- Fusion
- 기타저자
- The University of Wisconsin - Madison Physics
- 기본자료저록
- Dissertations Abstracts International. 87-02B.
- 전자적 위치 및 접속
- 로그인 후 원문을 볼 수 있습니다.
MARC
008260126s2025 us c eng d■001000017359466
■00520260202105123
■006m o d
■007cr#unu||||||||
■020 ▼a9798291547229
■035 ▼a(MiAaPQ)AAI32238487
■040 ▼aMiAaPQ▼cMiAaPQ
■0820 ▼a530
■1001 ▼aAlbosta, Ryan.
■24510▼aSimultaneous Measurement of the Pedestal Magnetic Pitch and Toroidal Velocity at ELM-Relevant Timescales via a Novel Dual-MSE/CER Spectrometer During Type-1 ELMs at DIII-D
■260 ▼a[Sl]▼bThe University of Wisconsin - Madison▼c2025
■260 1▼aAnn Arbor▼bProQuest Dissertations & Theses▼c2025
■300 ▼a155 p
■500 ▼aSource: Dissertations Abstracts International, Volume: 87-02, Section: B.
■500 ▼aAdvisor: Geiger, Benedikt.
■5021 ▼aThesis (Ph.D.)--The University of Wisconsin - Madison, 2025.
■520 ▼aFusion power represents a unique opportunity to meet the world's growing energy needs without exacerbating climate change via clean, carbon-free power generation from readily available hydrogen and lithium isotopes. One of the most promising approaches for achieving selfsustained fusion is by magnetically confining high temperature plasmas in so called tokamak devices, operated in the H-mode regime. This involves a doughnut shaped plasma with a self-generated barrier just inside its outer layer which keeps the heat and particles from leaving the confined region. However, this layer, deemed the "pedestal", is not fully understood. The goal of this thesis is to shed new light on the sub-millisecond dynamics occurring in the pedestal by developing a new diagnostic for the measurement of two key pedestal parameters: the local magnetic field and the toroidal plasma rotation velocity.To that end, two novel single-channel Czerny-Turner spectrometers (1) have been deployed at the DIII-D tokamak for simultaneous and co-located measurements of the full spectrally resolved Motional Stark Effect (MSE) Split Deuterium Beam Emission and the Carbon CVI charge exchange emission at high spectral (∆λ = 0.13 nm) and temporal resolution (1-5 kHz). High throughput optics (f/#=2.8) allow for good signal-to-noise at high time resolution using fast EMCCD detectors. Initial results from our 2024 DIII-D H-mode experiment show clear toroidal rotation collapse during ELM crashes from the CER channels, accompanied by Sigma/Pi ratio changes over a similar timescale from the MSE channels. Non-equilibrium neutral beam excited state populations appear to play a large role in pedestal MSE line ratios, as qualitatively predicted by the NOMAD quantum collisional model. Complex neutral beam physics have also been observed in beam-into-gas calibrations, and for the first time have been fully reproduced with a physics forward model, revealing a continuum of beam energies that further complicate the MSE spectrum. Taking all of these factors into consideration: simultaneous measurements of the magnetic pitch, local neutral beam non-equilibrium populations, and toroidal rotation velocity have been obtained for H-mode plasmas within the pedestal during type-1 ELMs at 5 kHz. Rotation and magnetic pitch changes seem to evolve on a similar timescale, agreeing qualitatively with recent nonlinear simulation work (2). The development of this technique, as well as the data produced by this thesis, will contribute towards future diagnosis and understanding of the formation and behavior of the H-mode pedestal. This will allow for better predictive modeling of future fusion power plants, and will also improve our ability to develop more advanced confinement regimes which have the potential to reduce the size and cost of fusion reactors moving forward.
■590 ▼aSchool code: 0262.
■650 4▼aPlasma physics
■650 4▼aNuclear physics
■650 4▼aPhysics
■653 ▼aCharge Exchange Recombination
■653 ▼aDiagnostic
■653 ▼aDIII-D tokamak
■653 ▼aEdge-Localized Modes
■653 ▼aFusion
■653 ▼aMotional Stark Effect
■690 ▼a0759
■690 ▼a0756
■690 ▼a0605
■71020▼aThe University of Wisconsin - Madison▼bPhysics.
■7730 ▼tDissertations Abstracts International▼g87-02B.
■790 ▼a0262
■791 ▼aPh.D.
■792 ▼a2025
■793 ▼aEnglish
■85640▼uhttp://www.riss.kr/pdu/ddodLink.do?id=T17359466▼nKERIS▼z이 자료의 원문은 한국교육학술정보원에서 제공합니다.
