M Giacomin, D Kennedy, F J Casson, Ajay C J, D Dickinson, B S Patel, C M Roach
{"title":"关于 STEP 中的电磁湍流和传输","authors":"M Giacomin, D Kennedy, F J Casson, Ajay C J, D Dickinson, B S Patel, C M Roach","doi":"10.1088/1361-6587/ad366f","DOIUrl":null,"url":null,"abstract":"In this work, we present first-of-their-kind nonlinear local gyrokinetic (GK) simulations of electromagnetic turbulence at mid-radius in the burning plasma phase of the conceptual high-<italic toggle=\"yes\">β</italic>, reactor-scale, tight-aspect-ratio tokamak Spherical Tokamak for Energy Production (STEP). A prior linear analysis in Kennedy <italic toggle=\"yes\">et al</italic> (2023 <italic toggle=\"yes\">Nucl. Fusion</italic>\n<bold>63</bold> 126061) reveals the presence of unstable hybrid kinetic ballooning modes (KBMs), where inclusion of the compressional magnetic field fluctuation, <inline-formula>\n<tex-math><?CDATA $\\delta B_{\\parallel}$?></tex-math>\n<mml:math overflow=\"scroll\"><mml:mrow><mml:mi>δ</mml:mi><mml:msub><mml:mi>B</mml:mi><mml:mrow><mml:mo>∥</mml:mo></mml:mrow></mml:msub></mml:mrow></mml:math>\n<inline-graphic xlink:href=\"ppcfad366fieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\n</inline-formula>, is crucial, and subdominant microtearing modes (MTMs) are found at binormal scales approaching the ion-Larmor radius. Local nonlinear GK simulations on the selected surface in the central core region suggest that hybrid KBMs can drive large turbulent transport, and that there is negligible turbulent transport from subdominant MTMs when hybrid KBMs are artificially suppressed (through the omission of <inline-formula>\n<tex-math><?CDATA $\\delta B_{\\parallel}$?></tex-math>\n<mml:math overflow=\"scroll\"><mml:mrow><mml:mi>δ</mml:mi><mml:msub><mml:mi>B</mml:mi><mml:mrow><mml:mo>∥</mml:mo></mml:mrow></mml:msub></mml:mrow></mml:math>\n<inline-graphic xlink:href=\"ppcfad366fieqn2.gif\" xlink:type=\"simple\"></inline-graphic>\n</inline-formula>). Nonlinear simulations that include perpendicular equilibrium flow shear can saturate at lower fluxes that are more consistent with the available sources in STEP. This analysis suggests that hybrid KBMs could play an important role in setting the turbulent transport in STEP, and possible mechanisms to mitigate turbulent transport are discussed. Increasing the safety factor or the pressure gradient strongly reduces turbulent transport from hybrid KBMs in the cases considered here. Challenges of simulating electromagnetic turbulence in this high-<italic toggle=\"yes\">β</italic> regime are highlighted. In particular the observation of radially extended turbulent structures in the absence of equilibrium flow shear motivates future advanced global GK simulations that include <inline-formula>\n<tex-math><?CDATA $\\delta B_\\parallel$?></tex-math>\n<mml:math overflow=\"scroll\"><mml:mrow><mml:mi>δ</mml:mi><mml:msub><mml:mi>B</mml:mi><mml:mo>∥</mml:mo></mml:msub></mml:mrow></mml:math>\n<inline-graphic xlink:href=\"ppcfad366fieqn3.gif\" xlink:type=\"simple\"></inline-graphic>\n</inline-formula>.","PeriodicalId":20239,"journal":{"name":"Plasma Physics and Controlled Fusion","volume":"57 1","pages":""},"PeriodicalIF":2.1000,"publicationDate":"2024-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"On electromagnetic turbulence and transport in STEP\",\"authors\":\"M Giacomin, D Kennedy, F J Casson, Ajay C J, D Dickinson, B S Patel, C M Roach\",\"doi\":\"10.1088/1361-6587/ad366f\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"In this work, we present first-of-their-kind nonlinear local gyrokinetic (GK) simulations of electromagnetic turbulence at mid-radius in the burning plasma phase of the conceptual high-<italic toggle=\\\"yes\\\">β</italic>, reactor-scale, tight-aspect-ratio tokamak Spherical Tokamak for Energy Production (STEP). A prior linear analysis in Kennedy <italic toggle=\\\"yes\\\">et al</italic> (2023 <italic toggle=\\\"yes\\\">Nucl. Fusion</italic>\\n<bold>63</bold> 126061) reveals the presence of unstable hybrid kinetic ballooning modes (KBMs), where inclusion of the compressional magnetic field fluctuation, <inline-formula>\\n<tex-math><?CDATA $\\\\delta B_{\\\\parallel}$?></tex-math>\\n<mml:math overflow=\\\"scroll\\\"><mml:mrow><mml:mi>δ</mml:mi><mml:msub><mml:mi>B</mml:mi><mml:mrow><mml:mo>∥</mml:mo></mml:mrow></mml:msub></mml:mrow></mml:math>\\n<inline-graphic xlink:href=\\\"ppcfad366fieqn1.gif\\\" xlink:type=\\\"simple\\\"></inline-graphic>\\n</inline-formula>, is crucial, and subdominant microtearing modes (MTMs) are found at binormal scales approaching the ion-Larmor radius. Local nonlinear GK simulations on the selected surface in the central core region suggest that hybrid KBMs can drive large turbulent transport, and that there is negligible turbulent transport from subdominant MTMs when hybrid KBMs are artificially suppressed (through the omission of <inline-formula>\\n<tex-math><?CDATA $\\\\delta B_{\\\\parallel}$?></tex-math>\\n<mml:math overflow=\\\"scroll\\\"><mml:mrow><mml:mi>δ</mml:mi><mml:msub><mml:mi>B</mml:mi><mml:mrow><mml:mo>∥</mml:mo></mml:mrow></mml:msub></mml:mrow></mml:math>\\n<inline-graphic xlink:href=\\\"ppcfad366fieqn2.gif\\\" xlink:type=\\\"simple\\\"></inline-graphic>\\n</inline-formula>). Nonlinear simulations that include perpendicular equilibrium flow shear can saturate at lower fluxes that are more consistent with the available sources in STEP. This analysis suggests that hybrid KBMs could play an important role in setting the turbulent transport in STEP, and possible mechanisms to mitigate turbulent transport are discussed. Increasing the safety factor or the pressure gradient strongly reduces turbulent transport from hybrid KBMs in the cases considered here. Challenges of simulating electromagnetic turbulence in this high-<italic toggle=\\\"yes\\\">β</italic> regime are highlighted. In particular the observation of radially extended turbulent structures in the absence of equilibrium flow shear motivates future advanced global GK simulations that include <inline-formula>\\n<tex-math><?CDATA $\\\\delta B_\\\\parallel$?></tex-math>\\n<mml:math overflow=\\\"scroll\\\"><mml:mrow><mml:mi>δ</mml:mi><mml:msub><mml:mi>B</mml:mi><mml:mo>∥</mml:mo></mml:msub></mml:mrow></mml:math>\\n<inline-graphic xlink:href=\\\"ppcfad366fieqn3.gif\\\" xlink:type=\\\"simple\\\"></inline-graphic>\\n</inline-formula>.\",\"PeriodicalId\":20239,\"journal\":{\"name\":\"Plasma Physics and Controlled Fusion\",\"volume\":\"57 1\",\"pages\":\"\"},\"PeriodicalIF\":2.1000,\"publicationDate\":\"2024-03-28\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Plasma Physics and Controlled Fusion\",\"FirstCategoryId\":\"101\",\"ListUrlMain\":\"https://doi.org/10.1088/1361-6587/ad366f\",\"RegionNum\":2,\"RegionCategory\":\"物理与天体物理\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"PHYSICS, FLUIDS & PLASMAS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Plasma Physics and Controlled Fusion","FirstCategoryId":"101","ListUrlMain":"https://doi.org/10.1088/1361-6587/ad366f","RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"PHYSICS, FLUIDS & PLASMAS","Score":null,"Total":0}
On electromagnetic turbulence and transport in STEP
In this work, we present first-of-their-kind nonlinear local gyrokinetic (GK) simulations of electromagnetic turbulence at mid-radius in the burning plasma phase of the conceptual high-β, reactor-scale, tight-aspect-ratio tokamak Spherical Tokamak for Energy Production (STEP). A prior linear analysis in Kennedy et al (2023 Nucl. Fusion63 126061) reveals the presence of unstable hybrid kinetic ballooning modes (KBMs), where inclusion of the compressional magnetic field fluctuation, δB∥, is crucial, and subdominant microtearing modes (MTMs) are found at binormal scales approaching the ion-Larmor radius. Local nonlinear GK simulations on the selected surface in the central core region suggest that hybrid KBMs can drive large turbulent transport, and that there is negligible turbulent transport from subdominant MTMs when hybrid KBMs are artificially suppressed (through the omission of δB∥). Nonlinear simulations that include perpendicular equilibrium flow shear can saturate at lower fluxes that are more consistent with the available sources in STEP. This analysis suggests that hybrid KBMs could play an important role in setting the turbulent transport in STEP, and possible mechanisms to mitigate turbulent transport are discussed. Increasing the safety factor or the pressure gradient strongly reduces turbulent transport from hybrid KBMs in the cases considered here. Challenges of simulating electromagnetic turbulence in this high-β regime are highlighted. In particular the observation of radially extended turbulent structures in the absence of equilibrium flow shear motivates future advanced global GK simulations that include δB∥.
期刊介绍:
Plasma Physics and Controlled Fusion covers all aspects of the physics of hot, highly ionised plasmas. This includes results of current experimental and theoretical research on all aspects of the physics of high-temperature plasmas and of controlled nuclear fusion, including the basic phenomena in highly-ionised gases in the laboratory, in the ionosphere and in space, in magnetic-confinement and inertial-confinement fusion as well as related diagnostic methods.
Papers with a technological emphasis, for example in such topics as plasma control, fusion technology and diagnostics, are welcomed when the plasma physics is an integral part of the paper or when the technology is unique to plasma applications or new to the field of plasma physics. Papers on dusty plasma physics are welcome when there is a clear relevance to fusion.