J H Nichols, P C Stangeby, A G McLean, J M Canik, A L Moser, M W Shafer, H Q Wang
{"title":"Reversed-direction 2-point modelling applied to divertor conditions in DIII-D *","authors":"J H Nichols, P C Stangeby, A G McLean, J M Canik, A L Moser, M W Shafer, H Q Wang","doi":"10.1088/1361-6587/ad2b90","DOIUrl":null,"url":null,"abstract":"A predictive form of the extended 2-point model known as the ‘reverse 2-point model’, Rev2PM, is applied to a range of detachment levels in the open lower divertor of DIII-D, showing that the experimentally measured electron temperature (<italic toggle=\"yes\">T<sub>e</sub>\n</italic>) and pressure (<italic toggle=\"yes\">p<sub>e</sub>\n</italic>) at the divertor entrance can be calculated within 50% from target measurements, if and only if <italic toggle=\"yes\">a posteriori</italic> corrections for convective heat flux are included in the model. Unlike the standard 2-point model, the Rev2PM calculates upstream scrape-off layer (SOL) quantities (such as separatrix <italic toggle=\"yes\">T<sub>e</sub>\n</italic> and <italic toggle=\"yes\">p<sub>e</sub>\n</italic>) from target conditions (such as <italic toggle=\"yes\">T<sub>e</sub>\n</italic> and parallel heat flux), with volumetric power and momentum losses depending solely on target <italic toggle=\"yes\">T<sub>e</sub>\n</italic>. The Rev2PM is tested against a database of DIII-D inter-ELM divertor Thomson scattering measurements, built from a series of 6 MW, 1.3 MA, LSN H-mode discharges with varied main ion density, drift direction, and nitrogen puffing rate. Measured target <italic toggle=\"yes\">T<sub>e</sub>\n</italic> ranged from 0.4–25 eV over this database, and upstream <italic toggle=\"yes\">T<sub>e</sub>\n</italic> ranged from 5–60 eV. Poor agreement is found between upstream measurements and Rev2PM calculations that assume purely conductive parallel heat transport. However, introducing <italic toggle=\"yes\">a posteriori</italic> corrections to account for convective heat transport brings the Rev2PM calculations within 50% of the measured upstream values across the dataset. These corrections imply that up to 99% of the parallel heat flux is carried by convection in detached conditions in the DIII-D open lower divertor, though further work is required to assess any potential dependencies on device size or divertor closure.","PeriodicalId":20239,"journal":{"name":"Plasma Physics and Controlled Fusion","volume":"44 1","pages":""},"PeriodicalIF":2.1000,"publicationDate":"2024-03-01","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/ad2b90","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}
引用次数: 0
Abstract
A predictive form of the extended 2-point model known as the ‘reverse 2-point model’, Rev2PM, is applied to a range of detachment levels in the open lower divertor of DIII-D, showing that the experimentally measured electron temperature (Te) and pressure (pe) at the divertor entrance can be calculated within 50% from target measurements, if and only if a posteriori corrections for convective heat flux are included in the model. Unlike the standard 2-point model, the Rev2PM calculates upstream scrape-off layer (SOL) quantities (such as separatrix Te and pe) from target conditions (such as Te and parallel heat flux), with volumetric power and momentum losses depending solely on target Te. The Rev2PM is tested against a database of DIII-D inter-ELM divertor Thomson scattering measurements, built from a series of 6 MW, 1.3 MA, LSN H-mode discharges with varied main ion density, drift direction, and nitrogen puffing rate. Measured target Te ranged from 0.4–25 eV over this database, and upstream Te ranged from 5–60 eV. Poor agreement is found between upstream measurements and Rev2PM calculations that assume purely conductive parallel heat transport. However, introducing a posteriori corrections to account for convective heat transport brings the Rev2PM calculations within 50% of the measured upstream values across the dataset. These corrections imply that up to 99% of the parallel heat flux is carried by convection in detached conditions in the DIII-D open lower divertor, though further work is required to assess any potential dependencies on device size or divertor closure.
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.