An examination of the Neutral Penetration Model 1/ne,ped scaling for its validity of spatially varying neutral sources
The core transport code, JETTO, coupled to the neutral Monte Carlo code, EIRENE, has been used to examine the sensitivity of the JET H-mode pedestal to the neutral flux crossing the separatrix. The Neutral Penetration Model (NPM) [Groebner et. al., Physics of Plasmas 9, 2134 (2002)] predicts the wid...
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| Format: | Article |
| Language: | English |
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Elsevier
2021-09-01
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| Series: | Nuclear Materials and Energy |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2352179121001101 |
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| author | J. Simpson D. Moulton C. Giroud F. Casson M. Groth A. Chankin L. Horvath D.S. Gahle L. Garzotti G. Corrigan F. Kochl |
| author_facet | J. Simpson D. Moulton C. Giroud F. Casson M. Groth A. Chankin L. Horvath D.S. Gahle L. Garzotti G. Corrigan F. Kochl |
| author_sort | J. Simpson |
| collection | DOAJ |
| description | The core transport code, JETTO, coupled to the neutral Monte Carlo code, EIRENE, has been used to examine the sensitivity of the JET H-mode pedestal to the neutral flux crossing the separatrix. The Neutral Penetration Model (NPM) [Groebner et. al., Physics of Plasmas 9, 2134 (2002)] predicts the width of the density pedestal along the neutral path to scale with the inverse of its height: 1/ne,ped. By keeping the same physics assumptions in the NPM, and setting the deuterium atoms to cross the separatrix at the same location as the synthetic diagnostic line of sight (i.e. at the outer mid-plane, OMP), we were able to reproduce this scaling in JETTO-EIRENE. However, when the atoms were set to cross the separatrix at the X-point (more consistent with EDGE2D-EIRENE simulations of JET H-modes), the density width at the OMP was found to be much more sensitive to the pedestal height (approximately proportional to 1/ne,ped2). This is attributed to a radial variation in the poloidal flux expansion from OMP to X-point, over the range of ionisation mean free path lengths explored in the scan. Accounting for this variation allowed the expected scaling at the OMP to be recovered. Implications are discussed for experimental comparisons to the NPM and its application to pedestal prediction models. |
| first_indexed | 2024-12-22T03:47:00Z |
| format | Article |
| id | doaj.art-e4cab46689ae407dabb55c8afd626e02 |
| institution | Directory Open Access Journal |
| issn | 2352-1791 |
| language | English |
| last_indexed | 2024-12-22T03:47:00Z |
| publishDate | 2021-09-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Nuclear Materials and Energy |
| spelling | doaj.art-e4cab46689ae407dabb55c8afd626e022022-12-21T18:40:06ZengElsevierNuclear Materials and Energy2352-17912021-09-0128101037An examination of the Neutral Penetration Model 1/ne,ped scaling for its validity of spatially varying neutral sourcesJ. Simpson0D. Moulton1C. Giroud2F. Casson3M. Groth4A. Chankin5L. Horvath6D.S. Gahle7L. Garzotti8G. Corrigan9F. Kochl10CCFE, Culham Science Centre, Abingdon OX14 3DB, UK; Aalto University, FI-00076 AALTO, Espoo, Finland; Corresponding author.CCFE, Culham Science Centre, Abingdon OX14 3DB, UKCCFE, Culham Science Centre, Abingdon OX14 3DB, UKCCFE, Culham Science Centre, Abingdon OX14 3DB, UKAalto University, FI-00076 AALTO, Espoo, FinlandMax-Planck-Institut für Plasmaphysik, Boltzmannstraße 2, D-85748 Garching, GermanyCCFE, Culham Science Centre, Abingdon OX14 3DB, UKUniversity of Strathclyde, 16 Richmond St, Glasgow G1 1XQ, UKCCFE, Culham Science Centre, Abingdon OX14 3DB, UKCCFE, Culham Science Centre, Abingdon OX14 3DB, UKCCFE, Culham Science Centre, Abingdon OX14 3DB, UKThe core transport code, JETTO, coupled to the neutral Monte Carlo code, EIRENE, has been used to examine the sensitivity of the JET H-mode pedestal to the neutral flux crossing the separatrix. The Neutral Penetration Model (NPM) [Groebner et. al., Physics of Plasmas 9, 2134 (2002)] predicts the width of the density pedestal along the neutral path to scale with the inverse of its height: 1/ne,ped. By keeping the same physics assumptions in the NPM, and setting the deuterium atoms to cross the separatrix at the same location as the synthetic diagnostic line of sight (i.e. at the outer mid-plane, OMP), we were able to reproduce this scaling in JETTO-EIRENE. However, when the atoms were set to cross the separatrix at the X-point (more consistent with EDGE2D-EIRENE simulations of JET H-modes), the density width at the OMP was found to be much more sensitive to the pedestal height (approximately proportional to 1/ne,ped2). This is attributed to a radial variation in the poloidal flux expansion from OMP to X-point, over the range of ionisation mean free path lengths explored in the scan. Accounting for this variation allowed the expected scaling at the OMP to be recovered. Implications are discussed for experimental comparisons to the NPM and its application to pedestal prediction models.http://www.sciencedirect.com/science/article/pii/S2352179121001101Density pedestal predictionNeutral penetrationNeutral penetration model1/neped scaling |
| spellingShingle | J. Simpson D. Moulton C. Giroud F. Casson M. Groth A. Chankin L. Horvath D.S. Gahle L. Garzotti G. Corrigan F. Kochl An examination of the Neutral Penetration Model 1/ne,ped scaling for its validity of spatially varying neutral sources Nuclear Materials and Energy Density pedestal prediction Neutral penetration Neutral penetration model 1/neped scaling |
| title | An examination of the Neutral Penetration Model 1/ne,ped scaling for its validity of spatially varying neutral sources |
| title_full | An examination of the Neutral Penetration Model 1/ne,ped scaling for its validity of spatially varying neutral sources |
| title_fullStr | An examination of the Neutral Penetration Model 1/ne,ped scaling for its validity of spatially varying neutral sources |
| title_full_unstemmed | An examination of the Neutral Penetration Model 1/ne,ped scaling for its validity of spatially varying neutral sources |
| title_short | An examination of the Neutral Penetration Model 1/ne,ped scaling for its validity of spatially varying neutral sources |
| title_sort | examination of the neutral penetration model 1 ne ped scaling for its validity of spatially varying neutral sources |
| topic | Density pedestal prediction Neutral penetration Neutral penetration model 1/neped scaling |
| url | http://www.sciencedirect.com/science/article/pii/S2352179121001101 |
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