Surface heat flux feedback controlled impurity seeding experiments with Alcator C-Mod’s high-Z vertical target plate divertor: performance, limitations and implications for fusion power reactors.
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| Title: | Surface heat flux feedback controlled impurity seeding experiments with Alcator C-Mod’s high-Z vertical target plate divertor: performance, limitations and implications for fusion power reactors. |
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| Authors: | D. Brunner1 brunner@mit.edu, S.M. Wolfe1, B. LaBombard1, A.Q. Kuang1, B. Lipschultz2, M.L. Reinke3, A. Hubbard1, J. Hughes1, R.T. Mumgaard1, J.L. Terry1, M.V. Umansky4, Team, The Alcator C-Mod1 |
| Source: | Nuclear Fusion. Aug2017, Vol. 57 Issue 8, p1-1. 1p. |
| Subjects: | Heat flux measurement, Diverters (Electronics), Fusion (Phase transformation), Impurity distribution in semiconductors, Thermocouples |
| Abstract: | The Alcator C-Mod team has recently developed a feedback system to measure and control surface heat flux in real-time. The system uses real-time measurements of surface heat flux from surface thermocouples and a pulse-width modulated piezo valve to inject low-Z impurities (typically N2) into the private flux region. It has been used in C-Mod to mitigate peak surface heat fluxes >40 MW m−2 down to <10 MW m−2 while maintaining excellent core confinement, H98 > 1. While the system works quite well under relatively steady conditions, use of it during transients has revealed important limitations on feedback control of impurity seeding in conventional vertical target plate divertors. In some cases, the system is unable to avoid plasma reattachment to the divertor plate or the formation of a confinement-damaging x-point MARFE. This is due to the small operational window for mitigated heat flux in the parameters of incident plasma heat flux, plasma density, and impurity density as well as the relatively slow response of the impurity gas injection system compared to plasma transients. Given the severe consequences for failure of such a system to operate reliably in a reactor, there is substantial risk that the conventional vertical target plate divertor will not provide an adequately controllable system in reactor-class devices. These considerations motivate the need to develop passively stable, highly compliant divertor configurations and experimental facilities that can test such possible solutions. [ABSTRACT FROM AUTHOR] |
| Copyright of Nuclear Fusion is the property of IOP Publishing and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
| FullText | Text: Availability: 0 |
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| Header | DbId: egs DbLabel: Engineering Source An: 124261764 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Surface heat flux feedback controlled impurity seeding experiments with Alcator C-Mod’s high-Z vertical target plate divertor: performance, limitations and implications for fusion power reactors. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22D%2E+Brunner%22">D. Brunner</searchLink><relatesTo>1</relatesTo><i> brunner@mit.edu</i><br /><searchLink fieldCode="AR" term="%22S%2EM%2E+Wolfe%22">S.M. Wolfe</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22B%2E+LaBombard%22">B. LaBombard</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22A%2EQ%2E+Kuang%22">A.Q. Kuang</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22B%2E+Lipschultz%22">B. Lipschultz</searchLink><relatesTo>2</relatesTo><br /><searchLink fieldCode="AR" term="%22M%2EL%2E+Reinke%22">M.L. Reinke</searchLink><relatesTo>3</relatesTo><br /><searchLink fieldCode="AR" term="%22A%2E+Hubbard%22">A. Hubbard</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22J%2E+Hughes%22">J. Hughes</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22R%2ET%2E+Mumgaard%22">R.T. Mumgaard</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22J%2EL%2E+Terry%22">J.L. Terry</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22M%2EV%2E+Umansky%22">M.V. Umansky</searchLink><relatesTo>4</relatesTo><br /><searchLink fieldCode="AR" term="%22Team%2C+The+Alcator+C-Mod%22">Team, The Alcator C-Mod</searchLink><relatesTo>1</relatesTo> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Nuclear+Fusion%22">Nuclear Fusion</searchLink>. Aug2017, Vol. 57 Issue 8, p1-1. 1p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Heat+flux+measurement%22">Heat flux measurement</searchLink><br /><searchLink fieldCode="DE" term="%22Diverters+%28Electronics%29%22">Diverters (Electronics)</searchLink><br /><searchLink fieldCode="DE" term="%22Fusion+%28Phase+transformation%29%22">Fusion (Phase transformation)</searchLink><br /><searchLink fieldCode="DE" term="%22Impurity+distribution+in+semiconductors%22">Impurity distribution in semiconductors</searchLink><br /><searchLink fieldCode="DE" term="%22Thermocouples%22">Thermocouples</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: The Alcator C-Mod team has recently developed a feedback system to measure and control surface heat flux in real-time. The system uses real-time measurements of surface heat flux from surface thermocouples and a pulse-width modulated piezo valve to inject low-Z impurities (typically N2) into the private flux region. It has been used in C-Mod to mitigate peak surface heat fluxes >40 MW m−2 down to <10 MW m−2 while maintaining excellent core confinement, H98 > 1. While the system works quite well under relatively steady conditions, use of it during transients has revealed important limitations on feedback control of impurity seeding in conventional vertical target plate divertors. In some cases, the system is unable to avoid plasma reattachment to the divertor plate or the formation of a confinement-damaging x-point MARFE. This is due to the small operational window for mitigated heat flux in the parameters of incident plasma heat flux, plasma density, and impurity density as well as the relatively slow response of the impurity gas injection system compared to plasma transients. Given the severe consequences for failure of such a system to operate reliably in a reactor, there is substantial risk that the conventional vertical target plate divertor will not provide an adequately controllable system in reactor-class devices. These considerations motivate the need to develop passively stable, highly compliant divertor configurations and experimental facilities that can test such possible solutions. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Nuclear Fusion is the property of IOP Publishing and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1088/1741-4326/aa7923 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 1 StartPage: 1 Subjects: – SubjectFull: Heat flux measurement Type: general – SubjectFull: Diverters (Electronics) Type: general – SubjectFull: Fusion (Phase transformation) Type: general – SubjectFull: Impurity distribution in semiconductors Type: general – SubjectFull: Thermocouples Type: general Titles: – TitleFull: Surface heat flux feedback controlled impurity seeding experiments with Alcator C-Mod’s high-Z vertical target plate divertor: performance, limitations and implications for fusion power reactors. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: D. Brunner – PersonEntity: Name: NameFull: S.M. Wolfe – PersonEntity: Name: NameFull: B. LaBombard – PersonEntity: Name: NameFull: A.Q. Kuang – PersonEntity: Name: NameFull: B. Lipschultz – PersonEntity: Name: NameFull: M.L. Reinke – PersonEntity: Name: NameFull: A. Hubbard – PersonEntity: Name: NameFull: J. Hughes – PersonEntity: Name: NameFull: R.T. Mumgaard – PersonEntity: Name: NameFull: J.L. Terry – PersonEntity: Name: NameFull: M.V. Umansky – PersonEntity: Name: NameFull: Team, The Alcator C-Mod IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 08 Text: Aug2017 Type: published Y: 2017 Identifiers: – Type: issn-print Value: 00295515 Numbering: – Type: volume Value: 57 – Type: issue Value: 8 Titles: – TitleFull: Nuclear Fusion Type: main |
| ResultId | 1 |
