Particle control via cryopumping and its impact on the edge plasma profiles of Alcator C-Mod
At the high ne proposed for high-field fusion reactors, it is uncertain whether ionization, as opposed to plasma transport, will be most influential in determining ne at the pedestal and separatrix. A database of Alcator C-Mod discharges is analyzed to evaluate the impact of source modification via...
Saved in:
| Main Authors: | , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2025-03-01
|
| Series: | Nuclear Materials and Energy |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2352179124002795 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1850228403150520320 |
|---|---|
| author | M.A. Miller J.W. Hughes S. Mordijck M. Wigram J. Dunsmore R. Reksoatmodjo R.S. Wilcox |
| author_facet | M.A. Miller J.W. Hughes S. Mordijck M. Wigram J. Dunsmore R. Reksoatmodjo R.S. Wilcox |
| author_sort | M.A. Miller |
| collection | DOAJ |
| description | At the high ne proposed for high-field fusion reactors, it is uncertain whether ionization, as opposed to plasma transport, will be most influential in determining ne at the pedestal and separatrix. A database of Alcator C-Mod discharges is analyzed to evaluate the impact of source modification via cryopumping. The database contains similarly-shaped H-modes at fixed IP=0.8 MA and Bt=5.4 T, spanning a large range in Pnet and ionization. Measurements from an edge Thomson scattering system are combined with those from a midplane-viewing Lyα camera to evaluate changes to ne and Te in response to changes to ionization rates, Sion. nesep and Teped are found to be most sensitive to changes to Sionsep, as opposed to neped and Tesep. Dimensionless quantities, namely αMHD and ν∗, are found to regulate attainable pedestal values. Select discharges at different values of Pnet and in different pumping configurations are analyzed further using SOLPS-ITER. It is determined that changes to plasma transport coefficients are required to self-consistently model both plasma and neutral edge dynamics. Pumping is found to modify the poloidal distribution of atomic neutral density, n0, along the separatrix, increasing n0 at the active X-point. Opaqueness to neutrals from high ne in the divertor is found to play a role in mediating neutral penetration lengths and hence, the poloidal distribution of neutrals along the separatrix. Pumped discharges thus require a larger particle diffusion coefficient than that inferred purely from 1D experimental profiles at the outer midplane. |
| format | Article |
| id | doaj-art-3af07e15be694aa2893f1624bc769e8e |
| institution | OA Journals |
| issn | 2352-1791 |
| language | English |
| publishDate | 2025-03-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Nuclear Materials and Energy |
| spelling | doaj-art-3af07e15be694aa2893f1624bc769e8e2025-08-20T02:04:33ZengElsevierNuclear Materials and Energy2352-17912025-03-014210185610.1016/j.nme.2024.101856Particle control via cryopumping and its impact on the edge plasma profiles of Alcator C-ModM.A. Miller0J.W. Hughes1S. Mordijck2M. Wigram3J. Dunsmore4R. Reksoatmodjo5R.S. Wilcox6MIT Plasma Science and Fusion Center, Cambridge, MA 02139, USA; Corresponding author.MIT Plasma Science and Fusion Center, Cambridge, MA 02139, USAWilliam & Mary, Williamsburg, VA 23188, USAMIT Plasma Science and Fusion Center, Cambridge, MA 02139, USAMIT Plasma Science and Fusion Center, Cambridge, MA 02139, USALawrence Livermore National Laboratory, Livermore, CA 94550, USAOak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831, USAAt the high ne proposed for high-field fusion reactors, it is uncertain whether ionization, as opposed to plasma transport, will be most influential in determining ne at the pedestal and separatrix. A database of Alcator C-Mod discharges is analyzed to evaluate the impact of source modification via cryopumping. The database contains similarly-shaped H-modes at fixed IP=0.8 MA and Bt=5.4 T, spanning a large range in Pnet and ionization. Measurements from an edge Thomson scattering system are combined with those from a midplane-viewing Lyα camera to evaluate changes to ne and Te in response to changes to ionization rates, Sion. nesep and Teped are found to be most sensitive to changes to Sionsep, as opposed to neped and Tesep. Dimensionless quantities, namely αMHD and ν∗, are found to regulate attainable pedestal values. Select discharges at different values of Pnet and in different pumping configurations are analyzed further using SOLPS-ITER. It is determined that changes to plasma transport coefficients are required to self-consistently model both plasma and neutral edge dynamics. Pumping is found to modify the poloidal distribution of atomic neutral density, n0, along the separatrix, increasing n0 at the active X-point. Opaqueness to neutrals from high ne in the divertor is found to play a role in mediating neutral penetration lengths and hence, the poloidal distribution of neutrals along the separatrix. Pumped discharges thus require a larger particle diffusion coefficient than that inferred purely from 1D experimental profiles at the outer midplane.http://www.sciencedirect.com/science/article/pii/S2352179124002795Particle controlCryopumpingSeparatrix densityPedestal fuelingPoloidal asymmetries |
| spellingShingle | M.A. Miller J.W. Hughes S. Mordijck M. Wigram J. Dunsmore R. Reksoatmodjo R.S. Wilcox Particle control via cryopumping and its impact on the edge plasma profiles of Alcator C-Mod Nuclear Materials and Energy Particle control Cryopumping Separatrix density Pedestal fueling Poloidal asymmetries |
| title | Particle control via cryopumping and its impact on the edge plasma profiles of Alcator C-Mod |
| title_full | Particle control via cryopumping and its impact on the edge plasma profiles of Alcator C-Mod |
| title_fullStr | Particle control via cryopumping and its impact on the edge plasma profiles of Alcator C-Mod |
| title_full_unstemmed | Particle control via cryopumping and its impact on the edge plasma profiles of Alcator C-Mod |
| title_short | Particle control via cryopumping and its impact on the edge plasma profiles of Alcator C-Mod |
| title_sort | particle control via cryopumping and its impact on the edge plasma profiles of alcator c mod |
| topic | Particle control Cryopumping Separatrix density Pedestal fueling Poloidal asymmetries |
| url | http://www.sciencedirect.com/science/article/pii/S2352179124002795 |
| work_keys_str_mv | AT mamiller particlecontrolviacryopumpinganditsimpactontheedgeplasmaprofilesofalcatorcmod AT jwhughes particlecontrolviacryopumpinganditsimpactontheedgeplasmaprofilesofalcatorcmod AT smordijck particlecontrolviacryopumpinganditsimpactontheedgeplasmaprofilesofalcatorcmod AT mwigram particlecontrolviacryopumpinganditsimpactontheedgeplasmaprofilesofalcatorcmod AT jdunsmore particlecontrolviacryopumpinganditsimpactontheedgeplasmaprofilesofalcatorcmod AT rreksoatmodjo particlecontrolviacryopumpinganditsimpactontheedgeplasmaprofilesofalcatorcmod AT rswilcox particlecontrolviacryopumpinganditsimpactontheedgeplasmaprofilesofalcatorcmod |