Investigation of merging/reconnection heating during solenoid-free startup of plasmas in the MAST Spherical Tokamak

H. Tanabe, T. Yamada, T. Watanabe, K. Gi, M. Inomoto, R. Imazawa, M. Gryaznevich, R. Scannell, N. J. Conway, C. Michael, B. Crowley, I. Fitzgerald, A. Meakins, N. Hawkes, K. G. McClements, J. Harrison, T. O'Gorman, Chio-Zong Cheng, Y. Ono

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

We present results of recent studies of merging/reconnection heating during central solenoid (CS)-free plasma startup in the Mega Amp Spherical Tokamak (MAST). During this process, ions are heated globally in the downstream region of an outflow jet, and electrons locally around the X-point produced by the magnetic field of two internal P3 coils and of two plasma rings formed around these coils, the final temperature being proportional to the reconnecting field energy. There is an effective confinement of the downstream thermal energy, due to a thick layer of reconnected flux. The characteristic structure is sustained for longer than an ion-electron energy relaxation time, and the energy exchange between ions and electrons contributes to the bulk electron heating in the downstream region. The peak electron temperature around the X-point increases with toroidal field, but the downstream electron and ion temperatures do not change.

Original languageEnglish
Article number056037
JournalNuclear Fusion
Volume57
Issue number5
DOIs
Publication statusPublished - 2017 Apr 3

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solenoids
electron energy
heating
coils
ions
toroidal plasmas
electrons
ion temperature
thermal energy
relaxation time
energy transfer
magnetic fields
temperature
energy

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Condensed Matter Physics

Cite this

Tanabe, H., Yamada, T., Watanabe, T., Gi, K., Inomoto, M., Imazawa, R., ... Ono, Y. (2017). Investigation of merging/reconnection heating during solenoid-free startup of plasmas in the MAST Spherical Tokamak. Nuclear Fusion, 57(5), [056037]. https://doi.org/10.1088/1741-4326/aa6608
Tanabe, H. ; Yamada, T. ; Watanabe, T. ; Gi, K. ; Inomoto, M. ; Imazawa, R. ; Gryaznevich, M. ; Scannell, R. ; Conway, N. J. ; Michael, C. ; Crowley, B. ; Fitzgerald, I. ; Meakins, A. ; Hawkes, N. ; McClements, K. G. ; Harrison, J. ; O'Gorman, T. ; Cheng, Chio-Zong ; Ono, Y. / Investigation of merging/reconnection heating during solenoid-free startup of plasmas in the MAST Spherical Tokamak. In: Nuclear Fusion. 2017 ; Vol. 57, No. 5.
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Tanabe, H, Yamada, T, Watanabe, T, Gi, K, Inomoto, M, Imazawa, R, Gryaznevich, M, Scannell, R, Conway, NJ, Michael, C, Crowley, B, Fitzgerald, I, Meakins, A, Hawkes, N, McClements, KG, Harrison, J, O'Gorman, T, Cheng, C-Z & Ono, Y 2017, 'Investigation of merging/reconnection heating during solenoid-free startup of plasmas in the MAST Spherical Tokamak', Nuclear Fusion, vol. 57, no. 5, 056037. https://doi.org/10.1088/1741-4326/aa6608

Investigation of merging/reconnection heating during solenoid-free startup of plasmas in the MAST Spherical Tokamak. / Tanabe, H.; Yamada, T.; Watanabe, T.; Gi, K.; Inomoto, M.; Imazawa, R.; Gryaznevich, M.; Scannell, R.; Conway, N. J.; Michael, C.; Crowley, B.; Fitzgerald, I.; Meakins, A.; Hawkes, N.; McClements, K. G.; Harrison, J.; O'Gorman, T.; Cheng, Chio-Zong; Ono, Y.

In: Nuclear Fusion, Vol. 57, No. 5, 056037, 03.04.2017.

Research output: Contribution to journalArticle

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T1 - Investigation of merging/reconnection heating during solenoid-free startup of plasmas in the MAST Spherical Tokamak

AU - Tanabe, H.

AU - Yamada, T.

AU - Watanabe, T.

AU - Gi, K.

AU - Inomoto, M.

AU - Imazawa, R.

AU - Gryaznevich, M.

AU - Scannell, R.

AU - Conway, N. J.

AU - Michael, C.

AU - Crowley, B.

AU - Fitzgerald, I.

AU - Meakins, A.

AU - Hawkes, N.

AU - McClements, K. G.

AU - Harrison, J.

AU - O'Gorman, T.

AU - Cheng, Chio-Zong

AU - Ono, Y.

PY - 2017/4/3

Y1 - 2017/4/3

N2 - We present results of recent studies of merging/reconnection heating during central solenoid (CS)-free plasma startup in the Mega Amp Spherical Tokamak (MAST). During this process, ions are heated globally in the downstream region of an outflow jet, and electrons locally around the X-point produced by the magnetic field of two internal P3 coils and of two plasma rings formed around these coils, the final temperature being proportional to the reconnecting field energy. There is an effective confinement of the downstream thermal energy, due to a thick layer of reconnected flux. The characteristic structure is sustained for longer than an ion-electron energy relaxation time, and the energy exchange between ions and electrons contributes to the bulk electron heating in the downstream region. The peak electron temperature around the X-point increases with toroidal field, but the downstream electron and ion temperatures do not change.

AB - We present results of recent studies of merging/reconnection heating during central solenoid (CS)-free plasma startup in the Mega Amp Spherical Tokamak (MAST). During this process, ions are heated globally in the downstream region of an outflow jet, and electrons locally around the X-point produced by the magnetic field of two internal P3 coils and of two plasma rings formed around these coils, the final temperature being proportional to the reconnecting field energy. There is an effective confinement of the downstream thermal energy, due to a thick layer of reconnected flux. The characteristic structure is sustained for longer than an ion-electron energy relaxation time, and the energy exchange between ions and electrons contributes to the bulk electron heating in the downstream region. The peak electron temperature around the X-point increases with toroidal field, but the downstream electron and ion temperatures do not change.

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