Electron and Ion Heating Characteristics during Magnetic Reconnection in the MAST Spherical Tokamak

H. Tanabe, T. Yamada, T. Watanabe, K. Gi, K. Kadowaki, M. Inomoto, R. Imazawa, M. Gryaznevich, C. Michael, B. Crowley, N. J. Conway, R. Scannell, J. Harrison, I. Fitzgerald, A. Meakins, N. Hawkes, K. G. McClements, T. O’Gorman, C. Z. Cheng, Y. Ono, and The MAST Team
Phys. Rev. Lett. 115, 215004 – Published 18 November 2015

Abstract

Electron and ion heating characteristics during merging reconnection start-up on the MAST spherical tokamak have been revealed in detail using a 130 channel yttrium aluminum garnet (YAG) and a 300 channel Ruby-Thomson scattering system and a new 32 chord ion Doppler tomography diagnostic. Detailed 2D profile measurements of electron and ion temperature together with electron density have been achieved for the first time and it is found that electron temperature forms a highly localized hot spot at the X point and ion temperature globally increases downstream. For the push merging experiment when the guide field is more than 3 times the reconnecting field, a thick layer of a closed flux surface form by the reconnected field sustains the temperature profile for longer than the electron and ion energy relaxation time 410ms, both characteristic profiles finally forming a triple peak structure at the X point and downstream. An increase in the toroidal guide field results in a more peaked electron temperature profile at the X point, and also produces higher ion temperatures at this point, but the ion temperature profile in the downstream region is unaffected.

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  • Received 5 May 2015

DOI:https://doi.org/10.1103/PhysRevLett.115.215004

© 2015 American Physical Society

Authors & Affiliations

H. Tanabe1,*, T. Yamada2, T. Watanabe1, K. Gi1, K. Kadowaki1, M. Inomoto1, R. Imazawa3, M. Gryaznevich4,†, C. Michael4, B. Crowley4, N. J. Conway4, R. Scannell4, J. Harrison4, I. Fitzgerald4, A. Meakins4, N. Hawkes4, K. G. McClements4, T. O’Gorman4, C. Z. Cheng1,5, Y. Ono1, and The MAST Team

  • 1Graduate School of Frontier Sciences, University of Tokyo, Tokyo 113-0032, Japan
  • 2Faculty of Arts and Science, Kyusyu University, Fukuoka 819-0395, Japan
  • 3Japan Atomic Energy Agency, Ibaraki 311-0193, Japan
  • 4CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom
  • 5Institute of Space and Plasma Sciences, National Cheng Kung University, Tainan 70101, Taiwan

  • *tanabe@k.u-tokyo.ac.jp
  • Present address: Tokamak Energy, Culham Innovation Centre, Abingdon, Oxfordshire, OX14 3DB, United Kingdom.

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Vol. 115, Iss. 21 — 20 November 2015

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