title: Electron and Ion Heating Characteristics during Magnetic Reconnection in the MAST Spherical Tokamak.
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 ~4-10 ms, 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.
authors.affiliation: Graduate School of Frontier Sciences, University of Tokyo, Tokyo 113-0032, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Tanabe
authors.affiliation: Faculty of Arts and Science, Kyusyu University, Fukuoka 819-0395, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Yamada
authors.affiliation: Graduate School of Frontier Sciences, University of Tokyo, Tokyo 113-0032, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Watanabe
authors.affiliation: Graduate School of Frontier Sciences, University of Tokyo, Tokyo 113-0032, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Gi
authors.affiliation: Graduate School of Frontier Sciences, University of Tokyo, Tokyo 113-0032, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Kadowaki
authors.affiliation: Graduate School of Frontier Sciences, University of Tokyo, Tokyo 113-0032, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Inomoto
authors.affiliation: Japan Atomic Energy Agency, Ibaraki 311-0193, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Imazawa
authors.affiliation: CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom.
authors.forename: M
authors.initials: M
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authors.affiliation: CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom.
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authors.lastname: Michael
authors.affiliation: CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom.
authors.forename: B
authors.initials: B
authors.lastname: Crowley
authors.affiliation: CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom.
authors.forename: N J
authors.initials: NJ
authors.lastname: Conway
authors.affiliation: CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom.
authors.forename: R
authors.initials: R
authors.lastname: Scannell
authors.affiliation: CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom.
authors.forename: J
authors.initials: J
authors.lastname: Harrison
authors.affiliation: CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom.
authors.forename: I
authors.initials: I
authors.lastname: Fitzgerald
authors.affiliation: CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom.
authors.forename: A
authors.initials: A
authors.lastname: Meakins
authors.affiliation: CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom.
authors.forename: N
authors.initials: N
authors.lastname: Hawkes
authors.affiliation: CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom.
authors.forename: K G
authors.initials: KG
authors.lastname: McClements
authors.affiliation: CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom.
authors.forename: T
authors.initials: T
authors.lastname: O'Gorman
authors.affiliation: Graduate School of Frontier Sciences, University of Tokyo, Tokyo 113-0032, Japan.|Institute of Space and Plasma Sciences, National Cheng Kung University, Tainan 70101, Taiwan.
authors.forename: C Z
authors.initials: CZ
authors.lastname: Cheng
authors.affiliation: Graduate School of Frontier Sciences, University of Tokyo, Tokyo 113-0032, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Ono