title: H-Mode operation in the START spherical tokamak
abstract: H-mode operation has been achieved in high current (I(p)>200 kA) plasmas in the START spherical tokamak for both neutral-beam-injection-heated and Ohmic discharges. The transition to H mode features the development of well-defined edge pedestals in density and temperature, which signifies the formation of an edge-transport barrier, and associated edge-localized modes. Recent operation at plasma currents exceeding 250 kA shows that these features are accompanied by increases in energy confinement time. This is the first clear demonstration of the H-mode regime in a spherical tokamak.
authors.affiliation: EURATOM/UKAEA Fusion Association, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom.
authors.initials: A
authors.lastname: Sykes
authors.initials: RJ
authors.lastname: Akers
authors.initials: LC
authors.lastname: Appel
authors.initials: PG
authors.lastname: Carolan
authors.initials: JW
authors.lastname: Connor
authors.initials: NJ
authors.lastname: Conway
authors.initials: GF
authors.lastname: Counsell
authors.initials: A
authors.lastname: Dnestrovskij
authors.initials: YN
authors.lastname: Dnestrovskij
authors.initials: M
authors.lastname: Gryaznevich
authors.initials: P
authors.lastname: Helander
authors.initials: MP
authors.lastname: Nightingale
authors.initials: C
authors.lastname: Ribeiro
authors.initials: CM
authors.lastname: Roach
authors.initials: M
authors.lastname: Tournianski
authors.initials: MJ
authors.lastname: Walsh
authors.initials: HR
authors.lastname: Wilson