L-H transition in the mega-amp spherical tokamak.
H-mode plasmas have been achieved on the MAST spherical tokamak at input power considerably higher than predicted by conventional threshold scalings. Following L- H transition, a clear improvement in energy confinement is obtained, exceeding recent international scalings even at densities approaching the Greenwald density limit. Transition is accompanied by an order-of-magnitude increase in edge-density gradient, a marked decrease in turbulence, the efficient conversion of internal electron Bernstein waves into free space waves, and the onset and saturation of edge poloidal rotation.
Akers
R J
RJ
EURATOM/UKAEA Fusion Association, Culham Science Centre, Abingdon, OXON, OX14 3DB, United Kingdom.
Counsell
G F
GF
Sykes
A
A
Appel
L C
LC
Arends
E R
ER
Byrom
C
C
Carolan
P G
PG
Conway
N J
NJ
Cunningham
G
G
Dnestrovskij
A
A
Dnestrovskij
Yu N
YN
Field
A R
AR
Fielding
S J
SJ
Gryaznevich
M
M
Helander
P
P
Kirk
A
A
Korsholm
S
S
Martin
R
R
Meyer
H
H
Nightingale
M P S
MP
Roach
C M
CM
Shevchenko
V
V
Tournianski
M
M
Walsh
M J
MJ
Warrick
C D
CD