1 - Nuclear Sciences and Applications - IAEA

INSIDE LAUNCH ELECTRON CYCLOTRON
HEATING AND CURRENT DRIVE ON DITE
IAEA-CN-50/E-I-3
M. ASHRAF, R. BARNSLEY 1 , N. DELIYANAKIS 2 , T. EDLINGTON,
S.J. FIELDING, J. HUGILL, P.C. JOHNSON, B. LLOYD, S. MANHOOD,
P. MANTICA 3 , G.F. MATTHEWS, W. MILLAR, M. O'BRIEN,
R.A. PITTS 4 , A.C. RIVIERE, D.C. ROBINSON, A. SIMONETTO 5 ,
G. VAYAKIS 2
Culham Laboratory,
Euratom-UKAEA Fusion Association,
Abingdon, Oxfordshire,
United Kingdom
Abstract
INSIDE LAUNCH ELECTRON CYCLOTRON HEATING AND CURRENT DRIVE ON DITE.
Electron cyclotron resonance heating at 60 GHz has been carried out on DITE (R = 1.2 m,
a = 0.24 m) to investigate heating and current drive using the extraordinary mode launched with finite
k| from the high field side. The first clear evidence of Doppler shifted resonance absorption in a nearthermal
plasma is obtained. The heating efficiency is observed to fall sharply at densities above cut-off
for the wave. At lower densities the increment in power to the limiter is measured during ECRH and
is compared with that expected from the global power balance. The degradation in particle confinement
often associated with ECRH is observed as an increased particle flux at the boundary driven by local
electrostatic fluctuations. Initial experiments on the electron cyclotron wave driven current at the second
harmonic show effects that are consistent with the low efficiency expected from theory including trapped
particle effects.
1 INTRODUCTION
At the fundamental EC resonance the right hand cut-off prevents X-mode
access to the plasma when the wave is launched from the low field side.
When launched from the HFS this limit is avoided and the cut-off density
is then given by
for a semi-infinite slab plasma. Here u> is the applied wave frequency, wp
is the electron plasma frequency, n\\ — ck\\/u> and u>c = eB/m0. Earlier
' Leicester University, Leicester, United Kingdom.
2 Oxford University, Oxford, United Kingdom.
3 Istituto di Fisica del Plasma, Consiglio Nazionale delle Ricerche, Milan, Italy.
Royal Holloway and Bedford New College, University of London, London, United
Kingdom.
Attached under a Euratom Fellowship.
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