1 - Nuclear Sciences and Applications - IAEA

80 JT-60 TEAM
The further development of the non-inductive current drive scheme is another
important issue of the JT-60 future programme, aiming at an exploration of steady
state tokamak operation and profile control. An LH launcher with recent improvements
for current drive will soon be installed. Studies are now under way to design
a high density current drive system, including negative ion beam injectors and a new
RF system (fast or LH wave).
10. CONCLUSIONS
During the past few years, substantial progress has been made in discharge control,
confinement, heating and current drive experiments on JT-60. The main results
are:
(1) High current (Ip = 3.2 MA, qeff = 2.2) and high density (fie = 1.2 X 10 20 irr 3 )
discharges have been obtained with the help of LH current ramp-up and NBI
stabilization of MHD activity.
(2) A maximum product of ne(0)TETi(0) = 6 x 10 19 m~ 3 -s-keV has been achieved
in hydrogen discharges with high power NBI heating
(PNB = 21 MW) of high density plasmas at high Ip.
(3) Essential divertor functions have been demonstrated experimentally for impurity
control and particle and heat exhaust during high power heating.
(4) An offset linear confinement property has been confirmed for limiter, outside
divertor and lower single-null divertor.
(5) Lower single-null divertor discharges have demonstrated an improvement in
confinement with high recycling of particles and strong radiation cooling in the
divertor region.
(6) Strong high energy beam ion acceleration and a high heating rate have been
achieved in combined NBI and ICRF heating of low f^ plasmas.
(7) Effective ion heating in the plasma core has been observed for LH wave injection
into pellet fuelled high density plasmas of up to ii,, = 1 X 10 20 m~ 3 . The
LH wave injected into NBI heated plasmas has preferentially been absorbed by
beam ions.
(8) An LH current drive of up to 2 MA has been realized with high efficiency, and
a simple relation for the current drive efficiency has been confirmed,
i.e. T?CD OC /(5 + Zeff).
ACKNOWLEDGEMENTS
The authors wish to thank the members of JAERI who have contributed to the
JT-60 project throughout its progress. The authors also wish to express their gratitude
to Drs S. Mori and K. Tomabechi for continued support and encouragement.