1 - Nuclear Sciences and Applications - IAEA

Ip = 3.2 MA lp = 2.7 MA
JT-60TEAM
R = 3.0 m R = 3.1 m
a = 0.91 m a =0.87 m
(a) LIMITER Ib) OUTSIDE DIVERTOR
FIG. 1. Magnetic field configurations ofJT-60.
Divertor Coil
Ip = 2.0 MA
R = 3.1 m
0.68x0.85m
LOWER SINGLE-
NULL DIVERTOR
A toroidal magnetic field of 4.8 T has been generated, exceeding its design
value of 4.5 T. The plasma current in limiter discharges has been increased to
3.2 MA beyond the design value by enhancement of the poloidal field power
supplies. Coil supports for a divertor coil and a quadrupole field coil have been
strengthened in order to increase the plasma current in the outside divertor discharges
from the design value of 2.1 MA to 2.7 MA. A new divertor coil was installed in
early 1988 to obtain lower single-null divertor discharges. Three typical configurations,
i.e. limiter, outside divertor (O-DFV) and lower single-null divertor (L-DIV),
are shown in Fig. 1.
All TiC coated Mo limiters and divertor plates were replaced by graphite tiles
during the April and May shutdown period of 1987. The surface area of the graphite
wall corresponds to half the vacuum vessel area. The residual is covered by the TiC
coated Inconel liners. The vacuum vessel is usually operated with wall temperatures
of 200-300°C in the present experiment.
The operation of the NBI and the RF heating systems has been improved successively
to increase the heating power and to extend the pulse length [3, 4]. The NBI
system has been operated regularly with an injected power of about 20 MW at a
hydrogen beam energy of 75 keV. The RF heating system consists of two schemes:
three units of the LHRF system operated in a frequency range of 1.7-2.2 GHz and
one unit of the ICRF system in a frequency range of 110-130 MHz. The frequency
of this ICRF system corresponds to the second harmonics of the hydrogen ion cyclotron
frequency in a toroidal magnetic field of about 4.5 T.