1 - Nuclear Sciences and Applications - IAEA

1. INTRODUCTION
IAEA-CN-50/A-I-4 69
JT-60 [1] constitutes a focus of the Japanese fusion development programme.
Its main objective is to investigate plasma confinement and heating in reactor-grade
plasmas and to conduct an integrated test of associated fusion technologies. The original
feature of JT-60 [2] is a long pulse tokamak device with a plasma of circular
cross-section and a poloidal divertor placed radially outside. A new divertor coil has
been installed recently to produce a non-circular cross-section divertor plasma with
a single null at the bottom.
The present paper concentrates on experiments and advances during the last two
years with intense neutral beam (NBI) and radiofrequency (RF) wave injection.
Major experimental issues are: (i) particle and impurity control by divertor and pellet
injection; (ii) energy confinement study for limiter and divertor discharges;
(iii) combined NBI and RF heating; and (iv) RF current drive. The RF system has
a lower hybrid range of frequency (LHRF) and an ion cyclotron range of frequency
(ICRF). The status of JT-60 is described in the next section. Experimental results and
future development are presented and discussed in later sections.
2. STATUS OF THE DEVICE
Machine conditions have progressively been improved during the operation
phase and during the shutdown periods. Achieved parameters are compared with
design values in Table I.
TABLE I. MAIN PARAMETERS OF JT-60
Parameter
Plasma current
Limiter
Outside divertor
Lower divertor
Toroidal field
(at R = 3 m)
Heating power
(into torus)
NBI
LHRF
ICRF
Wall material
Pellet
Design
2.7 MA
2.1 MA
2.2 MA
4.5 T
20 MW
15 MW
5 MW
TiC-Mo
1.3 km-s" 1
3.8 mm
Achieved
3.2 MA
2.7 MA
2.0 MA
4.8 T
25 MW
11 MW
3.1 MW
TiC-Mo (before March 1987)
Graphite (after June 1987)
1.5 knvs" 1
3.8 mm (diameter) x 3.8 mm (length)