Goals and status of Heliotron J

A new helical-axis heliotron device, Heliotron J, is now being constructed at the institute of Advanced Energy of Kyoto University with the goal of de monstrating its improved helical confinement property in the helical-axis h eliotron line. The design feature of Heliotron J is, as compared with that of Heliotron E, the reduced neoclassical transport (near the tokamak level according to the DKES code) and the enhanced average beta limit (4% for the Mercier criterion) with small bootstrap current, which carries the potenti al for developing the currentless 'quasi-isodynamic' optimization. The devi ce parameters are as follows: the major plasma radius of 1.2 m, the average plasma minor radius of 0.1-0.2 m, the magnetic field strength on the magne tic axis of 1.5 T, the vacuum rotational transform of 0.2-0.8 with a low ma gnetic shear, and the magnetic well depth of 1.5% at the plasma edge, with heating systems such as ECH(0.5 MW), NBI(1.5 MW), and ICRF(2.5 MW). The fea sibility of the helical-axis heliotron concept and its ability to explore h igh-quality confinement surfaces with a divertor will be fully tested in He liotron J. The first plasma was planned to be produced in the autumn of 199 9.