1. Device Parameters of Heliotron J Coil System L=1/M=4 helical coil 0.96MAT Toroidal coil A0.6MAT Toroidal coil B 0.218MAT Main vertical coil 0.84MAT Inner vertical coil0.48MAT Major radius 1.2m Minor radius of helical coil 0.28m Vacuum chamber2.1m 3 Aspect ratio7 Port65 Magnetic Field1.5T Pulse length 0.5sec Pitch modulation of helical coil Inner Vertical Coil Toroidal Coil A Outer Vertical Coil Toroidal Coil B Helical Coil Plasma Vacuum Chamber

2. The Heliotron J Device Main VFC TFC-A TFC-B Aux.VFC HFC

3. Configuration “A” is designed to create a helical divertor region shown in red and yellow. The position of the plasma is shown relative to the helical conductor and the vacuum vessel Other configurations island divertor standard from T. Mizuuchi, M. Nakasuga et al. Stellararor Workshop 1999 Heliotron-J surfaces: cfg “A” - helical divertor

4. Magnetic Surface Mapping Fig.3 The magnetic surfaces at  = 67.5  in the standard configuration. (a) The experimental results (corrected) and (b) The calculated magnetic surfaces. (a) (b) STD config, 0.03 Tesla, corrected for earth’s field

5. Electron Cyclotron Heating ECH 400kW 53GHZ 50ms ~ 0.2%, <20% radiated some Fe Ti C O impurities Plans: will upgrade to 70GHz, 500kW ultimately 4MW ~20kJ? impurity control explore bumpiness and hel. divertors Fig. 2 Dependence of the diamagnetic stored energy on the magnetic field strength. W-Diamagnetic vs B is peaked, 700J max

6. The Heliotron J Device Main VFC TFC-A TFC-B Aux.VFC HFC