Progress in LHD experiment

In the third campaign (07.13.99-12.14.99), NBI (≤4.2 MW), ICRH (≤1.4 MW) and ECRH (≤0.9 MW) were used to heat the plasma in LHD. The carbon tiles were installed as divertor plates, resulting in significant reduction in metal impurity concentration (Fe). The maximum field used in the experiment is 2.9 T. Upgrading of the key hardware systems led to (i) higher Te [Te(0)=4.4 keV at n-bare=5.3 x 1018 m-3 and Pabc=1.8 MW], (ii) higher confinement [τE=0.3 s, Te(0)=1.1 keV at ne(0)=6.5 x 1019 m-3 and Pabc=2.0 MW], (iii) higher stored energy Wp=880 kJ, (iv) higher volume averaged β-bar=2.4% (at B=1.3T). The temperature pedestal enhances the confinement significantly (50% higher than the ISS95 scaling). The ICRH heating was found to be as efficient as NBI heating. Long pulse discharges (80 sec NBI shot, 68 sec ICRH shot) have been achieved without any technical difficulty. (author)