HL -2A Experiment situation in Sep.-Oct., 2005  

——In 2005, more CFC were installed on HL -2A to protect divertor plates. The vessel wall conditions are totally different with those in passed years. In order to examine the actually effects of  more CFC, the discharges have been performed in the proper plasma parameter conditions. After several days commissioning, obtained parameters are toroidal fields 2.0 T, plasma current 200kA, flat-top time of 500ms, duration time of 1000ms. Reproducibility of discharge is quite well in 15 shots.
The results obtained by the end of Sep., 2005 are given in Figure.

——The Ohmic positive and negative power supplies should be precisely switched on in sequence. It has been achieved successfully. Stable and reproducible discharges were obtained using this toroidal field control mode.The plasma current (Ip), ohmic current (Ioh) and horizontal displacement (Dh) from shots 3735-3739 are shown in the figures with plasma duration time 2960ms, flat-top time 1800ms and  plasma current 250kA.

——With ohmic positive and negative power supplies working together and with motor speed adjustment based on frequency conversion for motors No.1 & 2, plasma current of 400kA was obtained . The parameters of SH03772 discharge are as following:
        toroidal magnetic fields BT = 2.65 T
        duration time TD            = 1980 ms

In the figure, the experimental plasma current (I_plas) is shown as the red line, the plasma current feedback control (ccIp) has been setup in advance as the green line,  400kA line shown as the blue dotted line .