Fusion Science and Technology / Volume 51 / Number 2T / February 2007 / Pages 118-121
Technical Paper / Open Magnetic Systems for Plasma Confinement
The Hanbit magnetic mirror has a central cell, one anchor cell and one plug cell plus associated vacuum chambers. The Hanbit device has been involved in a series of experiments on stabilization of the MHD flute type mode. Earlier work showed that it was possible to stabilize the m = -1 flute type MHD instability with RF power near the cyclotron resonance by the sideband coupling process. Divertors were used previously in experiments on the TARA mirror device and the HIEI mirror device. According to Pastukhov the main stabilizing effect is compressibility. The present configuration uses just one divertor coil in one end of Hanbit and produces a left-right asymmetry in the magnetic field. One of the central cell coils with reversed current is used as the divertor coil and two adjacent coils with increased current are used to compensate for the field droop and to prevent the field lines from intercepting the bare ion cyclotron resonant heating (ICRH) antenna. The divertor strongly reduces the m=-1 instability when the null point (x-point) is sufficiently inside the vacuum tank. However, the diverted plasma is directed into a wall and the divertor cannot be used to eliminate impurities.