Current profiles and major disruptions in a lower-hybrid current drive tokamak

Uehara, Kazuya; Nagashima, Takashi*

The radial rf current profile of the lower-hybrid current drive tokamak is estimated using an rf power damping model for various Gaussian type nz spectrum, and the stability of the major disruption is examined using the criterion of the tearing mode instability. The value of nzc determines the spatial damping of the rf power and in resultant the rf current profile. The value of hz determine the extent of the damping of the rf power and in resultant the absolute value of the rf current. The peaking and flattening rf current profile to be free from the disruption are obtained when the rf power does not damp at the boundary region and when the extent of damping is relatively small even if the rf power begins to damp at relatively boundary region, whose rf spectrum must be having relatively large phase velocity and must be not so broad.