A condition for setting up ultra-low q/sub /spl alpha// discharges in the SINP tokamak

The required rate of plasma current rise for setting up ultra-low q/sub /spl alpha// (ULQ) discharges have been quantified for the first time. It Is observed that the rate depends inversely on the value of the mode rational barrier to be crossed. The empirical relation obtained has important consequences as regards setting up of such discharges and design of ULQ devices.