Study of improved confinement by a stepwise increase of the input heating power for tokamak plasmas

Abstract

The article is an extension of the brief study by [Sarah Douglas et al., Phys. Plasmas 20, 114504 (2013)], where in the study a sinusoidal perturbation of the heating power has been studied. In this paper a stepwise increase of the heating power and its influence on the L-H transition are studied. Using a function,for the transition of input heating power for tokamak plasmas i.e. the addition of the perturbation, ) / tanh( T t A , to constant power q 0 is shown to promote the confinement, leading to the L-H transition at a lower value of q 0 , as compared to the case of constant q 0 without the ) / tanh( T t A perturbation. It is seen that the input heating power Q that consists of constant part q 0 in addition to a function ) / tanh( T t A provides the L-H transition for relatively small A and much wider range values of 1/T as compare to [Sarah Douglas et al., Phys. Plasmas 20, 114504 (2013)].