Possible achievement of second stability by means of lower hybrid current drive

It is shown that radial profiles of the safety factor q(r), necessary to access the ‘second stability’ regime in shaped, low aspect ratio tokamaks, can be achieved via off-axis lower hybrid current drive (LHCD). To accurately model the required current profiles, the previous simulation code for LHCD developed by the authors has been extended to non-circular equilibria and combined with an MHD equilibrium solver. As a particular example, results are presented for parameters of the Versator Upgrade tokamak.