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.
Multiple wave radio frequency current driven tokamak reactors in the first stability regime