[en] A new version of the former TM-1-MH tokamak, named CASTOR, was put into operation at the end of 1984. As an initial experiment after the tokamak reconstruction, a study of the start-up discharge phase was carried out. It was shown experimentally that during the inductive breakdown a strongly overthermal plasma potential was generated. Convective losses in the breakdown phase were also measured. Their physical mechanism and that of the generation of the observed electrostatic fields are discussed in the first part of the paper. In the second part, a lower hybrid current drive with a multijunction HF grill is reported. By applying HF power in the lower hybrid region, a HF-driven toroidal current was generated with the efficiency of 1A/W. A quasistationary plasma with a flat radial distribution was sustained during the HF pulse even after short-circuiting the tokamak transformer primary coil. (J.U.)