High-power heating of CTs and STs and TS-3/4 merging experiments

Novel high-power heating of compact torus (CT) has been demonstrated at TS-3/4 experiments, using its axial merging. Its advantage is that whole magnetic and thermal energies of a colliding CT can be injected into a target CT within short reconnection time. The maximum heating power of 10 MW was obtained in our initial low-field (0.03-0.08 T) and small-scale (R<0.2 m) experiment. This heating energy is provided mostly by ion acceleration effect of magnetic reconnection. The ion heating energy increases with decreasing the q-value (Bt component) of two toroids. The merging process causes the β-values of CTs to increase by factor 2-3 and the poloidal β increment increases with increasing the q-value of CT. Now larger device TS-4 (R-0.5 m) with less impurity is under construction to inspect a scaling of heating effect of merging, confinement and stability properties of high-β CTs/STs. (author)