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(EXP4/15) High-Power Initial Heating of Compact Torus by Means of Merging Effect

   
M. Inomoto , Y. Ueda , Y. Ono , T. Murakami , M. Tsuruda , M. Yamada ¹, M. Katsurai 
 
Department of Electrical Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
¹ Princeton Plasma Physics Laboratory, Princeton University, P. O. Box 451, Princeton, NJ 08543

Abstract
Novel high-power heating experiment of compact torus  (CT) has been developed in the TS devices by use of merging effects. This method enables us to inject whole magnetic and thermal energies of a colliding CT into a target CT within short reconnection time. The maximum heating power of 10MW was obtained in our initial low-field (0.3-0.8kG) and small-scale (R $<$ 0.2m) experiment. This heating energy is provided mostly by ion acceleration effect of magnetic reconnection. The q-value of the target CT was varied continuously from low-q reversed-field pinch (RFP) region (q»0.2) to high-q spherical tokamak (ST) region (q $\approx$ 30). The ion heating energy as well as the merging speed increases with decreasing the q-value ($\rm B_t$ component) of two toroids and with increasing their external compressing force of current sheet. The most probable interpretation for these phenomena is that unmagnetized ion motion causes the anomalous dissipation of the current sheet when it is compressed shorter than its ion gyroradius. The merging process causes the $\beta$-values of CTs to increase by factor 2-3 and the $\beta$ increment increases with increasing the q-value of CT.

     

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