Experiments of a Tokamak Device with Force-Balanced Coils

Abstract

High field is very favorable for magnetically confined fusion devices such as a tokamak, but electromagnetic force derived from the field becomes a fatal problem. Especially, the largest in-plane centering force hinders toroidal field coils from operating at higher fields. Although variable pitch multi-helical coils, we are calling force-balanced coils (FBCs), by which this force is drastically reduced, was proposed for the coil system of tokamak, there had been no tokamak device with FBCs. Therefore, TODOROKI-1, a small tokamak device with FBCs. are manufactured and experiments are started. In this paper, the structure of TODOROKI-1 is indicated, and stray magnetic field and centering force on FBCs are investigated. The plasmas have. been generated in the device and attempts for better plasmas are beginning.