Spontaneous Formation of Spherical Tokamak by ECH on LATE

Abstract

Spontaneous formation of spherical tokamak is observed during a microwave discharge at the electron cyclotron resonance (ECR) under a steady vertical magnetic field. In the course of slow plasma current increase, a fast rise of current (usually within several ms) occurs and the magnetic field topology changes drastically from open field type to closed one. After this current jump, a steady plasma current is maintained. The plasma current in the steady stage is proportional to the strength of the vertical field which balances the outward hoop force of the plasma current and maintains the MHD equilibrium. When a 5 GHz, 130 kW, 60 ms microwave power is injected at 85 G vertical field, plasma current of 6.8 kA is obtained. © 2005, The Institute of Electrical Engineers of Japan. All rights reserved.