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(EX/P4-16) Start-up and Formation of ST Plasmas by ECH on the LATE Device

T. Maekawa¹⁾, H. Tanaka¹⁾, M. Uchida¹⁾, H. Igami¹⁾, T. Yoshinaga¹⁾, K. Higaki^1)
 
1) Kyoto University, Kyoto, Japan

Abstract.  Main objective of the LATE (Low Aspect ratio Torus Experiment) device is to realize start-up and formation of spherical tokamak (ST) plasmas by ECH/ECCD alone without Ohmic heating power. Plasma current is started up to 3 kA and maintained for 1 second by injecting microwaves from a magnetron (2.45 GHz, 5 kW). The driven current increases by increasing microwave power and external vertical field for equilibrium. So far, plasma current up to 5 kA has been achieved by injecting microwaves in the range of 20-50 kW from a 2.0 GHz klystron. Magnetic measurement shows that last closed flux surface with a minor radius of a $\sim$ 13 cm and a major radius of R $\sim$ 18 cm (R/a $\sim$ 1.4) is formed. The electron density is higher than the plasma cutoff density, which suggests that ECH/ECCD by mode-converted Bernstein wave takes place.

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