Low Aspect ratio Torus Experiment (LATE)

 Non-inductive start-up without assistance of central solenoid (CS) is required for realization of low-cost fusion reactors of tokamak type. Among start-up scenarios without CS, use of electron cyclotron heating and current drive (ECH/ECCD) is promising because breakdown and current initiation can be fulfilled simultaneously and the required equipment for microwave power injection is only a small launcher remote from the plasma. Moreover, it is expected that ECH/ECCD occurs without density limit when the injected microwave is mode-converted to electron Bernstein wave (EBW).

 The startup phase of a torus plasma is a dynamic process since it involves drastic changes of field topology, plasma production, confinement and equilibrium, which affect each other strongly. The theoretical research is very difficult because of its strong nonlinearity and unknown factors. Then it is necessary to study on these subjects by experiments.

 The purpose of the LATE device is to investigate and establish the physical bases on formation of low-aspect-ratio torus plasmas by ECH/ECCD solely.

LATE Sideview

Device Parameters
 Vacuum vessel :
diameter = height = 100 cm
 Center post : diameter = 11.4 cm
 Toroidal field coils :
  0.48 kG (R=25cm), 10s,
  1.15 kG (R=25cm), 0.3s,
 Vertical field coils : 3 pairs
 Vertical position feedback

Microwave Source
 2.45GHz Magnetrons :
  5kW CW, 3 x 20kW 2s
 5GHz Klystron :
  200kW 70ms