Runaway discharge in the small Brazilian Tokamak TBR-1

Runaway discharges are studied in the small Brazilian Tokamak TBR-1 (R = 30 cm, a = 8 cm, B-t = 0.5 T, I-t = 12 kA). Low plasma density, up to 10(12) cm(-3), provides reproducible runaway discharges with the runaway current m ore than 95% of the total current, the Shafranov parameter up to 1.8, and t he effective kinetic energy of the runaway electrons about 300-360 keV. The runaway-related relaxation phenomenon is triggered by the biased electrode technique and the plasma resistance is determined from the time decay of t he loop voltage spikes. The experimental data are analyzed by comparison wi th the theory of runaway generation and equilibrium of the toroidal relativ istic beam-plasma system. (C) 1999 American Institute of Physics. [S1070-66 4X(99)04210-X].