Transport studies of ECH-heated bumpy torus plasmas in the Elmo Bumpy Torus(EBT) and in the Nagoya Bumpy Torus(NBT)

Abstract

A model of the measured potential profile for ECH-heated plasmas in EBT/NBT is used in the radial-transport equations for bumpy tori. The particle and energy confinement times are predicted along with the ECH power, the ion temperature and the neutral density necessary for a steady state to be maintained in these machines.

Bumpy torus plasma confinement (NBT)

“…The ion energy confinement is still dominated by charge exchange loss [18][19][20]. Experimental results, showing that the radial potential profile is concave (0 W = 150 V) for ECH plasmas (T e = 50-100 eV > Tj) and convex (0 P = Ti/e) for ICH plasmas (Ti = 300-500 eV > T e ), contradict neoclassical transport theory, which predicts a hill for T e > Ti and a dip for Ti > T e [20,21 ]. (e) The density was increased successfully up to n = 10 13 cm" 3 by high-power (9 MHz, 250 kW, 10 ms) ICRF heating by using the Nagoya Type HI antenna, and ion heating was carried out in this high-density plasma by using a 12 half-turn antenna system (7-28 MHz, 500 kW, 10 ms).…”