R. Yoshino et M. Seki, LOW ELECTRIC-FIELD (0.08 V M(-1)) PLASMA-CURRENT START-UP IN JT-60U, Plasma physics and controlled fusion, 39(1), 1997, pp. 205-222
Plasma breakdown for an electric field of 0.08 V m(-1) (loop voltage o
f 1.7 V) was demonstrated in JT-60U using helium prefilling gas and LH
RF heating. Runaway electrons were nor generated even for the low pref
illing pressure of (1.5-3) x 10(-6) Torr ((2-4) x 10(-4) Pa) required
for plasma breakdown at low loop voltage. Preionization was not obtain
ed by LHRF heating, but the time taken to pass the radiation barrier w
as significantly shortened and a subsequent plasma-current ramp-up at
a plasma current of < 30 kA was successfully obtained. As a result, a
plasma-current start-up of 0.2 MA s(-1) with a loop voltage of less th
an or equal to 1.8 V was demonstrated when the plasma current was 35 k
A to 1 MA.