Stabilization and Destabilization of Sawtooth Oscillations by Lower Hybrid Current Drive in the WT-3 Tokamak

抄録

Sawtooth oscillations appearing in Ohmically heated (OH) plasmas are suppressed by the lower hybrid current drive (LHCD) in the WT-3 tokamak (R=65 cm, a=20 cm, I_p\simeq100 kA, \barn_e=1−2×10¹³ cm⁻³, q_a\simeq4.5, and P_LH\gtrsim100 kW). After the suppression, sawteeth reappear following m=1 oscillations in the LHCD plasmas. The latter sawteeth have a large amplitude and long period (T_s=2–5 msec), compared with the former one (T_s=0.5–1.5 msec). Furthermore, they do not accompany a precursor and crash very fast.