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, Ip ≃ 100 kA, ne = 1 – 2 × 1013 cm–3, qa ≃ 4.5, and PLH ≳ 100 kW). After the suppression, sawteeth reappear following m = 1 oscillations in the LHCD plasmas. The latter sawteeth have a large amplitude and long period (Ts = 2–5 msec), compared with the former one (Ts = 0.5–1.5 msec). Furthermore, they do not accompany a precursor and crash very fast.
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