First Demonstration of Negative-Ion-Based Neutral Beam Injection into JT-60U Plasmas
The Negative-ion-based Neutral Beam Injection (NNBI) into tokamak plasmas has been successfully conducted for the first time at JT-60U in March 1996. Acceleration voltage, current, and pulse duration of the beam have reached 200 kV, 3.2 A, 0.47 s, respectively (400 kV, 13.5 A, 0.15 s in beam acceleration test).
The Negative-ion-based method is more efficient in producing neutral beams at high energies than the conventional positive-ion-based method, and therefore more beneficial for the heating and current drive of high-density core-plasmas.
The full capability of this system is 500 kV, 22A, 10 s. The heating and current drive experiments with this NNBI system will progress successively.