Design concepts and initial experimental results of LHRF launcher in JT-60

Efficient lower hybrid current drive using a multijunction launcher on JT-60

“…2). This conditioning time is about one-fifth of that of the conventional current drive launcher [23]. We believe that the RF conditioning without plasma on the multijunction launcher is more effective because of the high VSWR between the secondary waveguides.…”

“…Thus it is possible to investigate the optimization of N j ^ with a sharp spectrum in LHRF experiments on JT-60. Before starting the current drive experiment, the phase difference between adjacent main waveguides was checked by minimizing the reflected power of two adjacent main waveguides; this procedure had also been applied for the conventional launcher [23]. Then the new launcher was conditioned by high power RF injection into the vacuum vessel of JT-60 without plasma, and by Taylor discharge cleaning (TDC) of the plasma for two days.…”