1. Development of electron cyclotron resonance heating (ECRH) system
1-a Gyrotrons development
We are developing gyrotrons that are the oscillation source of the microwave for ECRH. The confinement potential and the electron temperature have been improved by the ECRH using 28 GHz 500 kW 0.1 s gyrotrons. A new 28 GHz 500 kW 0.1 s gyrotron is being developed for next GAMMA10 program. In addition, the development of the 77 GHz 1～2 MW gyrotrons for Large Helical Device (LHD) in National Institute for Fusion Science (NIFS) is carried out under the joint program between NIFS and PRC with the collaboration of Japan Atomic Energy Agency (JAEA) and Toshiba Electron Tube & Devices Co.,Ltd. (TETD).
1-b Development of high power microwave transmission line
To obtain the high efficient heating performances, it is important to design the high efficiency transmission wave guide, polarizer capable to control wave polarization and antenna with the high transmission efficiency and the axisymmetric RF beam profile. We are developing some high power microwave components such as polarizer and movable antenna system.
2．ECRH experiments
Axial confinement potential formation which is the plug potential for ions and the thermal barrier for electrons is performed by ECRH at the both end mirror regions. New record value of ion confining potential was obtained by development of the high power gyrotrons and improvement of the antenna system. In addition, ECRH is carried out to increase the stored energy of the hot ions by reducing the electron drag at the central mirror region. The effectiveness of the wave polarization control was confirmed in central ECRH experiments.
3．Diagnostic method
By the loss electron diagnostic (LED), the ion sensitive probe (ISP), the X-ray detector etc., we examine the heating characteristic of ECRH.
