High-energy neutral particle measurement system in the large helical device

The development of a high-energy neutral particle measurement system for io n temperature measurements and high-energy particle confinement analysis du ring neutral beam injection and ion cyclotron resonance frequency heating e xperiments in the large helical device (LHD) is described here. We have bee n improving the time-of-flight neutral particle analyzer for the LHD which had been developed in ENEA Frascati. The control and data acquisition syste ms were designed to be suitable for long discharges in the LHD. The horizon tal and vertical movable stage is prepared to investigate pitch-angle distr ibution and loss cone. We have resolved many difficulties at installation, for example, the strong leakage magnetic field from the LHD and the limitat ions of magnetized materials near the LHD, the quench of the superconductin g magnetic field, the narrow viewing port, and the fully remote control sys tem. The preliminary results in plasma experiments are also described here. (C) 2000 American Institute of Physics. [S0034-6748(00)02207-3].