Two-dimensional scanning high-energy particle diagnostic system in Large Helical Device

Abstract

A high-energy neutral particle measurement is one of the important diagnostics for ion temperature and high-energy particle confinement analysis. The neutral particle analyzer in the large helical device is capable of wide range scanning as a feature. We have obtained various data using the horizontal scan of the analyzer. Recently, in addition to the horizontal scan, a high-speed perpendicular scan became possible which enables acquisition of new information in the poloidal direction. Two stainless blocks are set on the opposite sides of the chain in order to balance the weight ͑700 kg͒ of the analyzer and reduce the load for the motor. Therefore a very high scan speed of 1°/ s can be obtained. The scanning speed is 1°/ s. By adding the vertical scan, the ion temperature profile and the radial variation of the signal loss associated with the resonant loss was obtained in preliminary experimental results.