Fast reciprocating probe system on the HL-2A tokamak

Abstract

A reciprocating probe system has been installed at the midplane of the HL-2A tokamak. The probe is used to measure plasma edge density, temperature, floating potential, and corresponding fluctuation profiles with 8cm scan from the scrape-off layer to the plasma boundary. The reciprocating probe can move at a speed of 1m∕s. A digital grating displacement measurement system that can provide a high displacement resolution of 0.04mm is applied to the reciprocating probe system for the first time. A port located behind the vacuum isolation valve is designed for viewing and the exchange of the probe head. Different probe heads can be used to satisfy different experimental requirements. The first probe head had four graphite measurement tips. For high frequency response, no isolation amplifier is used in the electric circuit of the probe measurement. A personal computer via an analog-to-digital digitizer card acquires probe system data, which are sent to a data server by optical fiber after a discharge. All data are sent to the centralized data management system of the HL-2A. In this article we presented the edge temperature and density profiles for the limiter and divertor configurations of a selected plasma discharge.