Investigation of gas puff imaging on HL-2A tokamak

Abstract

GPI (gas puff imaging) is one of the important diagnostics method for investigation of the radiation in the edge region of plasma. In this paper, atomic and molecular processes during GP (gas puff) passage are analyzed. The main radiation emitting from the gas is identified as the Hα line, appearing on the plasma edge region, and the expressions of its intensity and location are given. As viewed from imaging angle, space radiation photograph of hydrogen gas during the GP was obtained experimentally. Improvements of the imaging system and GP experiment arrangement on the HL-2A tokamak are introduced. The observation results confirm the above analysis. In the beginning stage of plasma, the GP hydrogen atoms can pass through the region where the plasma column is to be set up and the bright strip region is formed. In the general GP fuelling, CCD photos are in accordance with the control signals, and other diagnostic results. The strong Hα emissions in both the HFS and LFS sides of plasma are observed.