Preliminary result of cavity ring-down spectroscopy system for radio frequency negative ion source test facility

Lizhen Liang; Chundong Hu; Jingyang Yan; Yuanzhe Zhao; Yahong Xie

doi:10.1063/1.5128096

Preliminary result of cavity ring-down spectroscopy system for radio frequency negative ion source test facility

Rev Sci Instrum. 2019 Dec 1;90(12):123509. doi: 10.1063/1.5128096.

Authors

Lizhen Liang¹, Chundong Hu¹, Jingyang Yan¹, Yuanzhe Zhao¹, Yahong Xie¹

Affiliation

¹ Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China.

PMID: 31893840
DOI: 10.1063/1.5128096

Abstract

Negative ion source is a core part of the neutral beam injection system for magnetic confinement fusion devices. The density of produced hydrogen negative ions is a critical parameter of the negative ion source. Cavity ring-down spectroscopy (CRDS) is an ultrasensitive absorption diagnostic technique for density measurement. Based on the photodetachment process, CRDS can measure the integrated line-of-sight hydrogen negative ion density in a high power ion source. The CRDS diagnostic system has been applied to Hefei utility negative ion test equipment with the radio frequency (RF) source, which is now one of the references for the China Fusion Engineering Test Reactor neutral beam injection system. Typical ring-down signals are obtained to calculate the density of hydrogen negative ions. The time evolution of hydrogen negative ion density is successfully measured. Preliminary experiments show the accurate relationship between RF power and measured hydrogen negative ion density.