Design of phase contrast imaging on the HL-2A tokamak

In this article we present the design of a phase contrast imaging (PCI) system on the HL-2A tokamak. This diagnostic is developed to infer line integrated plasma density fluctuations by measuring the phase shift of an expanded CO2 laser beam passing through magnetically confined high temperature plasmas. This system is designed to diagnose plasma density fluctuations with the maximum wavenumber of 15 cm−1. The designed wavenumber resolution is 2 cm−1, and the time resolution can reach 2 μs. The broad kρs ranging from 0.2 to 3 makes it suitable for turbulence measurement.