Design of a multichannel polychromator for KTX Thomson scattering diagnostic

Abstract

A polychromator is designed based on the transmission volume phase holographic grating spectrometer coupled with avalanched photon diodes through fiber bundle and has been successfully implemented on the Keda Torus eXperiment [Plasma Phys. Control. Fusion 56 (2014) 094009] Thomson scattering system. The polychromator is operated with a 1064 nm laser, and the designed spectral range is from about 1000 nm to 1100 nm. The spectral channels have been optimized with a five-channel design to lower the estimated error of the electron temperature and density within 5% and 3% respectively when the temperature is around 100 eV. With a calibration method about the ratio of the channel average responses using bremsstrahlung radiation, we obtain an electron temperature of 7 eV in a typical experiment with low plasma currents.

Stray light suppression for Thomson scattering diagnostic on linear magnetized plasma device

“…According to the surface properties of different material in the actual TS system, the simulation needed to model the surface properties of different materials [11,12]. There were four different surface parameters set in the simulation to reflect the actual situation of the device, including transmissive optical surfaces, reflective optical surfaces, mechanical surfaces, and oxidized black surfaces [13,14]. The surface properties of different materials were described by the Bidirectional Scattering Distribution Function (BSDF), an ABg model defined by Fest [15].…”