Thomson scattering on the Large Plasma Device

TL;DR

This paper presents a new Thomson scattering diagnostic for measuring electron density and temperature on the Large Plasma Device, including its calibration and initial measurements demonstrating its effectiveness.

Contribution

Development and calibration of a non-collective Thomson scattering diagnostic for plasma measurements on the Large Plasma Device.

Findings

Measured electron densities from 4.0×10^{12} to 2.8×10^{13} cm^{-3}

Measured electron temperatures from 1.2 eV to 6.8 eV

Diagnostic successfully discriminates faint scattering signals from stray light.

Abstract

We have developed a non-collective Thomson scattering diagnostic for measurements of electron density and temperature on the Large Plasma Device. A triple grating spectrometer with a tunable notch filter is used to discriminate the faint scattering signal from the stray light. In this paper we describe the diagnostic and its calibration via Raman scattering, and present the first measurements performed with the fully commissioned system. Depending on the discharge conditions, the measured densities and temperatures range from 4.0$\times$10$^{12}$ cm$^{-3}$ to 2.8$\times$10$^{13}$ cm$^{-3}$, and from 1.2 eV to 6.8 eV, respectively. The variation of the measurement error with plasma parameters and discharges averaged is also discussed.