Temperature and lifetime measurements in the SSX wind tunnel

TL;DR

This paper reports on electron temperature measurements in the SSX wind tunnel using spectroscopic and probe methods, aiming to enhance Taylor state lifetime and proposing a model for magnetic relaxation prediction.

Contribution

It introduces two measurement techniques for electron temperature and a model to predict magnetic lifetime in the SSX wind tunnel.

Findings

Electron temperature measurements were successfully performed using line ratios and Langmuir probes.

A model accurately predicts the magnetic lifetime of relaxed states.

Proton cooling is explained through electron-proton equilibration.

Abstract

We describe electron temperature measurements in the SSX MHD wind tunnel using two different methods. First, we estimate $T_e$ along a chord by measuring the ratio of the $C_{III}~97.7~nm$ to $C_{IV}~155~nm$ line intensities using a vacuum ultraviolet monochrometer. Second, we record a biasing scan to a double Langmuir probe to obtain a local measurement of $T_e$. The aim of these studies is to increase the Taylor state lifetime, primarily by increasing the electron temperature. Also, a model is proposed to predict magnetic lifetime of relaxed states and is found of predict the lifetime satisfactorily. Furthermore, we find that proton cooling can be explained by equilibration with the electrons.