Temperature and Lifetime Measurements in the SSX Wind Tunnel

Journal Article · 07 October 2018 · Plasma

DOI: https://doi.org/10.3390/plasma1020020 · OSTI ID:1476681

Kaur, Manjit ; Gelber, Kaitlin ; Light, Adam ; Brown, Michael

We describe ion and electron temperature measurements in the Swarthmore Spheromak Experiment (SSX) MHD wind tunnel with the goal of understanding limitations on the lifetime of our Taylor-state plasma. A simple model based on the equilibrium eigenvalue and Spitzer resistivity predicted the lifetime satisfactorily during the first phase of the plasma evolution. We measured an average T e along a chord by taking the ratio of the C I I I 97.7 nm to C I V 155 nm line intensities using a vacuum ultraviolet (VUV) monochromator. We also recorded local measurements of T e and n e using a double Langmuir probe in order to inform our interpretation of the VUV data. Our results indicated that the plasma decayed inductively during a large part of the evolution. Ion Doppler spectroscopy measurements suggested that ions cooled more slowly than would be expected from thermal equilibration with the electrons, which maintained a constant temperature throughout the lifetime of the plasma.

• Sponsoring Organization: USDOE Advanced Research Projects Agency - Energy (ARPA-E)
• OSTI ID: 1476681
• Journal Information: Plasma, Journal Name: Plasma Journal Issue: 2 Vol. 1; ISSN 2571-6182; ISSN PLASEU
• Publisher: MDPI AGCopyright Statement
• Country of Publication: Switzerland
• Language: English