A multi-chord, two-color interferometer using Hilbert transform phase detection for measuring electron density in spheromak plasmas

Hossack, A. C.; Morgan, K. D.; Hansen, C. J.; Sutherland, D. A.

doi:10.1063/5.0097459

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A multi-chord, two-color interferometer using Hilbert transform phase detection for measuring electron density in spheromak plasmas

Hossack, A. C.·Morgan, K. D.·Hansen, C. J.·Sutherland, D. A.

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Abstract

A new, four-chord, CO 2 /He–Ne heterodyne interferometer has been designed and built for measuring line-averaged plasma density in the HIT-SI3 and subsequent HIT-SIU sustained spheromak devices. The two-color system successfully eliminates vibration-induced errors caused by mirrors that are secured to the vacuum chamber and is able to resolve electron densities ne in the full operating range of 10 18 –10 20 m –3 in both experiments with an integrated error of 4.7 × 10 17 m –2 . Here, data are presented from high toroidal current plasma discharges, showing the time evolution of electron densities n e and j Φ /n e along multiple chords.

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70 PLASMA PHYSICS AND FUSION TECHNOLOGY Beam splitter Crystal optics Electron density Interferometry Lasers Optical devices Plasma confinement Plasma devices Plasma discharges Plasma properties and parameters

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Hossack, A. C., Morgan, K. D., Hansen, C. J., Sutherland, D. A.. 2022-09-01. A multi-chord, two-color interferometer using Hilbert transform phase detection for measuring electron density in spheromak plasmas. https://doi.org/10.1063/5.0097459

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