Page 19 - Two-chord Interferometry using 3.39 µm He-Ne Laser on a Flux-Coil-Generated FRC

Two-chord infrared (λ~3.39 μm) He-Ne laser interferometer systems was developed on a Flux-Coil-Generated FRC.
Two-chordal density measurements at r=12, 20 cm
The line-integrated density is given by: ∫nedl ~1.047x1020Δφ [m-2]
The sensitivity to plasma density: ~2.9x1017 m-2 per one degree of phase change
Line-integrated density at peak on typical shot was up to 1x1020 m-2, and with combined the excluded-flux radius the averaged densities of <ne> ~1–10x1019 m-3 on chord 1 and ~2–15x1019 m-3 on chord 2 were observed.
The density shifts were observed on two-chordal interferometry and the inferred density profile from the magnetic measurement, and that shift agreed with FRC radial expansion/contraction.
Using pressure balance we observed that Ttotal ~5–10 eV.
19 HTPD2010, Wildwood, NJ, 5/17/2010 Presenter: Hiroshi Gota Privileged and Confidential
Summary