Two-colour interferometry and Thomson scattering measurements of a plasma gun

Journal Article · 07 February 2019 · Plasma Physics and Controlled Fusion

DOI: https://doi.org/10.1088/1361-6587/ab2571 · OSTI ID:1515007

Hare, J. D. ^[1]; MacDonald, J. ^[2]; Bland, S. N. ^[3]; Dranczewski, J. ^[3]; Halliday, J. W. D. ^[3]; Lebedev, S. V. ^[3]; Suttle, L. ^[3]; Tubman, E. R. ^[3]; Rozmus, W ^[4]

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1. Imperial College, London (United Kingdom). Blackett Lab.; Imperial College Cornell University
2. Imperial College, London (United Kingdom). Blackett Lab.; AWE Aldermaston, Reading, Berkshire (United Kingdom)
3. Imperial College, London (United Kingdom). Blackett Lab.
4. SLAC National Accelerator Lab., Menlo Park, CA (United States). High Energy Density Science Division; Univ. of Alberta, Edmonton, AB (Canada). Theoretical Physics Institute, Dept. of Physics

We present experimental measurements of a pulsed plasma gun, using two-colour imaging laser interferometry and spatially resolved Thomson scattering. Interferometry measurements give an electron density n_e ≈ 2:7 × 1017 cm^-3 at the centre of the plasma plume, at 5 mm from the plasma gun nozzle. The Thomson scattered light is collected from two probing angles allowed us to simultaneously measure the collective and non-collective spectrum of the electron feature from the same spatial locations. The inferred electron densities from the location of the electron plasma waves is in agreement with interferometry. The electron temperatures inferred from the two spectra are not consistent, with T_e ≈ 10 eV for non-collective scattering and T_e ≈ 30 eV for collective scattering. Here, we discuss various broadening mechanisms such as finite aperture effects, density gradients within the collective volume and collisional broadening to account for some of this discrepancy. We also note the significant red/blue asymmetry of the electron plasma waves in the collective scattering spectra, which could relate to kinetic effects distorting the distribution function of the electrons.

• Research Organization: Univ. of Rochester, NY (United States)
• Sponsoring Organization: Engineering and Physical Sciences Research Council (EPSRC); USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: NA0003764; SC0001063
• OSTI ID: 1515007
• Journal Information: Plasma Physics and Controlled Fusion, Journal Name: Plasma Physics and Controlled Fusion Journal Issue: 8 Vol. 61; ISSN 0741-3335
• Publisher: IOP ScienceCopyright Statement
• Country of Publication: United States
• Language: English