Creation of large temperature anisotropies in a laboratory plasma

• Published in: Physics of plasmas 2020-12, Vol.27 (12)
• Main Authors: Beatty, C. B., Steinberger, T. E., Aguirre, E. M., Beatty, R. A., Klein, K. G., McLaughlin, J. W., Neal, L., Scime, E. E.
• Format: Article
• Language: English
• Subjects: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Anisotropy; Data visualization; Distribution functions; Electric fields; Expanding plasmas; Ion temperature; Ion velocity; Laser induced fluorescence; Plasma; Plasma heating; Plasma instabilities; Plasma physics; Plasma properties and parameters; Plasma sheaths; Plasma sources; Plasma waves; Solar wind; Spatial resolution; Stability analysis; Two dimensional models; Velocity distribution
• ISSN: 1070-664X; 1089-7674
• DOI: 10.1063/5.0029315

Ion temperature anisotropy in an expanding magnetized plasma is investigated using laser induced fluorescence. Parallel and perpendicular ion velocity distribution functions (IVDFs) were measured simultaneously with high spatial resolution in the expanding plasma. Large ion temperature anisotropies ( T ⊥ i / T ∥ i ∼ 10) are observed in a conical region at the periphery of the expanding plasma plume. A simple 2D Boris stepper model that incorporates the measured electric field structure is able to reproduce the gross features of the measured perpendicular IVDFs. A Nyquist stability analysis of the measured IVDFs suggests that multiple instabilities with k ⊥ ρ i ∼ 1 and k | | ρ i ∼ 0.2 are likely to be excited in these plasmas.