Ion rotational velocity of a field‐reversed configuration plasma measured by neutral beam probe spectroscopy

• Published in: The Physics of fluids (1958) 1987-01, Vol.30 (1), p.168-174
• Main Authors: Ito, Yoshifumi, Tanjyo, Masayasu, Ohi, Shoichi, Goto, Seiichi, Ishimura, Tsutomu
• Format: Article
• Language: English
• Subjects: Exact sciences and technology; Magnetic confinement and equilibrium; Physics; Physics of gases, plasmas and electric discharges; Physics of plasmas and electric discharges
• ISSN: 0031-9171; 2163-4998
• DOI: 10.1063/1.866165

The ion rotational angular velocity Ω and the ion temperature T i of a translated field‐reversed configuration (FRC) plasma are measured using neutral beam probe spectroscopy. The value of Ω is ∼(1.0∼1.2)×Ω* at the onset time of the n=2 rotational instability, where Ω* is the ion diamagnetic frequency for a rigid‐rotor equilibrium. The ion rotational direction is the same as the ion diamagnetic direction. The value of Ω is smaller than the angular frequency ωre of the n=2 instability, which can yield experimental evidence of the ion kinetic effects on the n=2 instability in the FRC plasma. When the octupole field is applied to the plasma in order to suppress the n=2 deformation, Ω is slightly reduced. The ion temperature T i is ∼70 eV at the onset time of the n=2 instability.