Application of 20-moment approximation for ion velocity distribution function in calculations of incoherent scatter spectra

作者：Xue Kun^*; Guo Li Xin; Wu Jian; Xu Bin; Fang Chao Feng

来源：Chinese Journal of Geophysics, 2009, 52(4): 878-886.

DOI：10.3969/j.issn.0001-5733.2009.04.003

• 20-moment approximation
• Incoherent scatter spectra
• Non-Maxwellian distribution
• Incoherent scattering radar

According to Grad's theory., the ion velocity distribution function is expanded about a 20-moment approximation based on Maxwellian distribution. The effects of the stress tensor and the heat flow vector on the ion velocity distributions are discussed. When the electric field is weak, it is reasonable to neglect the heat flow vector and the stress tensor parallel to E X B and E respectively. The ion temperature anisotropy and asymmetry in the distribution function are caused by the stress tensor and the heat flow term. Then according to Sheffield's theory and the 20-moment approximation, normalized spectrum is calculated. Finally the incoherent scatter spectra Calculated by the 13-moment approximation and the 20-moment approximation are compared. When the electric field is weak. the 13-moment is nearly consistent with the 20-moment approximation. However it is unreasonable to neglect the heat flow tensor, and the temperature anisotropy is distinct in case of strong electric field. It is reasonable to use the 20-moment approximation to describe the non-Maxwellian plasma characterized by the temperature anisotropy.

• 出版日期2009-4
• 单位西安电子科技大学