太阳射电毫秒尖峰辐射的角方向和偏振的理论研究

THEORETICAL STUDY ON THE ANGULAR DIRECTION AND POLARIZATION OF SOLAR RADIO MILLISECOND SPIKE RADIATION

本文根据太阳磁拱镜点处非线性等离子体密度波传播期间,由损失锥分布的反射电子驱动的电子回旋微波激射不稳定性二次谐频波模支配太阳射电毫秒尖峰辐射的理论模型,着重研究了太阳毫秒尖峰辐射的角方向和偏振度问题.结果发现:O模辐射角方向(波矢与磁场夹角)θ约为40°—60°,X模角方向θ约为40°—80°;当辐射角θ>60°时,辐射呈100%的X模偏振,当40°<θ<60°时,只要非线性等离子体密度波幅在一定的范围之内,辐射呈100%的O模偏振,超过一定的范围时,辐射的偏振度将会由100%的O模下降,甚至降为X模偏振.本文还研究发现辐射源区载能电子的自由能仅有0.1%转化为辐射波能.

Based on the model in which the reflected electrons in a losscone distribution can drive the electron cyclotron maser instability exciting the second harmonic modes to produce solar radio millisecond spike radiation when the nonlinear plasma density wave is propagating in the flaring loop, this paper has mainly studied the angular direction and the polarization of sola(?) radio millisecond spike radiation. It can be seen from calculations that 1) the angular direction relative to magnetic field of the radiation, θ, is about 40°—60° for O-mode and about 40°—80° for X-mode; 2) the radiation appears in 100% X-mode for θ>60, the radiation appears in 100% O-mode or Sower polarization in O-mode or X-mode according to the amplitude of the nonlinear plasma density wave for 40°<θ<60°; and 3) the efficiency of the energy transformation is about 0.1%.