【摘要】 本文提出由非热电子（60keV）的空心束（hollow beam）分布激发回旋脉降作为太阳微波毫秒级尖峰辐射的产生机制。文中求得了非常波模二次谐波的增长率及其随时间的变化、脉泽的饱和时间、饱和波能密度及脉降辐射的方向特征。 结果得到,当磁场强度B=507G,等离子体数密度n_?=4×10⁹cm^-3,电子温度T_e=1.4×10⁶K,非热电子数密度与热电子数密度之比（n_s/n_e）≈4×10^-5,磁场标高时,将在2.84GHz频率上产生高亮温度(T_b≈5×10¹⁵K)的毫秒级尖峰辐射。更多还原

【Abstract】 A mechanism of solar microwave millisecond spike emission is presented in this paper. Once after a beam of nonthermal electrons is injected downwards into a magnetic arch, it will form a hollow beam distribution, which drives electron-cyclotron maser (ECM) to emit electromagnetic radiation.Assuming the hollow beam to be a Gaussian distribution, we calculated the growth rate of X-mode at the second harmonic. By solving the diffusion equation we obtained the evolution of the distribution of nonthermal electrons, the variation of the growth rate vs. time, the saturation time of ECM, tsat, and the saturation energy density of the waves.Takingwhere ns is the number density of nonthermal electrons, we find out that millisecond spike emission (tsat=0.42ms) with very high brightness temperature (Tb=5×1015K) would be produced at frequency ω=2π×2.84 GHz, in accordance with the observation of the spike event on May 16, 1981.It is also found that the maser emission propagates within a thin surface layer of a cone stretching an angle of about 65° around the magnetic field.As the distribution of nonthermal electrons evolves, the transverse velocity component decreases while the parallel one does not. As a result, when the pitch angle diminishes, the electrons can penetrate through the magnetic mirror points and rush into the transition region to produce hard X-ray bursts.更多还原