SPIKES和FFS辐射偏振状态的快速逆转

Quick Reverse of the Polarization Sense of the Spikes and FFS Radiation

本文简述了1991年5月16日叠加在一个47GB微波大爆发上的快速精细结构(FFS)和spike群的偏振状态.在相隔100MHz的2645、2545MHz两频率上,spike的偏振状态随时间或随频率在50～100ms量级短时标内发生快速交替变化.我们认为这可能与小尺度空间内spike辐射源区的等离子体密度出现短时标的波动及磁场强度的起伏有关.这种波动和起伏使得等离子体频率与磁迴旋频率的比值(ω_p/Q_e)在2^(1/2)附近起伏变化,从而造成电磁波X波模和O波模的电子迴旋脉塞不稳定性增长率交替支配着电磁波的辐射,产生spike 辐射偏振状态的逆转.

In this paper, the spikes and fast fine structures (FFS) superimposed on the microwave burst with the type 47GB on May 16, 1991 were introduced briefly. The polarizations of the spikes and FFS recorded at 2545 MHz and 2645 MHz were reversed quickly and alternately in 50-100 milliseconds time scale.We think it is related to the fluctuations of the plasma density and the magnetic field of the source region in a small space scale. Thle fluctuations bring aboutthe nudulation of the ratio of near 2^(1/2) 2 . And it leads to the growth of the electron-cyclotron maser to control the radiation of X-mode or O-mode wave, and to reverse the sense of the polarization of the spikes and FFS.