SOLAR METER NOISE STORM:WHISTLER MODEL
Liu Xu-zhao(Beijing Observatory, Academia Sinica)
In this paper, a storm model is presented taking the magnetic field ecolution of a coronal active region as the driving force of the noise storm phenomena. And it has been assumed that a coronal active region is inhomogeneous in magnetics, there are" strong magnetic field fibers in it. The evolution of the magneic structure of an active region will produce weak shocks. When the shocks pass a coronal arch, a fraction of electrons is heated. The, heated fast electrons form a local loss-cone distribution in strong magnetic fibers. The fast electron loss-cone instabilities will generate Langmuir wave and whistler wave with high temperature. When the Langmuir wave spectrum slip towards smaller wave number ranges due to differential transfer, it will strongly act with whistler wave to produce electromagnetic wave with high frequency in a narrow beam (type-1 buist). A strong field and associated configuiation determine the frequency band width and duration of a type-1 burst. And continuum is due to the coupling between the Langmuir wave from a fast electron isotropic distribution and an other low frequency wave.It is thought that the strong directivity of type-1 bursts is the intrinsic characteristics of them. To distinguish which low frequency disturbance will couple with a high frequency wave to generate a trasverse electromagnetic wave, the directivity should be referred to as a critical factor. And that is one of the differences of this model from others.