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A self‐consistent mechanism for electron cyclotron maser emission and its application to type III solar radio bursts
Author(s) -
Chen L.,
Wu D. J.,
Zhao G. Q.,
Tang J. F.
Publication year - 2017
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2016ja023312
Subject(s) - maser , physics , instability , electron , cyclotron , current (fluid) , radiation , astrophysics , optics , mechanics , nuclear physics , thermodynamics
Abstract Type III solar radio bursts (SRBs) produced by fast electron beams (FEBs) traveling along solar magnetic fields are the best known and the most important kind of SRBs because of their clearest association with FEBs as well as most frequent observations during solar activities. However, the physics of their emitting mechanism has been a controversial issue. Based on the electron cyclotron maser (ECM) instability driven directly by a magnetized FEB, whose physics is fairly well known from the Earth's auroral kilometric radiation, this paper proposes a self‐consistent mechanism for type III SRBs, in which the Alfvén wave (AW) produced by the current instability of the beam‐return current system associated with the FEB, called the self‐generated AW, plays an important and crucial role. Taking into account the return‐current effect of the FEB, the growth rate and the saturation intensity of the self‐generated AW are estimated. Then the effects of the self‐generated AW on the ECM emission via the ECM instability driven by the magnetized FEB are further investigated. The results show that the self‐generated AW can significantly influence and change the physical properties of the ECM emission. In particular, this novel ECM emission mechanism can effectively overcome the main difficulties of the conventional ECM emission mechanism in application to type III SRBs and may potentially provide a self‐consistent physics scenario for type III SRBs.