Frequency drift rate measurements of coronal temperatures

Abstract

Abstract The frequency drift rates of radio emission are traditionally used to determine the velocity of the exciting agency for a chosen coronal density model. The speed of the exciting agency, say an electron beam, is assumed to remain constant during its propagation through the radio emission region. Here, we allow the electron beam to decelerate either due to its collisions with the ambient coronal particles or due to any of the diffusion and plasma transport mechanisms. The deceleration is related to the time derivative of the frequency drift rate. Thus, assuming the plasma mechanism for the radio emission combined with the slowing down of the electron beam enables us to self consistently determine the plasma density profile and the temperature of the radio emitting region. Conversely, the frequency dependence of the drift rate can be determined for a given temperature of the emission region. A comparison with the observed drift rate can then tell us about the validity of the beam slow-down model.