Dependence of type II radio burst intensities on the electron thermal speed, the kappa parameter, and density turbulence

摘要: Type II radio bursts are generated by electron reflection at shocks, Langmuir wave growth, and nonlinear Langmuir wave processes. A recent theory combines these steps using analytic plasma theory and can predict the properties of the radio emission by integrating over the radio source. We have looked at the type II radio burst intensities in upper and lower split bands at specific frequencies while varying (a) the kappa parameter of the upstream electron velocity distribution between 1.5 and 20,(b) the electron thermal speed V_e between 5× 10^ 5 ms-1 and 8× 10^ 6 ms-1, and (c) the relative density irregularity amplitude δ n/n between 0.02 and 0.06 for a typical turbulence scale L= 1.3× 10^ 6 m. With analytical calculations we find that the radio fluxes for fundamental (M= F) and harmonic (M= H) emission F_M∝ κ-1 for smaller κ, F_M∝ const for larger κ, and F_M∝ o V_e from the radiation theory. We confirm these …