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Solar plasma radio emission and inertial Alfvén turbulence by O. Lyubchyk et al.*

26 Sep 2017, 11:03 UTC
Solar plasma radio emission and inertial Alfvén turbulence  by O. Lyubchyk et al.*
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We study the influence of kinetic-scale Alfvénic turbulence on the generation of plasma radio emission in the solar coronal regions where the plasma/magnetic pressure ratio $\beta $ is smaller than the electron/ion mass ratio $m_{e}/m_{i}$. The present study is motivated by the phenomenon of solar type I radio storms associated with the strong magnetic field of active regions. The measured brightness temperature of the type I storms can be up to $\leq 10^{10}$ K for continuum emission, and can exceed $10^{11}$ K for type I bursts. At present, there is no generally accepted theory explaining such high brightness temperatures and some other properties of the type I storms.
Theory
We propose the model with the imbalanced turbulence of kinetic-scale Alfvén waves producing an asymmetric quasilinear plateau on the upward half of the electron velocity distribution, $\sqrt{1+T_{i}/T_{e}}V_{Te}<V_{\parallel }<V_{A}$ (see Figure 1). Here $T_{i}/T_{e} $ is the ion to electron temperature ratio, $V_{Te}$ is the electron thermal velocity, $ V_{A}$ is the Alfvén velocity and $V_{\parallel }$ is the electron velocity component parallel to the mean magnetic field $\vec{B}_{0}$.

Figure 1. Illustration of the time-asymptotic electron velocity distribution $f_{e}$ modified by the IAW spectrum $W_{k}^{A}$. The quasilinear diffusion establishes a plateau on ...

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