Sensitivity of synchrotron radiation to the superthermal electron population in mildly relativistic plasma

Synchrotron radiation has markedly different behavior in $\sim 10\text{ keV}$ and in $\sim 100\text{ keV}$ plasma. We show that high-energy electrons which occupy the tail of velocity distribution function have disproportionate impact on power loss of $\sim 100\text{ keV}$ plasma. If electrons with energy more than a cutoff energy are redistributed while keeping the Maxwellian distribution function below cutoff energy intact, both emission and absorption of synchrotron radiation act to decrease the lost power. These novel radiation transport effects in non-equilibrium plasma suggest large utility in the deconfinement of high-energy electrons to reduce synchrotron radiation in applications where the radiation is deleterious.