We consider crossed electric and a magnetic fields $\left(\vec{B}=B\,\hat{z},~\vec{E}=E\,\hat{y}\right)$, with $E/B<1$, in presence of some initial number $e^{\pm}$ pairs. do not discuss here the mechanism generation these The field accelerates pairs to high-energies thereby radiating high-energy synchrotron photons. These photons interact via pair production process (MPP), i.e. $\gamma+B\right...