$\times (1-10)T_p$, and $(c/\omega_{Bp})$ and $T_p=2\pi / \omega_
{Bp}$ are the proton gyroradius and gyroperiod in the magnetic field of the barrier $B_0$, respectively. Non-thermal radiation of high-energy electrons from the examined space domain was calculated for the beam and barrier parameters which are relevant to cosmological GRBs ([@Smolsky96]; [@Usov98]). Figure 4 shows the intensity of radiation as a function of time $t$ for a simulation with $B_0=300$ G, $\Gamma_0=300$, $\alpha =2/3$, $x_{\rm min}=-5(c/\omega_{Bp})$ and $x_{\rm max}=30(c/\omega_{Bp})$. In all our simulations, the bulk of calculated radiation is generated via synchrotron mechanism in a compact vicinity, $x_{\rm pen}- 2 (c/\omega_{Bp}) <x
< x_{\rm pen}$, of the barrier front where both the strength of the magnetic field is of the order of $B_0$ and the mean energy of accelerated electrons is extremely high. Radiation of high-energy electrons in the fields of low-frequency waves is negligible ($\sim 1$% or less) because both the fields of these waves are about an order of magnitude smaller than $B_0$ (see below) and the length of the examined space domain (\[xt\]) is restricted for computational reasons.

At $\alpha\sim 1$, the mean energy of synchrotron photons generated at the front of the barrier is

$$\langle \varepsilon _\gamma \rangle 