High-Power $\gamma$-Ray Flash Generation in Ultraintense Laser-Plasma Interactions

When high-intensity laser interaction with matter enters the regime of dominated radiation reaction, the radiation losses open the way for producing short pulse high-power $\gamma$-ray flashes. The $\gamma$-ray pulse duration and divergence are determined by the laser pulse amplitude and by the plasma target density scale length. On the basis of theoretical analysis and particle-in-cell simulations with the radiation friction force incorporated, optimal conditions for generating a $\gamma$-ray flash with a tailored overcritical density target are found.

Figure 1

Electron orbits in (a) the ($q_{\parallel }$, $q_{\perp }$) plane, and (b) the ($q_2$, $q_3$) plane for ${\epsilon }_{\mathrm{rad}}={10}^{-8}$. Curves for (1) $a=0.35a_{\mathrm{rad}}$, (2) $a=a_{\mathrm{rad}}$, and (3) $a=5a_{\mathrm{rad}}$

Figure 2

Dependence of ${log}_{10}(\sigma /{\sigma }_T)$ on ${log}_{10}(a)$. For each curve the integer label $n$ corresponds to ${\epsilon }_{\mathrm{rad}}={10}^{-n}$.

Figure 3

(a) The radiation power, ${\mathcal{P}}_{\gamma }$ (PW), and energy, ${\mathcal{E}}_{\gamma }$ (J), vs time $t$ (fs). (b) The ion density distribution in the ($x$, $y$) plane for $t=260\mathrm{fs}$, constant density levels are shown for $n=n_c$ and $n=150n_c$. (c) The $\gamma$-ray intensity angular distribution.

Figure 4

Dependences of the emitted $\gamma$-ray pulse energy, ${\mathcal{E}}_{\gamma }$ (J) (a), duration, ${\mathcal{T}}_{\gamma }$ (fs) (b), and power, ${\mathcal{P}}_{\gamma }$ (PW) (c) on the plasma density scale length, $L$ ($\mu \mathrm{m}$).

Figure 5

(a) Dependence of the $\gamma$-ray power ${\mathcal{P}}_{\gamma }$ (PW) on the plasma scale length, $L$ ($\mu \mathrm{m}$) for the laser pulse energy of 300 J and the laser power, ${\mathcal{P}}_{\mathrm{las}}$, varying from 5 to 20 PW. (b) Energy conversion efficiency from laser to electron and radiation.