Collapse and revival of electromagnetic cascades in focused intense laser pulses

TL;DR

This paper explores how intense laser pulses can cause electromagnetic cascades to collapse and then revive, with potential for experimental observation at upcoming high-power laser facilities.

Contribution

It introduces the concept of cascade collapse and revival in focused intense laser pulses and proposes an experimental setup to observe these phenomena.

Findings

Cascade collapse occurs due to energy losses in secondary particles.

Laser fields can accelerate low-energy electrons, leading to cascade revival.

Observable effects are predicted at GeV electron energies and $10^{24}$W/cm$^2$ laser intensities.

Abstract

We consider interaction of a high-energy electron beam with two counterpropagating femtosecond laser pulses. Nonlinear Compton scattering and electron-positron pair production by the emitted photons result in development of an electromagnetic "shower-type" cascade, which however collapses rather quickly due to energy losses by secondary particles. Nevertheless, the laser field accelerates the low-energy electrons and positrons trapped in the focal region, thus giving rise to development of electromagnetic cascade of another type ("avalanche-type"). This effect of cascade collapse and revival can be observed at the electron beam energy of the order of several GeV and intensity of the colliding laser pulses of the level of $10^{24}$W/cm$^2$. This means that it can be readily observed at the novel laser facilities which are either planned for the nearest future, or are already under construction. The proposed experimental setup provides the most realistic and promissory way to observe the "avalanche-type" cascades.