Self-injection in corrugated plasma channel
Fig.1 (a) Corrugated plasma channel, (b) tracks of randomly selected trapped electrons (while line is the laser trajectory), (c) x-ray radiation spectrum, and (d) radiation spot profile in the transverse plane.
One of the potential applications of the accelerating and wiggling electrons in the blowout regime of laser wakefield acceleration is the generation of highly focused x-ray radiation in the direction of electron acceleration. The large accelerating fields associated with the blowout, which can trap and accelerate plasma electrons (self-injection), lead to the generation of quasi-mono-energetic multi-GeV electrons. In addition, the linear transverse focusing forces associated with the bubble triggers the wiggling of electrons which leads to the generation of x-ray radiation.
It has been already shown that laser frequency chirp and plasma density inhomogeneities provide a strong tool to control the transverse dynamics of laser and hence the dynamics of electron bunch in the bubble. A corrugated plasma channel, as well, induces transverse modulation in laser trajectory, and generates electron bunch with exotic trajectories [Fig.1(b)]. These electron bunches have distinct radiation signature, and can be used to generate collimated x-rays [Fig. 1(d)]. By modifying the corrugation frequency and the channel depth the frequency and the amplitudes of the electron bunch in the bubble can be tuned to generate certain radiation signature.