Nanoparticle-insertion scheme to decouple electron injection from laser evolution in laser wakefield acceleration

Abstract

A localized nanoparticle insertion scheme is developed to decouple electron injection from laser evolution in laser wakefield acceleration. Here we report the experimental realization of a controllable electron injection by the nanoparticle insertion method into a plasma medium, where the injection position is localized within the short range of 100 μm. Nanoparticles were generated by the laser ablation process of a copper blade target using a 3-ns 532-nm laser pulse with fluence above 100 J/cm2. The produced electron bunches with a beam charge above 300 pC and divergence of around 12 mrad show the injection probability over 90% after optimizing the ablation laser energy and the temporal delay between the ablation and the main laser pulses. Since this nanoparticle insertion method can avoid the disturbing effects of electron injection process on laser evolution, the stable high-charge injection method can provide a suitable electron injector for multi-GeV electron sources from low-density plasmas.

Multi-millijoule terahertz emission from laser-wakefield-accelerated electrons

“…The experiment was based on a 150-TW Ti:sapphire laser capable of producing >25-fs, 4-J pulses (after compression) at a repetition rate of 5 Hz, housed at the Center for Relativistic Laser Science (CoReLS), Institute for Basic Science (IBS), South Korea 28 . The laser was previously used to demonstrate LWFA for electron beam energy enhancement with plasma density shaping 32 , optical shaping of wakefields 33 , and nanoparticle-assisted electron injection 34 , 35 . In this experiment, the laser was operated in a single-shot mode to avoid thermal degradation of the laser’s compressor gratings under high-average-power operation.…”

Multi-millijoule terahertz emission from laser-wakefield-accelerated electrons

“…The experiment was based on a 150-TW Ti:sapphire laser capable of producing > 25-fs, 4-J pulses (after compression) at a repetition rate of 5 Hz, housed at Center for Relativistic Laser Science (CoReLS), Institute for Basic Science (IBS), South Korea [28]. The laser was previously used to demonstrate LWFA for electron beam energy enhancement with plasma density shaping [32], optical shaping of wake elds [33], and nanoparticle-assisted electron injection [34,35]. In this experiment, the laser was operated in a single-shot mode to avoid thermal degradation of the laser's compressor gratings under high-averagepower operation.…”