Prof. Yen-Chieh Huang - National Tsinghua University, Hsinchu, Taiwan

Title: Future Light Source Driven by Dielectric Laser Accelerator

Abstract:

A dielectric laser accelerator (DLA) accelerates charged particles by using a phase synchronized laser field in an optical dielectric structure. Owing to the high damage threshold of a dielectric, a DLA is expected to provide stable particle acceleration with a gradient approaching 1 GeV/m. To be compact, a future free-electron laser (FEL) driven by a DLA would prefer a dielectric laser undulator with a micro undulator period and a high undulator field. A short undulator period means a low energy beam from a DLA for a given radiation wavelength. When the radiation photon energy is not small compared with the electron kinetic energy, quantum recoil could knock the electron out of the FEL gain bandwidth and stop the FEL buildup.

On the other hand, a DLA, with its size scaled by the laser wavelength, is capable of generating nano-meter electron bunches. Since the electron bunch length is already on the order of the x-ray wavelength, a DLA beam is well suited for generating intense coherent x-ray radiation or building up x-ray FEL from a short undulator. 

In my presentation, I will first introduce DLA and our work toward a THz injector. I will then show a range of design parameters to avoid the disadvantageous quantum FEL regime, while take advantage of the coherent short-bunch radiation of a DLA beam for an ultra-compact x-ray FEL.