Study of Betatron x-ray enhancement and quasi-monoenergetic electron beam generation from ionization injection in LWFA

We present investigations on betatron x-ray source and electron beams from ionization injection in the nitrogen gas. Currently the betatron x-rays are usually produced via self-injected electron beams, which is not controllable and not optimized for x-ray yields. A total photon yield 8×108 /shot and 108 photons with energy over 110 keV are obtained. In particular, the yield is 10 times higher than the case of self-injection mode in helium under similar laser parameters. On the other hand, stable quasi-monoenergetic electron beams with peak energies > 220MeV were generated by incident the 80TW laser pulse into a single stage pure nitrogen gas jet target. The results suggest that nitrogen gas jet could be simply used as the first stage for multi-stage electron acceleration.HEDS 201