Speaker
Prof.
Howard Milchberg
(University of Maryland)
Description
We show that using high density gas jet targets approaching critical density makes possible electron acceleration to relativistic energies with low laser pulse energies, enabling high repetition rate operation. The near-critical density is approached in two ways. For 30 fs, lambda= 800nm, <10 mJ pulses from a 1 kHz Ti:Sapphire laser, we used cryo-cooled, continuous flow high density H_2 and He jets, with N_e/N_cr < 0.69. And in the first laser wakefield experiments using ultrashort mid-infrared laser pulses (100fs, lambda= 3.9um, <20 mJ pulses from a mid-IR OPCPA system), the non-cryo-cooled target density reaches N_e/N_cr < 2.2. In both experiments, the high electron density enables onset of relativistic self-focusing and few MeV electron acceleration at millijoule-scale laser energies. In the case of the mid-IR laser driver, we image the onset and scaling of relativistic self-focusing from single filament collapse through the multifilamentation regime.
Primary author
Prof.
Howard Milchberg
(University of Maryland)
