Search

We report our recent experimental results on CO2 laser acceleration of protons, with a near-critical hydrogen gas target tailored by a Nd:YAG laser-produced blast wave. Monoenergetic protons with energies up to 2.5 MeV were observed. [ABSTRACT FROM AUTHOR]

We report the generation of energetic protons from the interaction of an intense laser pulse with a near critical plasma density gaseous target. The target was formed by tailoring the gas flow of a hypersonic jet with externally generated hydrodynamic shocks. Configurations utilizing either a single or two colliding shocks were investigated. A 500mJ, 50 fs pulse from a Ti:Sapphire laser system was able to generate protons beams with energies <2MeV from a 70 µm thick, 3x1020 cm-3 hydrogen gas target. These results are consistent with simulations. Simulations indicate that acceleration is due to electrostatic fields as well as inductive fields produced by a strong azimuthal magnetic field. [ABSTRACT FROM AUTHOR]

An ultrashort laser pulse incident on a sharp plasma gradient undergoes a partial reversal in Poynting flux. The resulting counterpropagating field can Compton backscatter from electrons accelerated in the incident pulse's wakefield. We examine the reversal mechanism and properties of the counterpropagating field to optimize the Compton scattered radiation. [ABSTRACT FROM AUTHOR]

A unique Compton backscattering configuration for generating monochromatic, short pulse, and potentially coherent x-rays in a Laser Wakefield Accelerator (LWFA) is being studied at the Naval Research Laboratory. Reflection mechanisms such as stimulated Raman scattering and shock-created density gradients in a plasma can generate the required backward-travelling laser pulse directly from the same laser pulse used in the LWFA, i.e., the high energy electron beam and the counter-propagating photon beam are both self-generated by an ultrashort laser pulse in plasma. The automatic alignment of the counter-propagating electrons and photons together with the extended interaction distance and tightly guided beam sizes in a LWFA can lead to a high-gain situation for the Doppler upshifted forward propagating x-rays. Possibilities for exponential gain to achieve coherent generation of the x-rays are investigated. Using 1D warm beam FEL analysis, millimeter gain lengths could be obtained for optimistic energy spread and emittance parameters. [ABSTRACT FROM AUTHOR]

Short plasma channels may provide focusing or control of laser pulses at intensities far above the usual damage limitations of conventional optics. Analytical and simulation models that predict the behavior of a variety of channel lens configurations are presented. A laser wakefield accelerator (LWFA) that uses a series of plasma lenses to transport the laser pulse over extended distances is described. [ABSTRACT FROM AUTHOR]