Multi-dimensional particle-in-cell simulations are used to study the generation of electrostatic shocks in plasma and the reflection of background ions to produce high-quality and high-energy ion beams. Electrostatic shocks are driven by the interaction of two plasmas with different density and/or relative drift velocity. The energy and number of ions reflected by the shock increase with increasing density ratio and relative drift velocity between the two interacting plasmas. It is shown that the interaction of intense lasers with tailored near-critical density plasmas allows for the efficient heating of the plasma electrons and steepening of the plasma profile at the critical density interface, leading to the generation of high-velocity shock structures and high-energy ion beams. Our results indicate that high-quality 200 MeV shock-accelerated ion beams required for medical applications may be obtained with current laser systems.

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The current status of the beam-driven plasma wakefield accelerators is reviewed.

In most experiments, special consideration is given to the A 4.5 MeV photocathode RF Gun has been collection of all the charge produced by the injected photons.Since our goal is to create an electron beam, we measure the charge contained in the electron beam at the output of the rf gun and use it in the calculation of quantum efficiency. Therefore, this measurement defines an effective quantum efficiency of the photo-injected rf gun system which incorporates the collection efficiency of the beam.11. EXPERIMENTAL SETUP commissioned at UCLA. A photo-injector drive laser produces sub 2 ps pulses of UV (h=266 nm) light with up to 200 pJ/ pulse, and illuminates a copper cathode. The photoelectrons are accelerated to an energy of 3.5 MeV within the gun. The electron beam charge is measured as a function of laser energy using an integrating current transformer (ICT). We present measurements of qumtum efficiency as a function of laser polarization for injection angles of 2" and 70" with respect to the cathode normal. At 70" incidence a SO% enhancement in quantum efficiency ( > is observed for p-polarized light over s-polarized light.