Laser ion acceleration in a mass limited targets

Abstract
Laser interactions with mass-limited targets (MLT) are studied via 2D3V relativistic electromagnetic PIC simulations. Analytical estimates are derived to clarify the simulation results. MLT limit undesirable spread of absorbed laser energy out of the interaction zone. MLT, such as droplets, are shown here to enhance the achievable fast ion energy significantly. For given target dimensions, the existence is demonstrated of an optimum laser beam diameter when ion acceleration is efficient and geometrical energy losses are still acceptable. Ion energy also depends on target geometrical form and shaped targets are found to be preferable for high ion energy.