Maximum attainable ion energy in the radiation pressure acceleration regime
Authors: Bulanov SS., Esarey E., Schroeder CB., Bulanov SV., Esirkepov TZ., Kando M., Pegoraro F., Leemans WP.
Autors Affiliation: Univ Calif Berkeley, Lawrence Berkeley Natl Lab, Berkeley, CA 94720 USA; JAEA, Kansai Photon Sci Inst, Kyoto 6190215, Japan; Russian Acad Sci, Prokhorov Inst Gen Phys, Moscow 119991, Russia; Moscow Inst Phys & Technol, Dolgoprudnyi 141700, Moscow Region, Russia; Univ Pisa, Dept Phys, I-56127 Pisa, Italy; CNR, Ist Nazl Ott, I-56127 Pisa, Italy
Abstract: The laser group velocity plays a crucial role in laser driven acceleration of electrons and ions. In particular, a highly efficient mechanism of laser driven ion acceleration, Radiation Pressure Acceleration, has a fundamental limit on the maximum attainable ion energy, which is determined by the group velocity of the laser. However there is another limiting factor that may shed the group velocity effects. It is due to the transverse expansion of the target, which happens in the course of a tightly focused laser pulse interaction with a thin foil. Transversely expanding targets become increasingly transparent for radiation thus terminating the acceleration. Utilization of an external guiding structure for the accelerating laser pulse may provide a way of compensating for the group velocity and transverse expansion effects.
KeyWords: ULTRA-INTENSE; LASER-PULSES; FAST IGNITION; GENERATION; ELECTRODYNAMICS; PROTONS; PHYSICS