Isochoric Heating of Solid Targets with Laser Produced Proton Beams

Abstract

Summary form only given. Heating of solid targets with intense particle beams allows the creation of high density plasmas. Laser produced proton beams are well suited for generation of such plasmas due to the high intensity and short pulse length. In case of isochoric heating the energy is deposited so fast, that plasma can not expand during the deposition time. The entire energy is utilized for the heating of the material. The protons are accelerated from the rear surface of a thin dense target by an electrostatic field produced by the electrons emitted in the laser focus (TNSA model). A secondary target, which is heated by the proton beam, is located behind the laser target. In the performed calculations beam parameters, estimated for the PHELIX laser at GSI Darmstadt from previous petawatt experiments are taken. Using a hemispherical shell allows the focusing of the proton beam. The behavior of proton beam heated matter was studied with the help of two-dimensional radiation transport code MULTI-2D. The code was modified to describe non-monoenergetic beams. The proton beam was considered as a group of mono-energetic beamlets within one hydrodynamic time step. The number of beamlets depends on the cell size in the hydro calculation. The time scale of the heating process depends on the distance between the laser and the proton target. The accessible range of plasma parameters as well as requirements for the diagnostic were examined for divergent as well as for focused beam. The performed calculations show that the isochoric heating of matter by laser produced proton beams becomes a promising approach to study dense plasmas