Matching the laser generated p bunch into a crossbar-H drift tube linac

Abstract

Proton bunches with energies up to 30 MeV have been measured at the PHELIX laser. Because of the laser-plasma interactions at a power density of about 4×10^{19} W/cm^{2}, a total yield of 1.5×10^{13} protons was produced. For the reference energy of 10 MeV, the yield within ±0.5 MeV was exceeding 10^{10} protons. The important topic for a further acceleration of the laser generated bunch is the matching into the acceptance of an rf accelerator stage. With respect to the high space charge forces and the transit energy range, only drift tube linacs seem adequate for this purpose. A crossbar H-type (CH) cavity was chosen as the linac structure. Optimum emittance values for the linac injection are compared with the available laser generated beam parameters. Options for beam matching into a CH structure by a pulsed magnetic solenoid and by using the simulation codes LASIN and LORASR are presented.