Shogo Isayama (Kyushu University)
The laser-plasma interaction can generate high acceleration fields, which exceeds those of the conventional accelerators by orders of magnitude. Due to this excellent feature of a large acceleration gradient with a table-top facility, laser-driven proton acceleration possesses a high potential to realize the compact high energy proton sources. Proton beams with energies beyond 100 MeV are necessary for a wide range of applications, including modern cancer therapies.We propose an efficient hybrid scheme based on a tabletop laser system and dual-pulses (with a pulse duration of 60 fs and laser energy of a few J) and tandem solid density (SD) and near critical density (NCD) foils. The acceleration mechanism is the two-stage hybrid scheme of radiation pressure acceleration (RPA) and laser wake field acceleration (LWFA), where the injection of relativistic ions into wakefield is controllable with the parameters of the dual pulses. The results of a 2D particle-in-cell (PIC) simulation show this new acceleration scheme can considerably enhance the maximum proton energy to 150 MeV, which is about three times the proton energy achieved by only using the RPA or the LWFA. We also found that the proton energy spectrum can be greatly improved when the density modulated NCD foil is used for the second acceleration stage.