Quasimonoenergetic proton beam acceleration from intense laser interaction with a double cone target

A new double cone target for accelerating quasimonoenergetic proton beam is proposed in this paper. Using two-dimensional PIC (particle-in-cell) simulation, the physical process of accelerating protons and the quality of proton beam from interaction of intense laser with the double cone target are investigated. In the case of same laser parameters, the peak energy and divergence angle of proton beams accelerated by the double cone target are superior to those by the single cone or planar target. Especially, compared to the planar target, the peak proton energy in the double cone target is increased by more than five times and quasimonoenergy can be well maintained. The critical density of the inner cone of the double cone target can increase the laser absorption efficiency. Moreover, the larger quasistatic magnetic field inside the double cone target can confine and guide more fast electrons to transport through the cone tip, which may enhance the sheath field for proton acceleration.