Enhancement of proton collimation and acceleration by an ultra-intense laser interacting with a cone target followed by a beam collimator

A special method is proposed of a laser-induced cavity pressure acceleration scheme for collimating, accelerating and guiding protons, using a single-cone target with a beam collimator through a target normal sheath acceleration mechanism.In addition, the problems involved are studied by using two-dimensional particle-in-cell simulations.The results show that the proton beam can be collimated, accelerated and guided effectively through this type of target.Theoretically, a formula is derived for the combined electric field of accelerating protons.Compared with a proton beam without a beam collimator, the proton beam density and cut-off energy of protons in the type Ⅱ are increased by 3.3 times and 10% respectively.Detailed analysis shows that the enhancement is mainly due to the compact and strong sheath electrostatic field, and that the beam collimator plays a role in focusing energy.In addition, the simulation results show that the divergence angle of the proton beam in type Ⅱ is less than 1.67 times that of type Ⅰ.The more prominent point is that the proton number of type Ⅱ is 2.2 times higher than that of type Ⅰ.This kind of target has important applications in many fields, such as fast ion ignition in inertial fusion, high energy physics and proton therapy.