Proton angular distribution research by a new angle-resolved proton energy spectrometer

The proton spectral and angular distributions simultaneously within the target normal direction and laser propagation direction by using an angle-resolved proton energy spectrometer are studied. For the protons generated in the interactions of 100 fs, 800 nm laser pulses with aluminum foil targets, the deviations of proton beam centers of different energies from the target normal direction towards the laser propagation direction are different. This is probably because of the toroidal magnetic fields generated at the rear target surface, which deflect protons transversely. As a result, protons in low energy range have large deviation angles, protons in middle energy range have the smallest deviation angles, while protons in high energy tail have large deviation angles.