Generation of high-energy protons and light ions

Of great interest is the possibility of using high-power lasers for generation and acceleration of proton and light ion beams. The problem is urgent because laser beams with energies 100 MeV— 1 GeV are required for hadron cancer therapy, radiography of dense objects, and control of subcritical nuclear reactors. A series of theoretical studies headed by A. V. Kim and A. M. Sergeev were conducted at IAP RAS in that direction using original computer codes developed by A. A. Gonoskov and A. V. Korzhimanov.
An original ion acceleration scheme has been proposed that relies on the redistribution of electrons under the action of ponderomotive force in a solid target when its surface is normally exposed to circularly polarized light and protons are injected from the front side of the target. This scheme allows multi-cascade acceleration in successive thin foils. When the foil thickness is sufficiently small, the reflection coefficient drops as the incident intensity reaches a certain critical value so that the light passes through the foil and can be used to create the accelerating field in the second successive foil and so on.
In numerical simulation a quasi-monochromatic proton beam with energy of more than 200 MeV was generated in four foils.