Abstract:
The possibility of using plasma as an optical element for controlling non-relativistic proton beams with energies of the order of 250 MeV used in proton beam therapy is investigated numerically using the particle-in-cell method taking into account collisions. Such optics would allow a significant reduction in secondary radiation in the processes of collimation, scattering or rotation of a standard proton beam, and would also become an important part of controlling ion beams accelerated in plasma formed by short powerful laser pulses. Passive plasma optics for non-relativistic beams of proton beam therapy is possible only in plasma formed by optical ionization of the medium by short-pulse laser radiation. Optical ionization of the gas medium allows the formation of significant plasma gradients with an electron temperature depending on the intensity of the ionizing laser radiation. The transverse electric field generated in this case can have a strength sufficient to seriously affect proton and even ion beams. In experiments, this manifests itself as a rapid (explosive) formation of plasma channels even at relatively low intensities of short laser pulses. The structure of explosive plasma channels depends on the focusing and polarization of laser radiation and its power. When passing along such a channel, even non-relativistic proton beams can be focused, scattered or deviated from the original trajectory.
Keywords:proton beam therapy, medical physics, beams in plasma, plasma channels.
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