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MPINP:
Research group K. Z. Hatsagortsyan – Division C. H. Keitel
Abstract:
Collisionless shocks are of great interest in astrophysical scenarios as they are believed
to be responsible for high energy cosmic rays and non-thermal particles. The field
of laboratory astrophysics attempts to study astrophysical phenomena in a laboratory
with the help of intense lasers. In view of laboratory-astrophysics experiments and
laser-driven ion acceleration, collisionless shocks are studied semi-analytically and with
numerical simulations. In particular, how the particle collisions in plasma can affect the
laser-driven shock formation and subsequent ion acceleration is investigated. It is shown
in this thesis, how resistive reorganisation of electromagnetic fields in a plasma target
leads to significant improvement in the shock-accelerated ion-beam-profile without any
additional need of target-tailoring (i.e. a known technique currently used to achieve
a monoenergetic profile of the shock-accelerated ion-beam). This result is beneficial
especially for medical science that requires therapeutic proton beams, particularly for
the treatment of cancer. At ultra-high laser intensities, the effect of radiative losses
on particle's trajectory become important. These losses due to radiation emission have
been shown to modify the shock's field structure. It is also demonstrated that exclusion
of radiative losses can lead to overestimation of maximum ion-energy in a thin-target
regime.
