Laser-plasma acceleration of mono-energetic protons: Simulations of an energetic proton source for cancer therapy

In two dimensional simulation, we found that Raleigh-Taylor (R-T) instability of accelerating thin foil, plays a significant role in preventing the coherent acceleration of the double layer as a whole, particularly the nonlinear stage of its development. The usual nonlinear development of R-T instability generates fingers of high and low densities at the most unstable mode with wavelength comparable to the laser wavelength. Our preliminary simulations show that there are parameter regimes where the nonlinear evolution of R-T instability may have a range of self healing in which the density fingers are smoothed in transverse direction and near mono energetic protons can be continually be accelerated to over 200 MeV and beyond. This makes cancer therapy by protons generated by laser acceleration promising.