Laser Ion Acceleration in the Ultra-High Laser Intensity Regime

Radiation losses of electrons in intense laser fields constitute a process of major importance when considering laser-matter interaction at ultra-high intensities. Radiation losses can strongly modify the electron (and in turn ion) dynamics, and are associated with intense and directional emission of high energy photons. Accounting for such effects is therefore necessary for adequate modeling of electron and ion acceleration and creation of secondary photon sources at the forthcoming ultra-high power laser facilities. To account for radiation losses, the radiation friction force was introduced in the particle-in-cell code PICLS using a renormalized Lorentz-Abraham-Dirac model. A study of the effect of radiation friction on ultra high intensity laser ion acceleration with thin targets is presented and shows the importance of radiation losses for intensities higher than 10(22) W/cm(2). For ultra thin targets radiation losses can even improve laser ion acceleration. The regime of low density targets has also been investigated. It is shown that this regime of laser ion acceleration is still very efficient at ultra high intensities but that radiation losses are always detrimental to laser ion acceleration in this regime.