Laser-to-proton conversion e/iciency studies for proton fast ignition*

We assess the conversion e/iciency from intense picosecond laser pulses to multi-MeV

ion beams for a wide range of laser and target parameters,using 2D kinetic particle-in-cell

simulations. Scalings are addressed in a quasi-one-dimensional geometry, leaving out

beam divergence. Then, we study the conversion e/iciency into a narrow spatial band

along the laser axis for flat and hemispherical targets in large-scale 2D simulations.

Combining these findings allows us to calculate the energy requirements for ignition of a

compressed ICF target with an intense proton beam in a fast-ignition scenario.