Ultira-high quality, ultra-high current proton beams produced with a laser-virtual cathode sheath accelerator

By structuring the rear surface of the foil, the authors have succeeded to produce modulations in the transverse phase space, which resemble fiducial "beamlets" within the envelope of the expanding plasma. This allows to map the expansion of the beam envelope during the latter, sheath expansion phase. Using this technique that allows to directly image the initial accelerating sheath, and fully reconstruct the transverse phase space for protons of different energy