Ultra-low emittance, high current proton beams produced with a laser-virtual cathode sheath accelerator

The laminarity of high current multi-MeV proton beams produced by irradiating thin metallic foils with ultra-intense lasers has been measured. For proton energies >10 MeV, the transverse and longitudinal emittance are, respectively, <0.004 mm mrad and <10−4 eV s, i.e. at least 100-fold and may be as much as 104-fold better than conventional accelerators beams. The ion beam source size is measured to be <15 μm (fwhm) for proton energies >10 MeV. Magnetic stripping of the co-moving electrons out of the beam after a few cm of debunching is not observed to induce emittance growth.