Dual ion species plasma expansion from isotopically layered cryogenic targets

A dual ion species plasma expansion scheme from a novel target structure is introduced, in which a nanometer thick layer of pure deuterium exists as a buffer species at the target-vacuum interface of a hydrogen plasma. Modelling shows that by controlling the deuterium layer thickness, a composite H +/D+ ion beam can be produced by TNSA, with an adjustable ratio of ion densities, as high energy proton acceleration is suppressed by the acceleration of a spectrally peaked deuteron beam. Particle in cell modelling shows that a (4.3±0.7) MeV per nucleon deuteron beam is accelerated, in a directional cone of half angle 9◦ . Experimentally, this was investigated using state of the art cryogenic targetry and a spectrally peaked deuteron beam of (3.4±0.7) MeV per nucleon was measured in a cone of half angle 7-9◦ , whilst maintaining a significant TNSA proton component.