MeV/u cluster generation

Abstract

We propose a new principle for the generation of clusters with unit mass energy up to more than 1 MeV/u with some speculations. The dispersion force which acts between a positive ion and the induced atomic dipole with a specific large principal quantum number causes the ion and the neutral atom to attract each other in a high-energy beam. The ion feasibly gathers neutral atoms around it and grows to a large anionic cluster. The condition to produce anionic clusters in a partially-neutral beam is expressed by the capture condition, which requires the number density of neutral atoms e.g. Na ∗ ( n = 35) to be more than ρ = 4.8 × 10 11 cm −3 (i.e. two atoms in a sphere with a radius of 1 × 10 −4 cm around the core ion), when the mean kinetic energy of the neutral atoms in the center-of-mass frame is higher than 3 × 10 −8 eV. The capture condition which we estimated might not be what is expected in practice.