Emittance measurement of mass-separated high-current ion beams

We have developed an emittance measurement system which can observe emittance both in the horizontal plane (dispersive plane of a mass separator) and in the vertical plane of mass-separated high-current ion beams. Using this system, we have measured the emittance of several ion species and charge states from ion sources at various operational conditions. A large displacement of the deduced image of the ion source from the actual position due to the space charge effect, which depends basically on the current density of the total extracted beam and slightly on the ion species or the charge state, was observed. Mass dependent angular fluctuations observed from an identical plasma indicate that the extracted ion suffers from a strong scattering effect.