Emittance measurement of multi-species ion beam produced via two-step charge exchange process in a Li vapor cell

A Li vapor cell has successfully converted a He ion beam to a He ion beam by double charge exchange reaction. Emittance of the He ion beam and that of the He beam were independently measured to study emittance growth during the passage of the charge exchange cell. Each component was seperated by electrostatic deection after passing through a beam shaping slit. The result had shown that the emittance of the He ion beam was not changed by the passage of the charge exchange cell, while the emittance of the He ion beam had increased even with the presence of focusing electric eld produced by He ions. The emittance of the He ion beam had increased up to twice as large as that of the incident He beam. The normalized emittance of the He at the beam energy of 10-20 keV, which is an optimum energy range for charge exchange efficiency, was estimated to be 0.07-0.09 mm-mrad.