Heavy ion induction linac studies at LBL

Summary form only given. Recent experiments on the multiple beam induction linac MBE-4 are discussed. Early experiments concentrated on an initial current of 10 mA per beam and successfully demonstrated amplification of the current, by controlled bunch compression, to 90 mA per beam while simultaneously accelerating the bunch from its injection energy of 200 keV (nom.) to 900 keV. An increase in the normalized emittance of the beam during acceleration (by a factor of 2) was observed while the emittance of the drifting beam remained constant during transport through the linac. Recent studies have centered on a single beam from MBE-4 which is extracted from a modified ion source. The source modifications provide a beam whose transverse phase space distribution is more suitable for investigating the cause of observed emittance growth. The beam is lower in current (5 mA) but has reduced emittance in both transverse planes (~0.03 π mm-mrad), resulting in a brighter, more strongly space-charge-dominated beam (σ₀/σ~12) than the original