Transverse beam dynamics studies of a heavy ion induction linac

The multiple beam induction linac experiment (MBE-4) was built to study the accelerator physics of the low energy, electrostatically focused end of a driver for heavy ion inertial confinement fusion. In this machine four beams of Cs+ ions are accelerated through 24 common induction gaps while being focused in separate AG focusing channels. Each channel consists of a syncopated FODO lattice of 30 periods. The authors report results of the most recent studies of the transverse beam dynamics of a single drifting (180 keV) beam in this machine. The dependence of the emittance on the zero-current phase advance shows systematic variations which may be understood in the light of previous theoretical work on this topic. This result, unique to the beam parameters of a linac for heavy ion fusion, is discussed in the context of its implications for a driver design. In addition they discuss recent measurements of the motion of the beam centroid through the linac. These measurements, coupled with simulations, have proven to be a powerful tool in determining the presence of misalignment errors in the lattice of the accelerator