Multiturn Injection Techniques in the MURA 50-MeV Electron Accelerator. X

Abstract

Multiturn injection techniques employed in the MURA 50‐MeV electron accelerator are described, together with an evaluation of their performance. These include shifting of the equilibrium orbit by a time‐varying bump, damping of betatron oscillation amplitudes by an rf voltage, and damping of amplitudes by space‐charge effects. Multiturn injection is achieved by filling the accelerator radial phase space with injected beam. The capture of injected charge approaches 100% when the programmed field bump is used. This high efficiency has been achieved for about 15 turns of total beam from the inflector and for about 40 turns of collimated beam. Injection at the higher beam intensities gives rise to spontaneous longitudinal bunching of the circulating beam for all energies from injection to above transition with the magnitude generally greatest just above transition.