Quadrupole focusing of intense electron beams in low-frequency RF accelerators

Summary form only given. New options for compact accelerators of intense pulsed electron beams are being studied. Low-frequency RF accelerators have promise for this application. In low-frequency accelerators, it is possible to eliminate beam focusing elements like solenoids by using shaped accelerating electrodes to define quadrupole field components. Simplification of the beamline opens options for compact pulsed acceleration structures. The quadrupole geometries that have been investigated are the quasi-static equivalent of the RFQ and are closely related to recent quadrupole-enhanced ion accelerator columns. A new 3-D electrostatic computer code, E3, has been developed to analyze fields in acceleration structures and to determine limits on electron transport. Evaluation of focusing strength and field stress in quadrupole structures for multi-kA electron beams has been carried out.