BEAM TRAPPING IN A MODIFIED BETATRON ACCELERATOR WITH A LOCALIZED BIPOLAR ELECTRIC-FIELD PULSE

A trapping concept for the injected beam in a modified betatron accele rator using a localized inductive electric-field pulse generated by a charged coaxial pulse line is described. The average canonical angular momentum [P(theta)] is not conserved in this scheme. Numerical simula tions demonstrate trapping over a wide range of operating parameters. A 0.84 OMEGA, 45 ns water dielectric pulse line has been built for tes ting the trapping concept. The pulse line is switched using triggered vacuum surface flashover switches. Test results show that a single bip olar output pulse can be obtained if the pulse line is crowbarred. For 15-40 kV pulses, the observed rise time is roughly 20 ns.