Two-Dimensional Linacs
We describe several schemes for rf acceleration of ribbon beams. (Although the ribbon edges of course, need to be focussed, these configurations are essentially 2-D.) They allow simpler modeling than quadrupole systems and, if operable, provide good matching to certain types of ion sources and beam neutralizers. We discuss four possible configurations, in chronological order of conception: (1) an rf linac with dc transverse field focussing; (2) a similar linac, also with many pairs of electrodes, but using rf focussing; (3) an RFQ-like configuration with continuous electrodes, in which energy changes slowly along the beam axis; and (4) a similar system in which the beam energy oscillates along the axis. We discuss some of the advantages and disadvantages of these systems, and analyze the last case in some detail. 8 refs., 1 fig.