Beam focusing by decelerating RF fields in a drift tube linac
Abstract
A method of beam focusing by two-electrode RF crossed lenses with decelerating fields is proposed. The lenses are arranged in accelerating gaps of a drift tube linac. The crossed lens is a set of plane electrodes with rectangular apertures such that the apertures in the neighbouring electrodes are rotated 90° each other. Different variants of focusing periods with the RF crossed lenses are considered. The βλ FD period is shown to be used for a low-energy part of the linac. The transverse phase advance for the FD period is independent on a particle phase when a synchronous harmonics of the accelerating field is absent and is analogous to a RFQ with unmodulated vanes in the case. In the main part of linac it is worth to change to the 2 βλ FDOO or 3 βλ FOODOO period to obtain essentially higher acceleration rate.
- Publication:
-
Nuclear Instruments and Methods in Physics Research A
- Pub Date:
- February 2001
- DOI:
- 10.1016/S0168-9002(00)01013-5
- Bibcode:
- 2001NIMPA.459...87B