Minimizing transverse-field effects in superconducting quarter-wave cavities.
Superconducting (SC) cavities presently used for acceleration of ions in the velocity range from 0.01c to 0.3c are based frequently on quarter-wave resonators (QWR). Numerous types of QWR cavities over a frequency range from 50 to 240 MHz have been built or are proposed for a variety of applications. Recent studies have revealed an important drawback of the QWR: the presence of beam steering fields in the aperture [1]. We have shown that this effect can be eliminated by appropriate shaping of the drift tubes [2]. There is, however, another problem in QWR drift-tube design caused by quadrupole terms in the transverse Lorentz force which can cause appreciable emittance growth when the linac lattice includes transverse focusing by SC solenoids. Solenoidal focusing provides a compact lattice and maximizes transverse acceptance while maintaining low longitudinal emittance. We discuss the design of QWR cavity geometries which eliminate both the dipole and higher order components in the equations of motion in the transverse planes, while keeping the ratio of surface-to-accelerating field low. The resulting QWR designs minimize emittance growth, which is critical in some applications.
- Research Organization:
- Argonne National Lab., IL (US)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- W-31-109-ENG-38
- OSTI ID:
- 801603
- Report Number(s):
- ANL/PHY/CP-107623; TRN: US0205547
- Resource Relation:
- Conference: 21st International Linear Accelerator Conference (LINAC 2002)., Gyeongju (KR), 08/19/2002--08/23/2002; Other Information: PBD: 20 Sep 2002
- Country of Publication:
- United States
- Language:
- English
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