An Update on Windows, Couplers, Higher-Order-Mode Damping, and Interlocks
One of the more consistently challenging problems associated with superconducting RF systems is the introduction of RF power to the cavity and the extraction of beam-induced high-order-mode power from the cavity. This usually involves the transmission of RF power between atmosphere and cavity vacuum spanning a substantial difference in temperature. Dielectric RF windows, usually ceramic, provide atmospheric barriers, and carefully designed thermal transitions of waveguide or coaxial line span the temperature difference while minimizing heat flow to the refrigeration system from conduction and RF losses. There are exceptions, such as a proposed dual-beam accelerator in which RF power is generated in a parallel cavity structure which is RF coupled to accelerating cavities in a common vacuum environment. Some machines such as the DARMSTADT linac do not generate enough higher order mode fields to disturb the beam and require no damping at all. The CEBAF cavity, originally designed for higher current storage ring application at Cornell, generates only a few tenths of a watt with the CEBAF beam which is small enough to be economically dissipated at the cavity temperature and within the cavity vacuum envelope avoiding the need for a window. In general, this is not the case and larger values of higher order mode power must be dissipated at some intermediate shield temperature or outside of the cryostat at 300 K. An example is the HOM extraction system developed at KEK which is shown.
- Research Organization:
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research (ER) (US)
- DOE Contract Number:
- AC05-84ER40150
- OSTI ID:
- 791729
- Report Number(s):
- CEBAF-PR-93-053; DOE/ER/40150-2004; TRN: US200204%%176
- Resource Relation:
- Conference: 6th RF Superconductivity Workshop, Newport News, VA (US), 10/1993; Other Information: PBD: 1 Oct 1993
- Country of Publication:
- United States
- Language:
- English
Similar Records
Higher-Order-Mode damping and microwave absorption at 2K
HOM Couplers for the LHC Superconducting Crab Cavities. DOE-HEP SBIR Fast-Track Final Scientific Report