LANL, Los Alamos, New Mexico, USA
Niowave, Inc., Lansing, Michigan, USA
We present an update on the 2.1 GHz superconducting rf (SRF) photonic band gap (PBG) resonator experiment in Los Alamos. The SRF PBG cell was designed to operate at 2.1 GHz. PBG cells have great potential for outcoupling long-range wakefields in SRF accelerator structures without affecting the fundamental accelerating mode. Using PBG structures in superconducting particle accelerators will allow operation at higher frequencies and moving forward to significantly higher beam luminosities thus leading towards a completely new generation of colliders for high energy physics. However, the technology of fabrication of PBG accelerator cells from niobium has not been well developed to date. Here we report the results of our efforts to fabricate a 2.1 GHz PBG cell and to test it at high gradients in a liquid helium bath at the temperature of 2 Kelvin. The high gradient performance of the cell will be evaluated and the results will be compared to simulations with the CST Microwave Studio.
Niowave, Inc., Lansing, Michigan, USA
BNL, Upton, Long Island, New York, USA
Replacement of the normal conducting 28 MHz accelerating cavities in the RHIC ring with superconducting structures offers a number of advantages for the machine operation, including reduction of the number of cavities required and improved HOM performance. A prototype folded quarter wave structure is under construction at Niowave, Inc. to meet this need. This novel cavity geometry achieves the very low resonant frequency required with a relatively compact structure, and can provide the large tuning range required (~1% of the cavity frequency). Progress of the cavity fabrication will be presented along with room temperature RF measurements.
Niowave, Inc., Lansing, Michigan, USA
ODU, Norfolk, Virginia, USA
Multi-spoke cavities are well-known options for acceleration of heavy and light ions. A recently developed multi-spoke cavity for β=1 presents an attractive opportunity to use this cavity type for electron accelerators. One of the main attractive features of this cavity type is its compactness for relatively low frequency. A simplified design at 500 MHz allowed building of a multi-spoke cavity and cryomodule in a 2-year time frame with confidence and development of effective manufacturing techniques. It also constitutes an important step in proving the usefulness of this kind of cavity design for new applications in the electron machines. Niowave is now in a position to build on the success of this cavity to help advance the design of superconducting electron accelerators. Accelerating voltage of more then 4.3 MV in a single cavity at 4.5 K is expected with peak electric field of less then 21.7 MV/m, and peak magnetic field of less then 80 mT. The paper discusses the fabrication challenges of the complete cavity and the cryomodule, as well as room temperature and cryogenic test results.