Development of a Superconducting RF Multi-Spoke Cavity for Compact Light Sources

Superconducting radio frequency (SRF) accelerating cavities are being successfully used for acceleration of electron beams worldwide. The use of superconducting structures helps maximize the accelerating gradient, which is a highly desirable trait for applications involving linear accelerators or storage rings. Application of todays multi-spoke accelerating structures in future SRF electron linacs and storage rings will allow a further reduction in the overall size of acceleration sections without compromising its performance. Compact accelerators utilizing SRF cavities can be successfully used in the broad range of applications from x-rays machines for cancer therapy and sterilization, to tunable x-ray and gamma sources, to high energy electron accelerators and colliders. This SBIR proposal will develop a design of the 750 MHz superconducting multi-spoke cavity capable of accelerating electrons. The transverse size of the cavity is significantly reduced using the spoke geometry compared to the traditional elliptical accelerating structures. Phase I will demonstrate the technical feasibility of the project by completing the preliminary cavity and cryomodule designs. Phase II will finalize the design, then fabricate and test the SRF multi-spoke cavity. The cavity is designed to operate at 750 MHz and is capable of differential accelerating of electrons with electric and magnetic surface fields no more than ~50 MV/m and ~80 mT respectively. The cryogenic system operates at 4.2 K. The cryogenic load can be significantly reduced by operating in a pulsed mode or by reducing the overall accelerating voltage. Cryogenic tests will be carried out at Old Dominion University (ODU) and/or Thomas Jefferson National Laboratory (JLAB) to make use of their test facilities and cryogenics systems. Demonstration of this new type of SRF multi-spoke cavity creates many new possibilities for scientific and industrial applications