Description: Materials and Fabrication Technologies for SRF Cavities Material properties, surface features, processing procedures, and cavity geometry can have significant impact on the performance of superconducting radio-frequency (SRF) accelerator cavities. Grant applications are sought to develop (1) new raw materials streams, such as those utilizing large-grain Nb ingot slices; (2) new or improved SRF cavity fabrication techniques, such as seamless and weld-free approaches; (3) SRF cavity fabrication techniques that reduce use of expensive metals such as niobium while achieving equivalent performance as bulk niobium cavities; (4) new or improved bulk processing technologies, such as mechanical or plasma polishing; (5) new or improved final surface preparation and protection technologies; and (6) new cavity ideas aimed at breakthroughs in understanding and performance of SRF cavities.
SRF Cavities Grant applications are sought for the development of superconducting radiofrequency cavities for acceleration of proton and ion beams, with relativistic betas ranging from 0.1 to 1.0. Frequencies of current interest include 325, 650, and 1300 MHz. Continuous wave (CW) cavities are of the greater interest, although pulsed cavities could also be supported. Accelerating gradients above 15 MV-m, at Q0 in excess of 2 1010 (CW), and above 25 MV-m at Q0 in excess of 1 1010 (pulsed) are desirable. Topics of interest include: (1) cavity designs; (2) cavity fabrication alternatives to electron beam welding, including for example hydroforming and automatic TIG or laser welding of cavity end groups; (3) other cavity and cryomodule cost reduction methods; (4) cw power couplers at >50kW; (5) fast tuners for microphonics control; (6) higher order mode suppressors, including extraction of HOM power via the main power coupler and with photonic band gap cavities; (7) ecologically friendly or alternative cavity surface processing methods; (8) alternatives to high pressure rinsing that would allow in-situ cleaning of cavities to control field emission; (9) high resolution tomographic x-rays of electron beam welds in cavities; (10) specifically for muon acceleration, design of a cost-effective 325 MHz cavity capable of 20 MV-m with Qo > 109 that is compatible with expansion to a two or three cell cavity system; possible approaches could include: forming a cavity from a bonded sheet of thin Nb on Cu, robust sputter coating of Nb on a Cu cavity, and electroforming Cu on a thin Nb cavity shell