Radio Frequency Superconductivity has become an enabling technology for a variety of accelerators necessary for frontier research in nuclear physics, materials science and high energy physics. In the US, many accelerator facilities are firmly based on superconducting rf (SRF) technology. As the gradient capability of SRF continues to improve, prospects for new applications grow increasingly attractive. This proposal seeks to continue generic R&D on improving superconducting cavity gradients.
Gradients in niobium superconducting cavities have been steadily advancing over the last decade due to improvements in understanding the physics of cavity performance limitations and due to invention of appropriate cures to address these limitations. This proposal seeks to extend the record gradients to multi-cell structures of new shapes.
The intellectual merit of this proposal will be to understand the causes of yield limitations in full-scale structures clearing the path to realizing 60 MV/m gradients.
The broad impact of generic advances proposed here would be to benefit many of new facilities that will be based on SRF: Free Electron Lasers, Energy Recovery Linac based light sources, high intensity proton accelerators for neutrino beam lines or for accelerator transmutation of nuclear waste, rare isotope accelerators for nuclear astrophysics, the International Linear Collider, Muon accelerators for neutrino factories and ultimately a multi-TeV muon collider.
Particle accelerators have been the dominant large scientific from which we know (a) most information about the smallest building blocks of matter, (b) most of the properties of nuclei needed to understand star-formation and civilian / military energy production, (c) most atomic structures that have been found for biological molecules, e.g. for medical applications, (d) many advanced tools to image advanced material properties in high tech applications like airplanes or micro-devices. While particle accelerators have thus had a glorious past, an even brighter future is being realized with superconducting accelerating structures. These can accelerate to exceedingly large energies with significantly reduced power consumption and better capabilities for scientific applications. This grant focuses on the development of superconducting accelerating structure, on understanding how they work, how they can be improved, and how they can be analyzed. We have determined with experiment and theory the very largest accelerating fields a superconducting accelerator structure can achieve. We have constructed a Temperature-mapping system to find out how the energy consumption in accelerating structure can be minimized as much as physically possible, and we have analyzed cavities to see how their maximal field can be increased and their power consumption can be reduced, e.g. by chemical cleaning or heating to high temperatures. The better superconducting accelerator structures we are striving for will directly improve what can be found out with the most modern particle accelerators, from elementary building blocks of matter to medical applications and from marketable nano-structures to accelerators for energy production.
