Off-campus costs for Firm-fixed price proposal for the reimbursement of funds to Northwestern University for the services of Postdoctoral Research Associate

FNAL-Northwestern Center for Applied Physics and Superconducting Technologies (CAPST) brings together the complementary strengths of Fermilab and Northwestern University to advance the science and technology of superconducting RF cavities. One of the unique strengths of Northwestern University is the world class expertise in theoretical superconductivity. As part of CAPST, this specific effort will be a series of theoretical investigations performed by the Northwestern University postdoctoral research associate Wave Ngampruetikorn of the various mechanisms of the SRF cavity dissipation and quenching. Year 1: The focus of the first year of the work will be developing the calculation tools to fully analyze the non-equilibrium dynamics of the quasiparticles in SRF cavity driven by various levels of the input power. Kinetic equations coupled with the time-dependent density of states would have to be solved. The outcome will be the model to compare with the experiments performed at FNAL on nitrogen doping, nitrogen infusion, and other surface processing Year 2: The emphasis of the 2nd year of the work will be on determining the relevant timescales for nucleation and motion of vortices in niobium exposed to the surface microwave field with the amplitude higher than the superheating field. The outcome is the dependence of the vortex entry/exit dissipation on the magnitude of the rf field, its effect on cavity Q, as well as the stability of the overall process – does the flux entry/exit lead to quench? Furthermore, various measures to slow down nucleation and/or reduce dissipation will be theoretically explored. As part of the effort, reporting the results at major relevant conferences, as well as travel between Fermilab and Northwestern is expected.