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Yi Xie

Graduate Student
120 Newman Laboratory Cornell University Ithaca, NY 14853


I'm working on the Q-drop phenomenon in high gradient SRF cavities.

Superconducting rf resonating cavities made of niobium (Nb) are the essential parts of future accelerators such as the International Linear Collider (ILC) and Energy Recovery Linac (ERL) due to the fact that they can be operated at high gradient, high current and continuous wave conditions. Their benefits arise because of small dissipation in the cavity walls compared with normal conducting rf cavities. The performance of a superconducting rf cavity can be evaluated by measuring the Q factor at the accelerating field Eacc. Ideally the stored energy is proportional to the square of accelerating field, and the Q(Eacc) curve is flat under at all field levels. But experimental results from cavity RF tests have shown that there are anomalous losses depending on the surface magnetic field levels Hs which correspond to accelerating gradients Eacc. That is called Q-drop phenomenon.