UVa, Charlottesville, Virginia
JLAB, Newport News, Virginia
The lower critical magnetic field of an SRF cavity may be increased by screening the interior fields from the cavity bulk. This screening could be accomplished by coating the interior of a cavity with alternating layers of insulator and superconductor, each of which is thinner than the London penetration depth of the superconductor*. We have developed a method for measuring the behavior of such a multilayer system. A superconducting disk resonator is deposited on top of a small multilayer sample. The small sample approach allows for flexibility in the evaluation of many different materials and configurations. The onset of magnetic flux penetration in the superconductor can be observed from the change in resonator Q and the detection of flux flow voltages. Since the disk resonator applies a known field to the multilayer system, the lower critical magnetic field of the system may be measured. This poster presents design analysis and preliminary data from an experimental program for multilayer film evaluation.
*A. Gurevich, Applied Physics Letters 88, 012511 (2006).
