Thermal Analysis of Electron-Beam Absorption in Low-Temperature Superconducting Films

The absorption of an electron beam in a superconducting microbridge reduces its critical current, the maximum d-c electric current it can carry without resistance. A two-dimensional heat conduction analysis determines numerically the temperature field in the film caused by electron-beam heating, considering the nonlinear thermal boundary resistance between film and substrate. The method of Intrinsic Thermal Stability yields the critical current for this temperature field. The critical current predictions agree with experimental data from low-temperature scanning electron microscopy (LTSEM) with superconducting lead microbridges. The method developed in this study permits the quantitative prediction of LTSEM experiments, enhancing the value of this technique for the local characterization of superconducting films.