MIDIT OFD CATS Modelling, Nonlinear Dynamics Optics and Fluid Dynamics Chaos and Turbulence Studies and Irreversible Thermodynamics Risø National Laboratory Niels Bohr Institute and Technical University of Denmark Building 128 Department of Chemistry Building 321 P.O. Box 49 University of Copenhagen DK-2800 Lyngby DK-4000 Roskilde DK-2100 Copenhagen Ø Denmark Denmark Denmark
by Professor Alexander Zhuravel
Superconducting Electronics & Mesoscopic Systems
B. Verkin Institute for Low Temperature Physics,
National Academy of Sciences of Ukraine,
Kharkov, Ukraine,
MIDIT-seminar 489
Tuesday, May 22, 2001, 14.00 h
at IMM, Bldg. 305, Room 018, DTU
Abstract: The basic bottleneck for practical use of superconducting microwave devices is their relatively large and inhomogeneous surface impedance and nonlinear power dependence, even at modest power levels. This behavior is due, in part, to inhomogeneous current flow across thin superconducting films. The conventional methods of analyzing the nonlinear response are based on global characteristics of the device such as intermodulation and generation of har monics. This kind of analysis does not directly lead to a solution of this problem, i.e. to finding the origin of the observed nonlinearity. We devised a general experimental procedure for imaging the microwave current distributions which are caused by superconducting order parameter variations in operating devices. A new generation of Low-Temperature Laser Scanning Microscopy is developed to investigate the local origins of the nonlinearity in superconduct ing microwave devices.