Non-linear microwave impedance of short and long Josephson Junctions

The non-linear dependence on applied $ac$ field ($b_{\omega}$) or current ($i_{\omega}$) of the microwave (ac) impedance $R_{\omega}+iX_{\omega}$ of both short and long Josephson junctions is calculated under a variety of excitation conditions. The dependence on the junction width is studied, for both field symmetric (current anti-symmetric) and field anti-symmetric (current symmetric) excitation configurations.The resistance shows step-like features every time a fluxon (soliton) enters the junction, with a corresponding phase slip seen in the reactance. For finite widths the interference of fluxons leads to some interesting effects which are described. Many of these calculated results are observed in microwave impedance measurements on intrinsic and fabricated Josephson junctions in the high temperature superconductors, and new effects are suggested. When a $$ field ($b_{dc}$) or current ($i_{dc}$) is applied, interesting phase locking effects are observed in the ac impedance $Z_{\omega}$. In particular an almost periodic dependence on the dc bias is seen similar to that observed in microwave experiments at very low dc field bias. These results are generic to all systems with a $\cos (\phi)$ potential in the overdamped limit and subjected to an ac drive.Comment: 7 pages, 11 figure

Electrical and structural properties of MgB2 films prepared by sequential deposition of B and Mg on the NbN buffered Si(100) substrate

We introduce a simple method of an MgB2 film preparation using sequential electron-beam evaporation of B-Mg two-layer (followed by in-situ annealing) on the NbN buffered Si(100) substrate. The Transmission Electron Microscopy analyses confirm a growth of homogeneous nanogranular MgB2 films without the presence of crystalline MgO. A sensitive measurement of temperature dependence of microwave losses shows a presence of intergranular weak links close the superconducting transition only. The MgB2 films obtained, about 200 nm thick, exhibit a maximum zero resistance critical temperature of 36 K and critical current density of 3x10^7 A/cm^2 at 13.2 KComment: 11 pages, 6 figures, submitted to Appl. Phys. Let

Flachdaecher beurteilen und instandsetzen Schadensbilder, Ursachenermittlung, Instandsetzungsmoeglichkeiten

Available from TIB Hannover: RO 5830(16) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

ESARDA Bulletin n. 59

ESARDA is an association initially formed to advance and harmonize research and development for nuclear safeguards whose scope has in recent year expanded as the number and type of its working groups’ activities below indicates. Esarda is currently composed of about 30 laboratories, private and governmental institutions worldwide. Within Esarda (http://esarda.jrc.ec.europa.eu/), a number working groups have been over the years established and active namely: Techniques and Standards for Destructive Analysis, Techniques and Standards for Non-Destructive Analysis, Containment and Surveillance, Novel Approaches / Novel Technologies, Implementation of Safeguards, Verification Technologies and Methodologies, Training and Knowledge Management, Editorial Committee. ESARDA publishes a Bulletin containing peer reviewed scientific related to nuclear Safeguards, verification and non-proliferation. This publication appears generally twice a year. In addition, thematic special issues are published as proposed by the ESARDA community. The Bulletin Editorial Board is composed of about 10 experts in the various technical and scientific fields related to safeguards. They are all actively engaged in safeguards R&D or in safeguards implementation and other fields. The Editorial Board decides the contents of the Bulletin, selects the papers to be published and reviews them before publication. All ESARDA editorial activities are carried out at JRC in Ispra. Scientific papers submitted for publication are reviewed by independent authors and by members of the Editorial Committee. The Bulletin is currently submitted to Scopus for evaluation in view of citation. ESARDA Bulletin is published jointly by ESARDA and the Joint Research Centre of the European Commission and distributed free of charge to over 1000 registered members, libraries and institutions worldwide.JRC.G.II.7-Nuclear securit