L. Kang

Improved Epitaxy and Surface Morphology in YBa2Cu3Oy Thin Films Grown on Double Buffered Si Wafers

Highly epitaxial thin films of YBCO have been obtained on silicon wafers using a Eu2CuO4/YSZ (yttrium-stabilized ZrO2) double buffer. Our results showed that application of such a double buffer can significantly enhance the epitaxy of grown YBCO. It also leads to an excellent surface morphology. The average surface roughness was found less than 5 nm in a large range. The results of X-ray small angle reflection and positron spectroscpy demonstrate a very clear and flat interface between YBCO and buffer layers. The Eu2CuO4/YSZ double buffer could be promising for coating high-TC superconducting films on various reactive substrates.

Epitaxial YBa/sub 2/Cu/sub 3/O/sub y/ thin films grown on silicon with a double buffer of Eu/sub 2/CuO/sub 4//YSZ

We report a double buffer of Eu/sub 2/CuO/sub 4/ (ECO)/YSZ to improve the growth of YBa/sub 2/Cu/sub 3/O/sub y/(YBCO) on Si wafer. The ECO buffer material possesses a very stable 214-T structure. It has excellent structural and chemical compatibilities with YBCO and YSZ. Our study showed that the epitaxy and crystallinity of YBCO deposited on Si could be considerably enhanced by using such a double buffer of ECO/YSZ. The grown films were characterized by grazing incidence X-ray reflection, rocking curve, SEM, TEM, and surface profiler. It was also found that such a double buffer could lead to a very smooth surface in the YBCO layer.

Study of the dynamic characteristics of the AC dipole-girder system for CSNS/RCS

China Spallation Neutron Source (CSNS) is a high intensity proton accelerator-based facility. Its accelerator complex includes two main parts: an H- linac and a rapid cycling synchrotron (RCS). The RCS accumulates an 80 MeV proton beam and accelerates it to 1.6 GeV, with a repetition rate of 25 Hz. The AC dipole of the CSNS/RCS is operated at a 25 Hz sinusoidal alternating current which causes severe vibration. The vibration will influence the long-term safety and reliable operation of the magnet. The CSNS/RCS AC dipole-girder system takes vibration isolator to decrease the vibratory force and the vibration amplitude of the dipole. For the long-term safety and reliable operation of the dipole, it is very important to study the dynamic characteristics of the dipole-girder system. This paper takes the dipole-girder as a specific model system. A method for studying the dynamic characteristics of the system is put forward by combining theoretical calculation with experimental testing. The modal parameters with and without vibration isolator of the dipole-girder system are obtained through ANSYS simulation and testing. Then, the dynamic response of the system is calculated with modal analysis and vibration testing data. With the simulation and testing method, the dynamic characteristics of the AC dipole-girder are studied.