POSTER SESSION 2PO8: System Applications

Tuesday, Feb. 22, 1:30 p.m. – 3:30 p.m., Hall D (GRB)

*2PO8-1 Industry/Government Partnerships in Emerging Technologies

Christine E. Platt, NIST ATP, Gaithersburg, MD 20899-4730

Presenting Author: C.E. Platt

Successful development of high-performance high-temperature superconducting films, wires and tapes has been a result of unprecedented world-wide effort. Part of this effort has been outstanding industry/government partnerships in a number of countries. As more applications are demonstrated, component cost, demonstrated reliability, refrigeration, manufacturable processes and other critical factors emerge as the HTS industry looks to near-term commercialization around the world.

These HTS-enabled technologies have the potential to radically transform the telecommunications and electricity infrastructures. Similar transforming and enabling technologies have been developed in other industries by the NIST Advanced Technology Program, a public/private partnership now in its tenth year. ATP works with industry to address high technical risk R&D problems with excellent potential for significant future economic impact. Examples of such partnerships, and ATP's role and mission, will be presented.

2PO8-2 High Gradient Magnetic Separation Techniques with High T_c Superconductor

Jian X. Jin, Rong Zeng, and Shi X. Dou, Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong, NSW 2522, Australia

Presenting Author: J.X. Jin

High gradient magnetic separation techniques developed with superconductors provide an efficient method for the separation of very fine and weak magnetic materials. The separation efficiency is related to the strength of the magnetic field applied and the field gradient generated to trap the magnetic particles. High T_c superconducting (HTS) wires provide a new opportunity to build a HTS magnet for use in a high gradient magnetic separator (HGMS) with higher separation efficiency. HTS (Bi,Pb)₂Sr₂Ca₂Cu₃O_10+x Ag clad wires have been used for the design of a 2 T HTS magnet for application in a HGMS. The use of the HTS magnet for this application has been analyzed with regard to the HTS wire performance and the generated magnetic field. Results show that the HTS (Bi,Pb)₂Sr₂Ca₂Cu₃O_10+x Ag clad wires, with a relative higher operational temperature and a high critical current, have the capability for the implantation to a high efficient HGMS.

2PO8-3 Magnetic Saturable Reactor Type HTS Fault Current limiter

Jian X. Jin and Shi X. Dou, Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong, NSW 2522, Australia

Presenting Author: J.X. Jin

Magnetic saturable reactor is one of the concept which can be based on to develop an electrical fault current limiter (FCL) with high T_c superconducting (HTS) wire. A dc bias winding with high current ampere-turns is required by the FCL, and the HTS Bi-2223/Ag wire is suitable for the winding design by considering its electrical performance and economic operational temperature. The advantage of this type of HTS FCL will be identified in comparison with other HTS FCLs, and the industry application of this FCL device will also be analyzed.

2PO8-4 Fault Current Limiter Model Device: Characterisation and Simulation

N. Adamopoulos and S.K. Patapis, Section of Solid State Physics, Department of Physics, University of Athens, Panepistimiopolis, GR 157 84, Athens, Greece

Presenting Author: N. Adamopoulos

Fault Current Limiters are widely manufactured both as industrial application and laboratory-size devices. A detailed simulation of the performance of such supeconducting limiters is presented where the various superconducting and magnetic characteristics of the materials as well as the geometry of the circuit are based on experimental results in order to closely simulate their performance. Testing methods of the superconducting material are proposed in order to collect all the required material data. The response of the circuit is presented in the case of a fault with emphasis in the time delay and the recovery of the system. Thermal recovery is also included in order to simulate the performance of the device and its response under actual electro-thermal environment.

2PO8-5 Investigation of the behavior of a fault current limiter during the switching process

L. Antognazza 1, M. Decroux 1, S. Reymond 1, J.-M. Triscone 1, Ø. Fischer 1, W. Paul 2, and M. Chen 2. 1 Department of Condensed Matter Physics, University of Geneva, Switzerland. 2 ABB Corporate Research LTD, Dättwil, Switzerland.

Presenting Author: L. Antognazza

We have carried out detailed measurements on the occurrence of the dissipative state, as well as its propagation velocity, at the early stages of the switching process of a Superconducting Fault Current Limiter (SFCL) made of YBCO thin films grown epitaxially onto sapphire substrates. The experiments, performed with constant current pulses ranging from 10 microseconds to 1ms, show that a quasi spontaneous Highly Dissipative State (HDS) appears at high current density and starts to propagate with an initial velocity higher than 100 m/s. These velocities are almost one order of magnitude higher than any possible thermal velocities in the thermal environment of the superconducting line. We furthermore find evidence that this HDS does not originate from a thermal runaway of the superconducting line. We also measured the behaviour of a SFCL by applying constant voltage pulses to the superconducting line. We found that the initial spatial extent of the HDS along the YBCO line is a linear function of the applied voltage. This effect explains very well the fast switching properties of the resistive SFCL and the limiting of the current peak at approximately 3-4 times the critical current.

2PO8-6 Switching Performance of Nb₃Sn Persistent Current Switch

Masaru Tomita 1, Kaoru Nemoto 1, and Kazumi Sugawara 2. 1 Railway Technical Research Institute, 2-8-38, Hikari-cho, Kokubunji-shi, Tokyo 185-8540, Japan. 2 Ocean Foundation, 15-16, Toranomon 1-chome, Minato-ku, Tokyo 105, Japan.

Presenting Author: M. Tomita

We designed and manufactured a persistent current switch consisting of Nb₃Sn superconducting wire for Superconducting Magneto-Hydro-Dynamic Propulsion Ship (MHDS). Nb₃Sn has T_c higher than NbTi which is commonly used for the conventional persistent current switch, and thus is expected to have a higher stability to disturbance than NbTi wire. We therefore performed computer simulation for the heat transfer of Nb₃Sn persistent current switches by using the finite element method. The results of switching performance will be presented based on the computer simulation for temperature distribution during the heating and cooling processes. We also present the estimated time for the transition from the superconducting to normal state (off-state) and vice versa (on-state).

This work was supported by the Ship & Ocean Foundation.

2PO8-7 Measurements of the Magnetocardiography in Unshielded Environment Using High-T_c rf SQUID Gradiometer

D.F. He 1, F. Zhang 1, F.X. Xie 1, Y.D. Dai 1, S.G. Wang 1, P. Ma 1, T. Yang 1, S.Z. Wang 1, W.C. Chen 2, and Z.Q. Wang 2. 1 Department of Physics, Peking University, Beijing 100871. 2 Chinese-Japanese Friendship Hospital.

Presenting Author: D.F. He

We recorded the magnetocardiography (MCG) of a normal person at 9 points in an unshielded environment by Using a first-order gradiometer made by subtracting the outputs of two high-T_c YBCO rf SQUID magnetometers. We used a computer for data acquisition and data processing. The digital filtering and averaging methods was employed to improve the Signal-Noise Ratio (SNR), and an active compensation method was introduced to decrease the influence of 50Hz line interference. After data processing, the fine structures of the heart signal (P-wave, Q,R,S-complex, T-wave) could be seen clearly and a SNR of 120 could be attained. By comparing with the electrocardiography (ECG) recorded for the same person, We found the MCG could provide additional information for the conventional ECG methods. The isofield contour map based on our MCG measurements was also given in this paper.

2PO8-8 Nondestructive Evaluation of Flaws Using SQUIDs

H.E. Horng 1, J.T. Jeng 1, Chao-Hsiang Chen 2, J.H. Chen 2, and H.C. Yang 2. 1 Department of Physics, National Taiwan Normal University, Taipei 117, Taiwan, R.O.C. 2 Department of Physics, National Taiwan University, Taipei 106, Taiwan, R.O.C.

Presenting Author: H.E. Horng

Using SQUIDs, we have designed a high-T_c nondestructive evaluation system to probe buried cracks or holes and quantify the width of these cracks or holes. Eddy currents were induced by the excitation coils designed to produce minimal magnetic-field at the SQUIDs. The frequency of the excitation current was varied from 10 to 200 Hz while the magnetic field generated from the eddy current was lock-in detected. The SQUIDs output data revealed that the NDE system could detect the hidden cracks in metals under the several intervening metal or non-conducting materials. We present the design of the system and some data to demonstrate its capabilities.

2PO8-9 The Stability Analysis Of The Race Track Typed Ag/Bi-2223 Tape Through 3-Dimensional Magnetic Field Analysis Of The High-T_c Superconducting Synchronous Motor

Myung-Kon Song 1, Sang-Jin Lee 2, and Tae-Kuk Ko 1. 1 Dept. of EE. in Yonsei Univ., 120-749, 134 Shinchon-Dong, Seodaemun-GU, Seoul, Republic of Korea. 2 Dept. of EE. in Uiduk Univ., 780-713, Fangdong, Kyongju, Korea.

Presenting Author: S.J. Lee

The purpose of this paper is to know the 3-dimensional magnetic field distribution inside the motor in order to find out if the high-T_c superconducting tapes operate stably in actual motor operation. With this goal, magnetic field distribution in a detailed model of the actual motor was analyzed through F.E.M.(Finite Element Method). As a result, it has been proved that the high-T_c superconducting tapes can withstand 4 A of current with stability. 4 A was the amount of current needed to achieve 600 A¡¹ turns which is required by the previous simulation aimed at developing this motor. Also, it has been observed that the flux damper reduces armature reactance during the motor operation and during load changes, helping the stable motor operation. But, it was observed that the flux damper generates loss by means of leakage flux and this decreases the output of the motor by about 5 %.