低温工学協会 九州・西日本支部主催　

Ｈ１８年度外国人著名研究者による特別講演会

日時：2006年11月3日（金） 13:00〜15:45
場所：九州大学 大学院システム情報科学研究院講義棟　第１講義室

　　　 福岡市東区箱崎６−１０−１（箱崎キャンパス）

 

共催：九州大学超伝導システム科学研究センター

電気学会九州支部
IEEE Fukuoka Chapter

 

九州・西日本支部恒例の標記講演会ですが、今年度は、欧州、米国での超伝導研究分野からお二人の先生に講師をお務め頂きます。Freyhardt先生は、ヨーロッパにおける超伝導コミュニティーの中心的存在で、本年度のIEEE Council on Superconductivity Awardsを受賞されました。Barnes博士は、米空軍研究所の超伝導プログラムの責任者で、航空機搭載用の超伝導発電機やそのための材料開発に関するプログラムを指揮されています。次世代超伝導材料の、世界の開発現況を知る絶好の機会です。ご参集下さい。どなたでもご参加できます。

 

 

Processing of high-performance coated conductors. A challenge for basic R&D. Developments in Europe.

 

Prof. Dr. Herbert C. Freyhardt

Institut fuer Materialphysik, Universitaet Goettingen and ZFW Goettingen gGmbH, Germany

 

YBaCuO or REBaCuO coated conductors (CC) based on polycrystalline Ni-Cr alloys / stainless steel (SS) and thermomechanically treated (RABiTS) substrates are processed to exhibit high critical and engineering current densities. Both vacuum and non-vacuum technologies are employed to coat the substrate tapes with single/multilayer buffers, HTS films and conductive/protective overlayers. Recent developments in Europe will be addressed.

It was our goal to develop vacuum-technological methods with particular efforts on ion-beam assisted deposition (IBAD) of YSZ and pulsed laser deposition (PLD) of the HTS, where conductor architectures SS / IBAD-YSZ / CeO₂ / PLD-YBCO yielded conductors with attractive critical current densities in the HTS over 3 MA/cm² as well as I_c ∙ L values up to 9400 (A/cm-w) ∙ m in reproducibly processed and robust 40m-long CC.

Whereas the technological challenge is to reliably fabricate long lengths of robust CC, with specifications determined by the respective application, the supporting knowledge base and an advanced basic understanding will enable to control (i) the growth of multilayers with their interfaces, (ii) the mechanical and electromechanical properties of CC, (iii) current flow in the HTS film and through grain boundaries, as well as (iv) flux pinning in the HTS layer.

The contribution intends to highlight progress in fundamental R&D as a basis to reliably manufacture second generation wires.

 

 

Improving YBCO coated Conductors in the Air Force Research Laboratory

Dr. Paul N. Barnes

Superconductivity Group Leader, Air Force Research Laboratory, U.S.A.

 

The talk will cover some of the work conducted at the Air Force Research Laboratory to improve the performance of the YBCO coated conductor for use in applications. Areas that will particularly be covered include flux pinning and ac loss minimization. Data will be presented on pinning by minute doping and barium-tin-oxide (BSO) nanoparticulates both of which provide improvement to the YBCO conductor’s in-field current density. The minute doping is accomplished by the addition of very minor amounts (≤1% of Y) of typically deleterious rare earths into high quality YBCO. Standard deposition parameters for YBCO are used without additional optimization for the dopants.  BSO pinning is accomplished by the insertion of a pie-shaped wedge of BSO material into the PLD target. Data will be presented for 65 K and 77 K. A comparison of the pinning processes will also be provided. Regarding ac loss, interfilamentary current sharing schemes will be considered and post laser ablation treatment to minimize coupling currents will be discussed.

 

 

                                                      問い合わせ先：木須 隆暢

                                                   九州大学大学院システム情報科学研究院

                                                   Phone : 092-642-3910, Fax : 092-642-3963

                                                   E-mail: kiss@sc.kyushu-u.ac.jp