低温工学センターセミナー

日時: 2010-12-02 10:30 - 12:00
場所: 4号館1階セミナーホール
会議名: 加速器研究施設・超伝導低温工学センター共催セミナー
連絡先: kiyosumi.tsuchiyakek.jp
講演者: Tsuyoshi Tajima  (Los Alamos National Lab)
アブストラクト: A brief introduction of the Los Alamos Neutron Science Center (LANSCE) accelerator and R&D activities on the RF superconductivity at LANL will be presented. The LANSCE accelerator is an H+/H- accelerator with a maximum energy of 800 MeV. A 100 MeV H+ beam is used for isotope productions for medical purposes. 800 MeV H- beams are used for various sciences using neutrons. Regarding our R&D on RF superconductivity, there are 2 topics that have been studied in the last couple of years. One is to study the possibility of achieving high accelerating gradients with 805 MHz cavities. 805 MHz is the frequency of the high energy section of the LANSCE accelerator. The other topic is to improve the SRF cavity performance with multi-layer thin film coatings of another superconductor such as MgB2. Recently, we have achieved an accelerating gradient of ~50 MV/m with a newly-designed Nb single-cell 805 MHz cavity with only chemical polishing and low-temperature (115-130 C for 48 hours) in-situ vacuum baking. As for the thin film study, recent DC magnetization measurements of MgB2 films have shown that Hc1 (or the first field at which vortices start to penetrate into the film) is > 200 mT at 4.5 K, ~25 % higher than bulk Nb, with a ~200 nm thick film. RF measurements at SLAC, however, have shown much lower numbers such as ~25 mT.

[index]