|THPP32 ポスターセッション② 9月3日 ポスター会場 13:10-15:10|
|Measurement of vortex penetration field into NbN laminated thin-film structure|
○井藤 隼人，早野 仁司，久保 毅幸，佐伯 学行，片山 領（高エネルギー加速器研究機構），岩下 芳久，頓宮 拓（京都大学化学研究所），伊藤 亮平，永田 智啓（アルバック）
|○Hayato Ito, Hitoshi Hayano, Takayuki Kubo, Takayuki Saeki, Ryo Katayama (KEK), Yoshihisa Iwashita, Hiromu Tongu (Kyoto ICR), Ryohei Ito, Tomohiro Nagata (ULVAC, Inc.)|
The maximum accelerating gradient (Eacc) of the SRF cavity can be increased by raising the vortex penetration field (Hv). A laminated thin-film structure, in which a superconductor layer (S’) such as NbN and an insulating layer (I) are coated on bulk Nb (S) (S’-I-S structure), has been proposed to increase the Eacc. By using the S’-I-S structure, the field is screened by the superconductor layer, reducing the field applied to the bulk Nb. Hence, the bulk Nb will withstand against a higher applied magnetic field. It means the cavity can achieve higher Eacc than conventional SRF cavities. S’-S structure in which a superconductor layer (S’) is coated on bulk Nb directly is also expected to increase the Eacc. In order to study the magnetic property of the laminated thin-film structure, we developed the Hv measurement system, which can apply the AC magnetic field locally without the influence of the sample edge effects. Measurements were performed to NbN-SiO2-Nb (S’-I-S structure) samples and NbN-Nb (S’-S structure) samples of various superconductor layer thicknesses. In this report, the measurement results of the NbN-SiO2-Nb samples and NbN-Nb samples will be discussed.