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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

A superconducting RF deflecting cavity for the ARIEL e-linac separator

Storey, Douglas W. 13 March 2018 (has links)
The ARIEL electron linac is a 0.3MW accelerator that will drive the production of rare isotopes in TRIUMF's new ARIEL facility. A planned upgrade will allow a second beam to be accelerated in the linac simultaneously, driving a Free Electron Laser while operating as an energy recovery linac. To not disrupt beam delivery to the ARIEL facility, an RF beam separator is required to separate the interleaved beams after they exit the accelerating cavities. A 650MHz superconducting RF deflecting mode cavity has been designed, built, and tested for providing the required 0.3MV transverse deflecting voltage to separate the interleaved beams. The cavity operates in a TE-like mode, and has been optimized through the use of simulation tools for high shunt impedance with minimal longitudinal footprint. The design process and details about the resulting electromagnetic and mechanical design are presented, covering the cavity's RF performance, coupling to the operating and higher order modes, multipacting susceptibility, and the physical design. The low power dissipation on the cavity walls at the required deflecting field allows for the cavity to be fabricated using non-conventional techniques. These include fabricating from bulk, low purity niobium and the use of TIG welding for joining the cavity parts. A method for TIG welding niobium is developed that achieves minimal degradation in purity of the weld joint while using widely available fabrication equipment. Applying these methods to the fabrication of the separator cavity makes this the first SRF cavity to be built at TRIUMF. The results of cryogenic RF tests of the separator cavity at temperatures down to 2K are presented. At the operating temperature of 4.2K, the cavity achieves a quality factor of 4e8 at the design deflecting voltage of 0.3MV. A maximum deflecting voltage of 0.82MV is reached at 4.2K, with peak surface fields of 26MV/m and 33mT. The cavity's performance exceeds the goal deflecting voltage and quality factor required for operation. / Graduate
72

Investigations on Asymmetrical and Symmetrical Superconducting Thin-Film Tunnel Junctions

Simha, V. V. N. 04 1900 (has links)
Thesis / Master of Engineering (MEngr)
73

Topics in the theory of excitations in granular matter

Tiwari, Rakesh P. 15 January 2010 (has links)
No description available.
74

Modeling, analysis and experimental verification of variable-speed constant-frequency power conversion scheme with a permanent magnet synchronous generator

Rim, Geun-hie 06 June 2008 (has links)
A variable-speed constant frequency (VSCF) power conversion scheme with a permanent magnet synchronous generator (PMSG) is studied in this dissertation. The scheme consists of a PMSG, diode-rectifier bridge, dc-link filter, controlled converter for conversion to the constant frequency ac utility, and transformer. The various subsystems listed above are modeled for steady-state analysis and the simulation results are experimentally verified. All the relevant performance equations are derived for both the three-phase half-wave (THWI!) and full-wave (TFWI) controlled converter options and the harmonics are computed. / Master of Science
75

The fabrication and characterisation of High Temperature Superconducting tapes and coils

Al-Mosawi, Maitham Khazal January 1998 (has links)
No description available.
76

A system study on superconducting fault current limiting transformer (SFCLT) with the functions of fault current suppression and system stability improvement

Hayakawa, N., Kagawa, H., Okubo, H. 03 1900 (has links)
No description available.
77

Packaging and Characterization of NbN Superconducting Nanowire Single Photon Detectors

Orgiazzi, Jean-Luc Francois-Xavier 20 May 2009 (has links)
Superconducting nanowire single-photon detectors (SNSPDs) are nanodevices usually made from thin niobium nitride (NbN) films. Operated at liquid helium temperature, they can exhibit high detection efficiency with low dark-counts associated with a fast response time and a low timing jitter. Covering a broad detection range from ultraviolet to mid-infrared, SNSPDs are a very attractive alternative to silicon or gallium arsenide based semiconductor detectors for fiber based telecommunication when single-photon sensitivity and high counting rates are necessary. Efficient packaging and fiber coupling of a SNSPD is in itself a real challenge and is often a limiting factor in reaching high system quantum efficiency. Our approach makes use of a controlled expansion alloy which has been adequately heat treated to enhance its characteristics for cryogenic operation. This insures the integrity of the optical coupling at cryogenic temperatures while done at room temperature. It also provides a good attenuation for electromagnetic interference due to the high relative permeability of the nickel-iron alloy. The small form factor of this pigtailed optical fiber package makes it versatile and could be easily integrated with a commercial cryogen-free system or simply dipped into a standard helium transport Dewar. We report on our theoretical and experimental methodology to evaluate the optical coupling quality and present the optoelectronic characterization of two devices packaged in this way. Electrical simulation is studied to understand the speed limitation factor inherent to these devices and preliminary speed and jitter measurements are reported.
78

Packaging and Characterization of NbN Superconducting Nanowire Single Photon Detectors

Orgiazzi, Jean-Luc Francois-Xavier 20 May 2009 (has links)
Superconducting nanowire single-photon detectors (SNSPDs) are nanodevices usually made from thin niobium nitride (NbN) films. Operated at liquid helium temperature, they can exhibit high detection efficiency with low dark-counts associated with a fast response time and a low timing jitter. Covering a broad detection range from ultraviolet to mid-infrared, SNSPDs are a very attractive alternative to silicon or gallium arsenide based semiconductor detectors for fiber based telecommunication when single-photon sensitivity and high counting rates are necessary. Efficient packaging and fiber coupling of a SNSPD is in itself a real challenge and is often a limiting factor in reaching high system quantum efficiency. Our approach makes use of a controlled expansion alloy which has been adequately heat treated to enhance its characteristics for cryogenic operation. This insures the integrity of the optical coupling at cryogenic temperatures while done at room temperature. It also provides a good attenuation for electromagnetic interference due to the high relative permeability of the nickel-iron alloy. The small form factor of this pigtailed optical fiber package makes it versatile and could be easily integrated with a commercial cryogen-free system or simply dipped into a standard helium transport Dewar. We report on our theoretical and experimental methodology to evaluate the optical coupling quality and present the optoelectronic characterization of two devices packaged in this way. Electrical simulation is studied to understand the speed limitation factor inherent to these devices and preliminary speed and jitter measurements are reported.
79

Progress in Development of Superconducting Fault Current Limiting Transformer (SFCLT)

Okubo, Hitoshi, Hanai, Masahiro, Kojima, Hiroki, Hayakawa, Naoki 06 1900 (has links)
No description available.
80

Basic Studies on Persistent Current Compensator for Superconducting Magnet by Use of Linear Type Magnetic Flux Pump / リニア型磁束ポンプを適用した超伝導マグネット用永久電流補償装置に関する基礎研究 / リニアガタ ジソク ポンプ オ テキヨウシタ チョウデンドウ マグネットヨウ エイキュウ デンリュウ ホショウ ソウチ ニ カンスル キソ ケンキュウ

Chung, Yoon Do 25 September 2007 (has links)
学位授与大学:京都大学 ; 取得学位: 博士(工学) ; 学位授与年月日: 2007-09-25 ; 学位の種類: 新制・課程博士 ; 学位記番号: 工博第2864号 ; 請求記号: 新制/工/1421 ; 整理番号: 25549 / Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第13393号 / 工博第2864号 / 新制||工||1421(附属図書館) / 25549 / UT51-2007-Q794 / 京都大学大学院工学研究科電気工学専攻 / (主査)教授 引原 隆士, 教授 小林 哲生, 准教授 中村 武恒 / 学位規則第4条第1項該当

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