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A new high-T_c (HT_c) rf SQUID working at around 1.3GHz has been developed to avoid electromagnetic interference such as growing mobile communication jamming. This new system works in a frequency range from 1.23 to 1.42GHz (centred at 1.3GHz), which is not occupied by commercial communication. The sensor used in the 1.3GHz rf SQUID is made of a HT_c coplanar superconducting resonator and a large-area HT_c superconducting film concentrator. We have achieved in the 1.3GHz HT_c rf SQUID system a minimal flux noise of 2.5×10^{-5}Φ_0/\sqrt{Hz} and a magnetic field sensitivity of 38fT/\sqrt{Hz} in white noise range, respectively. The effective area of the concentrator fabricated on a 15×15mm^2 substrate is 1.35mm^2. It is shown that the 1.3GHz rf SQUID system has a high field sensitivity. Design and implementation of 1.3GHz HT_c rf SQUID offers a promising direction of rf SQUID development for higher working frequency ranges. 相似文献
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We have studied the basic characteristics of a radio frequency superconducting quantum interference device (rf SQUID) involving two Josephson junctions connected in series, the case for the widely used grain boundary junction (GBJ) rf SQUID. It is found that the SQUID properties are determined mainly by the weaker junction when the critical current of the weaker junction is much lower than that of the other junction. Otherwise, the effect of the other junction is not negligible. We also find that only when the hysteresis parameter β is less than 1-α, where α is the critical current ratio of the two junctions, will the SQUID operate in the nonhysteretic mode. 相似文献
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To test and verify the performance of the digital low-level radio-frequency (LLRF) and tuner system designed by the IHEP RF group, an experimental platform with a retired KEK 1.3 GHz nine-cell cavity is set up. A radio-frequency (RF) field is established successfully in the cavity and the frequency of the cavity is locked by the tuner in ±0.5° (about ±1.2 kHz) at room temperature. The digital LLRF system performs well in a five-hour experiment, and the results show that the system achieves field stability at amplitude <0.1% (peak to peak) and phase <0.1° (peak to peak). This index satisfies the requirements of the International Linear Collider (ILC), and this paper describes this closed-loop experiment of the LLRF system. 相似文献
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E. Il''ichev V. Schultze R. P. J. IJsselsteijn R. Stolz V. Zakosarenko H. E. Hoenig H. -G. Meyer M. Siegel 《Physica C: Superconductivity and its Applications》2000,330(3-4):155-159
Single-layer washer-type high-Tc YBa2Cu3O7−x rf SQUIDs with grain-boundary Josephson junctions, as well as low-Tc Nb rf SQUIDs with Nb–Al2O3–Nb tunnel junctions, have been investigated in finite magnetic fields. It was shown experimentally that the suppression of the critical current of the Josephson junction due to the magnetic field leads to a modulation of the amplitude of the SQUID output signal. The role of the “unwanted” junction in high-Tc rf SQUIDs, which is formed by the grain boundary running through the washer of the SQUIDs on bicrystal substrates, has also been clarified. The drop of the SQUID signal at a finite magnetic field is originated by the penetration of the magnetic field into the unwanted junction. Based on these results, a direct radio-frequency method for the determination of the first critical field Hc1 for long Josephson junctions has been developed. 相似文献
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RF SQUID behaviour has been observed at 77 K in YBaCuO thick films prepared by screen printing technique. A hole shunted with
a microbridge type of geometry is patterned manually for observing rf SQUID behaviour. Flux noise spectrum is also studied
and it is found to depend on the quality of the film. The spectral density of the flux noise in the white noise region is
1.7×10−3 Φ0/√Hz at 77 K. 相似文献
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针对低内禀噪声要求条件下HTcrf SQUID芯片制备成品率和优质率低等问题,通过对YBCO薄膜的PLD制备工艺参数及所制作的YBCO薄膜性能与微观形貌的观测分析,提出晶界结构的非均匀和不一致性可能是影响低噪声台阶边沿型晶界结制备质量的观点,进而以淀积温度为典型控制参数设计了一组实验,对实验获取的YBCO薄膜和SQUID芯片的性能测试表明:YBCO薄膜生长的三高条件(高淀积温度、高氧分压和高激光能量密度)易造成薄膜表面平整度恶化和晶界构型的不均匀,而选择合适的淀积温度可有效提高SQUID芯片的噪声性能。 相似文献
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GAO Jie 《中国物理C(英文版)》2009,33(4):306-310
In this paper we give a set of analytical formulae to describe the characteristics of photocathode rf guns at any rf frequencies, such as energy, energy spread, bunch length, out going current, and emittance etc.as functions of the laser injection phase, which are useful in the design and practical operation of rf guns. 相似文献
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RF SQUID behaviour due to grain boundary weak links in a bulk YBCO is observed at 77 K using modified commercial rf electronics.
Porous samples with lowI
c
are found to show this characteristic whereas dense samples with higherI
c
do not show SQUID behaviour.V-B modulation characteristic is found to be better when the rf pumping frequency is kept slightly higher than the resonance
frequency of the tank circuit. Designing of coil for tank circuit with appropriateQ has been found to be very crucial for seeing the SQUID behaviour. Estimation of parameters such as coupling constant, mutual
inductance, inductance and radius of the SQUID loop, have been made and their significance is discussed. Flux noise spectrum
of the bulk rf SQUID in flux locked mode is also reported. 相似文献
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In this paper we give a set of analytical formulae to describe the characteristics of photocathode rf guns at any rf frequencies, such as energy, energy spread, bunch length, out going current, and emittance etc. as functions of the laser injection phase, which are useful in the design and practical operation of rf guns. 相似文献
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XU Qing-Jin ZHAI Ji-Yuan LI Chun-Hua SUN Yi HOU Zhi-Long GAO Jie ZHAO Tong-Xian XIONG Lian-You LU Wen-Hai ZONG Zhan-Guo LIU Li-Qiang ZHANG Liang 《中国物理C(英文版)》2009,33(1):77-80
Research and development of a 1.3 GHz 9-cell cavity test cryomodule were carried out by a collaboration group between IHEP (Institute of High Energy Physics) and TIPC (Technical Institute of Physics and Chemistry) in China.The cryomodule is a "test model" for the ILC cryomodule,and a key component of a superconducting accelerator test unit which will be built in the near future,also can be used as a horizontal test facility for 1.3 GHz 9-cell cavities.This paper presents the development status of the cryomodule,including structure design,cryogenic flow diagram,thermal and mechanical simulations,heat load estimation and etc. 相似文献
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Research and development of a 1.3 GHz 9-cell cavity test cryomodule were carried out by a collaboration group between IHEP (Institute of High Energy Physics) and TIPC (Technical Institute of Physics and Chemistry) in China. The cryomodule is a "test model" for the ILC cryomodule, and a key component of a superconducting accelerator test unit which will be built in the near future, also can be used as a horizontal test facility for 1.3~GHz 9-cell cavities. This paper presents the development status of the cryomodule, including structure design, cryogenic flow diagram, thermal and mechanical simulations, heat load estimation and etc. 相似文献
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Flynn ER Bryant HC Bergemann C Larson RS Lovato D Sergatskov DA 《Journal of magnetism and magnetic materials》2007,311(1):429-435
Acute rejection in organ transplant is signaled by the proliferation of T-cells that target and kill the donor cells requiring painful biopsies to detect rejection onset. An alternative non-invasive technique is proposed using a multi-channel superconducting quantum interference device (SQUID) magnetometer to detect T-cell lymphocytes in the transplanted organ labeled with magnetic nanoparticles conjugated to antibodies specifically attached to lymphocytic ligand receptors. After a magnetic field pulse, the T-cells produce a decaying magnetic signal with a characteristic time of the order of a second. The extreme sensitivity of this technique, 10(5) cells, can provide early warning of impending transplant rejection and monitor immune-suppressive chemotherapy. 相似文献
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Bao-Long Liang Ji-Suo Wang Xiang-Guo Meng 《International Journal of Theoretical Physics》2007,46(5):1416-1423
The quantization scheme of a single-qubit structure with Superconducting Quantum Interference Device (SQUID) is given. By
introducing a unitary matrix and by means of spectral decomposition, the Hamiltonian operator of the system is exactly formulated
in compact forms in spin-1/2 notation. The eigenvalues and eigenstates of the system are discussed. 相似文献
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基于对S型结构的理论分析,将中心频率设置为60 GHz,通过合理的改变单元结构中相应的尺寸以实现所需电谐振和磁谐振频率,并且经过优化以实现负介电常量和负磁导率的重合频段尽可能理想. 运用反演参量提取方法进行电磁参量提取,可以得到本设计在58.1~61.4 GHz频段内其ε和μ同时为负,即左手频段. 分析散射参量的仿真结果,在58~62 GHz频段内S21大于-3 dB,在59.8~60.4 GHz频段内,S11小于-20 dB,因此该设计结果可以运用于60 GHz通信滤波器和天线等器件的研究与设计. 相似文献