排序方式: 共有144条查询结果,搜索用时 31 毫秒
91.
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
92.
Prof. Dr. Peter Comba Prof. Dr. Markus Enders Dr. Michael Großhauser Dr. Markus Hiller Prof. Dr. Rüdiger Klingeler Dr. Changhyun Koo Dr. Dennis Müller Prof. Dr. Gopalan Rajaraman Abinash Swain Msia Tavhelidse Prof. Dr. Hubert Wadepohl 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(36):9372-9382
93.
Abstract (50?x/2)Na2O–xCuO–(50?x/2)P2O5 glasses (x=1, 5, 15, or 30 mol%) have been prepared and characterized by electron paramagnetic resonance (EPR) and magnetic susceptibility measurements. The shape of the Cu2+ EPR spectrum depends on the Cu content, and the corresponding computer simulations suggest that the Cu2+ ions occupy two different sites in these glasses: one of them is preponderant at low Cu content and the other is preponderant at high content, in which the Cu2+–Cu2+ interactions are more important. From EPR parameters, it was found that for the site at low content, the covalency of copper ion bonding with the surrounding ligands is appreciable. The magnetic susceptibility data appear to follow the Curie–Weiss law (χ=C/(T?θp)) with negative paramagnetic Curie temperature θp indicating antiferromagnetic interactions between Cu2+ ions that are more significant in the samples with high Cu content, in agreement with EPR results. 相似文献
94.
在磁通调制超导量子干涉器件(SQUID)的读出电路中, 匹配变压器具有放大信号和阻抗匹配的功能, 是实现SQUID低噪声读出的关键元件. 利用模拟SQUID电路对匹配变压器进行性能测试, 研究了不同绕制匝数变压器的传输特性, 确定最佳绕制匝数比. 在变压器拾取SQUID电压信号的耦合网络中, 研究了不同电容对变压器传输特性的影响, 实现了变压器耦合网络参数的匹配和优化. 室温下匝数比为1:20的匹配变压器在匹配电容C=1μF时, 输出源电压增益为21.2, 带宽范围可达到210 kHz. 最后在基于磁通调制式DC SQUID读出电路中, 对匹配变压器的工作性能进行了评估与验证.
关键词:
超导量子干涉器件读出电路
匹配变压器
低噪声
传输特性 相似文献
95.
Jakoah Brgoch Ruslan Prozorov Gordon J. Miller 《Journal of solid state chemistry》2010,183(12):2917-2924
Polycrystalline samples of two complex intermetallic borides Zr2Fe1−δRu5+δB2 and Zr2Fe1−δ(Ru1−xRhx)5+δB2 (δ=ca. 0.10; x=0.20) were synthesized by high-temperature methods and characterized by single-crystal X-ray diffraction, energy dispersive spectroscopy, and magnetization measurements. Both structures are variants of Sc2Fe(Ru1−xRhx)5B2 and crystallize in the space group P4/mbm (no. 127) with the Ti3Co5B2-type structure. These structures contain single-atom, Fe-rich Fe/Ru or Fe/Ru/Rh chains along the c-axis with an interatomic metal-metal distance of 3.078(1) Å, a feature which makes them viable for possible low-dimensional temperature-dependent magnetic behavior. Magnetization measurements indicated weak ferrimagnetic ordering with ordering temperatures ca. 230 K for both specimens. Tight-binding electronic structure calculations on a model “Zr2FeRu5B2” using LDA yielded a narrow peak at the Fermi level assigned to Fe-Fe antibonding interactions along the c-axis, a result that indicates an electronic instability toward ferromagnetic coupling along these chains. Spin-polarized calculations of various magnetic models were examined to identify possible magnetic ordering within and between the single-atom, Fe-rich chains. 相似文献
96.
The synthesis of two oxoverdazyls based compounds, the 1,5-dimethyl-3-(2′-hydroxyphenyl)-6-oxoverdazyl 1 and the perchlorate salt of 1,5-dimethyl-3-(2′-imidazolium)-6-oxoverdazyl 2 are reported. The structural analysis of 1 reveals that radicals are closely packed in regular columns by way of π-stacking. In contrast, the packing in 2 is definitely influenced by the protonation state of the radical substituent and shows strong lateral staggering of the organic radicals. The organisation in the solid state strongly influences the intermolecular exchange interaction between π-stacked radicals which goes from J = −113 cm−1 (H = −J∑SiSi+1) in 1 to J = −1.0 cm−1 and J′ = −0.67 cm−1 in 2. 相似文献
97.
Keisuke Hatada Kuniko Hayakawa Fabrizio Palumbo Augusto Marcelli 《Journal of synchrotron radiation》2016,23(2):560-565
The occurrence of scissors modes in crystals that have deformed ions in their unit cells was predicted some time ago. The theoretical value of their energy is rather uncertain, however, ranging between ten and a few tens of eV, with the corresponding widths of 10?7 to 10?6 eV. Their observation by resonance fluorescence experiments therefore requires a photon spectrometer covering a wide energy range with a very high resolving power. Here, a new experiment is proposed and discussed in which such difficulties are overcome by measuring with a superconducting quantum interference device (SQUID) the variation of the magnetic field associated with the excitation of scissors modes. 相似文献
98.
Fetal magnetocardiography (MCG) is a sophisticated non-invasive technique for the fetal heart diagnosis. We constructed a multichannel fetal MCG system based on a novel superconducting quantum interference device (SQUID) direct readout scheme called SQUID bootstrap circuit (SBC). The system incorporates four SBC gradiometers for the signal detection and three SBC magnetometers as the references. The fetal MCG signal at a 28-weeks’ gestation was measured. By the fetal MCG signal separation and average, the P-wave and QRS complex can be clearly identified. These results indicate that the SBC is one of the most promising techniques for the fetal MCG recordings. 相似文献
99.
100.
Residual field suppression for magnetocardiography measurement inside a thin magnetically shielded room using bi-planar coil 下载免费PDF全文
For a magnetocardiography (MCG) system inside a magnetically shielded room (MSR), the residual field should be further suppressed to obtain high-quality MCG signals. In this paper, a compensation system has been developed based on the bi-planar coil and the proportional-integral-derivative (PID) controller. The bi-planar coil, derived from the target-field theory and the Tikhonov regularization method, is utilized to generate magnetic field with high uniformity in the pre-defined target region. And the PID controller is introduced to provide dynamic compensation current for the coil, according to the residual field change monitored by a reference SQUID magnetometer. The measurement results show that the noise suppression ratio (NSR) can reach above 20 dB in the low-frequency range from 0.1 Hz to 50 Hz. The DC component and the fluctuation of the residual field in time-domain can be respectively suppressed to 0 pT and 4 pT, indicating that this proposed compensation method is useful for the MCG measurement. 相似文献