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Your search keyword '"Tiequan Xu"' showing total 3 results
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3 results on '"Tiequan Xu"'

1. Development of an HTS-SQUID-Based Receiver for Long-Range Magnetic Induction Communication in Extreme Environments

Author

Yulong Li, Tiequan Xu, Yue Wang, Furen Wang, and Zizhao Gan

Subjects
magnetic induction communication, underwater communication, high temperature superconducting quantum interference devices, flux transformer, communication range, magnetic field sensitivity, Chemical technology, TP1-1185
Abstract

The communication range of magnetic-induction (MI) technology in extreme environments such as underwater or underground is limited by the dipole-like attenuation behavior of the magnetic field as well as the eddy current induced loss in conductive media, and therefore a highly sensitive receiver is generally required. In this work, we propose the use of a highly sensitive superconducting quantum interference device (SQUID) in MI communication and try to provide a comprehensive investigation on developing a SQUID-based receiver for practical MI applications. A portable receiver scheme integrating a SQUID sensor and a coil-based flux transformer was proposed. The high sensitivity and long-range communication capability of the proposed receiver was experimentally demonstrated by spectroscopic measurements and reception experiments on a receiver prototype. Based on the experimental demonstrations, the sensitivity optimization of the proposed scheme was further investigated by simulation studies, which suggest that a communication distance exceeding 100 m and a channel capacity of ∼20 kb/s in underwater environment could be achieved based upon the optimization of the developed prototype. The results presented in this work have highlighted the potential of deploying SQUID sensors for long-range MI applications in extreme environments.

Published
2023
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2. The step-edge type HTS rf SQUID coupling with a LC circuit in ultra-low field NMR system

Author

Zhengshan Guo, Dongning Zheng, Tiequan Xu, Wenhao Luo, Kehuan Linghu, Yirong Jin, Furen Wang, Zizhao Gan, Zigeng Huang, and Yulong Li

Subjects
Superconductivity, Coupling, Squid, High-temperature superconductivity, Materials science, biology, business.industry, Energy Engineering and Power Technology, LC circuit, Condensed Matter Physics, Electronic, Optical and Magnetic Materials, law.invention, law, Electromagnetic coil, biology.animal, Optoelectronics, Radio frequency, Electrical and Electronic Engineering, business, Direct-coupled amplifier
Abstract

The step-edge type high temperature superconductor (HTS) radio frequency (rf) superconducting quantum interference devices (SQUIDs) were fabricated from YBa2Cu3O7−δ thin films with a field sensitivity of 66 fT/Hz1/2. Even though the sensitivity of the rf SQUID sensor used in the experiments was degraded to 77 fT/Hz1/2 in the magnetic shielded room (MSR), the performance of the rf SQUID sensor was good enough for the ultra-low field (ULF) nuclear magnetic resonance (NMR) experiments at a measurement field of 61.5 μT. With the help of a strictly controlled fast switching circuit and a coupled LC circuit which acted as flux transformer, the signal-to-noise ratio (SNR) of the rf SQUID-based ULF NMR system with different operating points was measured. The optimum SNR was 40 dB which increased significantly by coupling an input coil closely beneath the rf SQUID sensor. The extracted 1/T1 value for pure water sample at 23 ∘C showed the rf SQUID based ULF NMR was an effective system for ULF NMR researches. All above, the direct coupled method and the control circuit show a great potential in the future rf SQUID-based ULF NMR &MRI system.

Published
2019
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3. High-Temperature Superconducting YBa2Cu3O7 – δ Josephson Junction Fabricated with a Focused Helium Ion Beam

Author

Ziwen Chen, Yulong Li, Rui Zhu, Jun Xu, Tiequan Xu, Dali Yin, Xinwei Cai, Yue Wang, Jianming Lu, Yan Zhang, and Ping Ma

Subjects
General Physics and Astronomy
Abstract

As a newly developed method for fabricating Josephson junctions, a focused helium ion beam has the advantage of producing reliable and reproducible junctions. We fabricated Josephson junctions with a focused helium ion beam on our 50 nm YBa2Cu3O7 – δ (YBCO) thin films. We focused on the junction with irradiation doses ranging from 100 to 300 ions/nm and demonstrated that the junction barrier can be modulated by the ion dose and that within this dose range, the junctions behave like superconductor–normal conductor–superconductor junctions. The measurements of the I–V characteristics, Fraunhofer diffraction pattern, and Shapiro steps of the junctions clearly show AC and DC Josephson effects. Our findings demonstrate high reproducibility of junction fabrication using a focused helium ion beam and suggest that commercial devices based on this nanotechnology could operate at liquid nitrogen temperatures.

Published
2022
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