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ISSN: 2772-8307
Copyright © 2026 Shanghai Jiaotong University. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
cited:12
Superconducting hot-electron bolometer mixers and their applications
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Article Number:Article 100009
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Abstract
Corresponding email:wzhang@pmo.ac.cn
Superconducting hot electron bolometer (HEB) mixers are the most sensitive heterodyne detectors at frequencies beyond 1 THz, and are used for many astronomical observations. HEB, consisting of a narrow and short superconducting thin film patch connected to an antenna via contact pads, is brought into a highly sensitive operating regime by applying a DC current and a certain amount of local-oscillator power. Potentially, superconducting HEB mixers are capable of exhibiting high sensitivity for frequencies up to several tens of THz, as their output noise and conversion gain are nearly frequency independent according to the mixing mechanism. Moreover, the understanding of mixing mechanism has evolved over time from lumped-element model to distributed hot-spot model. In this review, we provide an overview of theoretical and experimental studies on HEBs and their applications, especially in astronomical observations on ground, airborne and space telescopes.
cited:25
Progress in the development of the 122-type IBS wires
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Article Number:Article 100010
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Abstract
Corresponding email:ywma@mail.iee.ac.cn
Profit from their low anisotropy and high upper critical field, iron-based superconductors (IBSs) have great potential for high magnetic fields applications. Significant progress has been made for the current density improvement of (Sr,Ba)0.6K0.4Fe2As2 (122-type) IBS wires over the past fourteen years. In this article, an overview of the preparation procedures and key issues affecting the critical current performance of 122-type IBS wires is given, to provide a fundamental understanding of what controls the transport critical current density of 122-type IBS wires. Additionally, the recent developments for 122-type IBS wires are presented and future prospect and challenges in the development of 122-type IBS wires for practical applications are discussed.
cited:8
A new LFSR based high-frequency test method for RSFQ circuit
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Article Number:Article 100011
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Abstract
Corresponding email:niumh@mail.sim.ac.cn; jieren@mail.sim.ac.cn
Rapid single flux quantum (RSFQ) circuits have the advantages of high speed and low power consumption. The typical frequency of the RSFQ circuits is tens of GHz. Therefore, it is necessary to reliably test the high-frequency performance of RSFQ circuits simply and effectively. This paper proposes a new on-chip high-frequency testing method, which uses pseudo-random sequences generated by linear feedback shift register (LFSR) as the test vectors, and the output shift registers (SRs) to store the last piece of high-frequency testing result and read out it at low-frequency. Unlike the traditional high-frequency demonstration method of using the Input/Output SRs, our testing system can automatically generate a large number of test vectors to test the circuit at high frequency at low cost, making the whole high-frequency demonstration more reliable and convincing. On the other hand, this method is also a feasible and straightforward on-chip high-frequency test method for various RSFQ circuits. This work verified the proposed method, and the highest test frequency can reach 54 GHz while the circuit shows good operating margins.
cited:13
Recent progress on high-temperature superconducting filters
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Article Number:Article 100012
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Abstract
Corresponding email:sunliang@iphy.ac.cn
Since the discovery of high temperature superconducting (HTS) materials in 1987, the performance of microwave filters such as insertion loss, selectivity, and out-band rejection has been significantly improved by utilizing HTS films. Nowadays, HTS filters have been widely used in wireless communications, space exploration, satellite communications, and several other fields. HTS filters with a special performance, such as wideband, dual-band or multiband, frequency tunable, and high power-handling capability have been designed and fabricated in recent years to meet the increasing requirements of practical applications and to further extend the application areas. This paper reviews the various types of above-mentioned HTS filters as well as the developments of novel design methodologies.
cited:6
Cu/Ta sheaths for iron-based superconductors: First experimental findings in Ca/K-1144 wires
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Article Number:Article 100014
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Abstract
Corresponding email:andrea.masi@enea.it
Iron based superconducting wires (IBSCs) produced by the Powder in Tube (PIT) method rely on the use of silver sheaths as chemical buffer between the outer metal and the superconducting core. The adoption of silver entails however some limitations, such as the viable temperature range when coupled with copper, and the incompatibility with calcium-based IBSCs already at 600 °C, driving the research towards other wires architecture. Taking inspiration from the low temperature superconductors field, we decided to evaluate the adoption of tantalum as diffusion barrier in a layered Cu/Ta architecture, choosing a Ca/K-1144 IBSC as case study considering the high reactivity issues already reported in the case of silver sheaths for this compound. Squared wires were produced through a groove rolling lamination process coupled with a thermal treatment at 800 °C. The microstructural analyses show the absence of interdiffusion between the different parts of the wire, and the magnetic characterization shows performance in line with similar polycrystalline manufacts, with margin of enhancement to be pursued via the optimization of the mechanical process and other experimental variables. The reported results suggest thus the effectiveness of tantalum as diffusion barrier for Ca/K-1144 PIT wires.
cited:38
AC loss and contact resistance in highly flexible rebco cable for fusion applications
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Article Number:Article 100013
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Abstract
Corresponding email:chao.zhou@ipp.ac.cn; a.nijhuis@utwente.nl
High Temperature Superconductor (HTS) materials can operate at higher magnetic fields up to 20 T with high critical current and higher operating temperature, compared to low temperature superconductors (LTS). A Highly Flexible REBCO Cable (HFRC) is introduced at the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP); a cabling method that is suitable for REBCO HTS tape having anisotropic material properties in its thin REBCO layer. This type of HTS superconducting cable shows high potential for applications in nuclear fusion. The alternating currents and magnetic fields in tokamak type of fusion magnets, cause AC power losses in such cables, which can provoke instability of the conductor by induced currents and increase the temperature. As a first step in characterizing the electromagnetic (EM) performance of an HFRC cable, the AC loss and contact resistance of the HFRC prototype cable were measured at the University of Twente. The measurements were done in liquid helium (4.2 K) with AC magnetic fields, applied perpendicular to the cable's long axis. The AC loss was measured simultaneously by a calibrated gas flow calorimeter utilizing the helium boil-off method, and by the magnetization method using pick-up coils. For the applied test conditions, no coupling loss could be distinguished as a part of the overall AC loss. It is suggested that this might be explained by the shielding of the conductor interior from the applied magnetic field by the outer tape layer due to the high critical current density of the REBCO tape, leading to a high penetration field.
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