The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
A. Kushino - One of the best experts on this subject based on the ideXlab platform.
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Development of Semi-rigid Superconducting Coaxial Cables with Clad Central Conductor for Low-Noise Experiments
Journal of Low Temperature Physics, 2018Co-Authors: A. Kushino, Takeshi Okuyama, S. KasaiAbstract:In this study, semi-rigid Coaxial Cables with an outer diameter of less than 1 mm were developed for the readout of low-temperature detectors. A bilayer structure comprising a superconductor clad with a normal conductor was used for the central conductor. Structures of this type can exhibit low-pass filtering characteristics and reduce high-frequency noise. To obtain high attenuation along with low thermal conductance using this type of filtering cable, stainless steel (SUS304) was used to clad the NbTi central conductor because it has a high electrical resistivity compared to that of the conventionally used alloy CuNi. The semi-rigid cable considered in this study has a diameter of 0.86 mm and consists of a NbTi central conductor clad with SUS304 with a thickness of 13 $$\upmu \hbox {m}$$ μ m , a SUS304 outer conductor, and a polytetrafluoroethylene insulator. The low-temperature (2–8 K) thermal conductance of this cable was measured and found to be slightly higher than that of a semi-rigid cable of the same dimensions using SUS304 for the entire central conductor. Additionally, the attenuation measured in the frequency range of 150 MHz to 10 GHz was very large, and the expected low attenuation below approximately 1 GHz due to the superconducting NbTi was not observed. From SEM observation and EDS analysis, it was found that the NbTi region of the central conductor contained grains of approximately $$10~\upmu \hbox {m}$$ 10 μ m in size derived from the SUS304, which may have been the cause of the observed large attenuation.
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development of semi rigid superconducting Coaxial Cables as low pass filters
IEEE Transactions on Applied Superconductivity, 2017Co-Authors: A. Kushino, Soichi KasaiAbstract:We developed thin semi-rigid Coaxial Cables for use as readout noise filters in low temperature experiments. The Cables reported here had an outer diameter of 0.86 mm, and consisted of a standard cupronickel (CuNi) alloy as a seamless outer conductor and polytetrafluoroethylene (PTFE) as a dielectric material. The inner conductor was superconducting niobium-titanium (NbTi) covered by a CuNi cladding layer with a thickness of 0, 13, or 38 μm. The thermal conductance and transmission properties for the Cables were measured at cryogenic temperatures and compared to those for a conventional CuNi semi-rigid cable. Between 1.4 and 8.4 K, the thermal conductance was similar to that for the conventional cable because the contribution from the cladding was estimated to be small. On the other hand, measured at about 3 K, the attenuation at high frequency up to 10 GHz differed in that the cutoff frequency increased with decreasing CuNi cladding thickness. For a cladding thickness of 38 μm, the 3 dB cutoff frequency for a 1-m-long cable was 100 MHz, whereas for a cladding thickness of 13 μm, it was 500 MHz. This type of semi-rigid cable can, therefore, be used as a low-pass filter whose attenuation characteristics can be tailored by changing the thickness of the cladding layer.
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Low Temperature Properties of a Superconducting Niobium Coaxial Cable
Journal of Superconductivity and Novel Magnetism, 2013Co-Authors: A. Kushino, Yoshikazu Teranishi, Soichi KasaiAbstract:Semirigid Coaxial Cables with seamless metal shields are promising for readout from sensitive devices operating below liquid helium temperature. Low thermal conduction of such Cables are also essential to reduce heat penetration into cryogenic temperature. We have developed thin semirigid Coaxial Cables employing niobium-titanium and niobium in both center and outer conductors, taking advantage of low thermal conductivity and extreme small electrical resistivity of superconductors. We assembled an adiabatic demagnetization refrigerator and measured thermal and electrical characteristics of those superconducting Coaxial Cables below T c. Thin niobium Coaxial cable with an outer diameter of 0.86 mm showed two-orders lower thermal conduction than expected, which is considered as the effect of impurity of niobium and forming process. Small attenuation was observed up to high frequency above 10 GHz at 3 K.
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Development of superconducting Coaxial Cables for cryogenic detectors
Journal of Low Temperature Physics, 2008Co-Authors: A. Kushino, Sayaka Shiki, Shinya Kasai, Satoshi Kohjiro, Makoto OhkuboAbstract:Fast readout with low noise is essential to apply superconducting detectors to such experiments as time-of-flight mass spectrometry or X-ray spectroscopy, where high counting efficiency is required. We have developed a thin seamless superconducting Coaxial cable employing NbTi alloy in both of the outer and inner electrical conductors. The outer diameter is 1.60 mm, and both conductors are separated by dielectric material of PTFE. The Coaxial cable revealed to become superconductive below about 10 K. The thermal conductance was measured between 0.4 and 6 K and consistent with literature. Performance at high frequency was also measured at 4.2 K. The attenuation was very small and less than 1 dB up to about 7 GHz. The effect of mechanical treatment to thermal and electrical properties of NbTi alloy seems to be small in the present forming process of Coaxial cable.
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thermal conduction measurement of miniature Coaxial Cables between 0 3 and 4 5 k for the wiring of superconducting detectors
Cryogenics, 2005Co-Authors: A. Kushino, Masataka Ohkubo, K FujiokaAbstract:Abstract Thermal conduction of thin Coaxial Cables made of 70-30 CuNi and stainless steel 304 with a PTFE insulator was measured in a temperature range between 0.3 and 4.5 K. Thermal conductivity of the 70-30 CuNi and PTFE was measured independently and their contribution to the thermal conduction of the Coaxial Cables was investigated. The thermal conductivity of the 70-30 CuNi differed from the literature by 25% at 0.36 K and 40% at 4.2 K, and the alloy exhibited a weak temperature dependence, which indicated the effects of mechanical treatment. It has been confirmed that the thermal conduction of the Coaxial Cables are low enough to keep a cold stage of 3 He cryostats at a temperature below 0.3 K, even when one hundred Cables are installed between 0.3 and 3 K for the read-out of superconducting tunnel junction arrays. The Cables were installed in a cryogen-free 3 He cryostat, and the operation below 0.3 K was successful.
Soichi Kasai - One of the best experts on this subject based on the ideXlab platform.
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development of semi rigid superconducting Coaxial Cables as low pass filters
IEEE Transactions on Applied Superconductivity, 2017Co-Authors: A. Kushino, Soichi KasaiAbstract:We developed thin semi-rigid Coaxial Cables for use as readout noise filters in low temperature experiments. The Cables reported here had an outer diameter of 0.86 mm, and consisted of a standard cupronickel (CuNi) alloy as a seamless outer conductor and polytetrafluoroethylene (PTFE) as a dielectric material. The inner conductor was superconducting niobium-titanium (NbTi) covered by a CuNi cladding layer with a thickness of 0, 13, or 38 μm. The thermal conductance and transmission properties for the Cables were measured at cryogenic temperatures and compared to those for a conventional CuNi semi-rigid cable. Between 1.4 and 8.4 K, the thermal conductance was similar to that for the conventional cable because the contribution from the cladding was estimated to be small. On the other hand, measured at about 3 K, the attenuation at high frequency up to 10 GHz differed in that the cutoff frequency increased with decreasing CuNi cladding thickness. For a cladding thickness of 38 μm, the 3 dB cutoff frequency for a 1-m-long cable was 100 MHz, whereas for a cladding thickness of 13 μm, it was 500 MHz. This type of semi-rigid cable can, therefore, be used as a low-pass filter whose attenuation characteristics can be tailored by changing the thickness of the cladding layer.
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Low Temperature Properties of a Superconducting Niobium Coaxial Cable
Journal of Superconductivity and Novel Magnetism, 2013Co-Authors: A. Kushino, Yoshikazu Teranishi, Soichi KasaiAbstract:Semirigid Coaxial Cables with seamless metal shields are promising for readout from sensitive devices operating below liquid helium temperature. Low thermal conduction of such Cables are also essential to reduce heat penetration into cryogenic temperature. We have developed thin semirigid Coaxial Cables employing niobium-titanium and niobium in both center and outer conductors, taking advantage of low thermal conductivity and extreme small electrical resistivity of superconductors. We assembled an adiabatic demagnetization refrigerator and measured thermal and electrical characteristics of those superconducting Coaxial Cables below T c. Thin niobium Coaxial cable with an outer diameter of 0.86 mm showed two-orders lower thermal conduction than expected, which is considered as the effect of impurity of niobium and forming process. Small attenuation was observed up to high frequency above 10 GHz at 3 K.
Patrick Joly - One of the best experts on this subject based on the ideXlab platform.
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Asymptotic modelling of Skin-effects in Coaxial Cables
SN Partial Differential Equations and Applications, 2020Co-Authors: Geoffrey Beck, Sébastien Imperiale, Patrick JolyAbstract:In this work we tackle the modeling of non-perfectly conducting thin Coaxial Cables. From the non-dimensionnalised 3D Maxwells equations, we derive, by asymptotic analysis with respect to the (small) transverse dimension of the cable, a simplified effective 1D model and an effective reconstruction procedure of the electric and magnetic fields. The derived effective model involves a fractional time derivatives that accounts for the so-called skin effects in highly conducting regions.
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Mathematical modeling of electromagnetic wave propagation in heterogeneous lossy Coaxial Cables with variable cross section
Applied Numerical Mathematics, 2013Co-Authors: Sébastien Imperiale, Patrick JolyAbstract:In this work, we focus on the time-domain simulation of the propagation of electromagnetic waves in non-homogeneous lossy Coaxial Cables. The full 3D Maxwell equations, that described the propagation of current and elec- tric potential in such Cables, are classically not tackled directly, but instead a 1D scalar model known as the telegraphist's model is used. We aim at justifying, by means of asymptotic analysis, a time-domain "homogenized" telegraphist's model. This model, which includes a non-local in time op- erator, is obtained via asymptotic analysis, for a lossy Coaxial cable whose cross-section is not homogeneous.
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Error estimates for 1D asymptotic models in Coaxial Cables with non-homogeneous cross-section
Advances in Applied Mechanics, 2012Co-Authors: Sébastien Imperiale, Patrick JolyAbstract:This paper is the first contribution towards the rigorous justification of asymptotic 1D models for the time-domain simulation of the propagation of electromagnetic waves in Coaxial Cables. Our general objective is to derive error estimates between the "exact" solution of the full 3D model and the "approximate" solution of the 1D model known as the Telegraphist's equation.
R Tascone - One of the best experts on this subject based on the ideXlab platform.
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bloch wave analysis of long leaky Coaxial Cables
IEEE Transactions on Antennas and Propagation, 2008Co-Authors: G Addamo, Renato Orta, R TasconeAbstract:Leaky Coaxial Cables can be used as distributed radiators for indoor communications. When the number of slots is large, as it is often the case, the application of a full-wave analysis method is very demanding in terms of both memory and CPU time. In this paper an analysis technique, based on Bloch wave theory is presented. Slots are viewed as discontinuities in an open waveguide and a suitable basis of orthogonal polynomials is introduced to represent the modal amplitudes pertaining to the continuous spectrum. The radiation properties of the cable are discussed in detail in terms of the excited Bloch waves. Finally, the reflection coefficient at the junction between a uniform and a slotted cable is computed. The results are presented in the form of a chart, for general slot size and spacing.
Makoto Ohkubo - One of the best experts on this subject based on the ideXlab platform.
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Development of superconducting Coaxial Cables for cryogenic detectors
Journal of Low Temperature Physics, 2008Co-Authors: A. Kushino, Sayaka Shiki, Shinya Kasai, Satoshi Kohjiro, Makoto OhkuboAbstract:Fast readout with low noise is essential to apply superconducting detectors to such experiments as time-of-flight mass spectrometry or X-ray spectroscopy, where high counting efficiency is required. We have developed a thin seamless superconducting Coaxial cable employing NbTi alloy in both of the outer and inner electrical conductors. The outer diameter is 1.60 mm, and both conductors are separated by dielectric material of PTFE. The Coaxial cable revealed to become superconductive below about 10 K. The thermal conductance was measured between 0.4 and 6 K and consistent with literature. Performance at high frequency was also measured at 4.2 K. The attenuation was very small and less than 1 dB up to about 7 GHz. The effect of mechanical treatment to thermal and electrical properties of NbTi alloy seems to be small in the present forming process of Coaxial cable.