bluuebunny/crossref_metadata_2025 huggingface dataset:
Conceptual design of S3FEL cryogenic system
Authors: Hu L B , Wang X L , Yang L , Lai B H , Dong X B , Cui G L , Sun Z
Published: June 2022

A new project called Shenzhen SRF Soft Free Electron Laser (S3FEL) is under proposal phase at Institute of Advanced Science Facilities, Shenzhen (IASF), in China. The purpose is to produce high intensity coherent X-ray with laser properties. The S3FEL accelerator is based on the TESLA technologies and will deliver electrons with the energies of up to 2.5GeV. The electrons will be accelerated by 1.3 GHz superconducting cavities cooled down to the 2 K level. The 2 K cryostat will be protected against heat radiation and conduction by means of one thermal shields at 40- 80 K level and one thermal intercept at 4.5 – 8 K level. The S3FEL accelerator consists of twenty-six 1.3 GHz and two 3.9 GHz cryomodules, both operated in CW modes. Four independent cryoplants will be used for the S3FEL project. A 500 W@2 K helium refrigerator will be used for the test facility including two vertical test benches (VTB) for cavities, one magnet test bench for the superconducting magnet (MTB) and three horizontal test benches (HTBs) for cryomodules. A 1 kW@2 K helium refrigerator will be used for the prototype machine for R&D purpose of the superconducting accelerator. Two cryogenic plants with 4 kW@2 K refrigeration capacity will be used for supporting the S3FEL accelerator cryogenic cooling requirement. Ideally, one should have enough capacity to supply the cooling for the whole LINAC and the other is acting as a complete set of back up to keep the high availability. In addition, the second plant could compensate the cavity performance degradation due to the long term running or the unexpected cavity performance during the manufacture process. This paper describes the conceptual design of the S3FEL cryogenic system. The performance of the cryogenic system and the project schedule are also described.
Functional analysis and design of the cryogenic system for the HL-LHC IT String test bench at CERN
Authors: Rolando G , Sisti M , Duran Lucas O , Wanninger A , Mouleyre J , Perin A
Published: June 2022

The High Luminosity LHC (HL-LHC) is a project aiming to upgrade the LHC collider to maintain scientific progress and exploit its full capacity. In the HL-LHC configuration, the Inner Triplet (IT) magnets of the present LHC will be replaced by a new set of higher performance magnets. The collective behaviour of the new magnets and the related systems will be studied and validated in a dedicated cryogenic test facility, the IT String, currently under construction. This paper presents the results of the functional analysis performed to design the cryogenic system for the IT String. The required operation modes are identified and detailed together with the operational parameters and constraints used to define the cryogenic system. The layout of the cryogenic distribution system that fulfils the requirements of the IT String is presented and the characteristics of the main components are described.
SNS Carbon Bed Research Project Design, Commissioning, and Initial Results
Authors: DeGraff B , Barnhart D , Gold S , Howell M , Kim S , Kraft D , McMahan C , Moore L , Neustadt T , Vandygriff D J , Vandygriff D M
Published: June 2022

The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) has three operating cryogenic facilities: Central Helium Liquefier (CHL), Cryogenic Test Facility (CTF) and Cryogenic Moderator System (CMS). All three systems use vessels filled with activated carbon as the final major component to remove oil vapor from the compressed helium circuit prior to insertion into the system’s cryogenic cold box. However, different versions of carbon are used in different systems. A skid was designed which contains two separate carbon containing vessels for the purpose of comparing the relative efficacy of different versions of carbon filtration media. The design, fabrication, installation, commissioning, and initial results of this dual-bed test skid will be presented. Future testing plans utilizing different filter media will also be discussed.
Maintenance of the 1st NBI vacuum system for the KSTAR tokamak
Authors: Ju Lee Young , Taek Park Hyun , Su Kim Jong , Gu Kwak Jong
Published: June 2022

First neutral beam injection system for the KSTAR tokamak has been operated after the installation and commissioning on 2010. To provide 120 keV and more than 6 MW deuterium neutral beam, it requires large vacuum pumping system with the pumping speeds 1.0E6 l/s range. For this purpose, R&D works with a prototype cryosorption panel had performed from Korea Atomic Energy Research Institute (KAERI) and GM cooler based 2 stage cryosorption pump was accepted for the 1st NBI system. During 10 years of annual operation, the pumping speeds decreased continuously due to the damage in cryopanels and all of the cryopanels were repaired for the 2021 KSTAR campaign. Details of the 1st KSTAR NBI vacuum pumping system will be introduced and long operation results including the behavior after the repair, will be reported in this paper.
Static and dynamic characteristics of externally pressurized gas bearing for high-speed hydrogen turbo-expander
Authors: Yan H , Ke C L , Peng N , Li K R , Zhang X H , Zheng L W , Liang Y W , Xiong L Y , Dong B , Li J , Liu I Q
Published: June 2022

The high-speed hydrogen turbo-expander, serves as a key component of the large-scale hydrogen liquefaction system, receives a lot of attention. Being an essential part of the turbo-expander, gas bearings are widely used for its pollution-free and low viscosity advantages. However, studies on characteristics of hydrogen bearing, especially on the static and dynamic characteristics of externally pressurized hydrogen journal bearing, have not been conducted by many. Here, the finite difference method (FDM) was employed to solve the Reynolds equation thus obtaining the pressure distribution and the static load capacity. The partial derivative method (PDM) was used to calculate the dynamic stiffness coefficients and damping coefficients of hydrogen bearing. The critical mass was used to analyze the linear instability of the hydrogen bearing-rotor system. Relationship between various design parameters, including eccentricities, orifice diameter, clearance, supply pressure and rotor speeds, and static and dynamic behaviours of hydrogen bearing has been established. The results indicate that load capacity increase and volume flow rate decrease is viable through parameter optimization. The stability of the hydrogen bearing-rotor system is evaluated quantitatively.
Design of an in-situ measurement system for ortho and para liquid hydrogen fractions at ESS
Authors: Tatsumoto H , Lyngh D , Lee Y , Hartl M , Sina H , Arnold P , Beßler Y , Kobayashi H , Sakamoto Y , Hasegawa T
Published: June 2022

The Cryogenic Moderator System (CMS) is equipped with a catalyst to convert hydrogen from the ortho state to the para state, to keep desirably high parahydrogen fractions in the cold moderators, which is required to deliver a high brightness cold neutron beams to the scientific instruments using neutron scattering. An in-situ measurement system for the ortho and para fractions of liquid hydrogen (OPMS) where a Raman spectroscopy will be used is being developed. The required measurement precision is 0.1% to detect an undesirable shift towards a high orthohydrogen fraction caused by neutron scattering driven para-to-ortho back conversion. The dedicated OPMS sampling line has been designed and is placed in a bypass line from and to the CMS to minimize the hydrogen inventory and to make it physically isolated from the CMS if a sapphire window failure happens. Accident analysis for a hydrogen leak due to the sapphire window failure was carried out using an inhouse-developed simulation code, and the required safety relief size has been determined.
Cryogenic performances of a heat exchanger prototype suitable for the superconducting HL-LHC recombination dipole D2
Authors: Rousset B , Bancel F , Besson N , Bon-Mardion M , Claudet S , Goy T , Millet F , Nivelon P , Perin A
Published: June 2022

In the framework of the future High Luminosity upgrade of the Large Hadron Collider (HL-LHC) at CERN, most superconducting magnets in the Long Straight Sections will be replaced. Among them, the new D2 recombination dipole will be a He II conduction-cooled magnet with a larger aperture than the LHC dipoles. To provide the required cooling (up to 70 W) to the D2 and to comply with its cryostat integration constraints, a compact heat exchanger was designed by the CEA Département des Systèmes Basses Températures (DSBT) based on a CERN preliminary analysis and a CEA review of the possible cooling schemes. This heat exchanger provides the required heat transfer between the He II pressurized bath and the He II saturated bath to cool the D2 magnet in different operating conditions at 1.8 K and 2 K. The detailed design of the heat exchanger was defined and one prototype was manufactured by industry under the CEA supervision. The heat exchanger prototype is composed of roughly one hundred oxygen-free high purity copper tubes, electron beam welded to the stainless steel He II bath enclosure. The present paper describes the successful cryogenic performance tests of the prototype of the D2 heat exchanger measured in the CEA 400W@1.8K test facility in Grenoble.
Advanced exergy analysis of reverse Brayton cryocooler for 10 kW cooling capacity at 65 K
Authors: Kumar Dhillon Aman , Ghosh Parthasarathi
Published: June 2022

A reverse Brayton cryocooler is gaining attention as an intermediate and large-scale cooling device for many cryogenic applications such as liquefaction of natural gas, hydrogen, cooling of high-temperature superconducting devices. The present work is an inclusive analysis of reverse Brayton cryocooler by splitting the exergy destruction approach, known as advanced exergy analysis. The study aims to find the scope of improvement in the component by categorizing the exergy destruction as avoidable and unavoidable. Therefore, it is a more potent tool, compared to split exergy methods, to identify the scopes for enhancement of the thermodynamic performance of the equipment. In this work, a thermodynamic model based on the split exergy approach (conventional exergy analysis) is developed using Aspen HYSYS®. The conventional exergy analysis quantifies the exergy destruction in each component of the cryocooler. The advanced exergy analysis quantified the avoidable exergy destruction as 61 % of total exergy destruction in the system. The results of the analysis suggest ways to improve the performance of components of the reverses Brayton cryocooler from thermodynamic and design aspects. The recommendation and approach adopted in the present work, although it has been applied for reverse Brayton refrigerator, can be very useful for the research and design engineer working in the field of energy systems in general.
Thermodynamic Process and Analysis of Dilution Refrigerator
Authors: Zheng M W , Wei L J , Pan Z J , Liang J T , Zhao M G , Lin P
Published: June 2022

Thermodynamic analysis is essential for not only guiding the design of refrigerator, but also studying its operation mechanism. As the core component, the dilution unit plays an important role in deciding the performance of dilution refrigerator. In this study, a coupled thermodynamic model is established by analyzing each component separately for improving the operation of dilution refrigerator. And an optimization calculation based on that model is carried out to obtain some meaningful results on the dilution unit design. The optimal flow rate of the dilution refrigerator under different working conditions are pointed out. By considering the effect of viscous heat on the performance of the heat exchanger, the applicable conditions of the continuous heat exchanger and the methods to overcome the viscous heat are given.
Characteristics of reciprocating speed of a low power consumption 4 K G-M cryocooler
Authors: Masuyama S , Kamiya K , Numazawa T
Published: June 2022

This study is aiming to develop a low power consumption 4 K G-M cryocooler. As a first step, a two-stage G-M cryocooler with a 2 kW class compressor has been tested. The base model of cold head of two-stage G-M cryocooler is RDK-305D (Sumitomo Heavy Industries). We modified its second stage regenerator materials by filling magnetic materials Gd2O2S and HoCu2 spheres. An air-cooled compressor of SA115 (ULVAC CRYOGENICS) that rated input is 1.9 kW at 60 Hz was connected to the cold head. The experimental results showed that the cooling capacity of the second stage of 0.5 W at 4.2 K and the first stage of 25 W at 45 K was achieved with the cold head reciprocating speed of 48 rpm and the compressor electrical input of 2.09 kW. The relative Carnot efficiency of 1.7% at 4.2 K was calculated from the result. A low reciprocating speed of 48 rpm was chosen is to secure the sufficient expansion work in the second expansion space. This is considered an effective method to obtain a large cooling capacity at 4 K by low power compressor.
Comprehensive optimization design of low temperature insulation system of regeneration cryocooler
Authors: Wang Z K , Li L F , Zhou Y
Published: June 2022

The calculation of radiant heat leakage is a part of the design of cryogenic insulation system. The numerical radiation simulation considering geometric structure of cryogenic insulation system is established through Monte Carlo method and view factor. The difference of the multi-layer insulation outer surface temperature is about 0.5% between the simulation and experimental results. Additionally, the structure and shape of the insulation system would make radiation to redistribute between surfaces. The surface would have less heat leakage with large aspect ratio and small radius.
Development of a 20K two-stage Stirling type pulse tube cryocooler with pre-cooling inside second-stage pulse tube
Authors: Li Z. W. , Wang X. T. , Wang Y. N. , Dai W.
Published: June 2022

Cryocoolers working in the liquid hydrogen temperature are important for applications such as cryo-pump, superconductor cooling and cryogenic electronics. This paper analyzes and compares the 20K gas-coupled two-stage Stirling type pulse tube cryocooler with and without pre-cooling. The pre-cooling uses some of the cooling power generated by the first stage cold head to pre-cool the middle of the second stage pulse tube. Given the same input acoustic power, the simulation results show that the cooling capacity of the second stage increase from 0.64 W to 2 W@20 K while the first stage available cooling capacity decrease from 5.84 W to 3 W@77 K when the pre-cooling is used. Meanwhile, the cryocooler relative Carnot Efficiency in terms of acoustic power increases from 10.3% to 14.6%.
Numerical simulation of three-stage gas coupled pulse tube refrigerator
Authors: Fang Chushu , Duan Yanbo , Wang Zekun , Dong Hongyu , Li Laifeng , Zhou Yuan
Published: June 2022

For its compact structure, small mass, no moving parts at low temperature, strong reliability and stability, Stirling pulse tube refrigerator is regarded as a major development direction of small refrigerator at low temperatures. In order to obtain lower no-load cooling temperature and higher cooling efficiency, multi-stage structure is often used in pulse tube refrigerator. In this paper, a model of three-stage gas-coupled pulse tube refrigerator with multi-bypass and double-inlet is designed by SAGE software. The effects of double-inlet and multi-bypass on the gas distribution of multi-stage pulse tube refrigerator are analyzed. The results show that the multi-bypass and double-inlet do not independently affect the minimum temperature of the refrigerator at no-load, and there is a coupling relationship between their opening. The numerical simulation results are of great value for the construction of a three-stage gas coupled pulse tube refrigerator prototype.
50 kJ SMES magnet design optimization using real coded genetic algorithm
Authors: Anand A , Gour A S , Datta T S , Rao V V
Published: June 2022

SMES systems are being made and utilized for various applications i.e. dampening low frequency oscillations, instantaneous voltage drop compensation, pulsating power supply etc. Due to tape like structure of 2G HTS and fabrication limits of long continuous length , SMES coil is made via assembling individual single pancake coil/double pancaked coil in the solenoid or toroid fashion. A SMES magnet is designed optimally, using real coded genetic algorithm, with minimum length as objective function for fxed amount of stored energy(50 kJ), using 2G HTS tape. Simulated binary crossover and polynomial mutation function are used for crossover and mutation respectively. Elitism is also used for faster convergence of genetic algorithm. An minimum length is found for 50 kJ stored energy. Stress calculation is carried out for this confguration.
Methods of speeding up the cool-down of superconducting magnets that are cooled using Small coolers at temperatures below 30 K
Authors: Green Michael A
Published: June 2022

The two primary ways of cooling superconducting magnets with small coolers are by conduction from the magnet to one or more the coolers cold heads through high thermal conductivity straps or by fluid flow through a thermal siphon cooling loop. Both methods have been used for cooling down magnets. The thermal siphon cooling loop can also be used to produce liquid helium or liquid hydrogen within the cooling loop. Over 85 percent of the cooldown time is used to cool a magnet coil from 300 K to 80 K. This is also true when a helium refrigerator is used to cool down a magnet. The primary reason for this is the magnet material enthalpy at 80 K is between 4 and 6 percent of the material enthalpy at 300 K. The cooler refrigeration increases with the cold head temperature, but the magnet material enthalpy increases more. If one wants to speed up the cool-down rate, one must remove the heat faster in the temperature range between 80 K and 300 K. Two primary methods for speeding up the cooldown of magnet that is kept cold using coolers will be presented.
Short review on cryostats with superconducting magnets
Authors: Putselyk S
Published: June 2022

Modern accelerators typically include many components working at cryogenic temperatures, like superconducting (sc) magnets, sc cavities, cooled beam tube, sc undulators. In most of the cases, sc magnets or cavities are used. Sc magnets were intensively developed over the last 50 years, and it is possible to say that for some sc materials, like NbTi or Nb3Sn, the technology reached a maturity. The sc magnets could be installed either in liquid helium reservoirs or be mounted on metallic structures and passively cooled by the thermal conduction. Though there is a large variety of different types of cryostats, some general requirements posted on them by sc magnets, bus-bars or current leads could be seen. In the present paper a short review on cryostats with superconducting magnets is done as well as general design requirements on bus-bars and safety diodes are shortly mentioned. Two typical cryostat types used for scientific needs or industry applications are discussed. Cryostats with high-Tc current leads or magnets are also shortly mentioned.
A Review on Liquid Hydrogen Pool-Boiling Correlations
Authors: Shenton M , Leachman J
Published: June 2022

Recent advances in additive manufacturing and origami fuel bladders challenge the applicability of liquid hydrogen pool boiling correlations developed for metallic substrates. Empirical liquid hydrogen boiling data are compared to correlations available from the literature that model the heat transfer through single phase convection, nucleate boiling, transition boiling, and film boiling. The boiling correlations display a wide range of accuracies for hydrogen and exhibit a discontinuous boiling profile. Many of these equations utilize numeric constants to account for parameters such as geometry or material properties that have not been validated for a wide range of applications. A sensitivity study is presented for each boiling regime’s widely accepted equation, and manipulating the material/fluid properties has a significant impact on calculating the boiling curve for hydrogen in different storage containers. From this review, we identify major areas for improvement of liquid hydrogen boiling correlations including developing an accurate representation of hydrogen’s quantum property nature and expanding applicability to novel materials.
Two-phase pressure drop study for cryosurgical probes using one-dimensional homogeneous model
Authors: Gunjal Anish , Atrey Milind D. , Srivastava Atul
Published: June 2022

Cryosurgery is an effective medical treatment approach for treating solid cancerous malignancy, as it is a minimally invasive treatment therapy. The main aim of cryosurgery is to use extreme cold to destroy abnormal tissues while minimizing damage to healthy surrounding tissue. Recent technological advancements in cryogenics have attracted the attention of many researchers to study the low-temperature cryosurgical devices, generally termed cryoprobes. Saturated Liquid Nitrogen (LN2) from pressurized dewar is fed to the cryoprobe through a transfer hose. The fluid evaporates as it flows downstream because of various heat loads and experiences pressure drop. In this paper, a two-phase pressure drop solver is presented following a simplified one-dimensional analysis to estimate pressure losses occurring throughout the system. A qualitative discussion on the contribution of various pressure drop components is provided. It is observed that the major pressure loss occurs along the length of the cryoprobe tubes. The effect of the cryoprobe tube dimensions on the pressure drop is also studied. It is concluded that the miniaturized probe design demands higher system inlet pressure.
Tensile Properties of 22Cr-12Ni Austenitic Stainless Steel Thick Plates and Bars at Cryogenic Temperatures
Authors: Kato T , Kato Y , Umezawa O , Ono Y , Yuri T , Nishimura A , Kumagai S
Published: June 2022

The tensile properties of XM-19 austenitic stainless steels with thick plates (30 mm thickness), extra-thick plates (100 mm thickness), and rectangular bars (square of 14.3 mm) were examined at cryogenic temperatures. Influence of thermomechanical treatments on the steels was demonstrated. Even though their 0.2 % proof stresses were over 1200 MPa at 4.2 K, there were variations in strength depending on location. Namely, the 1/2t specimen (the position of the half in the thickness) of extra-thick plate showed lower 0.2% proof stress, elongation, and reduction of area at 4.2 K than the 1/4t (the position of the quarter in the thickness) and the thick plates. The effect of grain size on the 0.2% proof stress was clearly described by the Hall-Petch relationship for the materials.
Improved breakdown strength at cryogenic temperature in epoxy nanocomposites by a small amount of SiC nanoparticles
Authors: Miao Z C , Jia P , Wang Y G , Huang R J , Li L F
Published: June 2022

The study of the electrical properties of materials at cryogenic temperature is significant for the design of insulation structures of superconducting equipment. Here, epoxy resin was combined with a small amount of KH650 modified SiC nanoparticles. When the dosage of SiC nanoparticles increased from 0.1% to 0.3%, the DC breakdown strength of the composite increase from 83.93 kV/mm to 97.51 kV/mm at room temperature and from 90 kV/mm to 120 kV/mm at 77 K. Furthermore, we used differential scanning calorimeter (DSC) and dynamic thermomechanical analysis (DMA) to analyze the effect of low-content SiC nanoparticles on the thermal behavior of epoxy resin.
Thermal conductivity measurements of nano-particle-filled epoxies
Authors: Adams J L , Haight A , Michael P C , Bromberg L , Brisson J G
Published: June 2022

For conduction-cooled superconducting magnets to be truly effective, it is necessary to have good thermal conduction from the cooling source through the insulating epoxy resin to the magnet winding. We have developed epoxy resins filled with thermally conductive nanoparticles that have significantly increased thermal conductivities while retaining most of their dielectric and mechanical strengths. Base resins, including CTD101K, were filled with alumina, aluminum nitride, or diamond nanoparticles. A wire-based 3ω method was developed to measure the thermal conductivity of the nano-filled epoxies over the temperature range from 4 K to 300 K. A unique aspect of this experimental setup is the 10 μm diameter Invar wire heating element, which serves as a sensitive thermometer down to 4 K. Measurements show the filled resins have improved thermal conductivity, especially at temperatures of 15 K and higher.
Characterization of Candidate Insulation Resins for Training Reduction in High Energy Physics Magnets
Authors: Haight A E , Haynes M M , Krave S T , Rudeiros-Fernandez J L , Shen T
Published: June 2022

Superconducting magnets are critical components in particle accelerators and are used to generate and sustain the large magnetic fields needed for High Energy Physics programs. One significant issue with current epoxy insulated Nb3Sn magnets is the long training process required before stable magnet performance can be realized. It is believed that training can be significantly reduced by addressing magnet quenching through improvements in the epoxy electrical insulation. In this work, two approaches for insulation modification have been undertaken: (1) addition of thermally conductive fillers to help with quench management and (2) development of insulation resins with high strain capability at cryogenic temperatures. This paper will discuss the characterization of these insulation systems to verify their performance prior to evaluation in subscale Nb3Sn canted cosine theta accelerator dipole magnets.
Thermal Property Measurements of Al-Alloy for Space Cryogenic Missions
Authors: Shinozaki Keisuke , Mizutani Tadahito , Fujii Takenori , Onaka Takashi , Nakagawa Takao , Sugita Hiroyuki
Published: June 2022

In space cryogenic missions, the thermophysical properties of materials must be studied and measured to establish a highly reliable cooling chain. An Al-alloy is a primary material in cryogenic thermal structural designs and is particularly used for providing high thermal conductance of thermal shields and thermal straps. We measured low-temperature properties (the thermal conductivity and the electrical resistivity) of several Al-alloys and found that A6063 had a lower thermal conductivity than that reported previously. We also found that the Al-alloy ST-60, which has equivalent thermal conductivity as pure aluminum, has higher thermal conductivity than A6061 and A6063, and the material is a good candidate for the space cryogenic design at the temperature range between 4K and 300K. These results are critical for the thermal study of upcoming next-generation space astronomy missions, such as LiteBIRD, SPICA and ATHENA.
An investigation of internal heat flux in SiC/AlN/Epoxy composites by mesoscopic simulation
Authors: Zhou Z R , Huang R J , Wang T , Xie S Y , Zhao Y L , Wu S S , Zhao W Y , Wu Z X , Liu H M , Li L F
Published: June 2022

Polymer-matrix composites play an important role as packaging material in superconducting equipment. The research on thermal conductivity of composites by combining computer numerical simulation and reference data can not only save the expenses but also shorten the period of material development. Herein, the internal heat flow of silicon carbide/aluminum nitride/Epoxy composites was simulated by COMSOL finite element software. And the thermal conductivity calculated by the finite element software is compared with the existing thermal conductivity mechanism. Meanwhile, the influence of the fraction, gap distance, interfacial thermal resistance, etc. on the thermal conductivity of composites was analyzed. In short, it can provide a reference for the thermal conductivity design of polymer composites.
The calculation and measurement of electromagnetic energy flows for investigation of critical current estimation for high-temperature superconducting coil by means of pick-up coils
Authors: Omura Junya , Sato Go , Kawagoe Akifumi
Published: June 2022

For practical operations of high-temperature superconducting (HTS) devices, we have proposed a monitoring and diagnosing system to detect the degradations of superconducting properties before normal transitions occur locally in the HTS winding. The proposed system estimates the distributions of critical current indirectly from measurement results of the active power components of the Poynting vector around the monitoring HTS devices conducting ac currents by means of pick-up coils pairs mounted surrounding the HTS devices. For this purpose, it is necessary to solve the inverse problem. In order to estimate the critical current distribution, therefore, it is first necessary to be able to calculate the measurement signal distribution from the critical current distribution of the monitoring coil. This paper first proposes the calculation method of signal distributions measured by our system, next reports the results of the experiments and analysis, which were carried out to verify the validity of the calculation method. A pancake coil wound with Bi-2223 multifilamentary tape exposed to a uniform AC magnetic field was assumed as a monitoring coil in the experiments and analyses. The good agreement between the measured signals obtained from the experiments and the numerical analysis demonstrates the effectiveness of the proposed calculation method of measured signals.
Approaches for High Performance and Thermally Optimized Flexible Cryogenic Microwave Ribbon Cables
Authors: Peek Sherman E. , Shah Archit , Yelamanchili Bhargav , Gupta Vaibhav , Sellers John A. , Tuckerman David B. , Hamilton Michael C.
Published: June 2022

Design, fabrication, and testing of cryogenic cables with thermal performance considerations is presented in this work. Cables were designed with commercial off-the-shelf materials for low-GHz operation in a small form factor. Thermal and microwave simulations were performed during the design of cables. Fabrication processes were developed to create features in Cu-cladding and to successfully deposit thin-film metal in large step-height regions. Post-fabrication processes such as laser machining and connector assembly were used to cutout and interface with fabricated cables. Microwave performance was measured at room temperature and at 4.2 K with comparable results to simulations performed. Cables designed and fabricated in this work provide a solution to thermal and spatial limitations while achieving targeted microwave performance at cryogenic temperatures.
Computational Modelling of Russia’s First 2G-HTS Triaxial Cable
Authors: Clegg M. , Fareed M. U. , Kapolka M. , Ruiz H. S.
Published: June 2022

A better understanding of the interaction between three phases is required when developing superconducting cables for high voltage AC systems. With a particular focus on the energy losses of real power transmission cables, in this paper we utilize the so-called H-formulation of Maxwell equations to devise a 2D model for superconducting triaxial cables. The major aim of this model is to comprehend and reproduce the experimental observations reported on the first triaxial prototype cable developed by SuperOx and VNIIKP. The computationally modelled and prototyped cable is made of up to 87 tapes of 4 mm width SuperOx tape arranged across the three phases. Our computational results are compared to the experimental measurements performed by VNIIKP with the electrical contact method, showing a high degree of accuracy over the outer phase of the cable, whilst revealing technical issues with the experimental measurements at the inner phases. Thus, in consultation with VNIIKP it has been concluded that for the actual experimental measurement of the AC losses at the inner phases, and consequently of the overall cable, a sophisticated calorimetric setup must be built. Still our model is capable to provide an independent assessment of the VNIIKP-SuperOx cable design, by investigating the magnetic profiles per phase in the time domain. In this sense, we confirm that the unbalanced arrange of currents and distancing between the phases affirmatively lead to no magnetic leakages, and therefore to an adequate balance of the cabling inductance.
Electric Aircraft Fueled by Liquid Hydrogen and Liquefied Natural Gas
Authors: Telikapalli Srikar , Swain Roberto M. , Cheetham Peter , Kim Chul H. , Pamidi Sastry V.
Published: June 2022

The paper is a review of the opportunities and challenges of cryogenic power devices of electric aircraft, and the ongoing research and development efforts of the government agencies and the industry. Liquid Hydrogen (LH2) and Liquefied Natural Gas (LNG) are compared to support high temperature superconducting (HTS) and normal metal devices, respectively. The power devices were assumed to operate at the normal boiling point of the fuel used. The efficiencies of the electrical devices are estimated based on state-of-the-art technology. The mass flow rates and total fuel requirements for both the cryogenic fuels required to maintain the operating temperatures of the devices were simulated using thermal network models. A twin-aisle, 300 passenger aircraft with a 5.5 h flight duration was used for the models. The results show that the required masses of LH2 and LNG are 744 kg and 13,638 kg, respectively for the cooling requirement. The corresponding volumes of LH2 and LNG required are 9,760 and 30,300 L, respectively. In both cases, the estimated mass of the fuel needed for the aircraft is more than what is needed to maintain the cryogenic environment of the power devices. It was concluded that an electric aircraft with LNG cooled normal metal devices is feasible. However, an aircraft with HTS devices and cooled with LH2 is more attractive if the ongoing R&D efforts on HTS devices and LH2 infrastructure are successful. The emission reductions would be substantially higher with LH2, particularly when H2 is produced using renewable energy sources.
Investigation on Effect of Shape of HTS Pole Coil on Airgap Magnetic Field of HTS Synchronous Motor
Authors: Sharma D K , Muralidhar Bathula V A S , Gour A S , Rao V V
Published: June 2022

The High Temperature Superconducting (HTS) synchronous motors offer considerably higher torque and power densities along with higher efficiencies for strategic and critical industrial applications. The most widely explored airgap based topology for HTS synchronous motors has conventional copper windings in stator and HTS pole coils in the rotor. The shape of these rotor pole coils affects various electrical parameters of the motor. In this paper, a detailed investigation has been carried out on effect of shape of HTS pole coil on airgap magnetic field and rated open circuit characteristic (OCC) of an 8 MW HTS synchronous motor along with its other parameters like pole coil excitation current, peak magnetic field inside the motor, maximum perpendicular magnetic field on HTS tape and operating temperature of HTS pole coils through FEM based electromagnetic analysis. Based on the results of electromagnetic analysis, the optimum shape of HTS pole coil has been finalised.
Conceptual design of a wide band gap based cryogenically cooled MW-class inverter
Authors: Kar Soumen , Reddy Siddavatam Ravi Prakash , Rajashekara Kaushik
Published: June 2022

The increasing need for higher power density and closer integration of power subsystems consisting of superconducting motors/generators, degaussing coils, energy storage modules, and cables leads one to consider the merits of refrigerating the associated power electronics down to cryogenic temperatures. High temperature superconducting (HTS) components combined with cryogenic power converters resulting in high power density power conversion systems will have a significant effect on several industrial, commercial, transportation, and renewable energy applications. Cryogenic power converters provide promising benefits over their room temperature counterparts in terms of reduced size and weight due to increased power density, improved efficiency, switching speed, and reliability. Integration could result in significant weight and space savings for the overall system. In this paper, a conceptual design study on the wide-bandgap-based (especially SiC and GaN) MW-class power inverter/converter is reported. Based on the total power loss of the designed converter, different cryogenic cooling strategies are proposed. The cooling power requirements, cooler mass, the cooler cost is evaluated based on the operating temperature of MW-class power converter. Finally, a power density comparison for different types of conventional power applications and HTS applications together with MW-class power converters is presented. The future of the cryogenically cooled power electronics system together with superconducting power devices is described for large-scale applications such as for future electric aircraft.
Dynamics and Vibrations of Rotors of Electrical Drives with Additively Manufactured Materials at Cryogenic Temperatures
Authors: Steegers F , Weidermann C , Klöpzig M , Sattel T
Published: June 2022

The use of additive manufacturing and cryogenic cooling enables engineers to build electric machines with higher power densities than previously seen. Both the new manufacturing technologies and very low temperatures have a significant impact on the mechanical properties of materials. In the present work, a rotordynamics analysis of a permanent magnet synchronous motor concept from the AdHyBau project, funded by the German Federal Ministry for Economic Affairs and Energy, is conducted with an emphasis on the influence of additive manufacturing and cryogenic temperatures on vibrations and natural frequencies.
Using additive manufacturing technologies in high-field accelerator magnet coils
Authors: Novitski I , Coghill J , Beale T , Bergeron J , Davidoff R , Oshinowo B , Raje S , Swanson D , Wilson C , Zlobin AV
Published: June 2022

Recent advances with additive manufacturing (AM) technologies using various materials allow them to be considered for the manufacture of precise and complicated metal parts of the magnet coils of high field accelerator magnets from aluminum bronze, titanium alloy, stainless steel, etc. The 3D printing technology is also being used to fabricate prototype models of real parts to test and optimize their geometry. This paper discusses the designs of the complex stress-management coil parts developed at Fermilab, their fabrication using AM technologies, and quality control methods and results.
Design and thermal study of a test device for breakdown characteristics of insulation materials in low temperature vacuum environment
Authors: Huang Jun , Xu Qiufu , Wang Guodong
Published: June 2022

With the application and development of low-temperature superconductivity technology, the research on electrical properties of insulating materials under different low-temperature conditions has attracted more and more attention. According to the breakdown characteristics of materials in low-temperature environments, a test device for the discharge breakdown characteristics of insulating materials in vacuum low-temperature environments is designed. This device can meet test of the gaseous and solid insulating materials in different low temperature and vacuum conditions. Compared with the traditional low temperature electrical test device, it has the advantages of convenient replacement, short test cycle and multi-functional testing. The finite element simulation software is used to simulate the performance of the cooling device of gas and solid insulating materials, and the effects of liquid helium cooling and refrigerator cooling on the temperature distribution of the device are analyzed and compared. Finally, the flow field analysis of the cooling system defines the internal flow characteristics of liquid helium under liquid helium cooling, which provides theoretical guidance for the design of the low-temperature breakdown test device.
Space-charge effects in low-energy flat-beam transforms
Authors: Moroch Scott B , Koeth Timothy W , Carlsten Bruce E
Published: June 2022

Flat-beam transforms (FBTs) provide a technique for controlling the emittance partitioning between the beam’s two transverse dimensions. To date, nearly all FBT studies have been in regimes where the beam’s own space-charge effects can be ignored, such as in applications with high-brightness electron linacs where the transform occurs at high, relativistic, energies. Additionally, FBTs may provide a revolutionary path to high-power generation at high frequencies in vacuum electron devices where the beam emittance is currently becoming a limiting factor, which is the motivation for this paper. Electron beams in vacuum electron devices operate both at a much lower energy and a much higher current than in accelerators and the beam’s space-charge forces can no longer be ignored. Here we analyze the effects of space charge in FBTs and show there are both linear and nonlinear forces and effects. The linear effects can be compensated by retuning the FBT and by adding additional quadrupole elements. The nonlinear effects lead to an ultimate dilution of the lower recovered emittance and may lead to an eventual power limitation for high-frequency traveling-wave tubes and other vacuum electron devices.
Quantum circuit architectures via quantum observable Markov decision process planning
Authors: Kimura Tomoaki , Shiba Kodai , Chen Chih-Chieh , Sogabe Masaru , Sakamoto Katsuyoshi , Sogabe Tomah
Published: June 2022

Algorithms for designing quantum circuit architectures are important steps toward practical quantum computing technology. Applying agent-based artificial intelligence methods for quantum circuit design could improve the efficiency of quantum circuits. We propose a quantum observable Markov decision process planning algorithm for quantum circuit design. Our algorithm does not require state tomography, and hence has low readout sample complexity. Numerical simulations for entangled states preparation and energy minimization are demonstrated. The results show that the proposed method can be used to design quantum circuits to prepare the state and to minimize the energy.
A continuum of physics-based lithium-ion battery models reviewed
Authors: Brosa Planella F , Ai W , Boyce A M , Ghosh A , Korotkin I , Sahu S , Sulzer V , Timms R , Tranter T G , Zyskin M , Cooper S J , Edge J S , Foster J M , Marinescu M , Wu B , Richardson G
Published: June 2022

Physics-based electrochemical battery models derived from porous electrode theory are a very powerful tool for understanding lithium-ion batteries, as well as for improving their design and management. Different model fidelity, and thus model complexity, is needed for different applications. For example, in battery design we can afford longer computational times and the use of powerful computers, while for real-time battery control (e.g. in electric vehicles) we need to perform very fast calculations using simple devices. For this reason, simplified models that retain most of the features at a lower computational cost are widely used. Even though in the literature we often find these simplified models posed independently, leading to inconsistencies between models, they can actually be derived from more complicated models using a unified and systematic framework. In this review, we showcase this reductive framework, starting from a high-fidelity microscale model and reducing it all the way down to the single particle model, deriving in the process other common models, such as the Doyle–Fuller–Newman model. We also provide a critical discussion on the advantages and shortcomings of each of the models, which can aid model selection for a particular application. Finally, we provide an overview of possible extensions to the models, with a special focus on thermal models. Any of these extensions could be incorporated into the microscale model and the reductive framework re-applied to lead to a new generation of simplified, multi-physics models.
Deep learning via message passing algorithms based on belief propagation
Authors: Lucibello Carlo , Pittorino Fabrizio , Perugini Gabriele , Zecchina Riccardo
Published: June 2022

Message-passing algorithms based on the belief propagation (BP) equations constitute a well-known distributed computational scheme. They yield exact marginals on tree-like graphical models and have also proven to be effective in many problems defined on loopy graphs, from inference to optimization, from signal processing to clustering. The BP-based schemes are fundamentally different from stochastic gradient descent (SGD), on which the current success of deep networks is based. In this paper, we present and adapt to mini-batch training on GPUs a family of BP-based message-passing algorithms with a reinforcement term that biases distributions towards locally entropic solutions. These algorithms are capable of training multi-layer neural networks with performance comparable to SGD heuristics in a diverse set of experiments on natural datasets including multi-class image classification and continual learning, while being capable of yielding improved performances on sparse networks. Furthermore, they allow to make approximate Bayesian predictions that have higher accuracy than point-wise ones.
Multifaceted analysis of nanotoxicity using primary cultured neurons
Authors: Kamikubo Yuji , Yamana Tomohito , Inoue Yuriko , Sakurai Takashi
Published: June 2022

Various nanomaterials have been produced with the development of nanotechnology, some of which have been reported to have adverse effects on several types of cells, organs, and the environment. It has been suggested that some small nanoparticles can cross the blood-brain barrier and accumulate in the brain, which may be a potential cause of brain diseases. Neuronal cells are vulnerable to hypoxia, hypotrophy, and mechanical and oxidative stress. Therefore, it is essential to assess the toxicity of nanoparticles to neurons accurately. In this report, we describe a primary culture protocol to evaluate the toxicity of nanoparticles on neurons, a potential high-throughput method for assessing the cytotoxicity, and a method for evaluating the effect on neuronal maturation. This report assessed the toxicity of silicon dioxide, zinc oxide, and iron nanoparticles using rat hippocampal neurons, which are used frequently in pharmacological and physiological studies. Based on the methods and protocols we reported in this report, it may be possible to evaluate nanotoxicity to various neurons by using primary cultures of other brain regions (cerebral cortex, cerebellum, thalamus, etc.), spinal cord, and peripheral nerves.