bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design and experimental research of the cryogenic ejector to inject liquid nitrogen
Authors: Jia Q M , Li Z Y , Gong L H , Liu L Q , Zhu W P , Zhang M M , Su H K 
Published: June 2020

Abstract
With the development of cryogenics, the demand of cryogenic liquid increases constantly. However, there are some difficulties to control and to adjust the extraction of cryogenic liquid especially for liquid helium. Compared with the immersed pump, the ejector has huge advantages in pumping the cryogenic liquid from cryogenic Dewar, like stable operation and simple structure. Considering the similarity between liquid nitrogen and liquid helium and the high cost to conduct the liquid helium experiment, this paper reports a research on the cryogenic ejector in the nitrogen temperature range. The experiment platform customized for liquid nitrogen was set up and the experiment of injection was launched. The nitrogen gas, as the primary flow accelerating in the nozzle, injects the liquid nitrogen at the outlet of nozzle. Two flows blend in the mixing chamber and flow out from the diffuser. Based on the ideal gas assumption and energy conservation, the sound velocity can be derived from two kinds of equations, obtaining the critical condition of primary flow thermal properties. Depending on the properties and previous research experience, the structure of ejector is designed and established, which could effectively inject liquid nitrogen from the cryogenic liquid cylinder. The problems and challenges are analyzed. In conclusion, this paper introduces the design method of cryogenic ejector and builds a liquid nitrogen test instrument. This method makes the extraction of cryogenic liquid more convenient, which is of universal significance for the cryogenic research work.
Molecular simulation on adsorption of helium by activated carbon in 4-10 K
Authors: Xi X T , Wang J , Chen L B , Zhou Y , Wang J J 
Published: June 2020

Abstract
In the liquid helium temperature region, the specific heat of helium increases rapidly, so adsorption behavior of helium on activated carbon is expected to be used in the regenerator of 4-K class cryocoolers to improve the performance of the refrigerator. In this paper, we use Grand Canonical Monte Carlo method to simulate the adsorption of helium on the amorphous carbon in 4-10 K. And the structural parameters of amorphous carbons and the effect of temperature, pressure, graphite slice’s size and density of amorphous carbon on the adsorption amount were analyzed. The results show that the amorphous carbon constructed from the larger size graphite slice has a smaller specific surface area and a larger pore volume. And as the temperature decreases and the pressure increases, the amount of adsorbed helium increases. In addition, we have found that mixed-filled amorphous carbon can obtain higher specific surface area and pore volume, and has better comprehensive properties.
Failure modes, effects and criticality analysis of a 3kW@4.5K helium refrigerator
Authors: Zong Y W , Zhou Z W , Zhang Q Y , Zhu Z G , Yang P C , Hu B 
Published: June 2020

Abstract
The comprehensive research facility for key systems of fusion reactors was included in the “13th Five-Year Plan” priority project in China. In order to meet the requirements of cryogenic testing of large superconducting magnets, it is proposed to build a 3kW@4.5K refrigerator and carry out research on 3kW@4.5K superfluid helium cryogenic system. In order to evaluate the reliability of the 3kW refrigerator, the FMECA analysis was performed on the helium refrigerator. The refrigerator system is divided into three subsystems: the compressor system, the monitoring and control system and the cold box, to identify the failure mode and the impact on the refrigerator system related functions. The critical value is calculated and the critical matrix is drawn by the severity and the occurrence of the rating criteria. Identify the parts with high and medium risks and propose corresponding risk mitigation measures.
Analysis of freezing risk during LNG evaporation process
Authors: Brenk Arkadiusz , Rogala Zbigniew , Malecha Ziemowit 
Published: June 2020

Abstract
Liquid natural gas (LNG) boiling process concerns majority of LNG applications because of a need of its regasification. Depending on pressure an equilibrium temperature of LNG is 112-160K. The low boiling temperature of LNG makes the vaporisation process complicated. An important risk of the regasification is related to a possibility of a solid phase formation (freezing of a heating fluid). For a range of important applications the heating fluid is water or water-glycol mixture, characterized by freezing temperature considerably higher than the boiling temperature of LNG. The solid phase formation can lead to an increase of hydraulic pressures losses, deterioration of the heat transfer or even to the destruction of a heat exchanger and any accompanying device. It motivates a need for better understanding and control of a heat transfer related to the regasification to avoid the solid phase formation. The current work analyses a LNG regasification and a risk of solidification in a generalized shell and tube heat exchanger. The conducted study helped to define a critical Reynolds number below which the solidified ice totally blocks the flow.
Electrical Tree Aging of Epoxy-Based Nanocomposites at Cryogenic Temperature
Authors: Wang Yongguang , Huang Rongjin , Huang Chuanjun , Wu Zhixiong , Dong Hongyu , Shen Fuzhi , Zhang Kaikai , Li Xu , Li Laifeng 
Published: June 2020

Abstract
Electrical insulation at cryogenic temperatures is a key technology in the development of superconducting cables and superconducting current limiters. Due to their improved electrical, mechanical and thermal properties, the application of epoxy nanocomposites in high voltage power systems has shown a broad outlook. In this paper, tests were conducted to investigate the electrical tree aging phenomenon in epoxy resin/Al2O3 nanocomposites in liquid nitrogen under AC voltages. The test samples were prepared with six levels of nanofiller content: 0 wt %, 1 wt %, 2 wt %, 3 wt %, 4 wt %, and 5 wt % by weight ratio. Experimental results showed that nano-fillers below 3% are easy to cause the electric field distortion at the needle tip, which reduces the tree inception voltage in the composite sample compared to that in the neat epoxy sample. At low temperature, the effect of electric field distortion on the tree inception voltage is significantly weakened and the tree growth rate decreases sharply with the increase of the content of the nano-filler.
Thermal Analysis of a Superconducting Undulator Cryostat for the APS Upgrade
Authors: Shiroyanagi Y , Anliker E , Hasse Q , Ivanyushenkov Y , Kasa M , Fuerst J 
Published: June 2020

Abstract
The Advanced Photon Source Upgrade includes four 4.8-m-long superconducting undulator (SCU) cryostats, each containing two planar undulator NbTi magnets up to 1.9 m long. The cooling is provided by six cryocoolers arranged in three thermal circuits. The magnets are indirectly cooled with LHe penetrating through channels in the magnet cores. This 4 K circuit, which also includes a LHe tank, is cooled by five 4 K cryocooler 2nd stages. A beam vacuum, which is thermally isolated from the magnets, is cooled by one 10 K cryocooler 2nd stage. A thermal shield and warm parts of current leads are cooled by the 1st stages of all six cryocoolers. This paper presents an ANSYS-based thermal analysis of the new SCU cryostat including all thermal circuits. The benchmarked thermal conductance between the cryocooler cold heads and the LHe tank are used in the calculations as well as the measured cryocooler load lines. The model predicts temperatures in the system, total 4 K heat loads, and excess cooling power for various operational modes of the undulator.
Thermo-Electric Design of the Protection and Diagnostic Feeders of the HL-LHC Triplets
Authors: Pasdeloup F. , Prin H. , Williams L. 
Published: June 2020

Abstract
The HL-LHC Project currently undertaken by CERN that provides an upgrade to the existing LHC accelerator, is designed to increase the luminosity of the colliding particle bunches by a factor of at least five. Part of this upgrade will require the replacement of the existing groups of three superconducting LHC triplet magnets situated on each side of the ATLAS and CMS detectors with similar groups of four higher field HL-LHC triplet magnets of a new design that exploit coils manufactured with cables in Nb3Sn superconducting alloy. The HL-LHC triplet magnets require dedicated electric current feeders linking their cold masses to their cryostat vacuum vessels, thermo-electrically optimised and specifically designed to separately feed their quench protection, beam tuning and instrumentation systems with electric current. The HL-LHC instrumentation feedthrough system is similar, though containing a larger cable inventory, to that mounted on existing cryo-magnets in the LHC accelerator whereas the quench protection and beam tuning systems, both present new requirements calling for a substantially different design approach. Installed in a highly activated zone of the LHC, all three systems consequently exploit only natural heat convection to prevent the formation of condensation at their warm ends. This paper describes the functional design and thermo-electrical optimisation achieved for each of these electric current feeder systems.
Thermal engineering of optical mirrors for use at cryogenic temperature inside a LHC magnet cryostat
Authors: Micolon F , Dijoud T , Durand H Mainaud , Parma V , Rude V , Sosin M 
Published: June 2020

Abstract
In the frame of the HL-LHC project, innovative technical solutions are sought to measure accurately the position of the magnet helium vessel inside the cryostat. To this end, a system based on laser-interferometry is being designed to monitor the displacement of the vessel through dedicated openings in the new HL-LHC magnet cryostats. In order to test such a system on a full-scale setup in representative operating conditions, a LHC dipole cryostat was modified to integrate the system optical lines of sight and the reflective mirrors were mounted onto the magnet helium vessel.
Upon the first cool down of the magnet to 80 K, severe ice-like condensation started forming on the reflective surface of the mirrors hence making the system unusable at cold. This was attributed to the condensation of the residual gas remaining in the cryostat insulation vacuum on the mirror surface. In this configuration the mirrors acted as local “cold spots” since they were purposefully sticking out of the multi-layer insulation (MLI) that is otherwise covering the magnet helium vessel.
In order to cope with this condensation issue, a dedicated study was carried out to design and manufacture a passive temperature regulation system based on a thermal insulating support and a thermal radiation intercept in order to keep the mirrors just above the expected freezing temperature in operational conditions.
This paper details the thermal engineering study leading to the design of the insulated mirrors and presents the technical solution retained as well as the latest test results.
Demonstration of CW accelerating gradients on a cryogen-free, cryocooler conduction-cooled SRF cavity
Authors: Dhuley R C , Geelhoed M I , Zhao Y , Terechkine I , Alvarez M , Prokofiev O , Thangaraj J C T 
Published: June 2020

Abstract
Conduction-cooling of superconducting radiofrequency (SRF) cavities using closed-cycle cryocoolers can lead to compact linear accelerators by eliminating liquid helium and the associated infrastructure. In this paper, we present the first-ever experimental demonstration of continuous wave (CW) accelerating gradients on a niobium SRF cavity that is cooled without using liquid helium. In a newly developed experimental apparatus, a single-cell, 650 MHz niobium cavity was conductively coupled to a 2 W @ 4.2 K pulse tube cryocooler using a high-purity aluminum thermal link. The CW accelerating gradient slightly exceeded 1.5 MV/m, a limit imposed by our RF power supply. Using simple scaling, we project that the niobium cavity when coated with Nb3Sn and operated on the same experimental setup can produce >10 MV/m CW accelerating gradients.
Comparative Study of Heat Transfer Performance and Visualization Images of Superfluid Helium Boiling in Narrow Two-dimensional channel
Authors: Takada S. , Kobayashi H. , Murakami M. , Kimura N. 
Published: June 2020

Abstract
In a narrow channel, boiling heat transfer in He II is much different from that in the case of an open bath. Even under saturated pressure condition, rapid temperature rise due to the onset of film boiling is not seen when the temperature reaches the lambda temperature, but only the temperature oscillation is detected. The behaviour of this state looks like the nucleate boiling, though it is known the steady nucleate boiling state is absent in He II in open bath. The high heat transfer coefficient in this quasi-nucleation boiling state above the lambda temperature suggests the range where this advantage in heat transfer appears is wider than that based on simple prediction of He II heat transfer. The appearance of metastable states of superheated He II and superheated He I should be considered in the case of a narrow channel. In this study, the visualization experiment result using a transparent heater and the transient temperature measurement data on a copper heater surface had been compared with each other. In the case of rather high heat flux, several film boiling modes were observed in a narrow two-dimensional channel. The peak of the heat transfer coefficient appeared around the lambda pressure. In the case of low heat flux, the heat transfer coefficient variation with the pressure shows sudden rise around the lambda point. The heat transfer coefficient under nearly saturated pressure condition below the lambda pressure is larger than that above the lambda pressure.
Control and Commissioning of a Subcooled Helium Cryogenic Testing Platform with Cold Compressors
Authors: Zhou Z W , Zhang Q Y , Cheng A Y , Zhu P , Li S S , Zhu Z G 
Published: June 2020

Abstract
The subcooled helium cryogenic testing platform with cold compressors has been operated successfully in the end of 2018 at the Institute of Plasma Physics, Chinese Academy of Sciences (CASIPP). It is the first subcooled helium cryogenic system based on the cryogenic decompression technique in China, which has been designed and constructed over two years by our own team. The subcooled helium cryogenic testing platform was designed to provide the 4.5 K supercritical helium for the helium forced-flow cooling with one helium circulating pump, and provide the 3 K subcooled helium with two cold compressors in series. It consists of one 2.5 kW@4.5 K helium refregeator and one distribution valve box where the helium circulating pump and the cold compressors installed on it. This paper will present the process control flow of the distribution system and the design parameters of two cold compressors. During the commissioning, the startup and stop control flow of the two cold compressors have been determined. And their operation and control were performed within the safe operation area in the performance map. The testing result shows the lowest temperature and pressure of the saturated helium bath, and indicates the subcooled helium system has an equivalent refrigeration power greater than the design value of 700 W@3 K. The commissioning experience will help the reconstruction of the subcooled helium system for EAST Tokamak in future to enhance the cryogenic stability in higher magnetic field.
Cryogenic Upgrade of the Helium Central Liquefier and Superconducting Cable & Wire Test Facilities at CERN
Authors: Pirotte O , Lees A , Barbe T , Dupont T , Pezzetti M 
Published: June 2020

Abstract
The demand for liquid helium (LHe) for users at CERN without dedicated cryogenic infrastructure is set to increase due to future projects and experiments in the Antiproton Decelerator. LHe is supplied to the users by means of 500 liter dewars filled by the central liquefier (B165) that comprises a cryogenic plant of 400 W @ 4.5 K. In addition, the Superconducting Cable & Wire Test Facility (B163) located nearby will be upgraded to incorporate the forthcoming installation of the new test station FRESCA 2. B163 includes a second cryogenic plant of 400 W @ 4.5 K and a dedicated cryogenic distribution system. To maximize the production of the two cryogenic plants and their ancillary infrastructure, thus improving the subsequent distribution of LHe, a combined cryogenic distribution system has been developed. This system will increase the LHe storage capacity; allow the direct transfer of helium inventory between both facilities and the gravity filling of large capacity trailer dewars in addition to the 500 liter dewar fleet. This paper details the architecture of the new cryogenic distribution system, the analysis undertaken to define it, the design and specifications of the various components and the schedule of the realization of the project.
Compact cryogenic test stand for superconducting magnets characterization
Authors: Bruce Romain , Soulerin Sacha , Bouziat Denis , Cubizolles Robin , Gastineau Bernard , Juster François-Paul , Bredy Philippe 
Published: June 2020

Abstract
A new compact experimental facility for testing compact superconducting magnets down to 4.2 K using cryogenic fluids has been developed at CEA Paris-Saclay. This facility has been constructed to test the solenoid magnets for the next Soreq particle accelerator (SARAF) project. The magnets are cooled with liquid helium at 4.2 K and the liquid bath can be pressurized up to 2 bars to regulate the temperature of the magnet during operating conditions. In this facility, it is possible to measure and dissociate the heat loads coming from the magnet and the current leads by flow-metry. The voltage of the solenoids and their current leads are measured using National Instrument devices and monitored with a Labview program to identify and analyze eventual quenchs. The magnetic performance of the magnets are also monitored dynamically with 3D hall probes. Numerous cryogenic temperature sensors are used to characterize the thermal evolution of the magnet and its current leads during the test. In the present paper, the compact facility is described and the first results obtained on the current leads of the magnet prototype are presented.
A Leak Detection System for Valves Cooled to 20 K while Cooled with a GM Cryocooler
Authors: Lyu B K , Xu D , Nishimura A , Jia P , Huang R J , Huang C J , Shen F Z , Li X , Wang Y G , Sun W T , Li L F 
Published: June 2020

Abstract
Cryogenic valves are widely used in cryogenic systems such as aerospace propulsion systems and various cryostats. Under cryogenic temperatures, thermal shrinkage and sealing material hardening may dramatically enlarge the sealing gap of the valves, which leads to a serious leakage. Therefore, a detection system for cryogenic valves is badly needed. In this paper, a cryogenic leak detection system is established, which has the capability of detecting internal and external leakage of the valves at temperatures around 20 K. Compared with the traditional cryogenic leak detection system, this system, getting rid of threats from cryogenic liquid, successfully enhances the overall safety and is able to test five valves simultaneously to improve efficiency. This system optimizes the heat exchanger structure and shortens the cooling time.
Testing of SHIIVER MLI Coupons for Heat Load Predictions
Authors: Johnson W L , Oberg D , Frank D , Mistry V , Koci F D 
Published: June 2020

Abstract
The Structural Heat Intercept, Insulation, and Vibration Evaluation Rig (SHIIVER) is designed to demonstrate the performance benefits of installing multilayer insulation (MLI) and structural vapor cooling onto a large hydrogen tank as a part of an upper stage. The intent of the 4 meter sub-scale demonstration is to design the MLI in a manner that its performance can be scaled to a full sized application. In order to predict the performance of the blankets as well as aid in the design, several features needed to be tested. Four different coupons were tested and evaluated for thermal performance relating to the number of layers, the seams, and the attachment mechanisms. The attachment mechanisms were further tested for structural strength at nominal application temperatures. From the testing, the number of layers were determined to be 30, and heat load penalties were determined for the seams and attachments. The attachment mechanisms passed all load testing with a margin of greater than 40%.
Measurement of heat flux in multi-layer insulated helium cryostats after loss of insulating vacuum
Authors: Weber C , Henriques A , Schirle S , Grohmann S 
Published: June 2020

Abstract
The dimensioning of pressure relief devices (PRD) for cryogenic pressure equipment requires knowledge on the heat input at the maximum credible incident. In helium cryostats, this situation is typically defined by the loss of insulating vacuum (LIV), where the heat load is induced by desublimation and condensation of atmospheric air on the cryogenic surface. This surface is often covered with multi-layer insulation (MLI) in order to reduce the thermal radiation heat load in standard operation. During loss of insulating vacuum, the MLI represents a diffusive barrier for the air to reach the cryogenic surface, reducing the heat flux as well. Experimental reference data for the heat flux in case of LIV exist mainly for blank surfaces; only few data are published for MLI-covered helium surfaces. Therefore, the effect has been investigated in the cryogenic safety test facility PICARD at KIT. This paper presents the results of venting experiments carried out with different numbers of layers and different types of MLI.
The low temperature mechanical properties of a Nitronic 40 forging
Authors: Walsh R P , Radcliff K J , Lu J , Han K 
Published: June 2020

Abstract
Nitronic 40 forged shells are typically used for structural reinforcement in high field pulse magnet design and applications. To better understand the mechanical performance of this versatile high strength austenitic steel a series of mechanical tests were conducted. Tensile were performed at 295 K, 77 K and 4 K, and cryogenic fracture mechanics tests were performed at 77 K and 4 K. The effect of temperature on strength, ductility, toughness and fatigue crack growth rate are evaluated. Microstructure and composition effects are also presented and discussed.
DC surface flashover characteristics of ZnO/Epoxy composites at room temperature and 77 K
Authors: Zhang Kaikai , Huang Chuanjun , Wang Yongguang , Zhang Hua , Zhang Chi , Wu Zhixiong , Liu Huiming , Xu Dong , Huang Rongjin , Li Laifeng 
Published: June 2020

Abstract
Epoxy (EP) resin based nano-composites are widely used in high voltage direct current (HVDC) high temperature superconducting (HTS) power cable. In this paper, the DC surface flashover characteristics of ZnO/EP composites were studied at both room temperature and 77 K. The samples were made by dispersing ZnO nano-particles into EP resin with various weight percentages of 0%, 1%, 3%, 6% and 10%, respectively. The experiments were carried out with a cryogenic system in which DC high voltages ranging from 0 kV to 100 kV were supplied. The results showed that the surface flashover voltages increased with the increase of ZnO content at both room temperature and 77 K, and the surface flashover voltages at 77 K were higher than that at room temperature for composites with the same ZnO content.