bluuebunny/crossref_metadata_2025 huggingface dataset:
Phenotypic and Genotypic Identification to S. aureus isolates from Cattle in Bogor
Authors: Prihandani S S , Wibawan I W T , Safika  , Sumirah  , Noor S M , Putri AF , Nuradji H
Published: July 2024

S. aureus, commonly referred to as S. aureus, is a bacterium that responsible for a variety of infectious diseases that affect human being and animal health. Target of this study is to detect and clarify S. aureus phenotypically and genotypically using isolates originally derived from cattle. Phenotypic identification involves assessing biochemical characteristics such as Gram staining, catalase, and coagulase tests. Genotypic identification relies on detecting the presence of specific genes 23SrRNA and nuc associated with S. aureus through polymerase chain reaction (PCR) using appropriate primers. In this investigation, the focus of the genotypic detection PCR is on targeting the nuc genes, which serve as virulence factors. Out of the isolates tested, seven were identified as positive for the nuc genes, indicating the existence of the virulence factor in the S. aureus strain under study.
Dynamic loading capacity test system of thrust gas bearing of cryogenic turbo expander
Authors: Zhang X H , Dong B , Li K R , Ke C L , Liang Y W , Qiu S , Shi N Y , Peng N , Liu L Q , Gong L H
Published: July 2024

The gas film between the thrust disc of rotor and the thrust gas bearing in the axial direction is only tens of microns in the high-speed cryogenic turbo expander. The bearing loading capacity is one of the static characteristics, and the experimental research in the study of static characteristics is the same important as numerical simulation, a new and accurate type of test system for dynamic measurement of axial thrust bearing loading capacity of the high-speed cryogenic turbo expander is presented in this paper. The system can accurately measure the gas film force between the thrust disc and the hydrostatic or dynamic thrust gas bearing, study the influence of different structural parameters on the bearing loading capacity, and simultaneously monitor the dynamic relationship between the gas film force and the value of film gap.
Development of a dual flow transfer system with a centrifugal pump for liquid helium
Authors: Doll J , Haberstroh C
Published: July 2024

At research institutes, liquid helium is commonly transferred to mobile dewar vessels via a single flow transfer line, driven by a pressure build-up in the storage vessel. In this process, a considerable amount of the liquid evaporates according to the prevailing pressure drop and due to the heat leak into the transfer line. Further, the generated flash gas must undergo an energy intensive recovery and liquefaction procedure again. To significantly reduce these transfer losses, the cryogen can be transferred to the target dewar using a centrifugal pump. At the same time, the displaced cold gas is guided back to the storage dewar in a cold return line within the same insulated transfer housing. This article presents the current development status of the transfer system, including the thermo-hydraulic modeling and simulation.
Development of conformable cryogenic valve seats for resilience to foreign object debris
Authors: Wood M , Leachman J W.
Published: July 2024

Cryogenic valve sealing technology is notoriously more challenging than traditional fluids due to the combination of small atoms and molecules with extreme temperature and pressure profiles. Recently, flexible polymeric films folded into origami demonstrated considerable resilience to mechanical failure in the cryogenic extreme. Fluorinated polymers such as Polytetrafluoroethylene (PTFE) are observed to mechanically flex and not plastically deform in cryogenic conditions. This paper explores a new cryogenic valve sealing paradigm which uses multiple conformable polymer layers to provide constant seat mating surface area at cryogenic conditions. Stacking these thin discs in series with a spacer allows maximum bend around the seat while creating multiple sealing surfaces. Experimental measurements of leakage rates with and without the presence of Foreign Object Debris (FOD) are compared with traditional re-closable pressure relief valves. Conformable cryogenic valve seats have the potential to be more repeatable, decrease leakage rates from differing coefficients of thermal expansion, hysteresis, and FOD when compared to traditional market valves.
Loss of insulation vacuum tests on an EuXFEL cryomodule
Authors: Barbanotti S , Boeckmann T , Bozhko Y , Jensch K , Klos R , Ramalingam R , Dhillon A K , Schnautz T , Sellmann D
Published: July 2024

Many Free Electron Lasers (FEL) are nowadays based on linear superconducting accelerators (linacs). The typical layout of such a linac consists of a number of cryomodules (CMs) arranged in strings. Each cryogenic circuit in a string is protected by safety valves (SVs) in case of failure of the system or a catastrophic event. A typical worst-case scenario considers the venting of the insulation vacuum, causing a fast and uncontrolled warm up of the cryogenic circuits. Such venting can for example take place across a pump port belonging to a string. The amount of heat deposited on each circuit is a very important parameter to correctly size the safety devices.

This paper describes the tests performed at DESY on an EuXFEL cryomodule to evaluate the heat input to the three cryogenic circuits of the CM while venting the insulation vacuum. Test results are given with a particular focus of their application to long strings.
Conduction cooled cryostat for small-scale superconducting radio frequency accelerator applications
Authors: Nicol T H , Edwards C , Dhuley R C , Thangaraj J C
Published: July 2024

Fermilab’s Illinois Accelerator Research Center (IARC) is designing small-scale, ∼10 MeV prototype conduction cooled superconducting accelerators for projects ranging from medical device sterilization to road pavement modification. These accelerators are built using high-Q Nb3Sn coated superconducting radio-frequency cavities. The cryostat design for one such prototype being developed for the U.S. Army Engineer Research Development Center (ERDC) will be described. Cryostats for such conduction cooled accelerators require stringent control of thermal losses since the available power from cryocoolers is restricted to a few watts. The present state of the vacuum vessel, conduction cooling system, thermal shield, cavity support, and other ancillary system designs will be described as well as presentation of thermal and structural simulations. Hopefully the work described in this paper will lead to the engineering construction of a cryostat which will accelerate an electron beam to high energy, ∼10 MeV, with extremely low thermal losses.
Design and development of vehicle cryo-compressed hydrogen storage vessel
Authors: He Ming , Lv Cui , Wu Jihao , Li Ziwei , Zhou Han , Wang Jinzhen , Zhang Meimei , Gong Linghui
Published: July 2024

Compared with other hydrogen storage methods, cryo-compressed hydrogen storage has significant advantages in terms of mass hydrogen storage density, volume hydrogen storage density, hydrogen storage cost, safety and evaporation loss. The key component of cryo-compressed hydrogen storage is cryo-compressed hydrogen storage vessel. In order to reasonably design and optimize the performance of cryo-compressed hydrogen storage tank, the author uses carbon fiber and low temperature resin to prepare composite one-way plate from the material, and then makes the one-way plate into relevant splines for testing. The relevant parameters of the spline are tested in the liquid nitrogen temperature zone, such as elastic modulus, Poisson’s ratio, thermal conductivity, etc. Using the relevant mechanical properties of the carbon fiber composite one-way plate obtained from the experiment, the target storage tank is designed to provide the actual storage tank for the subsequent low temperature and high pressure storage tank experiment.
Compact cryogenic hydrogen test environment for small devices and material characterization
Authors: Grabowski M , Bischoff H , Haberstroh C , Baumann D , Lindackers D
Published: July 2024

Currently, there is a great need for testing capabilities for material samples and components in LH2. This includes low temperature compatibility at 20 K, H2 compatibility and potential degradation or permeation effects. The test environment required for this is challenging and quite costly due to LH2 supply. Therefore, an alternative test concept was developed whereby the required amount of LH2 (typically 2–3 L) is generated directly on-site by simple condensation. This is achieved with a power-controlled cryocooler (115 W @ 80 K, 18 W @ 20 K). A cylindrical pressure vessel with an inner diameter of d = 109 mm and a length of approx. 500 mm designed for 2.1 MPa is used to hold the LH2 bath and the samples. The cryocooler and the sample chamber are installed in a common vacuum cryostat and are thermally coupled at the lower end. At the 20 K level, thermal coupling is achieved by a sophisticated thermosiphon arrangement. Hydrogen is taken from a pressure reservoir, pre-cooled at the cryocooler 80 K level, and then injected and liquefied within a couple of hours.
Vacuum Pump-Down of the Annular Insulation Space for Large Field-Erected Liquid Hydrogen Storage Tanks
Authors: Swanger A M , Fesmire J E , Jacobson J , Butts M , Cihlar S
Published: July 2024

Insulation systems are critical to liquid hydrogen storage tank performance. Tanks in the capacity range of 100 to 1,000 m3 are typically shop built and designed with high-vacuum (HV) multi-layer insulation (MLI), whereas storage vessels larger than 1,000 m3 are typically field-erected and supplied with bulk fill insulation working at moderate vacuum (MV) levels (1-100 millitorr). For large, field-erected vessels, two types of bulk fill insulation typically used: perlite and hollow glass microspheres (glass bubbles). Selection of either material is driven by a tradeoff between CAPEX and OPEX, such as the material and construction cost versus operating thermal performance and maintenance. In either case, the vacuum level needed to achieve optimum performance is likely to drive the field testing and commissioning portion of the construction schedule. A primary goal of this paper is to present practical experience and data for warm vacuum pressure (WVP) and cold vacuum pressure (CVP) levels. Recommended WVP levels needed prior to cooldown consider both perlite powder and glass bubbles. Pumping time expected to achieve target vacuum levels, considering a variety of factors, is also discussed. Recommendations for a standard practice in vacuum-insulated tank commissioning are based on historical NASA data, and those collected during recent projects.
Design of the cryogenic moderator system for the second target station
Authors: Janney J , Lyngh D , Iverson E B
Published: July 2024

The Second Target Station (STS) at Oak Ridge National Laboratory will be a 700 kW pulsed spallation neutron source designed to provide the world’s highest brightness cold neutron beams. In order to produce the required neutron performance, two compact liquid hydrogen moderators are located adjacent to the tungsten spallation target and must be supplied with less than 20 K hydrogen and a para hydrogen fraction of 99.8% or greater. The Cryogenic Moderator System (CMS) will consist of a single hydrogen loop feeding the two moderators in series cooled by a helium refrigerator with a cooling capacity of 2.5 kW at 17 K. The hydrogen loop consists of a hydrogen circulator, hydrogen helium heat exchanger, ortho-para converter, accumulator, transfer lines and heater. The design of the hydrogen loop is based on the CMS design of the First Target Station at the Spallation Neutron Source and some of the component designs may be reused. General hydrogen temperature control is provided by controlling the flowrate of helium to the heat exchanger. The hydrogen loop will have a constant flowrate of 0.5 L/s and remove a nuclear heat load of about 850 W from the two moderators, which is deposited both directly in the hydrogen and the adjacent hydrogen containing structures. Because the nuclear heat load is accelerator driven, the hydrogen system must remain stable when the heat load is removed instantaneously during beam trips. System stability is maintained passively with the accumulator and actively with the heater. Ionizing radiation which interacts with the liquid hydrogen drives backconversion of the hydrogen from parahydrogen to orthohydrogen. The STS moderator performance is very sensitive to small fractions of orthohydrogen requiring an ortho-para converter to maintain the hydrogen supplied to the moderators at near equilibrium parahydrogen concentration. STS CMS is in the early stage of preliminary design and current focus is evaluating component sizing and system stability during beam transients.
Numerical modelling of the cool-down of the helium transfer-lines for FRIB LINAC and experimental systems
Authors: Kroll D , Howard J , Hasan N , Knudsen P
Published: July 2024

The cryogenic distribution system at FRIB is extensive, encompassing three Linac segments, fourteen experimental system superconducting magnets, cross-connect between FRIB and the reconfigured NSCL legacy system, and the A1900 magnets, as well as many other user experimental loads. The cool-down or warm-up of these transfer-lines is an inherently transient process and must be conducted at a gradual enough rate to keep local temperature gradients and corresponding thermal stress on the piping system within acceptable limits. To this end, estimation of this transient process is very helpful in operational planning. A two temperature (fluid and pipe wall) model was developed to capture the transient characteristics of the cool-down or warm-up process with real fluid properties, and considering the effects of heat in-leak, momentum, flow resistance, and piping components. It was employed to estimate the cool-down of different FRIB transfer line sections, and the results were compared against data obtained during actual cool-down of the transfer line.
Cryogenic Distribution System for Polish Free Electron Laser Facility
Authors: Banaszkiewicz T , Chorowski M , Duda P , Felisiak P , Poliński J
Published: July 2024

Polish Free Electron Laser facility (PolFEL), presently under construction at the National Centre for Nuclear Research in Warsaw, will consist of an electron gun and four cryomodules each housing two 9-cell superconducting TESLA RF cavities. The cryomodules comprising the cavities will be supplied with superfluid helium at 2 K. Other PolFEL cooling power requirements result from the demand of the power couplers for the accelerating cryomodules (5 K) and thermal shields (40 K – 80 K). The machine will make use of several helium thermodynamic states like two-phase superfluid HeII, supercritical helium and low-pressure helium vapours supplied to cold compressors. A Cryogenic Distribution System (CDS) will provide supercritical helium to the valve-boxes where thermodynamic processing of the helium to a superfluid state will take place. The paper presents the CDS architecture and discusses the possible design options like methods of the power couplers cooling, optional use and location of cold compressors. The second law of thermodynamics has been used for the optimization of the CDS configuration. A generalized approach to the design of helium distribution systems, taking into account thermomechanical aspects and the consequences of the second law of thermodynamics, is presented.
Status of the MINERVA cryomodules and associated cryogenic system (MYRRHA phase 1)
Authors: Berkowitz Zamora D , Bonthuys G , Dekhtiarov V , Dorda U , Marhauser F , Michel F , Bonne F , Millet F , Poncet J-M , Saugnac H , Joly Ch , Olivier G , Lhomme C , Junquera T , Dieudegard F , Beniken M-E A , Tijani Y , Thermeau J-P
Published: July 2024

MYRRHA at SCK CEN in Mol/Belgium will be a pre-industrial large-scale Accelerator Driven System for unparalleled research opportunities in spent nuclear fuel, nuclear medicine, and fundamental and applied physics. In 2018 the Belgian government released funding for MYRRHA’s first phase, MINERVA, for a staged implementation and operation. It covers the design, construction, and commissioning of the continuous-wave superconducting RF proton linac up to 100 MeV, as well as dedicated user target stations. The MINERVA proton linac will accommodate 30 identical cryomodules to boost the beam energy delivered by the normal-conducting frontend from 16.6 MeV to 100 MeV. Each cryomodule will contain two superconducting RF single-spoke cavities immersed in a superfluid Helium bath at 2 K. The design and architecture of the associated cryogenic system is derived from the stringent linac reliability requirements imposed by the future subcritical nuclear reactor. We present the architecture, design, and development status of the MINERVA cryomodules and associated cryogenic system towards the implementation phase of the project as part of a collaboration between ACS, CEA/DSBT, IJCLab, and SCK CEN. We also provide an overview of the initial outcomes of cryogenic and RF tests for the prototype MINERVA cryomodule, which are still ongoing at IJCLab.
LCLS-II Helium Refrigeration System Commissioning Results
Authors: Apte A. , Ravindranath V. , Fauve E. , Pflueckhahn D. , Vyawahare S. , Rama B. , Shrishrimal S. , Pucci J. , Robinson D. , Keenan M. , Creel J. , Norton R.
Published: July 2024

SLAC National Accelerator Laboratory has upgraded to LCLS-II, featuring a 4 GeV superconducting linear accelerator composed of 37 cryomodules and two large helium refrigeration systems with a cooling capacity of 4 kW at 2.0 K. The LCLS-II Helium Refrigeration System (HRS) consists of two compressor stations, each with a power of approximately 4.5 MW, two 4.5 K cold boxes, each with a power of 18 kW equivalent at 4.5 K, and two sets of cold compressors that can each produce a flow of 230 g/s at 31 mbar (2.0K). Performance tests of the HRS were meticulously planned and successfully carried out, with results demonstrating that it exceeded the process requirements for LCLS-II operations. This paper provides a detailed presentation of the LCLS-II HRS performance and the challenges encountered during the commissioning phase.
Preliminary studies of the MINERVA cryogenic supply system
Authors: Michel F , Berkowitz Zamora D , Bonne F , Bonthuys G , Millet F , Poncet J M
Published: July 2024

MYRRHA (Multi-purpose hYbrid Research Reactor for High-tech Applications) will be composed of a 600 MeV LINear ACcelerator (LINAC) with a large number of cryomodules and a 100 MW thermal power subcritical nuclear reactor cooled by lead-bismuth. The MINERVA MYRRHA Isotopes productioN coupling the linEar acceleRator to the Versatile proton target fAcility) project is the first phase of the MYRRHA project composed of a 100 MeV, 4 mA continuous-wave proton LINAC. The MINERVA LINAC takes advantage of 60 superconducting radiofrequency (RF) cavities cooled at 2 K by saturated superfluid helium (He II). The MINERVA cryoplant will supply the required cryogenic cooling power of the LINAC through cryogenic lines and cryogenic valve boxes. This paper describes the LINAC cryogenic system supply architecture, the different operating modes, the heat loads, the cryoplant main requirements and the strategy to comply with high reliability requirements. The MINERVA cryoplant shall provide helium flows at 40 K for the thermal shielding, at 5 K for the cooling of the RF couplers and at 2 K for the 60 superconducting cavities installed in 30 cryomodules. The total equivalent refrigeration power of the MINERVA cryoplant is about 3.5 kW at 4.5 K. The cryoplant is composed of a warm compression station including sub-atmospheric volumetric compressors, helium gas storages and a refrigeration cold box with cold centrifugal compressors.
End station refrigerator 2 cryoplant at Jefferson Lab
Authors: Bhattacharya R , Creel J , Perry C , Laverdure N , Yang S , Norton R , Matalevich J , Wijeratne T , Butler C , Wieliczko J , Wissler B , White B , Wilson J , Radovic S , Rath D , Reinhart B
Published: July 2024

The End Station Refrigerator 2 (ESR2) cryoplant will provide cryogens to three of the four experimental halls in support of 12 GeV Continuous Electron Beam Accelerator Facility (CEBAF) experimental demands. In particular, the near-future Measurement of a Lepton-Lepton Electroweak Reaction (MOLLER) experiment requires the additional capacity provided by ESR2. This new cryoplant consists of a 4.0 kW at 4.5-Kelvin cold box and a two-stage compressor system. The cold box and compressor equipment were received from the Superconducting Super Collider (SSC) project and are being refurbished to meet Jefferson Lab’s future operating needs. The ESR2 cryoplant includes a new, 50+ m long cold transfer line, bayonet-can, utility system, and control system. The paper describes the fabrication and installation challenges faced, mitigations adopted, and future work plans for the cryoplant.
The Design and Refurbishment of End Station Refrigerator 2 at JLab
Authors: Perry C , Bhattacharya R , Creel J , Laverdure N , Yang S , Norton R , Matalevich J , Wijeratne T , Butler C , Wieliczko J , Wissler B , White B , Wilson J , Radovic S , Rath D , Reinhart B , Stewart P
Published: July 2024

The future operation of the 4 kW 15 Kelvin MOLLER experiment at Jefferson lab necessitates an increase of cryogenic capacity at the End Station Refrigerator. The current plant is the former 1.5 kW (4.5 K) ESCAR plant that has been operating at Jefferson Lab since 1995. The existing 1.5 kW plant is not able to support the load for MOLLER and will be replaced with a refurbished plant comprised of the cold box and compressors of the 4 kW ASST-A plant from the Superconducting Super Collider in Texas. This paper outlines the assembly, repair and modifications made to the cold box, along with the design of the plant as a whole and its integration into the existing distribution system.
Development of a Portable Stand-Alone 20 K Brayton Cycle Helium Refrigeration System
Authors: Reaves W F , Swanger A M , Gordie R A , Taylor J D
Published: July 2024

From 2012 to 2015, NASA funded development of the Ground Operations Demonstration Unit for Liquid Hydrogen (GODU-LH2) at Kennedy Space Center that scaled up and matured Integrated Refrigeration and Storage (IRAS) technology. IRAS involves the integration of an external helium refrigeration system with a cryogenic storage tank via an internal heat exchanger and allows advanced operations such as zero boiloff and densification of the liquid. The refrigeration system employed for GODU-LH2 was a Linde LR1620 piston-Brayton cycle machine with an RSX helium compressor. The GODU-LH2 system was installed in two separate shipping containers—one housing the cold-box, compressor, and gas management hardware, and the other the water chiller unit—with 480 VAC and 120 VAC electrical power fed from external hardware at the test site, and data capture and controls achieved using four different, independent software packages. From 2017 to 2019, in support of a densified hydrogen loading test program, the entire system was repackaged into a single, 40’ (12 m) shipping container, including the refrigeration system, water chiller, and electrical power distribution hardware, and controls were consolidated into a single Allen Bradley PanelView. Details regarding the design, build-out, and testing of the system will be presented and discussed.
Study of operational modes of cool-down and warm-up processes for the ESS large-scale 20 K helium refrigeration system
Authors: Tatsumoto H , Arnold P , Horvath A , Boros M
Published: July 2024

In the beginning, the European Spallation Source (ESS) will install two hydrogen moderators where the nuclear heating is estimated to be 6.7 kW at 5 MW proton beam power. The ESS cryogenic moderator system (CMS) has the function to circulate a subcooled liquid hydrogen through the moderatos. It is cooled through a heat exchanger by a large-scale 20 K helium refrigeration system with a cooling capacity of 30.3 kW at 15K, which is called Target Moderator Cryoplant (TMCP). The commissioning of the TMCP cold box and the two compressor skids was completed in 2019. Cryogenic transfer lines with a length of 300 m (CTL) and a valve box located next to the CMS cold box were installed during the summer of 2022. In this paper, the TMCP cool-down and warm-up processes have been studied and the operational parameters have been optimized based on the result of the CMS cool-down simulation.
Development of an 18 kW@4.5 K & 4 kW@2 K Helium Refrigerator
Authors: Li J , Zhou G , Liu L Q , Li Z Y , Du J J , Wu J H , Wang J Z , Gong L H
Published: July 2024

An 18 kW@4.5 K & 4 kW@2 K helium refrigerator is being developed in China by the Technical Institute of Physics and Chemistry, CAS. This large-scale helium refrigerator provides different cooling capacity at the 50-75 K, 4.5-75 K and 2 K levels. This helium refrigerator works based on Claude cycle refrigeration process, which uses 5 sets of turbines (10 turbines totally) to bring the temperature down to 4.5 K. Four cold compressors are arranged in series to pump gaseous helium from atmospheric pressure to 0.03 bar in order to decrease the temperature of 2 K helium bath from 4.5 K down to 2 K. A set of subatmospheric pressure compressors is used to compress subatmospheric helium gas downstream from cold compressors to medium pressure 4.05 bar and is connected directly to high pressure compressors. This paper provides an overview on the process design, system design and preliminary component design results in the development of this 18 kW@4.5 K & 4 kW@2 K helium refrigerator.
Acoustic expanders for use in recuperative cryocoolers
Authors: Adams Jacob L. , Brisson J. G.
Published: July 2024

An acoustic expander has been developed for use in recuperative cryocoolers. The acoustic expander uses reed-valves to generate a standing acoustic wave from a continuously expanding flow. The mechanical energy from the wave is passively dissipated to the ambient environment. The acoustic expander does not require complex moving parts or control mechanisms at low-temperature; in contrast to piston- or turbo-expanders that require moving displacers or spinning shafts. This expander has demonstrated isentropic expansion efficiencies of 50% for a pressure ratio of 1.4 and expansion efficiencies of 40% for a pressure ratio of 1.9 with air as the working fluid.
An Experimental Study of the Influence of Cold Head Displacement Speed on Single-Stage Gifford-McMahon Cryocooler System Performance
Authors: Dunn Stephen
Published: July 2024

In positive displacement cryocooler systems, the cooling performance is generally driven by the interaction between the compressor’s displacement and the cold head’s displacement. An experimental investigation explored the relationship between performance and cold end displacement speed for a single-stage gas-driven GM-type cold head operated at different frequencies. As loss mechanisms can be frequency related, the investigation also compared varying the cold end displacement by changing stroke length instead of changing operating frequency. Results showing these relationships are presented, and their impact on seal wear and variable-speed operation are discussed.
High Efficiency Operation of a 4K-Gifford-McMahon Cryocooler without Rotary Valve with a Metal Bellows Compressor
Authors: Höhne J
Published: July 2024

Traditional Gifford-McMahon cryocoolers are operated with an integrated rotary valve which regulates the compressed Helium supply and return into and from the cold head. Theory predicts that about 50% of the input energy is lost in this rotary valve [1]. In this work we removed the rotary valve from a Sumitomo RDK-101G cold head and drove the Gifford-McMahon cryocooler in Stirling-mode directly with a slow-moving metal bellows compressor at around 1.2Hz. We could demonstrate that the energy efficiency of the cryocooler system improves by almost 50%. As a result, we were able to operate this cold head with 650W of total electrical input power with a cooling power of 140mW at 4.2K on the second stage and no-load temperatures of below 40K on the first stage. This corresponds to a COP of 215mW/1000W which one of the highest COPs reached for small and medium size 4K GM and pulse tube cryocoolers.
Performance of a Highly Integrated Micro Linear Stirling Cooler with Active Vibration Cancellation
Authors: Zhang Yibing , Wang Xiaotao , Huang Shengli , Chen Haigang , Long Xiaodan , Cao Haobin , Dai Wei , Li Haibing
Published: July 2024

In order to meet the requirements of weight, vibration, and size in the field of infrared imaging, Lihan Cryogenics has developed a lightweight and compact free-piston Stirling cooler. The cooler weighs 265g and includes a built-in electronic controller and active balancer. The system comprises a gas-bearing moving magnet compressor and a low-temperature rod-less displacer, are arranged in-line to have axial symmetry (SymCoolTM). This is also designed to be IDCA (integrated dewar cooler assembly) optional to meet industry-standard. Furthermore, an active vibration controller is developed to reduce vibration, utilizing an active motor on the same axis as the compressor piston to offset vibrations. The refrigeration performance is experimentally tested under different heat dissipation and cold head working temperatures. The test results show that the cooler acquires 0.5W cooling capacity at 77K with 12.6W power consumption, and the power consumption of the active vibration controller is less than 3W.
Numerical study on heat transfer characteristics of regenerator based on a simplified geometry
Authors: Li Z K , Ding X P , Yu F Q , Chen Y Y , Wang X T , Dai W
Published: July 2024

The heat transfer characteristics of regenerator in regenerative coolers such as pulse tube and Stirling coolers is important. Various methodologies of characterizing the Nusselt number between the regenerator matrix and working fluid have been established and applied. However, most of the existing formulas are based on the study of steady flow or oscillating flow with low pressure ratios at above ambient temperature. In this paper, a tube model with finite wall thickness was constructed to numerically simulate simplified #400 SS mesh and packed HoCu2 sphere, with the aim of investigating the Nusselt number in regenerators under various flow conditions, including different Valensi numbers and temperature ranges. The results provide more evidence to support that within the operating conditions, including Valensi numbers and pressure ratios typically used in coolers, the Nusselt number of oscillating flow and steady flow are similar. Additionally, a heat transfer deterioration effect is observed below 40 K, which is related to the heat capacity ratio between the solid matrix and working fluid. Based on these findings, the study emphasizes the importance of further investigating the heat transfer characteristics of oscillating flow at low temperatures.
Low-temperature photoluminescence measurement with a micromachined Joule-Thomson cooler
Authors: Pei Haiyue , Lu Yihan , Qi Limin , Liu Dongli , Zhao Ding , Qiu Min
Published: July 2024

This study evaluates the effectiveness of micromachined Joule-Thomson (MJT) cooling for photoluminescence (PL) materials. Achieving low temperatures is crucial for enhancing PL performance in semiconductors. However, the commonly used liquid nitrogen (LN2) cryostats require frequent refills, hindering their long-term operation. The MJT cooler offers a potential solution by enabling integration with devices and longer operating time. To validate its effectiveness, this study conducted low-temperature PL measurements using a nitrogen MJT cooler. A MAPbI3 thin film was used as the characterization sample owing to its clear PL mechanism. The experiment successfully preserved its temperature-dependent PL property, with an observed orthorhombic phase-change phenomenon between 155-165 K. Furthermore, the system demonstrated short cool-down time (<1 h), minimal temperature impact from laser stimulus (<±0.1 K), sample storage stability, and low coolant consumption.
Thermal Engineering of the Cryogenic Beam Position Monitors for the EIC Hadron Storage Ring
Authors: Micolon F , Bellon J , Chiechi V , Gassner D M , Hetzel C , Holmes D , Hulsart R , Ptitsyn V , Sangroula M , Verdu-Andres S
Published: July 2024

The Electron Ion Collider (EIC) Hadron Storage Ring (HSR) will reuse most of the existing superconducting magnets from the RHIC storage ring. However, the existing stripline beam position monitors (BPM) used for RHIC will not be compatible with the planned EIC hadron beam parameters that include higher intensity, shorter bunches, and some operational scenarios with large radial offsets of the beam in the vacuum chamber. To address these challenges, the existing RHIC stripline BPMs will be decommissioned, and a new BPM design using button pick-ups integrated in a new vacuum interconnect/bellows assembly will be installed adjacent to the decommissioned BPMs.

A dedicated analysis of the new BPM housing and button pick-up design has been conducted to assess the thermal effects caused by heat conduction, beam induced resistive wall heating and the RF heating from the BPM signal propagation through the cryogenic cables. This paper reports on the thermal design and analysis results to quantify the heat transfer and temperature distribution that can be expected on the new HSR cryogenic BPM.
Observation and analysis of the ultra-rapid cooling effect of cryoprotectant droplets on a sapphire surface
Authors: Zhu Wenxin , Pan Pingan , Huang Yonghua
Published: July 2024

Cryopreservation has emerged as a promising technology to realize semipermanent storage of biomaterials widely used in assisted reproduction and cell therapy. A large portion of successful cryopreservation requires the combination of ultra-rapid cooling and appropriate low-toxicity cryoprotectant agents, which inhibits the formation of ice crystals that damages the cells lethally. Conventional approaches are not competent in accurately capturing high enough cooling rate and more importantly, not able to simultaneously track the instant appearance of the sample at a microscale level during the momentary cooling process. A rapid freezing device for the droplet sample study purpose was designed and developed, which is capable of visualization of the sample on a sapphire surface at a vitrification cooling rate over 104 K/min. The instantaneous temperature changes and the appearance of the cooling samples were recorded at the speed of 10 kHz and 2000 frames. Typical vitrification and crystallization processes were observed and analysed. Low concentrations of the CPA solution inhibited the formation and growth of the crystals, and resulted in the formation of layered ice, punctate ice and scattered small ice. The experimental results could contribute to a better understanding of the ultra-rapid cooling mechanism on cryoprotectant droplets.
Characterization of the thermal properties of OFHC copper at cryogenic temperature
Authors: Valois J J , Nellis G F , Pfotenhauer J M
Published: July 2024

Advancements in electronics technology that operate at cryogenic temperature require the study of thermal properties of the materials and interfaces used to connect these systems to a source of cooling. A test facility has been developed to investigate thermal properties important to these applications, bulk conductivity and contact resistance, over the temperature range from 4 K to 40 K. Bulk conductivity tests were conducted on OFHC copper sourced from three different commercial vendors to determine the degree of variation between the commercial sources and the level of agreement with the values found in literature. Preliminary analysis found RRR values within the range of 50 to 75 for all sources examined. These results are in line with previous studies and confirm the consistency of copper conductivity regardless of the source. The contact resistance tests focus on measuring the variation of contact resistance with applied force over the range from 90 N to 161 N for gold-plated OFHC copper samples with surface roughness in the range of 1 to 2 micrometer. Results from these tests will provide insight into the significance of force on contact resistance. The results from both tests will help guide the design of heat paths in future cryogenic electronic technology.
From high-temperature superconductivity to room-temperature superconductivity: From ambient to high pressure; from very high pressure to ambient again!?
Authors: Deng L. Z. , Wu Z. , Bontke T. , Habamahoro T. , Schulze D. , Gooch M. , Kuo T. W. , Fujikawa R. , Chu C. W.
Published: July 2024

This article will first briefly review the impressive advancements made in high-temperature superconductivity (HTS) before the arrival of room-temperature superconductivity (RTS). Accompanying the advancements made in superconductivity science and technology over the last century, a solid experimental framework concerning the search, development, and even authentication of new discoveries has been established. All these can serve as valuable references in the infancy of RTS research. In this spirit, we will comment on the current status of rare-earth hydride RTS and present our preliminary negative results on Lu-N-H and LK-99, the two most studied materials in the search for RTS in the last few months, although several more reports of negation than affirmation have appeared.
Isolating electrical and cryogen flow for safe operation and design validation experimentation of HTS power cables for electric transportation
Authors: Mensah P , Cheetham P , Pamidi S
Published: July 2024

The need for protecting the cryogenic infrastructure during a fault in high-temperature superconducting (HTS) power distribution systems of electric transport platforms is highlighted. A dual grounding scheme with an isolator between the electrical and cryogen flow paths of HTS power cables is needed. Finite element analysis of the electric field distribution of the vacuum jacketed isolator showed electric field intensity at the triple points. The electric field intensity at the triple points is reasonable if high vacuum quality is maintained. There is a need for further investigations for design validation with experimentation of practical designs for effective isolation and protection of cryogenic infrastructure from damage during an electrical fault in a section of the power distribution network of electrical transport platforms, such as an electric aircraft or ship.
Airplane motors employing superconducting DC field windings and conventional conductor AC windings
Authors: Kalsi S S , Storey J G , Lumsden G , Badcock R A
Published: July 2024

Many organizations are developing compact lightweight highly efficient rotating machines for airplane applications. These machines include permanent magnets for excitation and an iron-core with and without superconducting windings. Air-core (no magnetic iron) machines have the potential to be the most lightweight and efficient. Such machines can use superconductors for both DC excitation field coils and AC armature coils, which need conductors under development, like MgB2 and Bi2212. If liquid-hydrogen (LH2) is available on a plane and can be used as a coolant, it becomes feasible to develop machines with AC armature coils made from conventional conductors like copper, aluminium, and high-conductivity aluminium.

This paper describes conceptual designs for a 3 MW, 4,500 RPM motor employing REBCO CORC conductor for the DC field coils and conventional conductor Litz cable for the AC armature coils cooled by LH2 available on the plane. Both rotor and stator coils are contained in separate cryostats. The DC excitation coils on the rotor are operated at 40 K to work successfully with a brushless flux pump exciter. Likewise, stator AC coils are cooled with available LH2 to take advantage of the lower resistivity of conventional conductors at cryogenic temperatures. Motor size, mass and losses are compared for stator windings employing copper, aluminium, and high-conductivity aluminium (Hyper-Al). Compared with copper and aluminium machines, the machine employing Hyper-Al has smaller size, mass and total losses.
Review of cryogenic power conversion and its potential in future all electric transportation systems: from silicon age to WBG era
Authors: Luo F , Ul Hassan M
Published: July 2024

Cryogenic power electronic conversion (< 123 K) is expected to offer higher efficiencies for future all-electric transportation platforms. Low temperature operation of converters together with integration of wide bandgap devices (WBG) can enable higher switching frequencies with reduced filtering components. This paper briefly reviews the passive components involved in the development of a cryogenic converter. The paper also reviews in detail the converter development with WBG devices by far, and provides a discussion on benefits achieved, and challenges in terms of auxiliary components and measurements. The last part of the paper gives a discussion on envisioned challenges, and different research directions for future superconducting power conversion systems.
Design, fabrication and test of high temperature superconducting magnet for heat flux and radio blackout mitigation experiments in plasma wind tunnels
Authors: Schlachter S I , Drechsler A , Gehring R , Eisele M , Gretschmann F , Hornung F , Westenfelder S , Willms J , Große V , Smara A , Dalban-Canassy M , Behnke A , Herdrich G , Oswald J , Pagan A S. , Helber B , Viladegut A , Lani A
Published: July 2024

High heat flux and radio blackout are well-known challenges space vehicles have been facing during re-entry into a planet’s atmosphere since the early days of space-flight. Thermal protection systems have been developed to protect spacecraft and astronauts, however, they are often heavy and some have to be replaced after each mission. High temperatures in the compressed gas in the shock wave lead to partial ionization. The dense plasma can cause radio blackout, i.e. attenuation or reflection of radio waves thus blocking data-telemetry and communication with ground stations or satellites. One approach to solve both problems is to influence the plasma with magnetohydrodynamic effects using a strong magnet. In the framework of the European project MEESST (Magnetohydrodynamic Enhanced Entry System for Space Transportation) heat flux mitigation and radio blackout mitigation is investigated by means of modelling and ground experiments in plasma wind tunnels at the Institute of Space Systems (Stuttgart, Germany) and at the Von Karman Institute for Fluid Dynamics (Brussels, Belgium) using an HTS magnet. After a short introduction to the scientific background of the MEESST project, the boundary conditions for the design of the magnet and calculations of field distributions are presented. The pancake coils of the magnet were wound with a robotic winding system. Results from a preliminary test of the conduction-cooled magnet are presented.
LTspice Modeling for GaN-GIT HEMT Including Cryogenic Temperature
Authors: Maksudul Hossain Md , Wei Yuqi , Alan Mantooth H.
Published: July 2024

Highly efficient electrically driven avionics have led to a renewed interest in cryogenic propulsion systems with the goal of reducing carbon emission footprint. Although cryogenic converters promise better efficiency and improved power density, the successful design is incumbent upon the appropriate switching device selection and simulation-based analyses prior to initial prototyping. In this work, a datasheet-driven compact model for a gallium nitride (GaN) Gate Injection Transistor (GIT) has been proposed and implemented in LTspice, a versatile, high performance, and free circuit simulator in order to investigate the merit of the chosen device in a power electronic system.
An update on the Colossus mK platform at Fermilab
Authors: Hollister Matthew I , Dhuley Ram C , James Christopher , Tatkowski Grzegorz L
Published: July 2024

As part of the efforts of the Superconducting Quantum Materials and Systems National Quantum Center at Fermilab, we will construct a large millikelvin refrigeration platform known as Colossus. The Colossus platform will be used for quantum computing applications, along with physics and sensing experiments. At the preceding CEC/ICMC meeting in 2021, we reported on the conceptual design of the platform. In the intervening time, the design of the system has been completed and passed through review, with construction now underway. This paper provides an update on the overall design of the system, and the status of and timeline for construction.
Dimensional stability of cryotreated diaphragms of pressure transducers
Authors: Nadig D S , Bharath G J , Mahishi Chandan , Akber Kashif , Suma M N
Published: July 2024

Accurate data of propellant pressures are very critical for the successful propulsion of launch vehicles. These pressures are measured using the integral diaphragm pressure transducers machined from precipitation hardened martensite stainless steel (APX4). The thin diaphragms of these transducers gradually develop dimensional changes with time due to the conversion of residual austenite to martensite, resulting in drift in output pressures. This situation calls for enhancement of dimensional stability of the diaphragms which is carried out by cryotreating them at 98K for 36 hours followed by tempering at 673K for one hour in vacuum furnace. The dimensional studies were carried out on three categories of diaphragm materials viz. normal, cryotreated and cryotreated followed by tempering using the Thermo Mechanical Analyser (TMA). The dimensional changes of the test specimens were determined at intervals of 5K in the temperature range from 123K to room temperature. The results are analysed and presented in this paper.
Multi-channel computational ghost imaging based on multi-scale speckle optimization
Authors: Wang Hong , Wang Xiaoqian , Gao Chao , Wang Yu , Yu Zhuo , Yao Zhihai
Published: July 2024

A multi-channel computational ghost imaging (GI) method based on multi-scale speckle optimization is proposed. We not only reduce imaging time and enhance imaging quality but also reduce interference among different channels. Using one bucket detector to receive total light intensity, the color speckle is formed by combining components obtained through the singular value decomposition of three self-designed multi-scale measurement matrices. Simulation and experimental results demonstrate that our designed method contributes to reducing imaging time and enhancing imaging quality, achieving improved visual quality even at low sampling rates. This approach enhances GI flexibility and holds potential for diverse applications, including target recognition and biomedical imaging.
The Account of the Minimally Good Life
Authors: Hassoun Nicole
Published: July 2024

What, if anything, do we owe others as a basic minimum? Sufficiency theorists claim that we must provide everyone with enough—but, to date, few well-worked out accounts of the sufficiency threshold exist. We need an account of the threshold to decide if we owe people any basic minimum. Previous theories do not provide adequate independent accounts of the resources, capabilities, and/or welfare that might play the requisite role. They often fail to explain what makes the sufficiency level special and how it can arbitrate competing claims. Moreover, I believe existing accounts do not provide nearly enough guidance for policymakers. So, this chapter provides a mechanism for arriving at an account of the minimally good life, and outlines an account, that can help locate the sufficiency threshold.