The effect of Graphene addition on levitation/suspension force of bulk MgB2 superconductor has been studied in both zero field cooling (ZFC) and field cooling (FC) conditions at different temperatures. For this, the pristine, 0.5, 1 and 3 wt% of Graphene added bulk MgB2 samples are prepared by solid state reaction method under argon atmosphere. X-Ray diffraction (XRD) and scanning electron microscopy

To improve the quality of welded joints between copper and 316L stainless steel, laser welding with Ni interlayer was carried out. A sound welded joint was obtained and the microstructures as well as mechanical properties were investigated. Results indicate that no welding defects or spherical particles were formed in the fusion zone. The microstructures in the fusion zone were characterized as dendritic

A typical cryogenic upper stage mission requires a reliable liquid–gas phase separation prior to engine restart in space, and auxiliary engines are usually used to provide positive acceleration effect to satisfy vapor-free liquid supplement purpose. To assist thruster logic design for an upper stage, bubble distribution inside a delivery tube and bubble spilling behaviors should be known previously

The Cold Compressor (CC) is used to lower the saturation temperature of liquid helium (LHe) under varying heat load conditions from the application side, i.e. superconducting magnets and cryopumps for large Tokamak machines. The CC is a key component of a typical cold box, attached to the LHe bath, which compresses and transfers the vapor generated during the heat exchange via heat exchangers as well

Large cooling capacity regenerative cryocoolers working at 20 K is indispensable in developing superconducting technology and hydrogen energy systems. Two-stage Stirling cryocooler is promising for its advantages such as large cooling capacity, high efficiency, fast cool-down process, and compact configuration. A two-stage large cooling capacity Stirling cryocooler is designed and numerically studied

Under disturbances, superconductors may experience sudden, most undesirable phase transitions (quench) from superconducting to normal conducting state. Quench may lead to damage or even to catastrophic conductor failure. A superconductor is stable if it does not quench. By numerical simulations, the paper investigates coupling between superconductor stability and time dependence of phase transitions

We present specific heat measurements in the 2 – 20 K range of several commercially available epoxies (Stycast 1266, Stycast 2850FT, EPO-TEK 377, and EPO-TEK 377H) and mixtures of one of these epoxy binders and fillers such as silica, carbon lamp black, and graphite. The results are briefly described in the context of the Debye model.

Based on the open source software OpenFOAM, a new computational fluid dynamics (CFD) solver is developed for trans/supercritical jets. Considering the real-fluid effects, the pressure Poisson equation is modified using two real-fluid equations of state (EOSs). Turbulent flows of liquid nitrogen jets are studied by different turbulence models based on Reynolds Average Navier-Stokes (RANS) under trans/supercritical

Design and analysis of chill-down operation in LH2 feed lines used for refuelling stations, liquid propulsion tests etc. require an accurate prediction model to capture complex phase change flow and conjugate heat transfer. Although there are reports in the literature for chill down modelling, there is still scope for investigation of accurate constitutive relations for the velocity of sound, heat

We have studied the effects of thallium fluoride TlF3 and yttrium Y3+ on phase formation and superconducting transport properties of Bi1.8−xTlxPb0.35Sr2Ca3−zYzCu4O12+δF3x superconductors. The samples are characterized by X-ray diffraction, SEM photographs, resistivity and AC susceptibility χ′(χ″) measurements. The study showed that the melting point of the sample doped with thallium fluorine and yttrium

Levitation strength provided by high temperature superconductors are limited for device applications. Although superconducting material properties are continuously improving, there is still strong necessity of efficient design mechanisms for the superconducting magnetic levitation systems. Studies in the last decades have shown that combining multi-surface superconductor and permanent magnet components

Cryogenic fluid is frequently used in such fields as cryogenic cooling, food engineering and chemical process, etc. It has been understood in pool quenching experiments that a thin low-thermal-conductive coating layer on the wall can greatly improve the cooling performance, while less is known about the flow quenching. In the present study, the experiments are conducted to investigate cryogenic flow

Sealing performance under cryogenic temperatures should be a consideration in the development of a cryogenic valve for use in cryogenic engineering. In the present work, a cryogen-free leak detection system at 20 K to conduct leakage testing of cryogenic valves was developed. The experimental system was composed of a cooling system, a leak detection system, and a PLC (Programmable Logic Controller)

Ground-based observatories across a wide range of wavelengths implement cryogenic cooling techniques to increase the sensitivity of instruments and enable low temperature detector technologies. Commercial pulse tube cryocoolers (PTCs) are frequently used to provide 40 K and 4 K stages as thermal shells in scientific instruments. However, PTC operation is dependent on gravity, giving rise to changes

Five 166.6 MHz beta = 1 quarter-wave resonator (QWR) superconducting cavities (SC) have been chosen for the High Energy Photon Source (HEPS), a 6 GeV kilometer-scale diffraction-limited storage light source to be built in Beijing suburb. Each cavity is equipped with one high power input coupler to deliver over 180 kW RF power in continuous mode (cw). Overheating and the result in excessive heat load

Prototypical cryocooler regenerators were assembled with several common regenerator filler materials and were tested under periodic helium flow at room and cryogenic temperatures. The mass flow and pressure drop data were analysed to determine the friction factor, Darcy Permeability and Forchheimer coefficients. The results are compared to previous investigations, and the relevance of room-temperature

Future long-duration crewed and robotic missions will require efficient methods with which to transfer cryogenic propellant from a depot storage tank to a customer receiver tank in the microgravity of space. Because unsettled cryogenic liquid cannot be transferred in microgravity with the vent valve open, the receiver tank must be pre-chilled to some “target temperature” that is sufficiently cold to

Active vibration control has been devised to suppress the vibration of spacecraft coolers. Although active control is effective in suppressing vibration, it may affect the cooler’s performance. In this paper, the effect of a control signal on the cooling performance of a two-stage Stirling cooler is quantitatively evaluated for the first time by comparing the effect of the added control signal with

Suppression of gas oscillation is essential to realize the stable operation of the cryogenic helium piping systems. In the current study, a structural solution, that is, a tube is connected to the main pipe as an adjustment accessory to control unfavourable gas oscillations. The model with dual temperature gradients is developed by introducing an adjustment tube. The effects of the parameter sensitive

In order to explore the potential advantages of HTS maglev vehicles, the dynamic response of HTS maglev vehicle-bridge coupling system model under different speeds and track beam spans is calculated by using Universal Mechanism (UM) software, which is further compared with two existing high-speed train systems, the high-speed EMS vehicle and wheel-rail vehicle. Before establishing the dynamic model

In this paper, we report on the quantitative characteristics of the DC current transport property of a superconducting bismuth strontium calcium copper oxide (BSCCO) stator winding that is used in a superconducting motor. The winding is in a slot of silicon steel core, and the DC voltage of such a winding is measured as a function of the transport current in atmospheric liquid nitrogen. Precise distribution

Flow boiling experimental data for liquid hydrogen (LH2), liquid methane (LCH4), and liquid oxygen (LO2) were compiled. The collected data represent saturated nucleate/forced convective evaporation boiling (pre-CHF), and film/dispersed droplet boiling (post-CHF). For LH2, pre-CHF data were compiled from six sources, and post-CHF data were compiled from 12 sources. Useful pre-CHF boiling data for LCH4

As an insertion device, the superconducting wiggler has been developed for about 40 years, the superconducting magnet of which is usually made of NbTi and set in a cryostat. The performance of the cryostat is vital to the success of the superconducting wiggler. In this paper, a cryostat of the superconducting wiggler with 32 poles and 2.6 T field for the High Energy Photon Source Test Facility (HEPS-TF)

The 4K Joule-Thomson (JT) cryocooler is a key cryogenic component for future astronomy missions such as ATHENA and LiteBIRD. It was originally developed for SMILES (2009) and upgraded for ASTRO-H/SXS (2016) and SPICA. The 20K two-stage Stirling cryocooler developed for AKARI (2006) was also upgraded and used as a precooler. The operational life is a critical factor in planning long-term missions. An

Cavitation is a severe problem in rocket turbopumps. As for turbopumps with liquid oxygen, it exhibits notable thermodynamic effects during cavitation, leading to complex flow characteristic. In this study, to assess the influence of thermodynamic effects on the cavitation flow in a liquid oxygen turbopump, the entire flow passage was numerically simulated using the shear stress transport k–ω turbulence

Bending tolerance is one of the most fundamental mechanical properties of REBCO coated conductors for application to a superconducting coil. In this study, we investigated critical current degradation of REBCO coated conductors under bending and uniaxial tensile strain at 77 K and self-field with three different kinds of production from SuperPower Inc, Suzhou Advanced Materials Research Institute (SAMRI)

Cryogenic air separation plants produce pressurized oxygen gas at 150 bar and 99.8% purity to fill oxygen cylinders directly. It is either produced by compression in oxygen compressor (external compression) or pumping and vaporizing liquid oxygen in main heat exchanger by incoming air (internal compression). Small and medium-scale plants differ in the types of main heat exchanger, compression and expansion

The image quality in a MRI magnet greatly depends on the mechanical, thermal and electromagnetic performance of the thermal shield in presence of any time varying field. A detailed analysis on the mechanical resonance frequency, temperature distribution and the eddy current distribution on a thermal shield of a zero-boil-off cryostat for 1.5T MRI magnet system is presented. Five combination of aluminum

This paper presents the modeling results of a pressure-controlled tank-to-manifold propellant cross-feed system for liquid rockets. A transient dynamic model has been developed based on the bond graph theory using AMESim software, and the predicted pressure and flow rate histories are in good agreement with experimental data. The simulation results indicate that the pressure-controlled tank-to-manifold

The axial heat leakage between the cold and hot ends of the regenerator caused by the huge temperature difference is an important part of the cryocooler loss, where the apparent thermal conductivity of regenerator materials is the key parameter that determines the heat leakage. At present, only the apparent thermal conductivity of stainless steel wire mesh, lead and copper sphere above 80 K can be

Optimal energy management is a major challenge for most energy storage systems (ESSs), which is especially a big concern for the superconducting fault current limiter-magnetic ESS (SFCL-MES). To prevent malfunction, the superconducting coil (SC) current of the SFCL-MES needs to be controlled strictly within a well-defined operational range. To optimally utilize the energy capability of the ESS while

The cryogenic thermal conductivity of high-strength 7050 aluminum alloy subjected to the processes with different combinations of solution, aging and deep cryogenic treatment, was measured by a one-dimensional steady-state thermal conduction method. The microstructure evolution of this alloy after different treatments was also characterized to investigate the changes in thermal conductivity. The results

Experimental investigations of two variants of a high pressure ratio cryogenic turboexpander, from a new series of turboexpanders for Bhabha Atomic Research Centre (BARC), are presented in the article. Both the variants are designed based on an earlier reported enhanced midstream method. The new turboexpanders are designed with larger turbine impeller-diffuser radial clearances and smaller turbine

In this study, the effect of multi-walled carbon nanotube doping to MgB2 compound on microhardness properties of MgB2 was investigated by using solid-state reaction method. The amount of multi-walled carbon nanotubes was chosen as 0, 1, 2, 3 and 4% by weight of total MgB2. All samples were obtained by sintered at 650 °C temperatures. The microhardness properties of the samples obtained were examined

We developed a soft and high thermal conductive thermal link for cryogenic applications. The measured maximum thermal conductivity was approximately 18500 W/m/K at 10 K. This spring constant was 1/43 of that of a single thick wire with the same cross-sectional area at room temperature. We reached these performances by utilizing high purity aluminum (99.9999%, 6 N) and by stranding many thin wires that

Large-scale cryogenic refrigeration equipment is the sole way to realize the cryogenic environment for scientific facilities such as space technology, quantum computer and magnetic levitation. As one of the key moving components in cryogenic system, the helium compressor determines the reliability and performance of the whole cryogenic system. The twin screw compressor is a promising choice to be used

Oxygen sensors play a vital role in ensuring the safety of employees and users at the National High Magnetic Field Laboratory. While most oxygen sensors have accurate and linear responses in nitrogen/argon environments, studies have highlighted a phenomenon in helium-air mixtures with certain types of oxygen sensors. A controlled experiment was performed to observe the behavior of two types of oxygen

In this study, six cubic equations of state (CEoSs) were used to predict the Joule-Thomson coefficient (JTC), specific heat capacity (SHC), inversion curve (IC) and outlet temperature of the Joule-Thomson (JT) valve parameters. The accuracy of each CEoS was evaluated from the comparison of experimental data with obtained results. Of the six CEoSs, three-paramter CEoSs— Esmaeilzadeh and Roshanfekr (ER)

Submerged combustion vaporizer (SCV) is widely used as a device to vaporize liquefied natural gas (LNG) stored in cryogenic state, which is effective in peak shaving and emergency response in LNG vaporization stations and receiving terminals. In this paper, a heat transfer calculation model of SCV based on numerical calculation is established and its accuracy is verified by a practical case. Based

Radial force (radial stiffness) is an important performance index of radial HTS magnetic bearing. However, it is difficult to calculate it due to the complexity and particularity of the structure. It is of great significance to establish an effective and convenient method to predict the radial force of radial bearing. In this paper, the moving mesh of COMSOL Multiphysics® software is introduced into

A Dewar is the key structure of motors with high temperature superconducting (HTS) armature windings. Traditional Dewars use total immersion cooling, which can cause additional mechanical losses and challenges for rotary sealing. To avoid these problems, a novel Dewar structure was developed with partial immersion cooling. A 15 kW cryogenic induction motor with the designed Dewar was then developed

This paper conducts systematic theoretical analyses of a hybrid cryocooler composed of a four-stage Stirling-type pulse tube cryocooler (SPTC) and a Joule-Thomson cooler (JTC), in which the former provides the necessary precooling powers to the latter which aims at reaching a temperature of 1.0 K. The structural design of the hybrid cryocooler is described and its working mechanism focused on. Both

Magnetization AC loss measurements of singe- and seven-core Ba122/Ag tapes have been done by calibration-free method in the range of temperature from 20 K to 42 K and field magnitudes up to 70 mT in RMS with two frequencies 72 Hz and 144 Hz. A strong effect of eddy current losses in highly conductive Ag sheath was observed for single-core sample, but negligible for seven-core tape with more resistive

In cryogenic conditions, a Pulsating heat pipe (PHP) can be used to transport a high heat flux across a relatively small temperature difference. Using empirical techniques to design such a PHP is unreliable due to the shortage of experimental dataset available for cryogenic operation. A numerical model developed for cryogenic temperatures and compared with experiments conducted at those temperatures

The experimental data accessible in the open literature related to pool boiling of liquid hydrogen (LH2), liquid methane (LCH4), and liquid oxygen (LO2) were compiled. Pool nucleate boiling of LH2 data were compiled from 17 sources, and pool film boiling of LH2 data were compiled from six sources. Pool nucleate boiling of LCH4 data were collected from eight sources, and useful data for pool film boiling

With the rapid development of aerodynamics for high speed aircraft, the flight experiments need to be carried out under ultra-high Reynolds number condition to simulate actual high-speed flight conditions, which puts forward higher requirements for the wind tunnel. Reynolds number increases rapidly as the decrease of the flow temperature because the viscosity of the working gas decreases and the density

The cooling systems of High-Temperature Superconducting (HTS) power transmission cables are unable to achieve the desired performance as prescribed in the cryogenic road map. Reverse Brayton cycle based Cryocooler (RBC) has been identified as a refrigerator that has the potential to achieve the desired performance for higher cooling load demand. In this article, an exergy analysis of the basic Reverse

This study evaluates the thermal expansion coefficient, as well as the elastic-, plastic- and fracture behaviour, at ambient and cryogenic (liquid nitrogen) temperatures, of four different epoxy systems that are used in high-field superconducting magnets, with the emphasis on rate-dependent plasticity as measured by uniaxial compression testing. As expected, both the elastic and plastic behaviour of

Spiral wound heat exchanger has compact structure, good thermal performance per volume and simple manufacture process. It is the key equipment for the superfluid helium cryogenic system, which is able to recover the cold capacity and improve the refrigeration effectiveness. To investigate the influence of fins structure on the thermal performance of spiral wound heat exchanger is essential for its

In this paper, a type of mutual inductance sensor based on the PCB technology is proposed for cryogenic radial displacement measurement. Firstly, the feasibility of the scheme is analyzed from the aspects of the low temperature usability of materials and components, and the temperature sensitivity of the sensor. Then the experiments at low temperature (77 K) and room temperature are carried out with

The measurements of self-fields and voltages for the stacked tapes assembled in rigid structure (STARS) conductor were carried out when the conductor immersed in liquid nitrogen was energized. In the measurements, a 3 m straight line shaped STARS conductor, which is composed of 45 REBCO tapes (15 tapes × 3 rows) embedded in a copper stabilizer, was used as a conductor sample. The measurement results

Helium has the lowest boiling point of any element in nature at normal atmospheric pressure. Therefore, any unwanted substance like impurities present in liquid helium will be frozen and will be in solid form. Even if these solid impurities can be easily eliminated by filtering, liquid helium may contain a non-negligible quantity of molecular hydrogen. These traces of molecular hydrogen are the causes

Abstract The purpose of this study was to investigate a parameterized mathematical approach for estimating the complex modulus of a polyimide film at extreme cryogenic temperatures (e.g. 4 K). Such films are used in extreme cryogenic applications such as superconducting magnets and electronic devices. A polymer core of the electronic laminate, Pyralux AP8525R (polyimide), was tested on a TA Instruments

Abstract Mechanical applications for polymers at cryogenic temperatures are extremely limited due to decreased atomic mobility and ductility, resulting from glass transitions above the cryogenic regime (

Remote Sensing Satellites use IR (Infra-Red) detectors for imaging in 1 um to 15 um bands. Most of these detectors are operated at cryogenic temperatures to extract the low-level signal from the background noise. Stirling cycle based miniature active linear cryocoolers are now being widely used for cooling these IR detectors to cryogenic temperatures. The Cryocooler Control Electronics (CCE) used for

Superconducting magnet is a key component in magnetic resonance imaging (MRI). In general, vacuum pressure impregnation (VPI) technology is used for insulating system of the superconducting magnet. Performance of the superconducting magnets is affected by the adhesion strength between superconducting wires and resins at cryogenic temperature. In this study, experimental superconducting coil was prepared

Experimental results on the electrical and thermal characteristics of GdBCO racetrack coils co-wound with stainless steel (SS) tapes of various thicknesses and winding tensions are presented in this paper. The SS thickness and winding tension are identified as the factors affecting the charging time and thermal stability of metal insulation (MI) coils. To verify these characteristics, three types of

Magneto-thermal properties and magnetocaloric effect of ErFe2 have been studied. Molecular field theory has been applied on ErFe2 to calculate the magnetization and the magnetic contribution to the heat capacity and entropy. Our calculation shows that ErFe2 is a ferrimagnetic compound with a compensation temperature of around 475 K and a Curie temperature of 596 K. Applying magnetic field to ErFe2

Cryogenic system working at 2 K is crucial for superconducting accelerator. A 70 W@2 K cryogenic system was developed for the testing of superconducting cavities used in the China Initiative Accelerator Driven System (CiADS). There will be more than 257 superconducting radio frequency (SRF) cavities to be vertically tested in the next three years. The system is designed with 2 testing dewars and the