Cryogenic Bath Research Articles

Development of a novel and useful methodology for the simultaneous analysis of multiclass contaminants in bovine fat.

The instrumental development of tandem mass spectrometers fosters the actual trend in the trace analysis of organic compounds to the development of methods that allow the analysis of contaminants of the most diverse origin in a single analytical sample. The multiclass methods are aligned with the Who's One Health initiative while accomplishing the concepts of green chemistry. However, there are few reports of wide scope multiclass methods for the analysis of contaminants in this matrix. In this work, a method for the simultaneous determination of 62 compounds in bovine fat, was developed and validated following DG-SANTE/11813/2021 guidance. Liquid nitrogen milled fat was extracted with toluene and acetonitrile. Then a clean-up in a cryogenic bath, followed by dispersive solid phase extraction was performed. Residue determination was done using liquid chromatography for 44 compounds and gas chromatography for 18 compounds, both coupled to tandem mass spectrometry in MRM mode. The method was first developed and validated for two ectoparasiticides, then the scope was expanded for the analysis of 13 veterinary drugs and 49 pesticides. Recovery percentages were in the range of 60-134%, high matrix effect was observed in 50% of the scope of the method. Most compounds presented limits of quantification of 10 μg kg-1 in compliance with international requirements. The method was applied to monitor 49 commercial samples to evaluate its performance. Eighty percent of samples contained ethion and 10% had fluazuron, both within MRLs, highlighting the need for proper withdrawal times.

A protocol for accurately calibrating thermocouples at cryogenic temperatures

To study the quenching characteristics of materials in a cryogenic liquid bath transient temperature measurements of high accuracy are necessary. Thermocouple is an ideal tool for this application because of its low self-heat capacity. However, they require calibration before usage that require multiple fixed-point temperatures. The common fixed-point temperatures are the water-ice melting temperature, the dry ice sublimation temperature, and the boiling temperature of liquid nitrogen. It is important to note that there are uncertainties associated with dry ice sublimation and liquid nitrogen boiling temperature inherent to the heat and mass transport phenomenon at their phase-changing interface or inside the bulk medium. The dry ice temperature is influenced by the mass transport phenomenon occurring at the interface between the dry ice and the ambient surrounding it. In a typical lab environment, dry ice temperature is significantly lower than the commonly quoted sublimation temperature of -78.5 °C at 1.013 bar. In the case of liquid nitrogen stored in a cryostat, temperature gradients develop in the liquid bath. This paper describes a protocol for calibrating thermocouples by accurately defining and using fixed-point temperatures of dry ice in a saturated environment and a liquid nitrogen slush.

Fabrication of lightweight ceramics of complex geometries in freezing weather

Natural freezing weather is used to fabricate lightweight ceramic monoliths with aligned pores for the first time. A stable aqueous-based alumina slurry (16 vol%) was formulated and frozen at −10 to −25 °C in natural freezing environment. The thermally treated ceramic monoliths achieved ∼82–88 vol% porosity with short-range aligned pores. Finally, the unidirectional pores in the structure are achieved using a mold with thermal insulation properties. Natural freezing saves 300 kJ of energy per kg of alumina slurry. Mechanically stable lightweight porous ceramics with complex geometries can be designed without cryogenic fluids, refrigeration, or thermal baths. Implementing natural freezing in the porous ceramics industries, particularly in the Arctic region, will bring forward a sustainable approach by reducing energy consumption and CO2 emissions.

Design and test of a DCT curved superconducting dipole magnet for ion-therapy

A curved superconducting dipole magnet based on Discrete Canted-Cosine-Theta (DCT) coil with magnetic field of 2.9 T, bend radius of 0.8 m, and bend angle of 90° for next- generation of compact ion-therapy treatment facility has been designed and tested. The curved dipole is comprised of eight layers of DCT coils embedded in the formers wound with NbTi wires, featuring compact ends and higher excitation efficiency. This paper presented the main mechanical structure design, analysis, and measurements of the curved DCT magnet. Based on the finite element method (FEM) model with ANSYS, a detailed analysis of the DCT magnet mechanical behavior during cool-down and excitation has been studied. Finally, the magnetic field and strain measurements are measured from a cryogenic test bath cooled with liquid helium, during which the magnet reached 70% of the expected goal. The reason for magnet failure based on the strain measurement results is also reported in this paper.

Structure Design and Test of a Fast Ramp Multilayer Canted Cosine Theta (CCT) Magnet

A fast ramp superconducting dipole magnet based on the Canted-Cosine-Theta (CCT) type coil with a magnetic field of 2 T, ramping rate of 3 T/s and a bore diameter of 60 mm has been designed for the compact synchrotron. The fast ramp magnet is comprised of four-layers of CCT coils embedded in the formers with high efficiency cooling channel and layer by layer pre-tightening structure to ensure structural reliability and thermal stability. This paper presented the main mechanical structure de-sign, analyze and measurements of the fast ramp CCT magnet. Based on the finite element method (FEM) model with ANSYS, a detailed analysis of the CCT magnet mechanical behavior during cool-down and excitation has been studied. Finally, the magnetic field and strain measurements are measured from a cryogenic test bath cooled with liquid helium, during which the magnet reached the expected goal. Comparisons of the strain measurements with 3D finite element model results are also reported in this paper.

The effect of cryogenic machining of S2 glass fibre composite on the hole form and dimensional tolerances

S2 glass fibre reinforced epoxy composites are widely used in aeronautical applications owing to their excellent strength to weight ratio. Drilling glass fibres can be cumbersome due to their abrasive nature and poor thermal conductivity. Moreover, the use of conventional coolants is not desirable due to contamination and additional costs for cleaning the machine part. An alternative is to use environmentally friendly coolants such as liquid nitrogen (LN2) which have been previously employed in machining metals and composites. The current study investigates the effect of drilling S2 glass fibre composite in a bath of LN2. The study aims to evaluate the effect of spindle speed, feed rate and the presence of cryogenic cooling on the form and dimensional tolerances of the hole (hole size, circularity, cylindricity and perpendicularity). Design of experiments and analysis of variance (ANOVA) were used to determine the contribution of the input parameters on the analysed hole quality metrics. Results indicated that drilling S2 glass fibre in a cryogenic bath increased hole size significantly beyond the nominal hole diameter. The hole circularity and cylindricity were reduced compared to holes drilled under dry condition under all cutting parameters due to enhanced thermal stability during the drilling process. The current study aims to provide the scientific and industrial communities with the necessary knowledge on whether cryogenic bath cooling strategy provides better hole quality output compared to dry drilling and other cryogenic cooling strategies which were previously reported in the open literature.

Microstructural investigation and hole quality evaluation in S2/FM94 glass-fibre composites under dry and cryogenic conditions

S2/FM94 glass fibre reinforced epoxy is an aerospace-grade composite currently bonded with aluminium alloys and installed in parts of the Airbus A380 fuselage. In addition to its abrasive and hard nature, S2/FM94 glass fibre is sensitive to thermal effects developed during the drilling process, and therefore using coolants becomes necessary. However, conventional oil and water-based coolants are not suitable for drilling of composites. Cryogenic coolants on the other hand are an attractive choice for machining composites and are environmentally friendly. In this study, a new environmentally friendly cryogenic cooling technique in a liquid nitrogen bath was used for the drilling of S2/FM94 glass fibre reinforced epoxy composite. The aim was to investigate the effect of drilling parameters and cryogenic cooling on cutting forces, surface roughness, hardness and delamination factor at hole entry and exit sides. The workpiece was drilled within a cryogenic bath. In this way, both cryogenic workpiece cooling and tool cooling were obtained. In addition, the drill geometry is fixed and only the cutting parameters (i.e. spindle speed and the feed rate) are varied under dry and cryogenic conditions. The results indicate that the spindle speed and cryogenic cooling had the most significant influence on the cutting forces and surface roughness parameters (Ra and Rz), while the use of cryogenic cooling had the most significant influence on increasing the hardness and size of delamination at entry and exit sides of the holes.

Temperature Effect on Yb-Doped Silica Fiber Laser Performance

The operation of the Ytterbium (Yb)-doped silica fiber laser is investigated under high temperature gradients generated by various cryogenic materials. A continuous-wave (CW) double-clad single-mode fiber laser working at 1082.51 nm with a linewidth (FWHM) of 0.16 nm and an average power of 10 W was used to study the effect of cooling rate on its output characteristics such as signal power, efficiency, central wavelength and spectral bandwidth. The cooling process is performed along the gain fiber using a cryogenic bath, while the cryo-coolants don't touch other laser components such as fiber Bragg gratings (FBGs), combiners and optical couplers. A series of rigorous experiments are carried out at room temperature - RT (22.5 °C) and cryo-states when the gain fiber is immersed in different coolants i.e., dry-ice ethylene-glycol - DIEG slurry (-29 °C), dry-ice debris (-58 °C) and liquid nitrogen - LN2 (-189.2 °C) with various pump powers ranging 2.9 - 16.5 W. The gain fiber of 10 m long demonstrates a 36 % power efficiency at LN2 against 66.4 % at RT. The signal power as well as the laser efficiency linearly reduces with temperature drop as to the linewidth undergoes a lucid spectral narrowing accompanying blue shift, mainly owing to the notable temperature response of the absorption / emission cross-section, broadening mechanisms and thermal population as well as energy level schemes, including sublevel and hyperfine structures of the transition accordingly.

Cryo-EM structures from sub-nl volumes using pin-printing and jet vitrification

The increasing demand for cryo-electron microscopy (cryo-EM) reveals drawbacks in current sample preparation protocols, such as sample waste and lack of reproducibility. Here, we present several technical developments that provide efficient sample preparation for cryo-EM studies. Pin printing substantially reduces sample waste by depositing only a sub-nanoliter volume of sample on the carrier surface. Sample evaporation is mitigated by dewpoint control feedback loops. The deposited sample is vitrified by jets of cryogen followed by submersion into a cryogen bath. Because the cryogen jets cool the sample from the center, premounted autogrids can be used and loaded directly into automated cryo-EMs. We integrated these steps into a single device, named VitroJet. The device’s performance was validated by resolving four standard proteins (apoferritin, GroEL, worm hemoglobin, beta-galactosidase) to ~3 Å resolution using a 200-kV electron microscope. The VitroJet offers a promising solution for improved automated sample preparation in cryo-EM studies.

Self-propulsion of inverse Leidenfrost drops on a cryogenic bath

When deposited on a hot bath, volatile drops are observed to stay in levitation: the so-called Leidenfrost effect. Here, we discuss drop dynamics in an inverse Leidenfrost situation where room-temperature drops are deposited on a liquid-nitrogen pool and levitate on a vapor film generated by evaporation of the bath. In the seconds following deposition, we observe that the droplets start to glide on the bath along a straight path, only disrupted by elastic bouncing close to the edges of the container. Initially at rest, these self-propelled drops accelerate within a few seconds and reach velocities on the order of a few centimeters per second before slowing down on a longer time scale. They remain self-propelled as long as they are sitting on the bath, even after freezing and cooling down to liquid-nitrogen temperature. We experimentally investigate the parameters that affect liquid motion and propose a model, based on the experimentally and numerically observed (stable) symmetry breaking within the vapor film that supports the drop. When the film thickness and the cooling dynamics of the drops are also modeled, the variations of the drop velocities can be accurately reproduced.

Friction setup and real-time insights of the contact under controlled cold environment: The KŌRI tribometer for rubber-ice contact application.

A friction setup combining real-time ice-rubber contact visualization, force measurement, and a compact controlled cold environment system was developed in order to investigate ice-rubber contact complex tribological response and the various contributions to friction, such as viscoelastic deformation, ice surface melting, adhesion, ice creep, or quasi-liquid layer effect. The cold system was based on a cryogenic bath circulator, an air convection circuit, and several thermal insulation combinations such as silica aerogel and expanded polystyrene. The KŌRI tribometer allows one to reach negative temperatures until -20 °C and to perform tribological experiments for velocity from 50 μm s-1 to 1 m s-1 under load up to 50 N and to simultaneously measure resultant forces until 30 N and visualize the contact in real-time. In parallel, an ice manufacturing unit and a specific protocol were developed to grow a transparent ice disc with a controlled initial roughness and surface state. Real-time and simultaneous visualization of the ice-rubber contact provides additional data, such as the apparent contact area and the mean size of a real contact spot during friction, after adequate and dedicated image processing. To illustrate the capability of the KŌRI tribometer, rubber-ice friction measurements were performed at -10 °C and the results are presented here, as a function of time and velocity.

Probing heat generation during tensile plastic deformation of a bulk metallic glass at cryogenic temperature

Despite significant research efforts, the deformation and failure mechanisms of metallic glasses remain not well understood. In the absence of periodic structure, these materials typically deform in highly localized, thin shear bands at ambient and low temperatures. This process usually leads to an abrupt fracture, hindering their wider use in structural applications. The dynamics and temperature effects on the formation and operation of those shear bands have been the focus of long-standing debate. Here, we use a new experimental approach based on localized boiling of liquid nitrogen by the heat generated in the shear bands to monitor the tensile plastic deformation of a bulk metallic glass submerged in a cryogenic bath. With the “nitrogen bubbles heat sensor”, we could capture the heat dissipation along the primary shear banding plane and follow the dynamics of the shear band operation. The observation of nitrogen boiling on the surface of the deforming metallic glass gives direct evidence of temperature increase in the shear bands, even at cryogenic temperatures. An acceleration in bubble nucleation towards the end of the apparent plastic deformation suggests a change from steady-state to runaway shear and premonitions the fracture, allowing us to resolve the sequence of deformation and failure events.

Comparison of cryogenic low-pass filters.

Low-temperature electronic transport measurements with high energy resolution require both effective low-pass filtering of high-frequency input noise and an optimized thermalization of the electronic system of the experiment. In recent years, elaborate filter designs have been developed for cryogenic low-level measurements, driven by the growing interest in fundamental quantum-physical phenomena at energy scales corresponding to temperatures in the few millikelvin regime. However, a single filter concept is often insufficient to thermalize the electronic system to the cryogenic bath and eliminate spurious high frequency noise. Moreover, the available concepts often provide inadequate filtering to operate at temperatures below 10 mK, which are routinely available now in dilution cryogenic systems. Herein we provide a comprehensive analysis of commonly used filter types, introduce a novel compact filter type based on ferrite compounds optimized for the frequency range above 20 GHz, and develop an improved filtering scheme providing adaptable broad-band low-pass characteristic for cryogenic low-level and quantum measurement applications at temperatures down to few millikelvin.

Thin-Layer Insulation of HTS: Analytical Study

The aim of this paper is to take into account the thin layer of insulation of a superconducting tape or a superconducting coil to calculate heat transfer during a quench. The main problem is that this thin layer is very difficult to mesh in finite-element method. In this paper, we propose a modified factor of the convection coefficient obtained due to an analytical solution of the heat equation. The aim of this modification is to take into account the thickness of the resin, which bands a thin coil, or a superconducting tape immersed in cryogenic bath. Introducing this modified factor leads to a significant simplification of the 3-D thermal study because the diffusion in the resin is taken into account due to the modifying factor.

Experimental investigation on sub-miliKelvin temperature control at liquid hydrogen temperatures

Temperature control around 20K with a tolerance of better than 1 mili-Kelvin is challenging but essential for applications like cooling deuterium/tritium target in fusion ignition experiments. To explore the practicability of cryogenic temperature control on this level with a cryocooler as the cold source instead of a cryogen bath, experimental investigations were conducted to approach the best performance by optimizing configurations of effective measures. A special heat sink was fabricated and attached to the second-stage cold head of a G-M cryocooler which could reach temperatures down to 2.5K and provide 13W cooling power at 18K. A thermal reservoir and/or temperature transmission damping were incorporated, as well as a manganin resistance wire electrical heater attached to the heat sink. Experimental results show that an optimal stability of the temperature of the shielded heat sink within±0.4 mK at 20K was achieved by choosing proper excitation for the sensors, control mode for the heater and capacity for the thermal reservoir.

Optimization of the TES-Bias Circuit for a Multiplexed Microcalorimeter Array

A transition-edge-sensor (TES) microcalorimeter’s shunt resistor (Rsh) and thermal conductance to the cryogenic bath (G) are often considered to be interchangeable knobs with which to control detector speed. Indeed, for otherwise-identical TES-parameter models, there are many combinations of Rsh and G that give the same decay time-constant (τcrit). However, our previous work showed that with time- or code-division-multiplexed readout, the distribution of signal-to-noise ratio with frequency, which depends strongly on Rsh and G, is just as important as τcrit. Here, we present a set of calculations to select the optimal values of Rsh and G, given a linear TES model and count-rate and energy-resolution requirements. Lower G and lower Rsh make multiplexing easier. Our calculations also determine the allowed combination of SQUID-readout noise (SΦ) and multiplexer row-period (trow) and row-count (Nrows). Recent improvements to SΦ and trow in the NIST time-division-multiplexing architecture have allowed a NIST eight-pixel TES array to be read out with 2.70 eV (full-width at half-maximum) average energy resolution at 6 keV. The improvements make the X-ray Microcalorimeter Spectrometer co-proposed by NASA and NIST for ESA’s Athena X-ray observatory straightforwardly achievable, including engineering margin, with Nrows=16.

Gas-phase chemiluminescence with ozone oxidation for the determination of total tin in environmental samples using flow injection hydride generation and cryotrapping

The gas-phase chemiluminescence detection system based on the ozonization of gaseous hydride was exploited and utilized for the determination of total tin in environmental samples. After sample treatment, tin was reduced to stannane by sodium borohydride in a phosphate buffer medium of pH 5.8. Flow injection technique was used to control the reaction precisely and reproducibly. The generated stannane, carried by helium, was separated from liquid and dried using an ice-salt cryogenic bath and subsequently trapped in a glass U-tube immersed in liquid nitrogen. The cryotrapped stannane was vaporized by bringing the tube to room temperature and subsequently carried in a flow of helium to a reaction chamber where ozone was used to oxidize the stannane. Chemiluminescence was produced during the oxidation process, which was utilized for the measurement of tin. Under optimal conditions, a detection limit of 0.32 μg L −1 was achieved with a relative standard deviation of 3.1% (10.0 μg L −1 Sn, n = 11). Interferences from transition metal ions and other hydride forming elements were reduced by the addition of 1,10-phenanthroline and through optimized hydride generation conditions. The proposed system was applied to the determination of Sn in water and soil samples with satisfactory results.

Determination of antimony in environment samples by gas phase chemiluminescence detection following flow injection hydride generation and cryotrapping

A novel method for the determination of antimony in environmental samples was developed with gas phase chemiluminescence detection following flow injection hydride generation and cryotrapping. The stibine, generated from samples by borohydride reduction of antimony using flow injection technique, was separated by using a new gas-liquid separator, dried with an ice-salt cryogenic bath and concentrated in a glass U-tube immersed in liquid nitrogen. Re-vaporization of stibine based on its boiling point was achieved by allowing the tube to warm at room temperature. A gas phase chemiluminescence signal was produced during the ozonation of the hydride in a reflective chamber. Under optimal conditions, the proposed method was characterized by a wide linear calibration range from 1.0microgL(-1) to 10.0mgL(-1) with a detection limit of 0.18microgL(-1) (n=11). The relative standard deviation for 10.0microgL(-1) antimony was 3.56% (n=11) and the sampling rate was 15 samples h(-1). Blank signal was reduced by the purification of reagents and the interference from transition metal ions was eliminated by the addition of L-cysteine into samples. The method was applied to the determination of antimony in environmental samples with satisfactory results.

The effects of mechanical and thermal perturbations on states within the hysteresis of sorption isotherms of mesoporous materials

We investigate thermodynamic states inside the hysteresis in the adsorption–desorption isotherms of mesoporous materials by perturbing the adsorbate at a point inside the loop. Scanning curves were run to points inside the hysteresis loop and then the system was perturbed by both mechanical and thermal means. Mechanical perturbations were performed by placing a speaker inside the cryogenic bath to expose the system to vibrations. Thermal disturbances were performed by changing the temperature bath ±10 K and back or by removing the bath for 30–60 s. We find that vibrations up to 500 kHz have no substantial effect on the quantity adsorbed for states that lie within the loop. On the other hand, thermal shocks do affect the system and the states inside the hysteresis loop are found to be unstable with respect to this sort of perturbation. The final state after the sample is returned to its original temperature bath depends on whether the temperature had been raised or lowered during the shock. For increases in temperature, the adsorbed state shifts onto the adsorption branch of the hysteresis; for decreases in temperature, the state shifts onto the desorption branch.

Apparatus for measuring physical adsorption on intact supported porous membranes

We present a non-destructive, reusable apparatus with which to measure physical adsorption isotherms of intact porous membranes. We developed a two-piece sample container to make reliable sorption measurements of porous membranes, the properties of which may differ from those of powders due to crystal intergrowth. This novel system employs a resealable container that can be immersed in a cryogenic bath, into which tubular, planar, or other porous membranes and films may be placed. Detailed sorption isotherms, including high-resolution adsorption in the low pressure (micropore-filling) region, are shown for MFI-type zeolite membranes grown on two types and configurations of α-alumina support.