Cryogenic Storage Research Articles

Unimolecular processes in diatomic carbon anions at high rotational excitation

On the millisecond to second time scale, stored beams of diatomic carbon anions C2− from a sputter ion source feature unimolecular decay of yet unexplained origin by electron emission and fragmentation. To account for the magnitude and time dependence of the experimental rates, levels with high rotational and vibrational excitation are modeled for the lowest electronic states of C2−, also including the lowest quartet potential. Energies, spontaneous radiative decay rates (including spin-forbidden quartet-level decay), and tunneling dissociation rates are determined for a large number of highly excited C2− levels and their population in sputter-type ion sources is considered. For the quartet levels, the stability against autodetachment is addressed and recently calculated rates of rotationally assisted autodetachment are applied. Nonadiabatic vibrational autodetachment rates of high vibrational levels in the doublet C2− ground potential are also calculated. The results are combined to model the experimental unimolecular decay signals. Comparison of the modeled to the experimental rates measured at the cryogenic storage ring facility CSR gives strong evidence that C2− ions in quasistable levels of the quartet electronic states are the so far unidentified source of unimolecular decay. Published by the American Physical Society 2024

Cellular resiliency and survival of Neuro-2a cells under extreme stress

Stressors such as hypoxia, hypothermia, and acute toxicity often result in widespread cell death. This study investigated the outcomes of Neuro-2a (N2a; mouse neuroblastoma) cells following a cryogenic storage failure that exposed them to a combination of these stressors over a period of approximately 24-30 hours. Remarkably, a small fraction of the cells survived the event, underwent a period of dormancy, and eventually recovered to a healthy state. To understand the underlying resilience mechanisms, we created a model to replicate the dewar failure event and examined changes in phenotype, transcriptomics, proteomics, and mitochondrial activity of the surviving cells during recovery. We found that the surviving cells initially displayed a stressed morphology with irregular membranes and a clustered apperance. They showed an increased expression of proteins related to DNA repair and chromatin modification pathways as well as heightened mitochondrial function shortly after the stress event. As recovery progressed, the stress-responsive pathways, mitochondrial activity, and growth rates normalized toward that of healthy controls, indicating a return to a stable baseline state. These findings suggest that an initial robust energetic state supports key stress-responsive and repair pathways at the early stages of recovery, facilitating cell survival and resiliency after extreme stress. This work provides valuable insights into cellular resilience mechanisms with potential implications for improving cell preservation and recovery in biomedical applications and developing therapeutic strategies for conditions involving cell damage and stress.

Multi-objective optimization of airfoils with integral tubular high-pressure tanks for hydrogen storage

Reducing the environmental impact of air transport is one of today's most important challenges in aviation industry and research. A promising key enabler is the use of hydrogen as an alternative to fossil fuels. The development of hydrogen-powered aircraft poses new engineering challenges due to its low volumetric energy density requiring high-pressure or cryogenic storage. If the volume in the wing shall be further used for storing hydrogen under high pressure, new demands arise to airfoil design. The present work focuses on this issue by presenting a multi-objective optimization approach aiming for airfoils with both low drag and high volume for internal tubular high-pressure tanks. This allows to directly address the new design objective and to find novel airfoil shapes providing the best compromise between aerodynamic efficiency and high storage volume for pressurized hydrogen. The resulting optimization problem is solved using Evolutionary Algorithms. For an efficient aerodynamic evaluation, the open source viscous-inviscid panel method XFOIL is used. An application example, based on the flight conditions of a general aviation aircraft, demonstrates the applicability of the method. Comparisons of the resulting aerodynamic characteristics obtained by XFOIL with RANS simulations confirm the feasibility of the results.

Numerical analysis of sloshing effects in cryogenic liquefied-hydrogen storage tanks for trains under various vibration conditions

This study examines the effects of hydrogen sloshing on internal pressure, temperature, and fluid behavior liquefied-hydrogen storage tanks designed for train usage by applying the natural frequency and frequency conditions from train vibration test standards. Notably, it investigates the impact on BOG generation using a transient volume-of-fluid phase change model. Here, simulations were conducted at vibrations of 0, 0.53, 1.53, and 3 Hz, which were established using sine wave acceleration. The results demonstrated that sloshing increased with higher frequencies, thereby resulting in a more intense heat transfer between the wall of the tanks and free surface of hydrogen and an increase in the BOG generation. Compared to the 0 Hz baseline, BOG generation increased by 13, 44, and 66 % at 0.53, 1.53, and 3 Hz, respectively.

Microstructure and mechanical properties of 9 % nickel steel welded joints using a CoCrNi filler wire for cryogenic storage tanks

A medium-entropy alloy of CoCrNi exhibits excellent cryogenic mechanical properties. It is possible to enhance the ductility of weld metal for cryogenic storage tank materials at cryogenic temperatures by employing CoCrNi alloys as filler metal. In this study, a CoCrNi multi-principal filler wire and a 308L stainless steel wire were used for welding 9 % Ni steel. The effects of the CoCrNi filler wire on the microstructure, hardness, mechanical properties, and deformation mechanisms of the weld metals were evaluated and discussed. A remarkable finding was that as the tensile temperature decreased from 298 K to 77 K, the fracture elongation of the CoCrNi joint increased by approximately 34.7 %, rather than decreasing. In contrast, a significant reduction in fracture elongation was observed in the 308L joint. The CoCrNi filler wire could promote the activation of twinning deformation in the weld metal at 77 K, thereby enhancing the ductility of the welded joints at cryogenic temperatures.

Extracellular filaments revealed by affinity capture cryo-electron tomography.

Cryogenic-electron tomography (cryo-ET) has provided an unprecedented glimpse into the nanoscale architecture of cells by combining cryogenic preservation of biological structures with electron tomography. Micropatterning of extracellular matrix proteins is increasingly used as a method to prepare adherent cell types for cryo-ET as it promotes optimal positioning of cells and subcellular regions of interest for vitrification, cryo-focused ion beam (cryo-FIB) milling, and data acquisition. Here we demonstrate a micropatterning workflow for capturing minimally adherent cell types, human T-cells and Jurkat cells, for cryo-FIB and cryo-ET. Our affinity capture system facilitated the nanoscale imaging of Jurkat cells, revealing extracellular filamentous structures. It improved workflow efficiency by consistently producing grids with a sufficient number of well positioned cells for an entire cryo-FIB session. Affinity capture can be extended to facilitate high resolution imaging of other adherent and non-adherent cell types with cryo-ET.

DEVELOPMENT OF SCIENTIFIC FOUNDATIONS AND METHOD OF AUTONOMOUS POWER AND GAS SUPPLY OF REMOTE CONSUMERS FROM GAS DISTRIBUTION NETWORKS

The development and implementation of independent power supply systems with a high degree of autonomy is becoming an urgent task for the development of remote and inaccessible regions of the country, both due to the lack of energy capacities and accessible networks in newly developed areas, and the high cost of allocating separate power lines for remote and compact settlements. The increase in the scale of central networks is associated with high capital investments and long project implementation time, which creates inconvenience for consumers and the development of small and medium-sized enterprises. At the same time, unlike power supply, gasification issues, which are actively being resolved in all regions of the country, make it possible to connect new consumers of natural gas several times faster and cheaper, which is due to the high manufacturability and speed of construction of polyethylene gas pipelines of distribution networks, provided that gas pipelines pass in the region. In addition to lower capital and operating costs, the process of transporting energy resources through pipelines in the form of a primary source — gas — is characterized by significantly lower losses compared to water and electricity. At the same time, network gas in combination with trigeneration technologies and cryogenic hydrocarbon storage can be used not only as boiler fuel, but also as motor fuel, a source for generating electricity, heat and even cold with a replenished autonomous reserve. Thus, as an alternative solution to traditional power systems, it is proposed to use hybrid power systems — systems based on trigeneration plants with gas piston installations, turbine and screw machines, as well as cryogenic gas storage facilities that can provide the population with electricity, heat, cold and motor fuel. The article analyzed the state and development of the fuel and energy complex in Russia, conducted a study of the needs for heat, gas and electricity for an average compact settlement with small and medium-sized enterprises. Analysis and selection of equipment parameters for uninterrupted autonomous power supply of the economy was carried out.

Investigating Taconis oscillations in a U-shaped tube with hydrogen and helium

Taconis oscillations are thermally induced spontaneous excitations of acoustic modes in tubes subjected to large temperature gradients. Cryogenic systems that experience these excitations suffer from increased heat leak and vibrations. This heat leak may also increase boil-off in long-term storage vessels for liquid hydrogen. In this study, U-shaped closed-end tubes with a cold mid-section are experimentally investigated to quantify the oscillation characteristics for hydrogen- and helium-filled systems at various mean pressures, including supercritical hydrogen states. Experimental measurements of the temperature distribution along the tube and acoustic pressure amplitudes and frequencies are taken in constant- and variable-diameter configurations near the onset of oscillations. Thirty different conditions are recorded with mean pressures ranging from 126 kPa to 1127 kPa for helium and 161 kPa to 1816 kPa for hydrogen. A low-amplitude thermoacoustic model is applied to predict the cold temperature and frequency corresponding to the onset of Taconis oscillations. The findings of this study indicate that Taconis oscillations in systems with hydrogen occur at smaller temperature differences than in more traditional helium systems by approximately 10 K. Hydrogen in the constant-diameter configuration excited when cryogenic temperatures reached 35–40 K, whereas helium excited when cryogenic temperatures reached 20–30 K. Special tubing networks, such as wider segments in the warm portion, can drastically elevate the excitation cold temperature resulting in onset temperatures between 50–60 K for both fluids. Taconis oscillations are also found to exist in conditions when liquid hydrogen starts forming in the cold zone of the system, as well as in supercritical states. The presented measurements are useful for designing cryogenic hydrogen storage systems to control these oscillations.

Assessment of the performance of implementation of renewable energy facilities with the prospect of hydrogen production using the example of southern Russia

Adopting experience and best practices for stimulating the development of RES in individual regions that most successfully implement RES-based installations into their energy balance is a necessary element in the development of the energy sector of disadvantaged regions, while a methodology is needed to determine what factors influenced the success of implementation and what criteria should be used to compare and to determine the success of the implementation of RES in the region, however, a generally accepted methodology has not been formed to date. It was proposed to determine the leading regions and disadvantaged regions from the point of view of success in introducing renewable energy sources into the regional energy system based on the success of fulfilling the regional demand. To assess the success of the use and implementation of installations based on renewable energy in the regional energy system, it is necessary to identify parameters that reflect the potential of renewable energy sources, the initial state of energy supply in the region, the costs of construction of the installation, the profit received from the sale of generated energy, and the current state of the regional energy system. Based on the developed technique, the six most energy-intensive regions included in the operating area of the Southern Branch of United Dispatch Control Center of Russian Power System Operator which have renewable energy power plants were analyzed. The chosen indicator was the share of energy resources generated from renewable energy sources in the total amount of energy resources. Based on the results of the analysis, recommendations were drawn for disadvantaged regions. Energy donation for disadvantaged areas is proposed through the production of a universal energy carrier - hydrogen - in prosperous areas. For energy storage, hydrogen cryogenic storage facilities have been considered promising. The standard cryogenic hydrogen tank RSV-1400 was adopted as part of the main element of the hydrogen storage facility. The capacity of such tanks is 1 000 000 L. To transport energy to consumers, the possibilities of transporting hydrogen by cryogenic tankers and hydrogen transport tanks have been considered.In addition, at present there is a fairly large scientific, technical and practical base for the creation of gas and cryogenic liquid hydrogen pipelines.

Dissociative recombination of rotationally cold ArH+

We have experimentally studied dissociative recombination (DR) of electronically and vibrationally relaxed ArH+ in its lowest rotational levels, using an electron-ion merged-beams setup at the Cryogenic Storage Ring. We report measurements for the merged-beams rate coefficient of ArH+ and compare it to published experimental and theoretical results. In addition, by measuring the kinetic energy released to the DR fragments, we have determined the internal state of the DR products after dissociation. At low collision energies, we find that the atomic products are in their respective ground states, which are only accessible via nonadiabatic couplings to neutral Rydberg states. Published theoretical results for ArH+ have not included this DR pathway. From our measurements, we have also derived a kinetic temperature rate coefficient for use in astrochemical models. Published by the American Physical Society 2024

Reinforcement Twinning: From digital twins to model-based reinforcement learning

The concept of digital twins promises to revolutionize engineering by offering new avenues for optimization, control, and predictive maintenance. We propose a novel framework for simultaneously training the digital twin of an engineering system and an associated control agent. The training of the twin combines methods from adjoint-based data assimilation and system identification, while the training of the control agent combines model-based optimal control and model-free reinforcement learning. The training of the control agent is achieved by letting it evolve independently along two paths: one driven by a model-based optimal control and another driven by reinforcement learning. The virtual environment offered by the digital twin is used as a playground for confrontation and indirect interaction. This interaction occurs as an “expert demonstrator”, where the best policy is selected for the interaction with the real environment and “cloned” to the other if the independent training stagnates. We refer to this framework as Reinforcement Twinning (RT). The framework is tested on three vastly different engineering systems and control tasks, namely (1) the control of a wind turbine subject to time-varying wind speed, (2) the trajectory control of flapping-wing micro air vehicles (FWMAVs) subject to wind gusts, and (3) the mitigation of thermal loads in the management of cryogenic storage tanks. The test cases are implemented using simplified models for which the ground truth on the closure law is available. The results show that the adjoint-based training of the digital twin is remarkably sample-efficient and completed within a few iterations. Concerning the control agent training, the results show that the model-based and the model-free control training benefit from the learning experience and the complementary learning approach of each other. The encouraging results open the path towards implementing the RT framework on real systems.

Enhanced magnetocaloric and cold storage properties in HoCu2-xNix (x=0.05–0.5) compounds for hydrogen liquefaction

Based on first-principle calculations and experiments, the electronic structure, magnetism, magnetocaloric effect and cold storage properties of HoCu2-xNix (x=0.05–0.5) compounds have been investigated. The theoretical calculations revealed that the magnetic interactions of the HoCu2-xNix compounds were gradually transformed to ferromagnetic states when the Ni element was added above 0.0625. In addition, the Ni element leads to a decreasing Fermi energy level, which results in a significant enhancement of orbital hybridization around the Fermi surface, which may be responsible for the magnetic jump. The magnetic phase transition temperatures of the HoCu1.75Ni0.25 and HoCu1.5Ni0.5 compounds are 14.4 K and 26.0 K, respectively. The ferromagnetic state transition is responsible for the excellent magnetocaloric effect of the HoCu2-xNix compounds under low magnetic fields. The maximum magnetic entropy changes of the HoCu1.75Ni0.25 and HoCu1.5Ni0.5 compounds were 14.7 J/kg K and 11.5 J/kg under varying magnetic fields from 0 to 2 T. In addition, the Ni element make the HoCu2 compound exhibit more excellent cold storage capability. The peak of specific heat capacities of HoCu1.75Ni0.25 and HoCu1.5Ni0.5 compounds were 0.6 J/cm−3K−1 and 0.9 J/cm−3K−1 under 0 T. The present results indicate that HoCu2-xNix (x=0.05–0.5) compounds have promising applications in cryogenic cold storage and magnetic refrigeration.

Trehalose, Glycerol and Dimethyl Sulfoxide Supplementation for Cryopreservation Media of Honey Bee Drone Semen

The cryogenic storage of honey bee drone (Apis mellifera) semen is a rapidly developing practice, driven by the need to preserve bee colonies and the decline in gamete quality following cryopreservation. Advances in cryobiology, coupled with procedural refinements and the development of new methods for cryopreservation of male gametes at different temperatures, provide promising results for improving drone semen preservation. Innovative strategies involve the incorporation of additives within preservation media to enhance important spermatozoa parameters. Our study aimed to assess the effectiveness of cryoprotectants (CPAs), namely trehalose, glycerol, and dimethyl sulfoxide (DMSO), on the motion characteristics of honey bee drone sperm cells during cryopreservation and subsequent thawing. Using Sperm Class Analyzer (SCA) and Computer-Assisted Sperm Analysis (CASA), we evaluated the impact of these supplements on sperm motility and kinetic parameters. Our findings indicated significant differences in sperm motility (non-progressiveness and progressiveness) and kinetics (curvilinear velocity and linearity) across treatments with trehalose, DMSO, and glycerol. Trehalose supplementation retained significantly higher percentages of sperm motility and kinetic parameters post-cryopreservation compared to DMSO and glycerol. Nevertheless, despite the utilization of new protocols, media, and supplementation, the results obtained are often unsatisfactory. The research provides valuable information for enhancing the efficacy of cryopreservation media to optimize the successful outcome of honey bee drone spermatozoa storage.

Coupled modeling and simulation of tank self-pressurization and thermal stratification

Numerical analysis of thermo-fluid dynamics for cryogenic propellant storage primarily consists of nodal and computational fluid dynamics (CFD) modeling approaches. While nodal approaches prioritize faster computation over fidelity, CFD approaches promise accuracy and fidelity at the expense of significant computational resources. This paper presents an efficient coupling methodology developed to facilitate the simulation of a long-term self-pressurization process of a cryogenic propellant tank as well as associated thermal stratification phenomenon under both normal and reduced gravity conditions. Key highlight of the methodology is the development of a coupling scheme based on a domain decomposition approach that separates the tank into two computational regions at the liquid-vapor interface. SINDA/FLUINT, the nodal code, is utilized to simulate the liquid region, while ANSYS Fluent, the CFD code, handles the vapor region. A data exchange algorithm was developed to compute required boundary conditions for each region using the local thermodynamic properties of assumed infinitely thin interface. The coupling between the nodal and CFD codes was demonstrated by simulating a self-pressurization process in a small size tank using hydrogen as the working fluid. A sensitivity study on the grid sizing and coupling time step was conducted to determine appropriate spatial and ensure a divergent-free explicit data exchange time step size. Using the coupling approach, two numerical case studies were performed to study tank self-pressurization by considering two initial hydrogen fill levels. The effectiveness and efficiency of the coupling methodology was assessed by comparing the temperature and pressure evolution results of the coupled simulation with those obtained solely from the CFD simulation. Results showed that the coupling scheme and data exchange algorithm were successfully implemented, and the coupled simulation agreed well with the CFD simulations. In addition, a stratification number was used to characterize the transient dynamic development of the thermal stratification. Lastly, the computational costs associated with both approaches were compared. Significant reductions in simulation time were achieved for both cases.

Research on the temperature control of a cryogenic urine storage system based on improved adaptive LADRC

Abstract Routine urine tests play a vital role in the diagnosis of kidney and urinary system diseases, with test outcomes directly affecting disease diagnosis. However, if urine is exposed to room temperature for extended periods, it may lead to rapid degradation of the sample, thus affecting the accuracy of the test. Therefore, for urine that requires long-term storage for testing, it is necessary to control the temperature within an appropriate range during the collection process to effectively preserve the activity of urinary proteins and ensure the reliability of the test. To address this issue, a cryogenic urine storage system was developed, and a fuzzy LADRC temperature control algorithm combined with a Smith predictor was proposed, specifically designed for optimizing the temperature stability during urine collection and storage processes. Initially, the characteristics of the cryogenic storage system were analyzed. A simulation model combining the fuzzy LADRC with a Smith predictor was built using the MATLAB/Simulink simulation toolkit, and a comparative simulation was conducted. The simulation results showed that the proposed algorithm significantly improved the time-domain response performance compared to PID control, verifying the superiority of the algorithm over PID control. The final experimental results demonstrated that the fuzzy LADRC temperature control algorithm with the Smith predictor essentially eliminated overshoot, with improvements in speed and stability compared to PID control.

Fungal cryopreservation across 61 genera: Practical application and method evaluation

ABSTRACT Fungi occupy important environmental, cultural, and socioeconomic roles. However, biological research of this diverse kingdom has lagged behind that of other phylogenetic groups. This is partially the result of the notorious difficulty in culturing a diverse array of filamentous fungal species due to their (i) often unpredictable growth, (ii) unknown preferences for culturing conditions, and (iii) long incubation times compared with other microorganisms such as bacteria and yeasts. Given the complexity associated with concurrently culturing diverse fungal species, developing practical methods for preserving as many species as possible for future research is vital. The widely accepted best practice for preserving fungal tissue is the use of cryogenic biobanking at −165 C, allowing for the preservation and documentation of stable genetic lineages, thus enabling long-term diversity-centered research. Despite the extensive literature on fungal cryopreservation, substantial barriers remain for implementation of cryogenic biobanks in smaller mycological laboratories. In this work, we present practical considerations for the establishment of a fungal culture biobank, as well as provide evidence for the viability of 61 fungal genera in cryogenic storage. By providing a pragmatic methodology for cryogenically preserving and managing many filamentous fungi, we show that creating a biobank can be economical for independently owned and operated mycology laboratories, which can serve as a long-term resource for biodiversity, conservation, and strain maintenance.

Thermodynamic modelling of low fill levels in cryogenic storage tanks for application to liquid hydrogen maritime transport

One of the key challenges in transporting liquid hydrogen (LH2) in bulk onboard carriers is the requirement for high performance insulation to reduce the heat transfer and cargo boil-off losses. After unloading their cargo, carriers on the return voyage may retain a small amount of liquid (heel) to keep tanks relatively cold, as well as to chill down to the tanks prior to cargo loading. Therefore, there is an aim to reduce net heat transfer into the tank while minimising the required volume of heel. While practices are relatively mature in the liquefied natural gas (LNG) industry, it is not clear how this may differ for future LH2 carriage. In this study, a new analytical, lumped-mass model was proposed to predict vapour stratification and tank warm-up. A 40,000 m3 double-walled LH2 spherical tank was considered with vacuum perlite and polyurethane foam (PUF) insulation, and the effects of tank pressurisation and fill level on cumulative heat gain were investigated. The model pointed to key differences between the two insulation types. Heat gain in the vacuum perlite tank was not predicted to be sensitive to changes in fill level, while heat gain in PUF tank was predicted to be less sensitive to pressurisation. In each case, pressurisation was predicted to enable reductions in heel boil-off which offset any associated increase in cumulative heat gain. In comparing LNG and LH2, the model pointed to a slower thermal response of the LH2 tanks. Consequently, the increase in inner shell temperature was not expected to lead to significant reductions in environmental heat transfer into the tank. The findings of this study point to potential operational differences in the management of LNG and LH2 heel during the ballast voyage as well as considerations for vacuum insulated tanks.

Advancing Hydrogen Sensing for Sustainable Aviation: A Metal Hydride Coated TFBG Optical Fibre Hydrogen Sensor

The aviation industry is undergoing a significant shift toward sustainability, with hydrogen emerging as a promising green fuel to reduce carbon emissions due to its high gravimetric energy density and clean combustion exhaust compared to traditional aviation fuels. However, realizing hydrogen's aviation potential requires advanced sensors to ensure safety and efficiency in challenging environments, particularly for monitoring hydrogen near high-temperature engines and cryogenic storage tanks. Fibre optic sensors offer an exceptional advantage in these demanding conditions due to their capacity to operate in harsh environments, their small size, immunity to electromagnetic interference, spark-free operation, and remote sensing capabilities. Metal hydrides are prominent sensing materials studied for hydrogen sensing, especially palladium (Pd). Nonetheless, existing literature pertaining to Pd-coated fiber optic sensors for hydrogen detection has brought to light concerns regarding response hysteresis, stability, and linearity of Pd hydrogen sensors, calling for innovative solutions. In response to these challenges, our research introduces an innovative fibre optic hydrogen sensor, introducing tantalum (Ta) based metal hydrides as the sensing material. The sensor's construction involved the deposition of a nanometer-thick Ta thin film onto the surface of a tilted fibre Bragg grating (TFBG) using a magnetron sputtering technique. The sensing mechanism relies on the modulation of optical constants of the Ta thin film in response to even minute hydrogen concentrations, culminating in spectral changes in the transmission spectrum of the TFBG. In this proof of concept work, changes in both amplitude and the centre wavelength of cladding resonances of the TFBG transmission spectrum were observed in the hydrogen concentration range from 0.01% to 4% at room temperature. These initial findings underscore the substantial potential of our approach in developing highly sensitive and robust fibre-optic hydrogen sensors tailored specifically for hydrogen-powered aviation.

Research on effective thermal conductivity of hollow glass microspheres under vacuum at low temperature

As insulation materials with excellent thermal insulation properties, high robustness, and low maintenance costs, hollow glass microspheres (HGM) are gradually being applied in large liquid hydrogen storage tanks. However, the low-temperature insulation mechanism of HGMs is still unknown, and the insulation effect of HGMs of different types under various conditions has been neglected in recent decades. In this study, an existing theoretical model was improved by considering the gas thermal conductivity equations under various pressure intervals, and an experimental platform was built based on the steady vertical heat flux method to measure the effective thermal conductivities of three commercially available HGM models. The effective thermal conductivities of HGM models K1, T15, and HL20 at 0.1 Pa were 10, 8.9, and 7.6 mW/(m·K), respectively. The values decreased to 2.5, 2.9, and 2.0 mW/(m·K), respectively, when the cold boundary temperature was 90 K. To analyse the effect of the HGM physical parameters and environment on the HGM insulation, the thermal conductivities were calculated using the derived theoretical model. It was found that continuing to reduce the pressure after the ambient pressure reached 10 Pa hardly improved the insulation performances of the HGMs. The radiative heat transfer was very sensitive to temperature changes and jointly dominated the heat transfer with integrated thermal conductivity in the low-temperature region. In summary, HGMs are advanced vacuum-insensitive insulation materials, which have great potential in the field of cryogenic liquid storage and transportation.

Merged-Beams Study of the Reaction of Cold HD+ with C Atoms Reveals a Pronounced Intramolecular Kinetic Isotope Effect

We present a merged-beams study of reactions between HD+ ions, stored in the Cryogenic Storage Ring (CSR), and laser-produced ground-term C atoms. The molecular ions are stored for up to 20 s in the extreme vacuum of the CSR, where they have time to relax radiatively until they reach their vibrational ground state (within 0.5 s of storage) and rotational states with J≤3 (after 5 s). We combine our experimental studies with quasiclassical trajectory calculations based on two reactive potential energy surfaces. In contrast to previous studies with internally excited H2+ and D2+ ions, our results reveal a pronounced isotope effect, favoring the production of CH+ over CD+ across all collision energies, and a significant increase in the absolute rate coefficient of the reaction. Our experimental results agree well with our theoretical calculations for vibrationally relaxed HD+ ions in their lowest rotational states. Published by the American Physical Society 2024