Pub Date : 2026-01-29DOI: 10.1016/j.cryogenics.2026.104296
Takashi Hirayama , Yutaro Koike
In regenerative cryocoolers, the regenerator is composed of stacked layers of the regenerator material in the form of wire meshes or spheres, and the voids of the regenerator are filled with a working fluid, such as helium gas. Widespread experiments have been carried out in the temperature range above room temperature on the friction factor which indicates flow resistance generated by the working gas as it passes through the regenerator. However, it remains unclear whether these experimental formulae are still valid in the cryogenic temperature range in which GM cryocoolers operate, where experimental uncertainty can become significant. Therefore, a new system was developed to measure the friction factor at cryogenic temperatures. The developed system was used to measure the friction factor in zinc spheres which are a typical regenerator material. The measurements revealed that the friction factor varied at cryogenic temperatures compared with that at room temperature. This variation was attributed to changes in the porosity within the regenerator. This paper describes the details of the developed system and the results of the experiments. These results provide necessary verification for applying room-temperature correlations to cryogenic regenerators.
{"title":"Experimental observation of friction factor variation in regenerators at cryogenic temperatures","authors":"Takashi Hirayama , Yutaro Koike","doi":"10.1016/j.cryogenics.2026.104296","DOIUrl":"10.1016/j.cryogenics.2026.104296","url":null,"abstract":"<div><div>In regenerative cryocoolers, the regenerator is composed of stacked layers of the regenerator material in the form of wire meshes or spheres, and the voids of the regenerator are filled with a working fluid, such as helium gas. Widespread experiments have been carried out in the temperature range above room temperature on the friction factor which indicates flow resistance generated by the working gas as it passes through the regenerator. However, it remains unclear whether these experimental formulae are still valid in the cryogenic temperature range in which GM cryocoolers operate, where experimental uncertainty can become significant. Therefore, a new system was developed to measure the friction factor at cryogenic temperatures. The developed system was used to measure the friction factor in zinc spheres which are a typical regenerator material. The measurements revealed that the friction factor varied at cryogenic temperatures compared with that at room temperature. This variation was attributed to changes in the porosity within the regenerator. This paper describes the details of the developed system and the results of the experiments. These results provide necessary verification for applying room-temperature correlations to cryogenic regenerators.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"156 ","pages":"Article 104296"},"PeriodicalIF":2.1,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146098544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-22DOI: 10.1016/j.cryogenics.2026.104294
Wenting Wu , Wang Yin , Hejun Hui , Kongkuai Ying , Zhenhua Jiang , Yinong Wu , Shaoshuai Liu
A two-stage Stirling-type pulse tube cryocooler (SPTC) can not only provide a cryogenic environment in the liquid hydrogen temperature region for space exploration payloads, but also serves as a precooler to supply pre-stage cooling for Joule-Thomson (JT) cryocoolers. The development of space exploration technology has placed higher requirements on two-stage SPTCs. One of the reasons limiting the performance improvement of two-stage SPTCs is the low regenerator efficiency at low temperatures. Selecting appropriate regenerator materials and filling schemes is an important means to improve the regenerator efficiency. In this paper, the regenerator efficiency of the second regenerator and the cooling performance of two-stage SPTCs with magnetic materials were investigated by simulations and experiments. Simulation results indicate that although magnetic materials lead to higher pressure drop loss, the irreversible heat transfer loss in the regenerator is significantly reduced due to the use of magnetic materials, and the irreversible heat transfer loss with Er3Ni is lower than that with HoCu2. When the cooling temperature is 15 K, the proportion of irreversible heat transfer loss in the cold-end PV power with Er3Ni and HoCu2 are 36.42% and 42.59%, respectively. Subsequently, a test platform for a thermal-coupled two-stage SPTC was built to test the influence of Er3Ni and HoCu2 on the cooling performance in the 10–30 K temperature range. According to experimental results, the cryocooler achieves a no-load temperature of 9.04 K when Er3Ni is used as the regenerator material, which is lower than the 10.40 K no-load temperature obtained with HoCu2. Cooling capacities obtained with Er3Ni and HoCu2 are 0.70 W and 0.57 W when the cooling temperature is 15 K; and the cooling capacities at 30 K are 2.79 W and 2.76 W, respectively.
{"title":"Comparison of hybrid Er3Ni/stainless steel screen with HoCu2/stainless steel screen in pulse tube cryocooler as regenerator materials","authors":"Wenting Wu , Wang Yin , Hejun Hui , Kongkuai Ying , Zhenhua Jiang , Yinong Wu , Shaoshuai Liu","doi":"10.1016/j.cryogenics.2026.104294","DOIUrl":"10.1016/j.cryogenics.2026.104294","url":null,"abstract":"<div><div>A two-stage Stirling-type pulse tube cryocooler (SPTC) can not only provide a cryogenic environment in the liquid hydrogen temperature region for space exploration payloads, but also serves as a precooler to supply pre-stage cooling for Joule-Thomson (JT) cryocoolers. The development of space exploration technology has placed higher requirements on two-stage SPTCs. One of the reasons limiting the performance improvement of two-stage SPTCs is the low regenerator efficiency at low temperatures. Selecting appropriate regenerator materials and filling schemes is an important means to improve the regenerator efficiency. In this paper, the regenerator efficiency of the second regenerator and the cooling performance of two-stage SPTCs with magnetic materials were investigated by simulations and experiments. Simulation results indicate that although magnetic materials lead to higher pressure drop loss, the irreversible heat transfer loss in the regenerator is significantly reduced due to the use of magnetic materials, and the irreversible heat transfer loss with Er<sub>3</sub>Ni is lower than that with HoCu<sub>2</sub>. When the cooling temperature is 15 K, the proportion of irreversible heat transfer loss in the cold-end PV power with Er<sub>3</sub>Ni and HoCu<sub>2</sub> are 36.42% and 42.59%, respectively. Subsequently, a test platform for a thermal-coupled two-stage SPTC was built to test the influence of Er<sub>3</sub>Ni and HoCu<sub>2</sub> on the cooling performance in the 10–30 K temperature range. According to experimental results, the cryocooler achieves a no-load temperature of 9.04 K when Er<sub>3</sub>Ni is used as the regenerator material, which is lower than the 10.40 K no-load temperature obtained with HoCu<sub>2</sub>. Cooling capacities obtained with Er<sub>3</sub>Ni and HoCu<sub>2</sub> are 0.70 W and 0.57 W when the cooling temperature is 15 K; and the cooling capacities at 30 K are 2.79 W and 2.76 W, respectively.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"155 ","pages":"Article 104294"},"PeriodicalIF":2.1,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146024420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Based on nitrogen adsorption isotherms at 77 K, this study develops a one-dimensional convolutional neural network (1D-CNN) model to predict the hydrogen adsorption capacity of porous carbons. A dataset comprising 859 adsorption data points from 116 porous carbon structures was constructed. The model achieved a high predictive accuracy, with a coefficient of determination (R2) of 0.9511 on the test set. Using synthetic isotherms generated via the Langmuir equation, optimal structural parameters were identified, revealing that porous carbons with parameters a = 100 and b = 830 exhibit superior hydrogen uptake below 1 bar. Non-local density functional theory (NLDFT) analysis further demonstrated that pores below 10.25 Å play a critical role in hydrogen adsorption at 77 K. SHapley Additive exPlanations (SHAP) analysis highlighted that only a small subset of structural features—mainly within relative pressure (P/P0) ranges of 0.08–0.27 and 0.80–0.92—significantly influences hydrogen adsorption. This work provides both a reliable predictive model and interpretable insights into the pore-level mechanisms governing hydrogen storage in porous carbon materials.
{"title":"Optimizing hydrogen adsorption capacity in porous carbon through CNN and SHAP analysis","authors":"Chen Huang , Junting Zhao , Yu Zhang , Linghui Gong","doi":"10.1016/j.cryogenics.2026.104291","DOIUrl":"10.1016/j.cryogenics.2026.104291","url":null,"abstract":"<div><div>Based on nitrogen adsorption isotherms at 77 K, this study develops a one-dimensional convolutional neural network (1D-CNN) model to predict the hydrogen adsorption capacity of porous carbons. A dataset comprising 859 adsorption data points from 116 porous carbon structures was constructed. The model achieved a high predictive accuracy, with a coefficient of determination (R<sup>2</sup>) of 0.9511 on the test set. Using synthetic isotherms generated via the Langmuir equation, optimal structural parameters were identified, revealing that porous carbons with parameters a = 100 and b = 830 exhibit superior hydrogen uptake below 1 bar. Non-local density functional theory (NLDFT) analysis further demonstrated that pores below 10.25 Å play a critical role in hydrogen adsorption at 77 K. SHapley Additive exPlanations (SHAP) analysis highlighted that only a small subset of structural features—mainly within relative pressure (P/P<sub>0</sub>) ranges of 0.08–0.27 and 0.80–0.92—significantly influences hydrogen adsorption. This work provides both a reliable predictive model and interpretable insights into the pore-level mechanisms governing hydrogen storage in porous carbon materials.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"155 ","pages":"Article 104291"},"PeriodicalIF":2.1,"publicationDate":"2026-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146024419","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-19DOI: 10.1016/j.cryogenics.2026.104293
Geyang Li , Tianshi Feng , Menglin Liang , Yanen Li , Qingjun Tang , Yuhong Zhang , Houlei Chen , Yue Xue Ma
Increasing the operating frequency is a key strategy for the miniaturization of the pulse tube cryocoolers. In the pursuit of high frequency and compact system designs, maintaining the phase relationship between the pressure and mass flow within the regenerator is essential for sustaining the cooling performance of the cryocoolers. However, at super-high operating frequencies, precise control of the phase angle becomes increasingly challenging when using the inertance tube and reservoir as the phase shifter. In this paper, a three-dimensional model of the inertance tube and reservoir was developed to investigate the critical internal flow parameters at super-high frequencies. The mass flow amplitude and the phase angle along the tube were compared for single-diameter and dual-diameter inertance tube configurations at 150 Hz. Experimental validation was conducted to evaluate the impact of these configurations on the pulse tube cryocooler’s performance. The results demonstrate that employing a dual-diameter inertance tube as the phase shifter significantly enhances the cooling performance in super-high frequency cryocoolers.
{"title":"Investigation of the dual-diameter inertance tube of a pulse tube cryocooler operating at super-high frequencies","authors":"Geyang Li , Tianshi Feng , Menglin Liang , Yanen Li , Qingjun Tang , Yuhong Zhang , Houlei Chen , Yue Xue Ma","doi":"10.1016/j.cryogenics.2026.104293","DOIUrl":"10.1016/j.cryogenics.2026.104293","url":null,"abstract":"<div><div>Increasing the operating frequency is a key strategy for the miniaturization of the pulse tube cryocoolers. In the pursuit of high frequency and compact system designs, maintaining the phase relationship between the pressure and mass flow within the regenerator is essential for sustaining the cooling performance of the cryocoolers. However, at super-high operating frequencies, precise control of the phase angle becomes increasingly challenging when using the inertance tube and reservoir as the phase shifter. In this paper, a three-dimensional model of the inertance tube and reservoir was developed to investigate the critical internal flow parameters at super-high frequencies. The mass flow amplitude and the phase angle along the tube were compared for single-diameter and dual-diameter inertance tube configurations at 150 Hz. Experimental validation was conducted to evaluate the impact of these configurations on the pulse tube cryocooler’s performance. The results demonstrate that employing a dual-diameter inertance tube as the phase shifter significantly enhances the cooling performance in super-high frequency cryocoolers.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"155 ","pages":"Article 104293"},"PeriodicalIF":2.1,"publicationDate":"2026-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146024348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The investigation of the evolution of the cryogenic gas–liquid interface is crucial for the storage and management of cryogenic propellants in on-orbit tanks. Studying the non-isothermal growth of isolated bubbles under normal gravity provides a foundation for understanding the distribution of the cryogenic gas–liquid interface. However, a low boiling point, low surface tension coefficient, and low viscosity lead to bubble behaviors that differ from those of room-temperature liquids, increasing the difficulties in investigating cryogenic behaviors, and the related studies are limited. In this work, a visualization experimental platform for liquid oxygen single bubble pool boiling was established. Liquid oxygen was produced by cooling oxygen with liquid nitrogen, and an optical visualization system was designed to observe bubble behavior. The effects of wall superheat, liquid subcooling, and pressure on bubble growth rate and detachment parameters were investigated. Results indicate that higher wall superheat reduces the waiting time for bubble growth, shortens the bubble growth cycle, and increases the bubble diameter. During the initial growth stage, the bubble diameter follows a trend, transitioning to in the later stage. Bubble growth slows with increasing liquid subcooling, while higher pressure leads to smaller detachment diameters and higher detachment frequencies. The findings compensate for the scarcity of data on the growth of isolated bubbles in cryogenic liquids, and provide important guidance for the development of on-orbit storage and transport technology.
{"title":"Influencing mechanism of the non-isothermal behavior of an isolated vapor bubble in liquid oxygen","authors":"Mingkun Xiao, Yonghua Huang, Guang Yang, Chunyu Li, Aifeng Cai, Jingyi Wu","doi":"10.1016/j.cryogenics.2026.104292","DOIUrl":"10.1016/j.cryogenics.2026.104292","url":null,"abstract":"<div><div>The investigation of the evolution of the cryogenic gas–liquid interface is crucial for the storage and management of cryogenic propellants in on-orbit tanks. Studying the non-isothermal growth of isolated bubbles under normal gravity provides a foundation for understanding the distribution of the cryogenic gas–liquid interface. However, a low boiling point, low surface tension coefficient, and low viscosity lead to bubble behaviors that differ from those of room-temperature liquids, increasing the difficulties in investigating cryogenic behaviors, and the related studies are limited. In this work, a visualization experimental platform for liquid oxygen single bubble pool boiling was established. Liquid oxygen was produced by cooling oxygen with liquid nitrogen, and an optical visualization system was designed to observe bubble behavior. The effects of wall superheat, liquid subcooling, and pressure on bubble growth rate and detachment parameters were investigated. Results indicate that higher wall superheat reduces the waiting time for bubble growth, shortens the bubble growth cycle, and increases the bubble diameter. During the initial growth stage, the bubble diameter follows a <span><math><mi>D</mi><mrow><mo>∼</mo></mrow><msup><mi>t</mi><mrow><mn>1</mn><mrow><mo>/</mo></mrow><mn>2</mn></mrow></msup></math></span> trend, transitioning to <span><math><mi>D</mi><mrow><mo>∼</mo></mrow><msup><mi>t</mi><mrow><mn>1</mn><mrow><mo>/</mo></mrow><mn>3</mn></mrow></msup></math></span> in the later stage. Bubble growth slows with increasing liquid subcooling, while higher pressure leads to smaller detachment diameters and higher detachment frequencies. The findings compensate for the scarcity of data on the growth of isolated bubbles in cryogenic liquids, and provide important guidance for the development of on-orbit storage and transport technology.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"155 ","pages":"Article 104292"},"PeriodicalIF":2.1,"publicationDate":"2026-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146024345","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-16DOI: 10.1016/j.cryogenics.2026.104286
Ingrid Torres , Alex Krasnok
The performance and scalability of cryogenic microwave systems, particularly for quantum processors, are fundamentally limited by the thermal stability and loss of their constituent dielectric materials. While mixed titanate ceramics like MgTiO3–CaTiO3 (MCT) and (Zr,Sn)TiO4 (ZST) are primary candidates, their comparative performance as radiative antennas in the deep-cryogenic regime has remained uncharacterized. Here we present a side-by-side comparison of MCT and ZST operated as dielectric resonator antennas from 296 K down to 7 K–10 K under identical fixtures and protocols. While the MCT resonator exhibits large, nonlinear frequency drift (230 MHz by 10 K), pronounced thermal hysteresis, and a collapse of the loaded quality factor at low temperature—behavior consistent with incipient/relaxor-like losses—the ZST resonator demonstrates exceptional stability. Its resonant frequency shifts by only 30 MHz, its loaded -factor is enhanced by 20%–25%, and it shows negligible thermal hysteresis. Leveraging these properties, we operate the ZST disk as a radiative antenna at 10 K with only 1 mW input, establishing a through-window wireless link that detects room-temperature dielectric targets over multiple wavelengths via near-field frequency shifts and far-field magnitude modulations. Full-wave simulations are used to set a room-temperature baseline; window-related multipath is isolated experimentally via open/closed-window control measurements. This presents a viable path toward non-invasive cryogenic diagnostics and wireless interconnects that circumvent the thermal load of physical cabling. Our findings establish ZST as a foundational material for high-coherence cryogenic interfaces and provide a practical template for designing wireless cryogenic systems.
{"title":"A cryogenic dielectric antenna for wireless sensing and interfacing outside the 10 K environment","authors":"Ingrid Torres , Alex Krasnok","doi":"10.1016/j.cryogenics.2026.104286","DOIUrl":"10.1016/j.cryogenics.2026.104286","url":null,"abstract":"<div><div>The performance and scalability of cryogenic microwave systems, particularly for quantum processors, are fundamentally limited by the thermal stability and loss of their constituent dielectric materials. While mixed titanate ceramics like MgTiO<sub>3</sub>–CaTiO<sub>3</sub> (MCT) and (Zr,Sn)TiO<sub>4</sub> (ZST) are primary candidates, their comparative performance as radiative antennas in the deep-cryogenic regime has remained uncharacterized. Here we present a side-by-side comparison of MCT and ZST operated as dielectric resonator antennas from 296 K down to 7 K–10 K under identical fixtures and protocols. While the MCT resonator exhibits large, nonlinear frequency drift (<span><math><mo>∼</mo></math></span>230 MHz by 10 K), pronounced thermal hysteresis, and a collapse of the loaded quality factor at low temperature—behavior consistent with incipient/relaxor-like losses—the ZST resonator demonstrates exceptional stability. Its resonant frequency shifts by only <span><math><mo>∼</mo></math></span>30 MHz, its loaded <span><math><mi>Q</mi></math></span>-factor is enhanced by <span><math><mo>≈</mo></math></span>20%–25%, and it shows negligible thermal hysteresis. Leveraging these properties, we operate the ZST disk as a radiative antenna at 10 K with only 1 mW input, establishing a through-window wireless link that detects room-temperature dielectric targets over multiple wavelengths via near-field frequency shifts and far-field magnitude modulations. Full-wave simulations are used to set a room-temperature baseline; window-related multipath is isolated experimentally via open/closed-window control measurements. This presents a viable path toward non-invasive cryogenic diagnostics and wireless interconnects that circumvent the thermal load of physical cabling. Our findings establish ZST as a foundational material for high-coherence cryogenic interfaces and provide a practical template for designing wireless cryogenic systems.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"155 ","pages":"Article 104286"},"PeriodicalIF":2.1,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146024342","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-16DOI: 10.1016/j.cryogenics.2026.104290
Junpeng Gu , Haitao Li , Zhenyu Liu , Xue Ai , Shanhui Mi , Ningze Ma
The inductive pulse power supply based on superconducting energy storage has the advantages of low primary power demand, high energy storage density, and low resistance loss, making it have great application prospects in fields such as electromagnetic propulsion and directional energy equipment. However, how to limit the voltage of the opening switch in a superconducting inductive pulse power supply (SPPS) remains an inherent technical challenge. This study proposes a voltage limiting method for the opening switch using a combination of ZnO nonlinear resistors and pulse capacitors. During the discharge stage of superconducting inductors, pulse capacitors can be used to limit the sudden changes in the voltage of the opening switch, while ZnO nonlinear resistors can be used to limit the maximum voltage of the opening switch. Simulations and experiments were conducted using an SPPS circuit constructed with a high-temperature superconducting pulse power transformer (HTSPPT) to demonstrate the combined voltage limiting method. At the same time, the feasibility of using ZnO nonlinear resistors for voltage limiting in liquid nitrogen environment was verified. The results show that the combination of ZnO nonlinear resistors and pulse capacitors can significantly limit the opening switch voltage in SPPS circuits, and ZnO nonlinear resistors can still maintain stable voltage limiting performance in liquid nitrogen environments.
{"title":"Study of the voltage limiting method of combining nonlinear resistors and pulse capacitors for superconducting inductive pulse power supply","authors":"Junpeng Gu , Haitao Li , Zhenyu Liu , Xue Ai , Shanhui Mi , Ningze Ma","doi":"10.1016/j.cryogenics.2026.104290","DOIUrl":"10.1016/j.cryogenics.2026.104290","url":null,"abstract":"<div><div>The inductive pulse power supply based on superconducting energy storage has the advantages of low primary power demand, high energy storage density, and low resistance loss, making it have great application prospects in fields such as electromagnetic propulsion and directional energy equipment. However, how to limit the voltage of the opening switch in a superconducting inductive pulse power supply (SPPS) remains an inherent technical challenge. This study proposes a voltage limiting method for the opening switch using a combination of ZnO nonlinear resistors and pulse capacitors. During the discharge stage of superconducting inductors, pulse capacitors can be used to limit the sudden changes in the voltage of the opening switch, while ZnO nonlinear resistors can be used to limit the maximum voltage of the opening switch. Simulations and experiments were conducted using an SPPS circuit constructed with a high-temperature superconducting pulse power transformer (HTSPPT) to demonstrate the combined voltage limiting method. At the same time, the feasibility of using ZnO nonlinear resistors for voltage limiting in liquid nitrogen environment was verified. The results show that the combination of ZnO nonlinear resistors and pulse capacitors can significantly limit the opening switch voltage in SPPS circuits, and ZnO nonlinear resistors can still maintain stable voltage limiting performance in liquid nitrogen environments.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"155 ","pages":"Article 104290"},"PeriodicalIF":2.1,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146024343","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-16DOI: 10.1016/j.cryogenics.2026.104288
P. Kováč, J. Kováč
Today, km-long MgB2 wires are commercially produced using the Power-in-Tube (PIT) process; however, commercial companies that also conduct measurements of basic properties often lack more detailed characterizations. Therefore, more detailed studies are usually done by research institutes or universities. We have measured the low-temperature properties of two commercial MgB2 wires, manufactured by ex-situ and in-situ processes, and compared their behaviour from the point of application. It was demonstrated that a higher critical temperature of 39 K for ex-situ wires provides a larger temperature window for applications. On the other hand, in-situ made wires have higher engineering current densities at lower temperatures and higher magnetic fields. Consequently, ex-situ wires are more suitable for higher working temperatures and low magnetic fields, and in-situ ones for higher magnetic fields and temperatures ≤ 20 K. In addition, lower AC losses are measured for in-situ wire due to the smaller amount of magnetic materials (Ni and Monel) and also the application of short pitch twisting, which is not possible for ex-situ wire.
{"title":"Properties of filamentary MgB2 superconducting wires commercially produced by ex-situ and in-situ process","authors":"P. Kováč, J. Kováč","doi":"10.1016/j.cryogenics.2026.104288","DOIUrl":"10.1016/j.cryogenics.2026.104288","url":null,"abstract":"<div><div>Today, km-long MgB<sub>2</sub> wires are commercially produced using the Power-in-Tube (PIT) process; however, commercial companies that also conduct measurements of basic properties often lack more detailed characterizations. Therefore, more detailed studies are usually done by research institutes or universities. We have measured the low-temperature properties of two commercial MgB<sub>2</sub> wires, manufactured by <em>ex-situ</em> and <em>in-situ</em> processes, and compared their behaviour from the point of application. It was demonstrated that a higher critical temperature of 39 K for <em>ex-situ</em> wires provides a larger temperature window for applications. On the other hand, in-situ made wires have higher engineering current densities at lower temperatures and higher magnetic fields. Consequently, <em>ex-situ</em> wires are more suitable for higher working temperatures and low magnetic fields, and <em>in-situ</em> ones for higher magnetic fields and temperatures ≤ 20 K. In addition, lower AC losses are measured for <em>in-situ</em> wire due to the smaller amount of magnetic materials (Ni and Monel) and also the application of short pitch twisting, which is not possible for <em>ex-situ</em> wire.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"155 ","pages":"Article 104288"},"PeriodicalIF":2.1,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146024469","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-16DOI: 10.1016/j.cryogenics.2026.104289
Yue Xiang , Zhicong Miao , Zhixiong Wu , Tao Wang , Yuqiang Zhao , Yemao Han , Chuanjun Huang , Rongjin Huang , Laifeng Li
To address the quenching issues caused by the low thermal conductivity of epoxy resin (EP) in superconducting applications, this study enhances the comprehensive performance of epoxy-based composites by constructing a three-dimensional boron nitride thermal network. A self-supporting framework integrating boron nitride nanoribbons (BNNR) and boron nitride nanosheets (BNNS) was developed and incorporated into the epoxy matrix. The influence of filler content on the thermal conductivity, electrical insulation, and thermal expansion behavior of the composite was systematically investigated. The results demonstrate that the fabricated composites exhibit excellent thermal performance across the temperature range from 70 K to room temperature. With an 18.96 wt% incorporation of the three-dimensional thermal network, the composite achieves a thermal conductivity of 0.63 W/(m·K) at 70 K, representing a 575% enhancement compared to pure epoxy resin. Simultaneously, the material maintains outstanding electrical insulation characteristics, with volume resistivity consistently exceeding 1014 Ω·cm. Moreover, the composites’ linear coefficient of thermal expansion (CTE) decreases significantly with increasing filler content, effectively mitigating thermal stress in superconducting devices. This study provides novel insights and experimental foundations for developing high-thermal-conductivity epoxy-based insulating materials suitable for superconducting applications.
{"title":"Constructing 3D boron nitride nanoribbons and nanosheets networks for enhanced cryogenic thermal management in epoxy composites","authors":"Yue Xiang , Zhicong Miao , Zhixiong Wu , Tao Wang , Yuqiang Zhao , Yemao Han , Chuanjun Huang , Rongjin Huang , Laifeng Li","doi":"10.1016/j.cryogenics.2026.104289","DOIUrl":"10.1016/j.cryogenics.2026.104289","url":null,"abstract":"<div><div>To address the quenching issues caused by the low thermal conductivity of epoxy resin (EP) in superconducting applications, this study enhances the comprehensive performance of epoxy-based composites by constructing a three-dimensional boron nitride thermal network. A self-supporting framework integrating boron nitride nanoribbons (BNNR) and boron nitride nanosheets (BNNS) was developed and incorporated into the epoxy matrix. The influence of filler content on the thermal conductivity, electrical insulation, and thermal expansion behavior of the composite was systematically investigated. The results demonstrate that the fabricated composites exhibit excellent thermal performance across the temperature range from 70 K to room temperature. With an 18.96 wt% incorporation of the three-dimensional thermal network, the composite achieves a thermal conductivity of 0.63 W/(m·K) at 70 K, representing a 575% enhancement compared to pure epoxy resin. Simultaneously, the material maintains outstanding electrical insulation characteristics, with volume resistivity consistently exceeding 10<sup>14</sup> Ω·cm. Moreover, the composites’ linear coefficient of thermal expansion (CTE) decreases significantly with increasing filler content, effectively mitigating thermal stress in superconducting devices. This study provides novel insights and experimental foundations for developing high-thermal-conductivity epoxy-based insulating materials suitable for superconducting applications.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"155 ","pages":"Article 104289"},"PeriodicalIF":2.1,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146024468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-14DOI: 10.1016/j.cryogenics.2026.104287
Zhouhang Hu , Xuan Yu , Zhenxing Li , Mingsheng Tang , Huiming Zou , Jun Shen
Magnetic resonance linear compressors play a critical role in the miniaturization and reliability enhancement of miniature cryocoolers. In this study, a finite element analysis system is employed to investigate the mechanism of the magnetic spring effect in magnetic resonance linear compressors. Furthermore, the magnetic spring force of the linear compressor was measured through experimental testing. The experimental results are compared with simulation outcomes, validating the reliability of the simulation model. The magnetic spring effect caused by electromagnetic–mechanical coupling in magnetic resonance linear motors is studied through finite element simulation and experimental verification. The results reveal asymmetric stiffness characteristics, stroke dependence, and frequency independence in magnetic spring behavior. Quantitative analysis of stiffness nonlinearity across displacement ranges is conducted via static and dynamic magnetic spring tests. Experimental data demonstrate: under static conditions, magnetic spring stiffness increases from 28.9 N/mm to 37.4 N/mm (an increase of 29.4 %) during compression (0 to +7.4 mm), and from 21.5 N/mm to 34.1 N/mm (an increase of 58.6 %) during expansion (-15 mm to 0 mm). Dynamic conditions show resonant frequency increasing with stroke magnitude, validating displacement-dependent stiffness. At 7 mm stroke, the relative error between theoretical equivalent stiffness (24.6 N/mm) and frequency-scanned measured value (24.5 N/mm) is merely 0.58 %, confirming the feasibility of predicting dynamic stiffness using static test results. Furthermore, the integration of the magnetic resonance linear motor into the pulse tube cryocooler demonstrates the feasibility of applying magnetic resonance linear motors in miniature cryocoolers.
{"title":"Investigation of magnetic spring stiffness characteristics in magnetic resonance linear compressors for pulse tube cryocoolers","authors":"Zhouhang Hu , Xuan Yu , Zhenxing Li , Mingsheng Tang , Huiming Zou , Jun Shen","doi":"10.1016/j.cryogenics.2026.104287","DOIUrl":"10.1016/j.cryogenics.2026.104287","url":null,"abstract":"<div><div>Magnetic resonance linear compressors play a critical role in the miniaturization and reliability enhancement of miniature cryocoolers. In this study, a finite element analysis system is employed to investigate the mechanism of the magnetic spring effect in magnetic resonance linear compressors. Furthermore, the magnetic spring force of the linear compressor was measured through experimental testing. The experimental results are compared with simulation outcomes, validating the reliability of the simulation model. The magnetic spring effect caused by electromagnetic–mechanical coupling in magnetic resonance linear motors is studied through finite element simulation and experimental verification. The results reveal asymmetric stiffness characteristics, stroke dependence, and frequency independence in magnetic spring behavior. Quantitative analysis of stiffness nonlinearity across displacement ranges is conducted via static and dynamic magnetic spring tests. Experimental data demonstrate: under static conditions, magnetic spring stiffness increases from 28.9 N/mm to 37.4 N/mm (an increase of 29.4 %) during compression (0 to +7.4 mm), and from 21.5 N/mm to 34.1 N/mm (an increase of 58.6 %) during expansion (-15 mm to 0 mm). Dynamic conditions show resonant frequency increasing with stroke magnitude, validating displacement-dependent stiffness. At 7 mm stroke, the relative error between theoretical equivalent stiffness (24.6 N/mm) and frequency-scanned measured value (24.5 N/mm) is merely 0.58 %, confirming the feasibility of predicting dynamic stiffness using static test results. Furthermore, the integration of the magnetic resonance linear motor into the pulse tube cryocooler demonstrates the feasibility of applying magnetic resonance linear motors in miniature cryocoolers.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"155 ","pages":"Article 104287"},"PeriodicalIF":2.1,"publicationDate":"2026-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146024344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号