Thermodynamical aspects of pulse tubes

NARCIS (Netherlands)

Waele, de A.T.A.M.; Steijaert, P.P.; Gijzen, J.

1997-01-01

The cooling power of cryocoolers is determined by the work done by the compressor and the entropy produced by the irreversible processes in the various components of the system. In this paper we discuss the thermodynamics of pulse tubes, but many of the relationships are equally valid for other

Development of High Capacity Split Stirling Cryocooler for HTS

Science.gov (United States)

Yumoto, Kenta; Nakano, Kyosuke; Hiratsuka, Yoshikatsu

Sumitomo Heavy Industries, Ltd. (SHI) developed a high-power Stirling-type pulse tube cryocooler for cooling high-temperature superconductor (HTS) devices, such as superconductor motors, superconducting magnetic energy storage (SMES), and fault current limiters. The experimental results of a prototype pulse tube cryocooler were reported in September 2013. For a U-type expander, the cooling capacity was 151 W at 70 K with a compressor input power of 4 kW. Correspondingly, the coefficient of performance (COP) was about 0.038. However, the efficiency of the cryocooler is required to be COP > 0.1 and it was found that, theoretically, it is difficult to further improve the efficiency of a pulse tube cryocooler because the workflow generated at the hot end of the pulse tube cannot be recovered. Therefore, it was decided to change the expander to a free-piston type from a pulse tube type. A prototype was developed and preliminary experiments were conducted. A cooling capacity of 120 W at 70 K with a compressor input power of 2.15 kW with corresponding COP of 0.056, was obtained. The detailed results are reported in this paper.

Acoustic cryocooler

International Nuclear Information System (INIS)

Swift, G.W.; Martin, R.A.; Radebaugh, R.

1990-01-01

This patent describes an acoustic cryocooler with no moving parts is formed from a thermoacoustic driver (TAD) driving a pulse tube refrigerator (PTR) through a standing wave tube. Thermoacoustic elements in the TAD are spaced apart a distance effect to accommodate the increased thermal penetration length arising from the relatively low TAD operating frequency in the range of 15--60 Hz. At these low operating frequencies, a long tube is required to support the standing wave. The tube may be coiled to reduce the overall length of the cryocooler. One or two PTR's are located on the standing wave tube adjacent antinodes in the standing wave to be driven by the standing wave pressure oscillations. It is predicted that a heat input of 1000 W at 1000 K will maintain a cooling load of 5 W at 80 K

Method for estimating off-axis pulse tube losses

Science.gov (United States)

Fang, T.; Mulcahey, T. I.; Taylor, R. P.; Spoor, P. S.; Conrad, T. J.; Ghiaasiaan, S. M.

2017-12-01

Some Stirling-type pulse tube cryocoolers (PTCs) exhibit sensitivity to gravitational orientation and often exhibit significant cooling performance losses unless situated with the cold end pointing downward. Prior investigations have indicated that some coolers exhibit sensitivity while others do not; however, a reliable method of predicting the level of sensitivity during the design process has not been developed. In this study, we present a relationship that estimates an upper limit to gravitationally induced losses as a function of the dimensionless pulse tube convection number (NPTC) that can be used to ensure that a PTC would remain functional at adverse static tilt conditions. The empirical relationship is based on experimental data as well as experimentally validated 3-D computational fluid dynamics simulations that examine the effects of frequency, mass flow rate, pressure ratio, mass-pressure phase difference, hot and cold end temperatures, and static tilt angle. The validation of the computational model is based on experimental data collected from six commercial pulse tube cryocoolers. The simulation results are obtained from component-level models of the pulse tube and heat exchangers. Parameter ranges covered in component level simulations are 0-180° for tilt angle, 4-8 for length to diameter ratios, 4-80 K cold tip temperatures, -30° to +30° for mass flow to pressure phase angles, and 25-60 Hz operating frequencies. Simulation results and experimental data are aggregated to yield the relationship between inclined PTC performance and pulse tube convection numbers. The results indicate that the pulse tube convection number can be used as an order of magnitude indicator of the orientation sensitivity, but CFD simulations should be used to calculate the change in energy flow more accurately.

Role of size on the relative importance of fluid dynamic losses in linear cryocoolers

Science.gov (United States)

Kirkconnell, Carl; Ghavami, Ali; Ghiaasiaan, S. Mostafa; Perrella, Matthew

2017-12-01

Thermodynamic modeling results for a novel small satellite (SmallSat) Stirling Cryocooler, capable of delivering over 200 mW net cooling power at 80 K for less than 6 W DC input power, are used in this paper as the basis for related pulse tube computational fluid dynamics (CFD) analysis. Industry and government requirements for SmallSat infrared sensors are driving the development of ever-more miniaturized cryocooler systems. Such cryocoolers must be extremely compact and lightweight, a challenge met by this research team through operating a Stirling cryocooler at a frequency of approximately 300 Hz. The primary advantage of operating at such a high frequency is that the required compression and expansion swept volumes are reduced relative to linear coolers operating at lower frequencies, which evidently reduces the size of the motor mechanisms and the thermodynamic components. In the case of a pulse tube cryocooler, this includes a reduction in diameter of the pulse tube itself. This unfortunately leads to high boundary layer losses, as the presented results demonstrate. Using a Stirling approach with a mechanical moving expander piston eliminates this small pulse tube loss mechanism, but other challenges are introduced, such as maintaining very tight clearance gaps between moving and stationary elements. This paper focuses on CFD modelling results for a highly miniaturized pulse tube cooler.

8th International Cryocooler Conference

CERN Document Server

1995-01-01

The last few years have witnessed a substantial maturing of long life Stirling-cycle cryocoolers built upon the heritage of the flexure-bearing cryocoolers from Oxford University, and have seen the emergence of mature pulse tube cryocoolers competing head-to-head with the Stirling cryocoolers. Hydrogen sorption cryocoolers, Gifford-McMahon cryocoolers with rare earth regenerators, and helium Joule-Thomson cryocoolers have also made tremendous progress in opening up applications in the 4 K to 10 K temperature range. Tactical Stirling cryocoolers, now commonplace in the defense industry, are finding application in a number of cost­ constrained commercial applications and space missions, and are achieving ever longer lives as they move to linear-drive, clearance-seal compressors. Building on this expanding availability of commercially viable cryocoolers, numerous new applications are being enabled; many of these involve infrared imaging systems, and high­ temperature superconductors in the medical and ...

A novel method to hit the limit temperature of Stirling-type cryocooler

Science.gov (United States)

Wang, Jue; Pan, Changzhao; Zhang, Tong; Luo, Kaiqi; Zhou, Yuan; Wang, Junjie

2018-02-01

The Stirling-type cryocooler with its compact size and high efficiency is always expected to obtain its temperature limit of below 3 K. However, the pressure drop losses caused by high-frequency oscillation create large obstacles for this objective. This paper reports a novel thermal-driven Stirling-type cryocooler to obtain the lowest temperature of a Stirling-type cryocooler. The advantages of a thermal-driven cryocooler (Vuilleumier cryocooler) and pulse tube cryocooler are combined with a new type of cryocooler, called the Vuilleumier gas-coupling pulse tube hybrid cryocooler (VM-PT). A prototype of the VM-PT was recently developed and optimized in our laboratory. By using helium-4 as the working gas and magnetic regenerative materials (HoCu2 and Er3Ni), the lowest temperature of 2.5 K was obtained, which can be regarded as an important breakthrough for the Stirling-type cryocooler to achieve its limit temperature of below 3 K. It can supply >30 mW cooling power at 4.2 K and >500 mW cooling power at 20 K simultaneously. Theoretically, it is feasible to use this VM-PT for cooling the superconducting devices in space applications.

Investigation of pressure drop in capillary tube for mixed refrigerant Joule-Thomson cryocooler

International Nuclear Information System (INIS)

Ardhapurkar, P. M.; Sridharan, Arunkumar; Atrey, M. D.

2014-01-01

A capillary tube is commonly used in small capacity refrigeration and air-conditioning systems. It is also a preferred expansion device in mixed refrigerant Joule-Thomson (MR J-T) cryocoolers, since it is inexpensive and simple in configuration. However, the flow inside a capillary tube is complex, since flashing process that occurs in case of refrigeration and air-conditioning systems is metastable. A mixture of refrigerants such as nitrogen, methane, ethane, propane and iso-butane expands below its inversion temperature in the capillary tube of MR J-T cryocooler and reaches cryogenic temperature. The mass flow rate of refrigerant mixture circulating through capillary tube depends on the pressure difference across it. There are many empirical correlations which predict pressure drop across the capillary tube. However, they have not been tested for refrigerant mixtures and for operating conditions of the cryocooler. The present paper assesses the existing empirical correlations for predicting overall pressure drop across the capillary tube for the MR J-T cryocooler. The empirical correlations refer to homogeneous as well as separated flow models. Experiments are carried out to measure the overall pressure drop across the capillary tube for the cooler. Three different compositions of refrigerant mixture are used to study the pressure drop variations. The predicted overall pressure drop across the capillary tube is compared with the experimentally obtained value. The predictions obtained using homogeneous model show better match with the experimental results compared to separated flow models

Operating characteristics of a three-stage Stirling pulse tube cryocooler operating around 5 K

Science.gov (United States)

Qiu, L. M.; Cao, Q.; Zhi, X. Q.; Han, L.; Gan, Z. H.; Yu, Y. B.; Liu, Y.; Zhang, X. J.; Pfotenhauer, J. M.

2012-07-01

A Stirling pulse tube cryocooler (SPTC) operating at the liquid-helium temperatures represents an excellent prospect for satisfying the requirements of space applications because of its compactness, high efficiency and reliability. However, the working mechanism of a 4 K SPTC is more complicated than that of the Gifford McMahon (GM) PTC that operates at the relatively low frequency of 1-2 Hz, and has not yet been well understood. In this study, the primary operating parameters, including frequency, charge pressure, input power and precooling temperature, are systematically investigated in a home-developed separate three-stage SPTC. The investigation demonstrates that the frequency and precooling temperature are closely coupled via phase shift. In order to improve the cooling capacity it is important to lower the frequency and the precooling temperature simultaneously. In contrast to the behavior predicted by previous studies, the pressure dependence of the gas properties results in an optimized pressure that decreases significantly as the temperature is lowered. The third stage reaches a lowest temperature of 4.97 K at 29.9 Hz and 0.91 MPa. A cooling power of 25 mW is measured at 6.0 K. The precooling temperature is 23.7 K and the input power is 100 W.

Analysis of DC control in double-inlet GM type pulse tube refrigerators for detectors

Science.gov (United States)

Du, B. Y.

2016-10-01

Pulse tube refrigerators have demonstrated many advantages with respect to temperature stability, vibration, reliability and lifetime among cryo-coolers for detectors. Double-inlet type pulse tube refrigerators are popular in GM type pulse tube refrigerators. The single double-inlet valve may introduce DC flow in refrigerator, which deteriorates the performance of pulse tube refrigerator. One new type of DC control mode is introduced in this paper. Two parallel-placed needle valves with opposite direction named double-valve configuration, instead of single double-inlet valve, are used in our experiment to reduce the DC flow. With two double-inlet operating, the lowest cold end temperature of 18.1K and a coolant of 1.2W@20K have been obtained. It has proved that this method is useful for controlling DC flow of the pulse tube refrigerators, which is very important to understand the characters of pulse tube refrigerators for detectors.

Development of a miniature Stirling cryocooler for LWIR small satellite applications

Science.gov (United States)

Kirkconnell, C. S.; Hon, R. C.; Perella, M. D.; Crittenden, T. M.; Ghiaasiaan, S. M.

2017-05-01

The optimum small satellite (SmallSat) cryocooler system must be extremely compact and lightweight, achieved in this paper by operating a linear cryocooler at a frequency of approximately 300 Hz. Operation at this frequency, which is well in excess of the 100-150 Hz reported in recent papers on related efforts, requires an evolution beyond the traditional Oxford-class, flexure-based methods of setting the mechanical resonance. A novel approach that optimizes the electromagnetic design and the mechanical design together to simultaneously achieve the required dynamic and thermodynamic performances is described. Since highly miniaturized pulse tube coolers are fundamentally ill-suited for the sub-80K temperature range of interest because the boundary layer losses inside the pulse tube become dominant at the associated very small pulse tube size, a moving displacer Stirling cryocooler architecture is used. Compact compressor mechanisms developed on a previous program are reused for this design, and they have been adapted to yield an extremely compact Stirling warm end motor mechanism. Supporting thermodynamic and electromagnetic analysis results are reported.

Computational Investigation on the performance of thermo-acoustically driven pulse tube refrigerator

Science.gov (United States)

Skaria, Mathew; Rasheed, K. K. Abdul; Shafi, K. A.; Kasthurirengan, S.; Behera, Upendra

2017-02-01

A Thermoacoustic Pulse Tube Refrigeration (TAPTR) system employs a thermo acoustic engine as the pressure wave generator instead of mechanical compressor. Such refrigeration systems are highly reliable due to the absence of moving components, structural simplicity and the use of environmental friendly working fluids. In the present work, a traveling wave thermoacoustic primmover (TWTAPM) has been developed and it is coupled to a pulse tube cryocooler. The performance of TAPTR depends on the operating and working fluid parameters. Simulation studies of the system has been performed using ANSYS Fluent and compared with experimental results.

Numerical simulation of tubes-in-tube heat exchanger in a mixed refrigerant Joule-Thomson cryocooler

Science.gov (United States)

Damle, R. M.; Ardhapurkar, P. M.; Atrey, M. D.

2017-02-01

Mixed refrigerant Joule-Thomson (MRJT) cryocoolers can produce cryogenic temperatures with high efficiency and low operating pressures. As compared to the high system pressures of around 150-200 bar with nitrogen, the operational pressures with non-azeotropic mixtures (e.g., nitrogen-hydrocarbons) come down to 10-25 bar. With mixtures, the heat transfer in the recuperative heat exchanger takes place in the two-phase region. The simultaneous boiling and condensation of the cold and hot gas streams lead to higher heat transfer coefficients as compared to single phase heat exchange. The two-phase heat transfer in the recuperative heat exchanger drastically affects the performance of a MRJT cryocooler. In this work, a previously reported numerical model for a simple tube-in-tube heat exchanger is extended to a multi tubes-in-tube heat exchanger with a transient formulation. Additionally, the J-T expansion process is also considered to simulate the cooling process of the heat exchanger from ambient temperature conditions. A tubes-in-tube heat exchanger offers more heat transfer area per unit volume resulting in a compact design. Also, the division of flow in multiple tubes reduces the pressure drop in the heat exchanger. Simulations with different mixtures of nitrogen-hydrocarbons are carried out and the numerical results are compared with the experimental data.

CFD modeling and experimental verification of oscillating flow and heat transfer processes in the micro coaxial Stirling-type pulse tube cryocooler operating at 90-170 Hz

Science.gov (United States)

Zhao, Yibo; Yu, Guorui; Tan, Jun; Mao, Xiaochen; Li, Jiaqi; Zha, Rui; Li, Ning; Dang, Haizheng

2018-03-01

This paper presents the CFD modeling and experimental verifications of oscillating flow and heat transfer processes in the micro coaxial Stirling-type pulse tube cryocooler (MCSPTC) operating at 90-170 Hz. It uses neither double-inlet nor multi-bypass while the inertance tube with a gas reservoir becomes the only phase-shifter. The effects of the frequency on flow and heat transfer processes in the pulse tube are investigated, which indicates that a low enough frequency would lead to a strong mixing between warm and cold fluids, thereby significantly deteriorating the cooling performance, whereas a high enough frequency would produce the downward sloping streams flowing from the warm end to the axis and almost puncturing the gas displacer from the warm end, thereby creating larger temperature gradients in radial directions and thus undermining the cooling performance. The influence of the pulse tube length on the temperature and velocity when the frequencies are much higher than the optimal one are also discussed. A MCSPTC with an overall mass of 1.1 kg is worked out and tested. With an input electric power of 59 W and operating at 144 Hz, it achieves a no-load temperature of 61.4 K and a cooling capacity of 1.0 W at 77 K. The changing tendencies of tested results are in good agreement with the simulations. The above studies will help to thoroughly understand the underlying mechanism of the inertance MCSPTC operating at very high frequencies.

CFD study of a simple orifice pulse tube cooler

Science.gov (United States)

Zhang, X. B.; Qiu, L. M.; Gan, Z. H.; He, Y. L.

2007-05-01

Pulse tube cooler (PTC) has the advantages of long-life and low vibration over the conventional cryocoolers, such as G-M and Stirling coolers because of the absence of moving parts in low temperature. This paper performs a two-dimensional axis-symmetric computational fluid dynamic (CFD) simulation of a GM-type simple orifice PTC (OPTC). The detailed modeling process and the general results such as the phase difference between velocity and pressure at cold end, the temperature profiles along the wall as well as the temperature oscillations at cold end with different heat loads are presented. Emphases are put on analyzing the complicated phenomena of multi-dimensional flow and heat transfer in the pulse tube under conditions of oscillating pressure. Swirling flow pattern in the pulse tube is observed and the mechanism of formation is analyzed in details, which is further validated by modeling a basic PTC. The swirl causes undesirable mixing in the thermally stratified fluid and is partially responsible for the poor overall performance of the cooler, such as unsteady cold-end temperature.

Characterization of a low frequency magnetic noise from a two stage pulse tube cryocooler

International Nuclear Information System (INIS)

Eshraghi, Mohamad Javad; Sasada, Ichiro; Kim, Jin Mok; Lee, Yong Ho

2008-01-01

Magnetic noise of a two stage pulse tube cryocooler(PT) has been measured by a fundamental mode orthogonal fluxgate magnetometer and by a LTS SQUID gradiometer. The magnetometer was installed in a Dewar made of aluminum at 12 cm apart from a section containing magnetic regenerative materials of the PT. The magnetic noise shows a clear peak at 1.8 Hz which is the fundamental frequency of the He gas pumping rate. The 1.8 Hz magnetic noise took a peak, during the cooling process, when the cold stage temperature was at (or close to) 12 K, which resembles the variation of the temperature of the second cold stage of 1.8 Hz. Hence we attributed the main source of this magnetic noise to the temperature dependency of magnetic susceptibility of magnetic regenerative materials such as Er3Ni and HoCu2 used at the second stage. We pointed out that the superconducting magnetic shield by lead sheets reduced the interfering magnetic noise generated from this part. With this scheme, the magnetic noise amplitude measured with the first order gradiometer DROS, mounted in the vicinity of the magnetic regenerator, when the noise amplitude is minimum, which could be found from the fluxgate measurement results, was less than 500 pT peak to peak. Whereas without lead shielding the noise level was higher than the dynamic range of SQUID instrumentations which is around ±10nT. (author)

Cryocooler With Cold Compressor for Deep Space Applications, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — The unique built-in design features of the proposed mini pulse tube cryocooler avoid all thermal expansion issues enabling it to operate within a cold, 150 K...

Raytheon's next generation compact inline cryocooler architecture

Science.gov (United States)

Schaefer, B. R.; Bellis, L.; Ellis, M. J.; Conrad, T.

2014-01-01

Since the 1970s, Raytheon has developed, built, tested and integrated high performance cryocoolers. Our versatile designs for single and multi-stage cryocoolers provide reliable operation for temperatures from 10 to 200 Kelvin with power levels ranging from 50 W to nearly 600 W. These advanced cryocoolers incorporate clearance seals, flexure suspensions, hermetic housings and dynamic balancing to provide long service life and reliable operation in all relevant environments. Today, sensors face a multitude of cryocooler integration challenges such as exported disturbance, efficiency, scalability, maturity, and cost. As a result, cryocooler selection is application dependent, oftentimes requiring extensive trade studies to determine the most suitable architecture. To optimally meet the needs of next generation passive IR sensors, the Compact Inline Raytheon Stirling 1-Stage (CI-RS1), Compact Inline Raytheon Single Stage Pulse Tube (CI-RP1) and Compact Inline Raytheon Hybrid Stirling/Pulse Tube 2-Stage (CI-RSP2) cryocoolers are being developed to satisfy this suite of requirements. This lightweight, compact, efficient, low vibration cryocooler combines proven 1-stage (RS1 or RP1) and 2-stage (RSP2) cold-head architectures with an inventive set of warm-end mechanisms into a single cooler module, allowing the moving mechanisms for the compressor and the Stirling displacer to be consolidated onto a common axis and in a common working volume. The CI cryocooler is a significant departure from the current Stirling cryocoolers in which the compressor mechanisms are remote from the Stirling displacer mechanism. Placing all of the mechanisms in a single volume and on a single axis provides benefits in terms of package size (30% reduction), mass (30% reduction), thermodynamic efficiency (>20% improvement) and exported vibration performance (≤25 mN peak in all three orthogonal axes at frequencies from 1 to 500 Hz). The main benefit of axial symmetry is that proven balancing

Raytheon's next generation compact inline cryocooler architecture

International Nuclear Information System (INIS)

Schaefer, B. R.; Bellis, L.; Ellis, M. J.; Conrad, T.

2014-01-01

Since the 1970s, Raytheon has developed, built, tested and integrated high performance cryocoolers. Our versatile designs for single and multi-stage cryocoolers provide reliable operation for temperatures from 10 to 200 Kelvin with power levels ranging from 50 W to nearly 600 W. These advanced cryocoolers incorporate clearance seals, flexure suspensions, hermetic housings and dynamic balancing to provide long service life and reliable operation in all relevant environments. Today, sensors face a multitude of cryocooler integration challenges such as exported disturbance, efficiency, scalability, maturity, and cost. As a result, cryocooler selection is application dependent, oftentimes requiring extensive trade studies to determine the most suitable architecture. To optimally meet the needs of next generation passive IR sensors, the Compact Inline Raytheon Stirling 1-Stage (CI-RS1), Compact Inline Raytheon Single Stage Pulse Tube (CI-RP1) and Compact Inline Raytheon Hybrid Stirling/Pulse Tube 2-Stage (CI-RSP2) cryocoolers are being developed to satisfy this suite of requirements. This lightweight, compact, efficient, low vibration cryocooler combines proven 1-stage (RS1 or RP1) and 2-stage (RSP2) cold-head architectures with an inventive set of warm-end mechanisms into a single cooler module, allowing the moving mechanisms for the compressor and the Stirling displacer to be consolidated onto a common axis and in a common working volume. The CI cryocooler is a significant departure from the current Stirling cryocoolers in which the compressor mechanisms are remote from the Stirling displacer mechanism. Placing all of the mechanisms in a single volume and on a single axis provides benefits in terms of package size (30% reduction), mass (30% reduction), thermodynamic efficiency (>20% improvement) and exported vibration performance (≤25 mN peak in all three orthogonal axes at frequencies from 1 to 500 Hz). The main benefit of axial symmetry is that proven balancing

Effect of Low Temperature on a 4 W/60 K Pulse-Tube Cryocooler for Cooling HgCdTe Detector

Science.gov (United States)

Zhang, Ankuo; Liu, Shaoshuai; Wu, Yinong

2018-04-01

Temperature is an extremely important parameter for the material of the space-borne infrared detector. To cool an HgCdTe-infrared detector, a Stirling-type pulse-tube cryocooler (PTC) has been developed based on a great deal of numerical simulations, which are performed to investigate the thermodynamic behaviors of the PTC. The effects of different low temperatures are presented to analyze different energy flows, losses, phase shifts, and impedance matching of the PTC at a temperature range of 40-120 K, where woven wire screens are used. Finally, a high-efficiency coaxial PTC has been designed, built, and tested, operating around 60 K after a number of theoretical and experimental studies. The PTC can offer a no-load refrigeration temperature of 40 K with an input electric power of 150 W, and a cooling power of 4 W at 60 K is obtained with Carnot efficiency of 12%. In addition, a comparative study of simulation and experiment has been carried out, and some studies on reject temperatures have been presented for a thorough understanding of the PTC system.

Computational Fluid Dynamic Investigation of Loss Mechanisms in a Pulse-Tube Refrigerator

International Nuclear Information System (INIS)

Martin, K; Esguerra, J; Dodson, C; Razani, A

2015-01-01

In predicting Pulse-Tube Cryocooler (PTC) performance, One-Dimensional (1-D) PTR design and analysis tools such as Gedeon Associates SAGE® typically include models for performance degradation due to thermodynamically irreversible processes. SAGE®, in particular, accounts for convective loss, turbulent conductive loss and numerical diffusion “loss” via correlation functions based on analysis and empirical testing.In this study, we compare CFD and SAGE® estimates of PTR refrigeration performance for four distinct pulse-tube lengths. Performance predictions from PTR CFD models are compared to SAGE® predictions for all four cases. Then, to further demonstrate the benefits of higher-fidelity and multidimensional CFD simulation, the PTR loss mechanisms are characterized in terms of their spatial and temporal locations. (paper)

Vibrations on pulse tube based Dry Dilution Refrigerators for low noise measurements

Energy Technology Data Exchange (ETDEWEB)

Olivieri, E. [CSNSM, Univ. Paris-Sud, CNRS/IN2P3, Université Paris-Saclay, 91405 Orsay (France); Billard, J.; De Jesus, M.; Juillard, A. [Univ Lyon, Université Lyon 1, CNRS/IN2P3, IPN-Lyon, F-69622 Villeurbanne (France); Leder, A. [Massachussets Institute of Technology, Laboratory for Nuclear Science, 77 Massachusetts Avenue Cambridge, MA 02139-4307 (United States)

2017-06-21

Dry Dilution Refrigerators (DDR) based on pulse tube cryo-coolers have started to replace Wet Dilution Refrigerators (WDR) due to the ease and low cost of operation. However these advantages come at the cost of increased vibrations, induced by the pulse tube. In this work, we present the vibration measurements performed on three different commercial DDRs. We describe in detail the vibration measurement system we assembled, based on commercial accelerometers, conditioner and DAQ, and examined the effects of the various damping solutions utilized on three different DDRs, both in the low and high frequency regions. Finally, we ran low temperature, pseudo-massive (30 and 250 g) germanium bolometers in the best vibration-performing system under study and report on the results.

Raytheon's next generation compact inline cryocooler architecture

Energy Technology Data Exchange (ETDEWEB)

Schaefer, B. R.; Bellis, L.; Ellis, M. J.; Conrad, T. [Raytheon Space and Airborne Systems, 2000 E. El Segundo Blvd., El Segundo, CA 90245 (United States)

2014-01-29

Since the 1970s, Raytheon has developed, built, tested and integrated high performance cryocoolers. Our versatile designs for single and multi-stage cryocoolers provide reliable operation for temperatures from 10 to 200 Kelvin with power levels ranging from 50 W to nearly 600 W. These advanced cryocoolers incorporate clearance seals, flexure suspensions, hermetic housings and dynamic balancing to provide long service life and reliable operation in all relevant environments. Today, sensors face a multitude of cryocooler integration challenges such as exported disturbance, efficiency, scalability, maturity, and cost. As a result, cryocooler selection is application dependent, oftentimes requiring extensive trade studies to determine the most suitable architecture. To optimally meet the needs of next generation passive IR sensors, the Compact Inline Raytheon Stirling 1-Stage (CI-RS1), Compact Inline Raytheon Single Stage Pulse Tube (CI-RP1) and Compact Inline Raytheon Hybrid Stirling/Pulse Tube 2-Stage (CI-RSP2) cryocoolers are being developed to satisfy this suite of requirements. This lightweight, compact, efficient, low vibration cryocooler combines proven 1-stage (RS1 or RP1) and 2-stage (RSP2) cold-head architectures with an inventive set of warm-end mechanisms into a single cooler module, allowing the moving mechanisms for the compressor and the Stirling displacer to be consolidated onto a common axis and in a common working volume. The CI cryocooler is a significant departure from the current Stirling cryocoolers in which the compressor mechanisms are remote from the Stirling displacer mechanism. Placing all of the mechanisms in a single volume and on a single axis provides benefits in terms of package size (30% reduction), mass (30% reduction), thermodynamic efficiency (>20% improvement) and exported vibration performance (≤25 mN peak in all three orthogonal axes at frequencies from 1 to 500 Hz). The main benefit of axial symmetry is that proven balancing

Advances in single- and multi-stage Stirling-type pulse tube cryocoolers for space applications in NLIP/SITP/CAS

Science.gov (United States)

Dang, Haizheng; Tan, Jun; Zha, Rui; Li, Jiaqi; Zhang, Lei; Zhao, Yibo; Gao, Zhiqian; Bao, Dingli; Li, Ning; Zhang, Tao; Zhao, Yongjiang; Zhao, Bangjian

2017-12-01

This paper presents a review of recent advances in single- and multi-stage Stirling-type pulse tube cryocoolers (SPTCs) for space applications developed at the National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences (NLIP/SITP/CAS). A variety of single-stage SPTCs operating at 25-150 K have been developed, including several mid-sized ones operating at 80-110 K. Significant progress has been achieved in coolers operating at 30-40 K which use common stainless steel meshes as regenerator matrices. Another important advance is the micro SPTCs with an overall mass of 300-800 g operating at high frequencies varying from 100 Hz to 400 Hz. The main purpose of developing two-stage SPTCs is to simultaneously acquire cooling capacities at both stages, obviating the need for auxiliary precooling in various applications. The three-stage SPTCs are developed mainly for applications at around 10 K, which are also used for precooling the J-T coolers to achieve further lower temperatures. The four-stage SPTCs are developed to directly achieve the liquid helium temperature for cooling space low-Tc superconducting devices and for the deep space exploration as well. Several typical development programs are described and an overview of the cooler performances is presented.

Advanced cryocooler electronics for space

Energy Technology Data Exchange (ETDEWEB)

Harvey, D.; Danial, A.; Godden, J.; Jackson, M.; McCuskey, J.; Valenzuela, P. [Northrop Grumman Space Technology, Redondo Beach, CA (United States); Davis, T. [Air Force Research Lab., Albuquerque, NM (United States)

2004-08-01

Space pulse-tube cryocoolers require electronics to control the cooling temperature and self-induced vibration. Other functions include engineering diagnostics, telemetry and safety protection of the unit against extreme environments and operational anomalies. The electronics must survive the harsh conditions of launch and orbit, and in some cases severe radiation environments for periods exceeding 10 years. A number of our current generation high reliability radiation hardened electronics units have been launched and others are in various stages of assembly or integration on a number of space flight programs. This paper describes the design features and performance of our next generation flight electronics designed for the STSS payloads. The electronics provides temperature control with better than +/-50 mK short-term stability. Self-induced vibration is controlled to low levels on all harmonics up to the 16th. A unique active power filter limits peak-to-peak reflected ripple current on the primary power bus to less than 3% of the average DC current. The 3 kg unit is capable of delivering 180 W continuous to NGST's high-efficiency cryocooler (HEC). (author)

Experimental study on a co-axial pulse tube cryocooler driven by a small thermoacoustic stirling engine

Science.gov (United States)

Chen, M.; Ju, L. Y.; Hao, H. X.

2014-01-01

Small scale thermoacoustic heat engines have advantages in fields like space exploration and domestic applications considering small space occupation and ease of transport. In the present paper, the influence of resonator diameter on the general performance of a small thermoacoustic Stirling engine was experimentally investigated using helium as the working gas. Reducing the diameter of the resonator appropriately is beneficial for lower onset heating temperature, lower frequency and higher pressure amplitude. Based on the pressure distribution in the small thermoacoustic engine, an outlet for the acoustic work transmission was made to combine the engine and a miniature co-axial pulse tube cooler. The cooling performance of the whole refrigeration system without any moving part was tested. Experimental results showed that further efforts are required to optimize the engine performance and its match with the co-axial pulse tube cooler in order to obtain better cooling performance, compared with its original operating condition, driven by a traditional electrical linear compressor.

Miniature PT Cryocooler Activated by Resonant Piezoelectric Compressor and Passive Warm Expander

Science.gov (United States)

Sobol, S.; Grossman, G.

2017-12-01

A novel type of PZT-based compressor operating at mechanical resonance, suitable for pneumatically-driven Stirling-type cryocoolers, was presented at CEC-ICMC 2015. The detailed concept, analytical model and the test results on the preliminary prototype were reported earlier and presented at ICC17. Despite some mismatch between the impedances and insufficient structural stiffness, this compressor demonstrated the feasibility to drive our miniature Pulse Tube cryocooler MTSa, operating at 103 Hz and requiring an average PV power of 11 W, filling pressure of 40 Bar and a pressure ratio of 1.3. At ICC19 the prototype of a miniature passive warm expander (WE) was presented. The WE mechanism included a phase shifting piston suspended on a silicone diaphragm, a mass element, and a viscous damping system. Several technical drawbacks prevented perfect matching between the WE and MTSa; however, the presented prototype proved the ability to create any flow-to-pressure phase appropriate for a PT cryocooler. This paper concentrates on integration of the MTSa cryocooler with the recently modified PZT compressor operating at corrected mechanical resonance and the modified WE, which was also updated recently to match the MTSa requirements.

Low-Cost High-Performance Cryocoolers for In-Situ Propellant Production

Science.gov (United States)

Martin, J. L.; Corey, J. A.; Peters, T. A.

1999-01-01

A key feature of many In-Situ Resource Utilization (ISRU) schemes is the production of rocket fuel and oxidizer from the Martian atmosphere. Many of the fuels under consideration will require cryogenic cooling for efficient long-term storage. Although significant research has been focused on the techniques for producing the fuels from Martian resources, little effort has been expended on the development of cryocoolers to efficiently liquefy these fuels. This paper describes the design of a pulse tube liquefier optimized for liquefying oxygen produced by an In-Situ Propellant Production (ISPP) plant on Mars.

Theoretical and experimental investigations on the cooling capacity distributions at the stages in the thermally-coupled two-stage Stirling-type pulse tube cryocooler without external precooling

Science.gov (United States)

Tan, Jun; Dang, Haizheng

2017-03-01

The two-stage Stirling-type pulse tube cryocooler (SPTC) has advantages in simultaneously providing the cooling powers at two different temperatures, and the capacity in distributing these cooling capacities between the stages is significant to its practical applications. In this paper, a theoretical model of the thermally-coupled two-stage SPTC without external precooling is established based on the electric circuit analogy with considering real gas effects, and the simulations of both the cooling performances and PV power distribution between stages are conducted. The results indicate that the PV power is inversely proportional to the acoustic impedance of each stage, and the cooling capacity distribution is determined by the cold finger cooling efficiency and the PV power into each stage together. The design methods of the cold fingers to achieve both the desired PV power and the cooling capacity distribution between the stages are summarized. The two-stage SPTC is developed and tested based on the above theoretical investigations, and the experimental results show that it can simultaneously achieve 0.69 W at 30 K and 3.1 W at 85 K with an electric input power of 330 W and a reject temperature of 300 K. The consistency between the simulated and the experimental results is observed and the theoretical investigations are experimentally verified.

CFD simulation and experimental validation of a GM type double inlet pulse tube refrigerator

Science.gov (United States)

Banjare, Y. P.; Sahoo, R. K.; Sarangi, S. K.

2010-04-01

Pulse tube refrigerator has the advantages of long life and low vibration over the conventional cryocoolers, such as GM and stirling coolers because of the absence of moving parts in low temperature. This paper performs a three-dimensional computational fluid dynamic (CFD) simulation of a GM type double inlet pulse tube refrigerator (DIPTR) vertically aligned, operating under a variety of thermal boundary conditions. A commercial computational fluid dynamics (CFD) software package, Fluent 6.1 is used to model the oscillating flow inside a pulse tube refrigerator. The simulation represents fully coupled systems operating in steady-periodic mode. The externally imposed boundary conditions are sinusoidal pressure inlet by user defined function at one end of the tube and constant temperature or heat flux boundaries at the external walls of the cold-end heat exchangers. The experimental method to evaluate the optimum parameters of DIPTR is difficult. On the other hand, developing a computer code for CFD analysis is equally complex. The objectives of the present investigations are to ascertain the suitability of CFD based commercial package, Fluent for study of energy and fluid flow in DIPTR and to validate the CFD simulation results with available experimental data. The general results, such as the cool down behaviours of the system, phase relation between mass flow rate and pressure at cold end, the temperature profile along the wall of the cooler and refrigeration load are presented for different boundary conditions of the system. The results confirm that CFD based Fluent simulations are capable of elucidating complex periodic processes in DIPTR. The results also show that there is an excellent agreement between CFD simulation results and experimental results.

Advances in a high efficiency commercial pulse tube cooler

Science.gov (United States)

Zhang, Yibing; Li, Haibing; Wang, Xiaotao; Dai, Wei; Yang, Zhaohui; Luo, Ercang

2017-12-01

The pulse tube cryocooler has the advantage of no moving part at the cold end and offers a high reliability. To further extend its use in commercial applications, efforts are still needed to improve efficiency, reliability and cost effectiveness. This paper generalizes several key innovations in our newest cooler. The cooler consists of a moving magnet compressor with dual-opposed pistons, and a co-axial cold finger. Ambient displacers are employed to recover the expansion work to increase cooling efficiency. Inside the cold finger, the conventional flow straightener screens are replaced by a tapered throat between the cold heat exchanger and the pulse tube to strengthen its immunity to the working gas contamination as well as to simplify the manufacturing processes. The cold heat exchanger is made by copper forging process which further reduces the cost. Inside the compressor, a new gas bearing design has brought in assembling simplicity and running reliability. Besides the cooler itself, electronic controller is also important for actual application. A dual channel and dual driving mode control mechanism has been selected, which reduces the vibration to a minimum, meanwhile the cool-down speed becomes faster and run-time efficiency is higher. With these innovations, the cooler TC4189 reached a no-load temperature of 44 K and provided 15 W cooling power at 80K, with an input electric power of 244 W and a cooling water temperature of 23 ℃. The efficiency reached 16.9% of Carnot at 80 K. The whole system has a total mass of 4.3 kg.

Design of a large heat lift 40 K to 80 K pulse tube cryocooler for space applications

NARCIS (Netherlands)

Trollier, T.; Tanchon, J.; Buquet, J.; Ravex, A.; Charles, I.; Coynel, A.; Duband, L.; Ercolani, E.; Guillemet, L.; Mullié, J.; Dam, J.A.M.; Benschop, T.; Linder, M.; Miller, S.D.; Ross, Jr. R.G.

2007-01-01

A Large heat lift Pulse Tube Cooler (LPTC) is under development in partnership with AL/ DTA, CEA/SBT and THALES Cryogenics. The engineering model is expected to provide 2.3 W at 50 K at a 10 °C rejection temperature and 160 watts of electrical input power to the compressor. The split coaxial design

Two-stage high frequency pulse tube refrigerator with base temperature below 10 K

Science.gov (United States)

Chen, Liubiao; Wu, Xianlin; Liu, Sixue; Zhu, Xiaoshuang; Pan, Changzhao; Guo, Jia; Zhou, Yuan; Wang, Junjie

2017-12-01

This paper introduces our recent experimental results of pulse tube refrigerator driven by linear compressor. The working frequency is 23-30 Hz, which is much higher than the G-M type cooler (the developed cryocooler will be called high frequency pulse tube refrigerator in this paper). To achieve a temperature below 10 K, two types of two-stage configuration, gas coupled and thermal coupled, have been designed, built and tested. At present, both types can achieve a no-load temperature below 10 K by using only one compressor. As to gas-coupled HPTR, the second stage can achieve a cooling power of 16 mW/10K when the first stage applied a 400 mW heat load at 60 K with a total input power of 400 W. As to thermal-coupled HPTR, the designed cooling power of the first stage is 10W/80K, and then the temperature of the second stage can get a temperature below 10 K with a total input power of 300 W. In the current preliminary experiment, liquid nitrogen is used to replace the first coaxial configuration as the precooling stage, and a no-load temperature 9.6 K can be achieved with a stainless steel mesh regenerator. Using Er3Ni sphere with a diameter about 50-60 micron, the simulation results show it is possible to achieve a temperature below 8 K. The configuration, the phase shifters and the regenerative materials of the developed two types of two-stage high frequency pulse tube refrigerator will be discussed, and some typical experimental results and considerations for achieving a better performance will also be presented in this paper.

Thermal Analysis of Cryocooler-Cooled Bi2223 Pulsed Coil

International Nuclear Information System (INIS)

Miyazaki, H; Chigusa, S; Tanaka, I; Iwakuma, M; Funaki, K; Hayashi, H; Tomioka, A

2006-01-01

We fabricated a cryocooler-cooled Bi2223 superconducting pulsed coil and experimentally studied thermal runaway in dc or ac operation. We carried out numerical simulation of thermal properties of the coil in order to explain thermal runaway of the coil. Firstly, we analyzed the total heat generation of flux-flow loss and ac loss inside the winding from the experimental results of the external field losses and the E-J characteristics for the Bi2223 strands. Secondly, we numerically simulated the thermal properties by using 2- dimensional heat conduction equation with axial symmetry. The numerical simulation shows the relation between the initiation of thermal runaway and the temperature distribution with highly concentrated heat source in the winding. We have a semi-quantitative agreement between the numerical results and the experimental ones for the condition of the thermal runaway

An efficient cooling loop for connecting cryocooler to a helium reservoir

International Nuclear Information System (INIS)

Taylor, C.E.; Abbott, C.S.R.; Leitner, D.; Leitner, M.; Lyneis, C.M.

2003-01-01

The magnet system of the VENUS ECR Ion Source at LBNL has two 1.5-watt cryocoolers suspended in the cryostat vacuum. Helium vapor from the liquid reservoir is admitted to a finned condenser bolted to the cryocooler 2nd stage and returns as liquid via gravity. Small-diameter flexible tubes allow the cryocoolers to be located remotely from the reservoir. With 3.1 watts load, the helium reservoir is maintained at 4.35 K, 0.05K above the cryocooler temperature. Design, analysis, and performance are presented

Thermodynamic analysis of a pulse tube engine

International Nuclear Information System (INIS)

Moldenhauer, Stefan; Thess, André; Holtmann, Christoph; Fernández-Aballí, Carlos

2013-01-01

Highlights: ► Numerical model of the pulse tube engine process. ► Proof that the heat transfer in the pulse tube is out of phase with the gas velocity. ► Proof that a free piston operation is possible. ► Clarifying the thermodynamic working principle of the pulse tube engine. ► Studying the influence of design parameters on the engine performance. - Abstract: The pulse tube engine is an innovative simple heat engine based on the pulse tube process used in cryogenic cooling applications. The working principle involves the conversion of applied heat energy into mechanical power, thereby enabling it to be used for electrical power generation. Furthermore, this device offers an opportunity for its wide use in energy harvesting and waste heat recovery. A numerical model has been developed to study the thermodynamic cycle and thereby help to design an experimental engine. Using the object-oriented modeling language Modelica, the engine was divided into components on which the conservation equations for mass, momentum and energy were applied. These components were linked via exchanged mass and enthalpy. The resulting differential equations for the thermodynamic properties were integrated numerically. The model was validated using the measured performance of a pulse tube engine. The transient behavior of the pulse tube engine’s underlying thermodynamic properties could be evaluated and studied under different operating conditions. The model was used to explore the pulse tube engine process and investigate the influence of design parameters.

Performance of a tapered pulse tube

International Nuclear Information System (INIS)

Swift, G.; Allen, M.; Woolan, J.J.

1998-02-01

In a well instrumented pulse tube refrigerator having 1,500 W of cooling power at 125 K, the authors have measured the figure of merit of a tapered pulse tube at several operating points. At operating points near the operating point for which the taper was designed, the figure of merit is 0.96. This is close to the theoretical optimum figure of merit 0.97 calculated for this pulse tube considering only two loss mechanisms: heat conduction in the metal pulse tube wall and ordinary thermoacoustic heat transport in the gas within a few thermal penetration depths of the wall. At operating points farther from the design operating point, the measured figure of merit is much lower, as streaming driven convection adds a third loss mechanism

Optimizing the Thermoacoustic Pulse Tube Refrigerator Performances

Directory of Open Access Journals (Sweden)

E. V. Blagin

2014-01-01

Full Text Available The article deals with research and optimization of the thermoacoustic pulse tube refrigerator to reach a cryogenic temperature level. The refrigerator is considered as a thermoacoustic converter based on the modified Stirling cycle with helium working fluid. A sound pressure generator runs as a compressor. Plant model comprises an inner heat exchanger, a regenerative heat exchanger, a pulse tube, hot and cold heat exchangers at its ends, an inertial tube with the throttle, and a reservoir. A model to calculate the pulse tube thermoacoustic refrigerator using the DeltaEC software package has been developed to be a basis for calculation techniques of the pulse tube refrigerator. Momentum, continuity, and energy equations for helium refrigerant are solved according to calculation algorithm taking into account the porosity of regenerator and heat exchangers. Optimization of the main geometric parameters resulted in decreasing temperature of cold heat exchanger by 41,7 K. After optimization this value became equal to 115,01 K. The following parameters have been optimized: diameters of the feeding and pulse tube and heat exchangers, regenerator, lengths of the regenerator and pulse and inertial tubes, as well as initial pressure. Besides, global minimum of temperatures has been searched at a point of local minima corresponding to the optimal values of abovementioned parameters. A global-local minima difference is 0,1%. Optimized geometric and working parameters of the thermoacoustic pulse tube refrigerator are presented.

Status of pulse tube development at CEA/SBT

International Nuclear Information System (INIS)

Ravex, A.; Rolland, P.

1994-01-01

Interest in the pulse tube comes from its potential for high reliability and low level of induced vibration. A numerical model has been developed to provide a tool for practical design. It has been successfully validated against the experimental results obtained with a single stage double inlet pulse tube which has achieved a temperature of 28 K at a frequency of a few Hz. Further developments have demonstrated the capability of operating a pulse tube at higher frequencies in association with a Stirling pressure oscillator. Current projects include coaxial geometry for miniature pulse tubes with linear resonant pressure oscillators. A 4 K multistaged pulse tube is also in development. (authors). 5 figs., 12 refs

Experimental study and modelisation of a pulse tube refrigerator

International Nuclear Information System (INIS)

Ravex, A.; Rolland, P.; Liang, J.

1992-01-01

A test bench for pulse tube refrigerator characterization has been built. In various configurations (basic pulse tube, orifice pulse tube and double inlet pulse tube), the ultimate temperature and the cooling power have been measured as a function of pressure wave amplitude and frequency for various geometries. A lowest temperature of 28 K has been achieved in a single staged double inlet configuration. A modelisation taking into account wall heat pumping, enthalpy flow and regenerator inefficiency is under development. Preliminary calculation results are compared with experimental data

Linear Resonance Compressor for Stirling-Type Cryocoolers Activated by Piezoelectric Stack-Type Elements

International Nuclear Information System (INIS)

Sobol, S; Grossman, G

2015-01-01

A novel type of a PZT- based compressor operating at mechanical resonance, suitable for pneumatically-driven Stirling-type cryocoolers was developed theoretically and built practically during this research. A resonance operation at relatively low frequency was achieved by incorporating the piezo ceramics into the moving part, and by reducing the effective piezo stiffness using hydraulic amplification. The detailed concept, analytical model and the test results of the preliminary prototype were reported earlier and presented at ICC17 [2]. A fine agreement between the simulations and experiments spurred development of the current actual compressor designed to drive a miniature Pulse Tube cryocooler, particularly our MTSa model, which operates at 103 Hz and requires an average PV power of 11 W, filling pressure of 40 Bar and a pressure ratio of 1.3. The paper concentrates on design aspects and optimization of the governing parameters. The small stroke to diameter ratio (about 1:10) allows for the use of a composite diaphragm instead of a clearance-seal piston. The motivation is to create an adequate separation between the working fluid and the buffer gas of the compressor, thus preventing possible contamination in the cryocooler. Providing efficiency and power density similar to those of conventional linear compressors, the piezo compressor may serve as a good alternative for cryogenic applications requiring extreme reliability and absence of magnetic field interference. (paper)

Numerical simulation of pulse-tube refrigerators

NARCIS (Netherlands)

Lyulina, I.A.; Mattheij, R.M.M.; Tijsseling, A.S.; Waele, de A.T.A.M.

2004-01-01

A new numerical model has been introduced to study steady oscillatory heat and mass transfer in the tube section of a pulse-tube refrigerator. Conservation equations describing compressible gas flow in the tube are solved numerically, using high resolution schemes. The equation of conservation of

Experimental studies on twin PTCs driven by dual piston head linear compressor

Science.gov (United States)

Gour, Abhay S.; Joy, Joewin; Sagar, Pankaj; Sudharshan, H.; Mallappa, A.; Karunanithi, R.; Jacob, S.

2017-02-01

An experimental study on pulse tube cryocooler is presented with a twin pulse tube configuration. The study is conducted with a dual piston head linear compressor design which is developed indigenously. The two identical pulse tube cryocoolers are operated by a single linear motor which generates 1800 out of phase dual pressure waves. The advantages of the configuration being the reduction in fabrication cost and the increased cooling power. The compressor is driven at a frequency of 48 Hz using indigenously developed PWM based power supply. The CFD study of pulse tube cryocooler is discussed along with the experimental cool down results. A detailed experimental and FEM based studies on the fabrication procedure of heat exchangers is conducted to ensure better heat transfer in the same.

Eddy-current inspection of ferromagnetic tubing using pulsed magnetic saturation

Energy Technology Data Exchange (ETDEWEB)

Dodd, C V; Deeds, W E

1986-07-01

A pulsed eddy-current system has been designed and developed for nondestructive evaluation of 2.25Cr-1Mo steam generator tubing from the bore side. Since the tubing is ferromagnetic, a large current pulse is sent through a driver coil to produce magnetic saturation all the way through the tube wall. A pickup coil produces an output pulse that is dependent upon the tube properties as well as the driving pulse. The output pulse heights at selected times are used as data that are computer-correlated with calibration data taken from machined standards. Performance data, circuit diagrams, and computer programs are given for the system, which has been demonstrated to detect small flaws located near the outside of a thick ferromagnetic tube.

The pulsed-gas tube, statement and perspectives; Le tube a gaz pulse, bilan et perspectives

Energy Technology Data Exchange (ETDEWEB)

Domblides, J P; Neveau, P; Castaing-Lasvignottes, J [Laboratoire du froid du CNAM, 75 - Paris (France)

1998-12-31

The pulsed-gas tube has several advantages with respect to the other types of cryo-refrigerating machineries classically used to reach very low temperatures: no mobile parts moving at very low temperatures and no vibrations. However, this system discovered in 1963 is handicapped by its lack of power and by its low energy efficiency. Todays researches about pulsed-gas tubes concern: the technical adaptation of existing systems to applications where its simplicity makes it competitive, the improvement of its energetic performances (refrigerating power and range of temperatures of use), and the development of numerical models in order to better understand the functioning of the system and to optimize it. (J.S.) 19 refs.

The pulsed-gas tube, statement and perspectives; Le tube a gaz pulse, bilan et perspectives

Energy Technology Data Exchange (ETDEWEB)

Domblides, J.P.; Neveau, P.; Castaing-Lasvignottes, J. [Laboratoire du froid du CNAM, 75 - Paris (France)

1997-12-31

The pulsed-gas tube has several advantages with respect to the other types of cryo-refrigerating machineries classically used to reach very low temperatures: no mobile parts moving at very low temperatures and no vibrations. However, this system discovered in 1963 is handicapped by its lack of power and by its low energy efficiency. Todays researches about pulsed-gas tubes concern: the technical adaptation of existing systems to applications where its simplicity makes it competitive, the improvement of its energetic performances (refrigerating power and range of temperatures of use), and the development of numerical models in order to better understand the functioning of the system and to optimize it. (J.S.) 19 refs.

Development of miniature moving magnet cryocooler SX040

Science.gov (United States)

Rühlich, I.; Mai, M.; Rosenhagen, C.; Schreiter, A.; Möhl, C.

2011-06-01

State of the art high performance cooled IR systems need to have more than just excellent E/O performance. Minimum size weight and power (SWaP) are the design goals to meet our forces' mission requirements. Key enabler for minimum SWaP of IR imagers is the operation temperature of the focal plane array (FPA) employed. State of the art MCT or InAsSb nBn technology has the potential to rise the FPA temperature from 77 K to 130-150 K (high operation temperature HOT) depending on the specific cut-off wavelength. Using a HOT FPA will significantly lower SWaP and keep those parameters finally dominated by the employed cryocooler. Therefore compact high performance cryocoolers are mandatory. For highest MTTF life AIM developed its Flexure Bearing Moving Magnet product family "SF". Such coolers achieve more than 20000 h MTTF with Stirling type expander and more than 5 years MTTF life with Pulse Tube coldfinger (like for Space applications). To keep the high lifetime potential but to significantly improve SWaP AIM is developing its "SX" type cooler family. The new SX040 cooler incorporates a highly efficient dual piston Moving Magnet driving mechanism resulting in very compact compressor of less than 100mm length. The cooler's high lifetime is also achieved by placing the coils outside the helium vessel as usual for moving magnet motors. The mating ¼" expander is extremely compact with less than 63 mm length. This allows a total dewar length from optical window to expander warm end of less than 100 mm even for large cold shields. The cooler is optimized for HOT detectors with operating temperatures exceeding 95 K. While this kind of cooler is the perfect match for many applications, handheld sights or targeting devices for the dismounted soldier are even more challenging with respect to SWaP. AIM therefore started to develop an even smaller cooler type with single piston and balancer. This paper gives an overview on the development of this new compact cryocooler. Technical

Pressure cryocooling protein crystals

Science.gov (United States)

Kim, Chae Un [Ithaca, NY; Gruner, Sol M [Ithaca, NY

2011-10-04

Preparation of cryocooled protein crystal is provided by use of helium pressurizing and cryocooling to obtain cryocooled protein crystal allowing collection of high resolution data and by heavier noble gas (krypton or xenon) binding followed by helium pressurizing and cryocooling to obtain cryocooled protein crystal for collection of high resolution data and SAD phasing simultaneously. The helium pressurizing is carried out on crystal coated to prevent dehydration or on crystal grown in aqueous solution in a capillary.

Pulse tube coolers for Meteosat third generation

International Nuclear Information System (INIS)

Butterworth, James; Aigouy, Gérald; Chassaing, Clement; Debray, Benoît; Huguet, Alexandre

2014-01-01

Air Liquide's Large Pulse Tube Coolers (LPTC) will be used to cool the focal planes of the Infrared Sounder (IRS) and Flexible Combined Imager (FCI) instruments aboard the ESA/Eumetsat satellites Meteosat Third Generation (MTG). This cooler consists of an opposed piston linear compressor driving a pulse tube cold head and the associated drive electronics including temperature regulation and vibration cancellation algorithms. Preparations for flight qualification of the cooler are now underway. In this paper we present results of the optimization and qualification activities as well as an update on endurance testing

Low temperature high frequency coaxial pulse tube for space application

Energy Technology Data Exchange (ETDEWEB)

Charrier, Aurelia; Charles, Ivan; Rousset, Bernard; Duval, Jean-Marc [SBT, UMR-E CEA / UJF-Grenoble 1, INAC, 17, rue des Martyrs, Grenoble, F-38054 (France); Daniel, Christophe [CNES, 18, avenue Edouard Belin, Toulouse, F-31401 (France)

2014-01-29

The 4K stage is a critical step for space missions. The Hershel mission is using a helium bath, which is consumed day by day (after depletion, the space mission is over) while the Plank mission is equipped with one He4 Joule-Thomson cooler. Cryogenic chain without helium bath is a challenge for space missions and 4.2K Pulse-Tube working at high frequency (around 30Hz) is one option to take it up. A low temperature Pulse-Tube would be suitable for the ESA space mission EChO (Exoplanet Characterisation Observatory, expected launch in 2022), which requires around 30mW cooling power at 6K; and for the ESA space mission ATHENA (Advanced Telescope for High ENergy Astrophysics), to pre-cool the sub-kelvin cooler (few hundreds of mW at 15K). The test bench described in this paper combines a Gifford-McMahon with a coaxial Pulse-Tube. A thermal link is joining the intercept of the Pulse-Tube and the second stage of the Gifford-McMahon. This intercept is a separator between the hot and the cold regenerators of the Pulse-Tube. The work has been focused on the cold part of this cold finger. Coupled with an active phase shifter, this Pulse-Tube has been tested and optimized and temperatures as low as 6K have been obtained at 30Hz with an intercept temperature at 20K.

Comparison of pulsed fluoroscopy by direct control using a grid-controlled x-ray tube with pulsed fluoroscopy by primary control

International Nuclear Information System (INIS)

Chida, Koichi; Zuguchi, Masayuki; Ito, Daisuke; Sato, Kunihiko; Shimura, Hirotaka; Sasaki, Masatoshi

2001-01-01

Interventional radiology (IVR) procedures may involve high radiation doses that are potentially harmful to the patient. In IVR procedures, pulsed fluoroscopy can greatly decrease the radiation that the physician and patient receive. There are two types of pulsed fluoroscopy: direct control and primary (indirect) control. The purpose of this study was to compare pulsed fluoroscopy by direct control, using a grid-controlled x-ray tube, with pulsed fluoroscopy using primary control. For both types of pulsed fluoroscopy, we measured the waveforms (x-ray tube voltage, x-ray tube current, and x-ray output) and the relative radiation dose. In addition, we compared the decrease in radiation during pulsed fluoroscopy using a care filter. The studies were performed using a Siemens Bicor Plus x-ray System (direct control) and a Siemens Multistar Plus x-ray System (primary control). Using primary pulse control, a 50% decrease in the x-ray output waveform took approximately 0.5-1.0 msec, or longer with a lower x-ray tube current. Using direct pulse control, a 50% decrease in the x-ray output waveform took approximately 0.1 msec, and was independent of x-ray tube current. The rate of radiation reduction with primary pulse control using the care filter with a lower x-ray tube current had a slope exceeding 10%. Pulsed fluoroscopy by direct control using a grid-controlled x-ray tube permits an optimal radiation dose. To decrease the radiation in primary pulse control, a care filter must be used, particularly with a lower x-ray tube current. (author)

Research and simulation of intense pulsed beam transfer in electrostatic accelerate tube

International Nuclear Information System (INIS)

Li Chaolong; Shi Haiquan; Lu Jianqin

2012-01-01

To study intense pulsed beam transfer in electrostatic accelerate tube, the matrix method was applied to analyze the transport matrixes in electrostatic accelerate tube of non-intense pulsed beam and intense pulsed beam, and a computer code was written for the intense pulsed beam transporting in electrostatic accelerate tube. Optimization techniques were used to attain the given optical conditions and iteration procedures were adopted to compute intense pulsed beam for obtaining self-consistent solutions in this computer code. The calculations were carried out by using ACCT, TRACE-3D and TRANSPORT for different beam currents, respectively. The simulation results show that improvement of the accelerating voltage ratio can enhance focusing power of electrostatic accelerate tube, reduce beam loss and increase the transferring efficiency. (authors)

18th International Cryocooler Conference

CERN Document Server

Ross, Ronald G

2014-01-01

Cryocoolers 18 Cryocoolers 18 archives developments and performance measurements in the field of cryocoolers based on the contributions of leading international experts at the 18th International Cryocooler Conference that was held in Syracuse, New York, on June 9-12, 2014. The program of this conference lead to the 76 peer-reviewed papers that are published here. Over the years the International Cryocoolers Conference has become the preeminent worldwide conference for the presentation of the latest developments and test experiences with cryocoolers. The typical applications of this technology include cooling space and terrestrial infrared focal plane arrays, space x-ray detectors, medical applications, and a growing number of high-temperature superconductor applications.

Displacer Diameter Effect in Displacer Pulse Tube Refrigerator

Science.gov (United States)

Zhu, Shaowei

2017-12-01

Gas driving displacer pulse tube refrigerators are one of the work recovery type of pulse tube refrigerators whose theoretical efficiency is the same as Stirling refrigerators'. Its cooling power is from the displacement of the displacer. Displace diameter, rod diameter and pressure drop of the regenerator influence the displacement, which are investigated by numerical simulation. It is shown that the displacement ratio of the displacer over the piston is almost not affected by the displacer diameter at the same rod diameter ratio, or displacer with different diameters almost has the same performance.

One-dimensional numerical simulation of the Stirling-type pulse-tube refrigerator

NARCIS (Netherlands)

Etaati, M.; Mattheij, R.M.M.; Tijsseling, A.S.; Waele, de A.T.A.M.

2007-01-01

Change of title: One-dimensional numerical simulation of the Stirling-type pulse-tube cooler. Pulse-tube refrigeration (PTR) is a new technology for cooling down to extremely low temperatures. In this paper a particular type, the so-called Stirling single-stage refrigerator, is considered. A

17th International Cryocooler Conference

CERN Document Server

Ross, Ronald G

2012-01-01

Cryocoolers 17 archives developments and performance measurements in the field of cryocoolers based on the contributions of leading international experts at the 17th International Cryocooler Conference that was held in Los Angeles, California, on July 9-12, 2012. The program of this conference consisted of 94 papers; of these, 71 are published here. Over the years the International Cryocoolers Conference has become the preeminent worldwide conference for the presentation of the latest developments and test experiences with cryocoolers. The typical applications of this technology include cooling space and terrestrial infrared focal plane arrays, space x-ray detectors, medical applications, and a growing number of high-temperature superconductor applications.

16th International Cryocooler Conference

CERN Document Server

Ross, Ronald G

2011-01-01

Cryocoolers 16 archives developments and performance measurements in the field of cryocoolers based on the contributions of leading international experts at the 16th International Cryocooler Conference that was held in Atlanta, Georgia, on May 17-20, 2010. The program of this conference consisted of 116 papers; of these, 89 are published here. Over the years the International Cryocoolers Conference has become the preeminent worldwide conference for the presentation of the latest developments and test experiences with cryocoolers. The typical applications of this technology include cooling space and terrestrial infrared focal plane arrays, space x-ray detectors, medical applications, and a growing number of high-temperature superconductor applications.

10th International Cryocooler Conference

CERN Document Server

2002-01-01

Cryocoolers 10 is the premier archival publication of the latest advances and performance of small cryogenic refrigerators designed to provide localized cooling for military, space, semi-conductor, medical, computing, and high-temperature superconductor cryogenic applications in the 2-200 K temperature range. Composed of papers written by leading engineers and scientists in the field, Cryocoolers 10 reports the most recent advances in cryocooler development, contains extensive performance test results and comparisons, and relates the latest experience in integrating cryocoolers into advanced applications.

Cryogenic Thermal Absorptance Measurements on Small-Diameter Stainless Steel Tubing

Science.gov (United States)

Tuttle, James; Jahromi, Amir; Canavan, Edgar; DiPirro, Michael

2015-01-01

The Mid Infrared Instrument (MIRI) on the James Webb Space Telescope includes a mechanical cryocooler which cools its detectors to their 6 Kelvin operating temperature. The coolant gas flows through several meters of small-diameter stainless steel tubing, which is exposed to thermal radiation from its environment. Over much of its length this tubing is gold-plated to minimize the absorption of this radiant heat. In order to confirm that the cryocooler will meet MIRI's requirements, the thermal absorptance of this tubing was measured as a function of its environment temperature. We describe the measurement technique and present the results.

Tube welding by the pulsed tig method

International Nuclear Information System (INIS)

Dick, N.T.

1973-01-01

During the construction of the helical wound boiler pods for the AGR stations at Hartlepool and Heysham, automatic TIG-welding techniques were used. In some cases limited access excluded the use of wire feed techniques and autogenous techniques had to be used. To resolve the problem of excessive concavity which occurred when using constant current autogenous techniques on 14.5 mm OD mild steel tubes of 1.8 mm thickness, pulsed-TIG welding was applied. By modifying the trailing edge of the pulse to produce a crater fill with each pulse, susceptibility to porosity and solidification cracking was reduced. The incorporation of digital counter permitted pulse duration, background duration, and electrode indexing distance to be monitored. (U.K.)

A blind test on the pulse tube refrigerator model (PTRM)

International Nuclear Information System (INIS)

Yuan, S.W.K.; Radebaugh, R.

1996-01-01

The Stirling Refrigerator Performance Model (SRPM) has been validated extensively against the Lockheed built Stirling Coolers and various units in the literature. This model has been modified to predict the performance of the Pulse Tube Coolers (PTCs). It was successfully validated against a Lockheed in-house-built PTC. The results are to be published elsewhere. In this paper, the validation of PTRM against a NIST (National Institute of Standards and Technology) orifice pulse tube cooler is reported. Dimensions and operating condition of the PTC were obtained from NIST without prior knowledge of the performance. In other words, this is a open-quote blind test close-quote on the PTRM with the help of the National Institute of Standards and Technology. Good correlation was found between the test data and the prediction. PTRM is a generic model that gives accurate performance prediction of the pulse tube coolers

Development of a fluorescent cryocooler

International Nuclear Information System (INIS)

Edwards, B.C.; Buchwald, M.I.; Epstein, R.I.; Gosnell, T.R.; Mungan, C.E.

1995-01-01

Recent work at Los Alamos National Laboratory has demonstrated the physical principles for a new type of solid-state cryocooler based on anti-Stokes fluorescence. Design studies indicate that a vibration-free, low-mass ''fluorescent cryocooler'' could operate for years with efficiencies and cooling powers comparable to current commercial systems. This paper presents concepts for a fluorescent cryocooler, design considerations and expected performance

Performance characterization of the TRW 35K pulse tube cooler

International Nuclear Information System (INIS)

Collins, S.A.; Johnson, D.L.; Smedley, G.T.; Ross, R.G. Jr.

1996-01-01

The TRW 35K pulse tube cooler is configured as an integral cooler, with the pulse tube attached perpendicular to a pair of compressors operating into a common compression chamber. The cooler was optimized for 35K operation and has a nominal cooling capacity of 850 mW at 35 K with a cooler input power of 200 W. It also provides 2 W of cooling at 60 K for 90 W of input power. The cooler was extensively characterized by JPL, measuring the thermal performance and the cooler-generated vibration and EMI as a function of piston stroke and offset position. The thermal performance was found to be quite sensitive to the piston offset position. The pulse tube parasitic conduction levels were also measured and shown to have a strong angular dependence relative to gravity. Magnetic shielding studies were performed to examine radiated magnetic emission levels from compressors with and without shielding

International Cryocooler Conference

CERN Document Server

Cryocoolers 13

2005-01-01

This is the 13th volume in the conference series. Over the years the International Cryocoolers Conference has become the preeminent worldwide conference for the presentation of the latest developments and test experiences with cryocoolers. The typical applications of this technology include cooling space and terrestrial infrared focal plane arrays, space x-ray detectors, medical applications, and a growing number of high-temperature super-capacitor applications.

Ideal pulse-tube refrigerators with real gases

NARCIS (Netherlands)

Will, M.E.; Waele, de A.T.A.M.

2005-01-01

The factor of 100 difference between experiments and theory in the coefficient of performance (COP) of pulse-tube refrigerators is always attributed to the nonideal behavior of these devices. We show that the thermodynamic properties of the nonideal working fluid have a profound influence on the

Pressure heat pumping in the orifice pulse-tube refrigerator

International Nuclear Information System (INIS)

Boer, P.C.T. de

1996-01-01

The mechanism by which heat is pumped as a result of pressure changes in an orifice pulse-tube refrigerator (OPTR) is analyzed thermodynamically. The thermodynamic cycle considered consists of four steps: (1) the pressure is increased by a factor π 1 due to motion of a piston in the heat exchanger at the warm end of the regenerator; (2) the pressure is decreased by a factor π 2 due to leakage out of the orifice; (3) the pressure is further decreased due to motion of the piston back to its original position; (4) the pressure is increased to its value at the start of the cycle due to leakage through the orifice back into the pulse tube. The regenerator and the heat exchangers are taken to be perfect. The pressure is assumed to be uniform during the entire cycle. The temperature profiles of the gas in the pulse tube after each step are derived analytically. Knowledge of the temperature at which gas enters the cold heat exchanger during steps 3 and 4 provides the heat removed per cycle from this exchanger. Knowledge of the pressure as a function of piston position provides the work done per cycle by the piston. The pressure heat pumping mechanism considered is effective only in the presence of a regenerator. Detailed results are presented for the heat removed per cycle, for the coefficient of performance, and for the refrigeration efficiency as a function of the compression ratio π 1 and the expansion ratio π 2 . Results are also given for the influence on performance of the ratio of specific heats. The results obtained are compared with corresponding results for the basic pulse-tube refrigerator (BPTR) operating by surface heat pumping

Analytical Approximation of Spectrum for Pulse X-ray Tubes

International Nuclear Information System (INIS)

Vavilov, S; Fofanof, O; Koshkin, G; Udod, V

2016-01-01

Among the main characteristics of the pulsed X-ray apparatuses the spectral energy characteristics are the most important ones: the spectral distribution of the photon energy, effective and maximum energy of quanta. Knowing the spectral characteristics of the radiation of pulse sources is very important for the practical use of them in non-destructive testing. We have attempted on the analytical approximation of the pulsed X-ray apparatuses spectra obtained in the different experimental papers. The results of the analytical approximation of energy spectrum for pulse X-ray tube are presented. Obtained formulas are adequate to experimental data and can be used by designing pulsed X-ray apparatuses. (paper)

4th International Cryocoolers Conference

CERN Document Server

Patton, George; Knox, Margaret

1987-01-01

The Cryocoolers 4 proceedings archives the contributions of leading international experts at the 4th International Cryocooler Conference that was held in Easton, Maryland on September 25-26, 1986. About 170 people attended the conference representing 11 countries, 14 universities, 21 government laboratories and 60 industrial companies. Thirty-one papers were presented describing advancements and applications of cryocoolers in the temperature range below 80K. This year's conference was sponsored by the David Taylor Naval Ship Research and Development Center of Annapolis, Maryland, and the conference proceedings reproduced here was published by them.

Hydrodynamic parameters of micro porous media for steady and oscillatory flow: Application to cryocooler regenerators

Science.gov (United States)

Cha, Jeesung Jeff

Pulse Tube Cryocoolers (PTC) are a class of rugged and high-endurance refrigeration systems that operate without a moving part at their low temperature ends, and are capable of easily reaching 120°K. These devices can also be configured in multiple stages to reach temperatures below 10 °K. PTCs are particularly suitable for applications in space, missile guiding systems, cryosurgery, medicine preservation, superconducting electronics, magnetic resonance imaging, weather observation, and liquefaction of nitrogen. Although various designs of PTCs have been in use for a few decades, they represent a dynamic and developmental field. PTCs ruggedness comes at the price of relatively low efficiency, however, and thus far they have been primarily used in high-end applications. They have the potential of extensive use in consumer products, however, should sufficiently higher efficiencies be achieved. Intense research competition is underway worldwide, and newer designs are continuously introduced. Some of the fundamental processes that are responsible for their performance are at best not fully understood, however, and consequently systematic modeling of PTC systems is difficult. Among the challenges facing the PTC research community, besides improvement in terms of system efficiency, is the possible miniaturization (total fluid volume of few cubic centimeters (cc)) of these systems. The operating characteristics of a PTC are significantly different from the conventional refrigeration cycles. A PTC implements the theory of oscillatory compression and expansion of the gas within a closed volume to achieve desired refrigeration. Regenerators and pulse tubes are often viewed as the two most complex and essential components in cryocoolers. An important deficiency with respect to the state of art models dealing with PTCs is the essentially total lack of understanding about the directional hydrodynamic and thermal transport parameters associated with periodic flow in

Miniature Joule-Thomson cryocooling principles and practice

CERN Document Server

Maytal, Ben-Zion

2013-01-01

This book is the first in English being entirely dedicated to Miniature Joule-Thomson Cryocooling. The category of Joule-Thomson (JT) cryocoolers takes us back to the roots of cryogenics, in 1895, with figures like Linde and Hampson. The "cold finger" of these cryocoolers is compact, lacks moving parts, and sustains a large heat flux extraction at a steady temperature. Potentially, they cool down unbeatably fast. For example, cooling to below 100 K (minus 173 Celsius) might be accomplished within only a few seconds by liquefying argon. A level of about 120 K can be reached almost instantly with krypton. Indeed, the species of coolant plays a central role dictating the size, the intensity and the level of cryocooling. It is the JT effect that drives these cryocoolers and reflects the deviation of the "real" gas from the ideal gas properties. The nine chapters of the book are arranged in five parts. • The Common Principle of Cyrocoolers shared across the broad variety of cryocooler types • Theoretical Aspec...

5th International Conference on Cryocoolers

CERN Document Server

1989-01-01

The Cryocoolers 5 proceedings archives the contributions of leading international experts at the 5th International Cryocooler Conference that was held in Monterey, California on August 18-19, 1988. The authors submitted twenty six papers describing advancements and applications of cryocoolers in the temperature range below 80K. This year's conference was hosted by the U.S. Naval Postgraduate School in Monterey, California, and the conference proceedings reproduced here were published by the Wright-Patterson AFB in Ohio.

A compact nanosecond pulse generator for DBD tube characterization

Science.gov (United States)

Rai, S. K.; Dhakar, A. K.; Pal, U. N.

2018-03-01

High voltage pulses of very short duration and fast rise time are required for generating uniform and diffuse plasma under various operating conditions. Dielectric Barrier Discharge (DBD) has been generated by high voltage pulses of short duration and fast rise time to produce diffuse plasma in the discharge gap. The high voltage pulse power generators have been chosen according to the requirement for the DBD applications. In this paper, a compact solid-state unipolar pulse generator has been constructed for characterization of DBD plasma. This pulsar is designed to provide repetitive pulses of 315 ns pulse width, pulse amplitude up to 5 kV, and frequency variation up to 10 kHz. The amplitude of the output pulse depends on the dc input voltage. The output frequency has been varied by changing the trigger pulse frequency. The pulsar is capable of generating pulses of positive or negative polarity by changing the polarity of pulse transformer's secondary. Uniform and stable homogeneous dielectric barrier discharge plasma has been produced successfully in a xenon DBD tube at 400-mbar pressure using the developed high voltage pulse generator.

Numerical simulation of a three-stage Stirling-type pulse-tube refrigerator

NARCIS (Netherlands)

Etaati, M.A.

2011-01-01

The pulse-tube refrigerator (PTR) is a rather new device for cooling down to extremely low temperatures, i.e. below 4 K. The PTR works by the cyclic compression and expansion of helium that flows through a regenerator made of porous material, a cold heat exchanger, a tube, a hot heat exchanger and

Optimization of a Two Stage Pulse Tube Refrigerator for the Integrated Current Lead System

Science.gov (United States)

Maekawa, R.; Matsubara, Y.; Okada, A.; Takami, S.; Konno, M.; Tomioka, A.; Imayoshi, T.; Hayashi, H.; Mito, T.

2008-03-01

Implementation of a conventional current lead with a pulse tube refrigerator has been validated to be working as an Integrated Current Lead (ICL) system for the Superconducting Magnetic Energy Storage (SMES). Realization of the system is primarily accounted for the flexibility of a pulse tube refrigerator, which does not posses any mechanical piston and/or displacer. As for an ultimate version of the ICL system, a High Temperature Superconducting (HTS) lead links a superconducting coil with a conventional copper lead. To ensure the minimization of heat loads to the superconducting coil, a pulse tube refrigerator has been upgraded to have a second cooling stage. This arrangement reduces not only the heat loads to the superconducting coil but also the operating cost for a SMES system. A prototype two-stage pulse tube refrigerator, series connected arrangement, was designed and fabricated to satisfy the requirements for the ICL system. Operation of the first stage refrigerator is a four-valve mode, while the second stage utilizes a double inlet configuration to ensure its confined geometry. The paper discusses the optimization of second stage cooling to validate the conceptual design

On random pressure pulses in the turbine draft tube

Science.gov (United States)

Kuibin, P. A.; Shtork, S. I.; Skripkin, S. G.; Tsoy, M. A.

2017-04-01

The flow in the conical part of the hydroturbine draft tube undergoes various instabilities due to deceleration and flow swirling at off-design operation points. In particular, the precessing vortex rope develops at part-load regimes in the draft tube. This rope induces periodical low-frequency pressure oscillations in the draft tube. Interaction of rotational (asynchronous) mode of disturbances with the elbow can bring to strong oscillations in the whole hydrodynamical system. Recent researches on flow structure in the discharge cone in a regime of free runner had revealed that helical-like vortex rope can be unstable itself. Some coils of helix close to each other and reconnection appears with generation of a vortex ring. The vortex ring moves toward the draft tube wall and downstream. The present research is focused on interaction of vortex ring with wall and generation of pressure pulses.

15th International Cryocooler Conference

CERN Document Server

Ross, Ronald G

2009-01-01

This is the 15th volume in the conference series. Over the years the International Cryocooler Conference has become the preeminent worldwide conference for the presentation of the latest developments and test experiences with cryocoolers. The typical applications of this technology include cooling space and terrestrial infrared focal plane arrays, space x-ray detectors, medical applications, and a growing number of high-temperature superconductor applications.

14th International Cryocooler Conference

CERN Document Server

Ross, Ronald G

2007-01-01

This is the 14th volume in the conference series. Over the years the International Cryocoolers Conference has become the preeminent worldwide conference for the presentation of the latest developments and test experiences with cryocoolers. The typical applications of this technology include cooling space and terrestrial infrared focal plane arrays, space x-ray detectors, medical applications, and a growing number of high-temperature superconductor applications.

Development of a 100 KV 10 a pulse generator on the basis of electron tubes for plasma immersion ion implantation

International Nuclear Information System (INIS)

Kaur, Mandeep; Barve, D.N.; Chakravarthy, D.P.

2006-01-01

The design of a high-voltage pulsing system on the basis of hard tube of hard tube for a plasma immersion ion implantation (PIII) facility is presented. A list of requirements, which have to be fulfilled by a high-voltage pulse generator to get best results and an optimum operation of the PIII system, is given. The requirement for the pulse generator can be fulfilled well using a pulse generator design, which employs a hard tube switch. The pulse generator design presented is optimized for PIII systems. The hard tube control can produce nearly rectangular pulses of any duration and repetition frequencies and is especially optimized for obtaining voltage rise times as short as possible. (author)

High-power stirling-type pulse tube cooler for power engineering applications of high temperature superconductivity; Hochleistungspulsrohrkuehler vom Stirling-Typ fuer energietechnische Anwendungen der Hochtemperatursupraleitung

Energy Technology Data Exchange (ETDEWEB)

Dietrich, Marc

2015-12-15

For the cooling of high temperature superconducting 4 MVA machines (motors or generators), a single-stage Stirling-type pulse-tube cryocooler was built. The cooling power, which the cryocooler was aimed for, is 80 - 100 W at 30 K with an electrical input power of 10 kW (8 kW pV-power). The advantages of this cooler type compared to traditional cooling concepts are an increased reliability and long maintenance intervals. While single-stage Stirling-type pulse-tube cryocoolers for the temperature range of liquid nitrogen (77 K) are already commercially available, there exist currently no commercial systems for the temperature range near 30 K, which is the important range for applications of high-temperature superconductivity. The experimental setup consisted of a 10 kW linear compressor, type 2S297W, from CFIC Inc. which was used as the pressure wave generator. The compressor was operated by a Micromaster 440 frequency inverter from Siemens, which was controlled by a custom-made computer program. The cold head was made in inline configuration, in order to avoid deflection losses. During the first cool-downs tests a temperature inhomogeneity occurred in the regenerator at low temperature and high pV-power, which was attributed to a constant mass flow (circular dc-flow) within the regenerator. This firstly observed dc-flow, generates a net energy flow from the hot end to the cold end of the regenerator, which reduces the cooling capacity considerably and hence the minimum attainable temperature is severely increased. For the design and optimization of the cold-head, a cryocooler model was initially created using the commercial simulation software Sage, which did not include the regenerator inhomogeneity seen in the experiment. For the modeling of the observed streaming inhomogeneity caused by the dc-flow, the regenerator was replaced by two identical parallel regenerators with variable transverse thermal coupling. In the inhomogeneous case (without dc-flow) the

Outgas analysis of mechanical cryocoolers for long lifetime

Science.gov (United States)

Sato, Yoichi; Shinozaki, Keisuke; Sawada, Kenichiro; Sugita, Hiroyuki; Mitsuda, Kazuhisa; Yamasaki, Noriko Y.; Nakagawa, Takao; Tsunematsu, Shoji; Otsuka, Kiyomi; Kanao, Kenichi; Yoshida, Seiji; Narasaki, Katsuhiro

2017-12-01

Mechanical cryocoolers for space applications are required to have high reliability to achieve long-term operation in orbit. ASTRO-H (Hitomi), the 6th Japanese X-ray astronomy mission, has a major scientific instrument onboard-the Soft X-ray Spectrometer (SXS) with several 20K-class two-stage Stirling (2ST) coolers and a 4K-class Joule Thomson (JT) cooler, which must operate for 3 years to ensure the lifetime of liquid helium as a cryogen for cooling of its detectors [1,2]. Other astronomical missions such as SPICA [3,4], LiteBIRD [5], and Athena [6] also have top requirements for these mechanical cryocoolers, including a 1K-class JT cooler to be operated for more than 3-5 years with no cryogen system. The reliability and lifetime of mechanical cryocoolers are generally understood to depend on (1) mechanical wear of the piston seal and valve seal, and (2) He working gas contaminated by impurity outgases, mainly H2O and CO2 released from the materials in the components of the cryocoolers. The second factor could be critical relative to causing blockage in the JT heat exchanger plumbing and the JT orifice or resulting in blockage in the Stirling regenerator and thereby degrading its performance. Thus, reducing the potential for outgassing in the cryocooler design and fabrication process, and predicting the total amount of outgases in the cryocooler are very important to ensure cryocooler lifetime and cooling performance in orbit. This paper investigates the outgas analysis of the 2ST and the 1K/4K-JT coolers for achieving a long lifetime. First, gas analysis was conducted for the materials and components of the mechanical cryocoolers, focusing on non-metallic materials as impurity gas sources. Then gas analysis of the mechanical wear effect of the piston seal materials and linear ball bearings was investigated. Finally, outgassing from a fully assembled cryocooler was measured to evaluate whether the outgas reduction process works properly to meet the requirement

Useful scaling parameters for the pulse tube

International Nuclear Information System (INIS)

Lee, J.M.; Kittel, P.; Timmerhaus, K.D.

1996-01-01

A set of dimensionless scaling parameters for use in correlating performance data for Pulse Tube Refrigerators is presented. The dimensionless groups result after scaling the mass and energy conservation equations, and the equation of motion for an axisymmetric, two-dimensional ideal gas system. Allowed are viscous effects and conduction heat transfer between the gas and the tube wall. The scaling procedure results in reducing the original 23 dimensional variables to a set of 11 dimensionless scaling groups. Dimensional analysis is used to verify that the 11 dimensionless groups obtained is the minimum number needed to describe the system. The authors also examine 6 limiting cases which progressively reduce the number of dimensionless groups from 11 to 3. The physical interpretation of the parameters are described, and their usefulness is outlined for understanding how heat transfer and mass streaming affect ideal enthalpy flow

Nitrogen heat pipe for cryocooler thermal shunt

International Nuclear Information System (INIS)

Prenger F.C.; Hill, D.D.; Daney, D.E.

1996-01-01

A nitrogen heat pipe was designed, built and tested for the purpose of providing a thermal shunt between the two stages of a Gifford-McMahan (GM) cryocooler during cooldown. The nitrogen heat pipe has an operating temperature range between 63 and 123 K. While the heat pipe is in this temperature range during the system cooldown, it acts as a thermal shunt between the first and second stage of the cryocooler. The heat pipe increases the heat transfer to the first stage of the cryocooler, thereby reducing the cooldown time of the system. When the heat pipe temperature drops below the triple point, the nitrogen working fluid freezes, effectively stopping the heat pipe operation. A small heat leak between cryocooler stages remains because of axial conduction along the heat pipe wall. As long as the heat pipe remains below 63 K, the heat pipe remains inactive. Heat pipe performance limits were measured and the optimum fluid charge was determined

A 4 K tactical cryocooler using reverse-Brayton machines

Science.gov (United States)

Zagarola, M.; Cragin, K.; McCormick, J.; Hill, R.

2017-12-01

Superconducting electronics and spectral-spatial holography have the potential to revolutionize digital communications, but must operate at cryogenic temperatures, near 4 K. Liquid helium is undesirable for military missions due to logistics and scarcity, and commercial low temperature cryocoolers are unable to meet size, weight, power, and environmental requirements for many missions. To address this need, Creare is developing a reverse turbo-Brayton cryocooler that provides refrigeration at 4.2 K and rejects heat at 77 K to an upper-stage cryocooler or through boil-off of liquid nitrogen. The cooling system is predicted to reduce size, weight, and input power by at least an order of magnitude as compared to the current state-of-the-art 4.2 K cryocooler. For systems utilizing nitrogen boil-off, the boil-off rate is reasonable. This paper reviews the design of the cryocooler, the key components, and component test results.

MODELLING AND FAILURE ANALYSIS OF FLEXURE SPRINGS FOR A STIRLING CRYOCOOLER

Directory of Open Access Journals (Sweden)

RAJESH V. R.

2017-04-01

Full Text Available In the range of milliwatt to a few watts cooling capacity, Stirling cycle and pulse tube coolers are most suitable for producing cryogenic temperatures owing to their eco-friendliness, high efficiency, cooling capacity to mass ratio etc. The compressor of a Stirling cooler is powered by a linear motor. The power piston of the cooler is held in position and moves to and fro with the support of so called flexure springs or flexure bearings. Flexures avoid direct contact between moving parts of the compressor of the cooler. Thus, if designed adequately to withstand fatigue, flexure bearings can easily outlast rolling element bearings and slider bearings. In this work, a computational analysis is used to study the performance of flexure spring by varying the geometrical parameters. Three of the most common spring materials namely, SS304, beryllium copper and spring steel are considered for analysis. The analysis was made by varying the parameters like spiral sweep angle, slot width, number of spirals and disc thickness. The influence of each of these parameters on the fatigue life of the spring has been investigated. The results suggest that flexure springs of three spiral arms would be the ideal choice for the selected cryocooler. The variation of stress developed with respect to different design parameters and fatigue damage factor are presented graphically.

Air Force Research Laboratory Spacecraft Cryocooler Endurance Evaluation Facility Closing Report

Science.gov (United States)

Armstrong, J.; Martin, K. W.; Fraser, T.

2015-12-01

The Air Force Research Laboratory (AFRL) Spacecraft Component Thermal Research Group has been devoted to evaluating lifetime performance of space cryocooler technology for over twenty years. Long-life data is essential for confirming design lifetimes for space cryocoolers. Continuous operation in a simulated space environment is the only accepted method to test for degradation. AFRL has provided raw data and detailed evaluations to cryocooler developers for advancing the technology, correcting discovered deficiencies, and improving cryocooler designs. At AFRL, units of varying design and refrigeration cycles were instrumented in state-of-the-art experiment stands to provide spacelike conditions and were equipped with software data acquisition to track critical cryocooler operating parameters. This data allowed an assessment of the technology's ability to meet the desired lifetime and documented any long-term changes in performance. This paper will outline a final report of the various flight cryocoolers tested in our laboratory. The data summarized includes the seven cryocoolers tested during 2014-2015. These seven coolers have a combined total of 433,326 hours (49.5 years) of operation.

Study on pulsed-operation of the drift tube quadrupole magnets

International Nuclear Information System (INIS)

Mutou, M.

1982-01-01

The heavy ion linac for NUMATRON project is designed not only as a injector for a synchrotron but also as a supplier of heavy ion beams for experiments with linac beam. In one repetition cycle of the synchrotron (1sec), the linac injects nearly 25 beam pulses with pulse width of 300 μsec and pulse interval of 30 msec. And the ion species can be varied every repetition. On the other hand, when it is off duty of injection to the synchrotron, the linac accelerates the beams that are directly used for the experiments. Also in this case, the ion species should be varied according to the requests of the experiments, for instance every 1 sec. Therefore, the quadrupole magnets installed in the drift tubes of the linac must be excited with pulse mode. The power supply of the quadrupole magnets will consists of two parts, namely pulse-excitation and dc-excitation power sources. The report describes the posibilities on the pulse-operation of the quadrupole magnets with the field gradient of asymptotically equals 10 KG/cm, and the analysis of the power supply of the quadrupole magnets. (author)

MODIL cryocooler producibility demonstration project results

International Nuclear Information System (INIS)

Cruz, G.E.; Franks, R.M.

1993-01-01

The production of large quantities of spacecraft needed by SDIO will require a cultural change in design and production practices. Low rates production and the need for exceedingly high reliability has driven the industry to custom designed, hand crafted, and exhaustively tested satellites. These factors have mitigated against employing design and manufacturing cost reduction methods commonly used in tactical missile production. Additional challenges to achieving production efficiencies are presented by the SDI spacecraft mission requirement. IR sensor systems, for example, are comprised of subassemblies and components that require the design, manufacture, and maintenance of ultra precision tolerances over challenging operational lifetimes. These IR sensors demand the use of reliable, closed loop, cryogenic refrigerators or active cryocoolers to meet stringent system acquisition and pointing requirements. The authors summarize some spacecraft cryocooler requirements and discuss observations regarding Industry's current production capabilities of cryocoolers. The results of the Lawrence Livermore National Laboratory (LLNL) Spacecraft Fabrication and Test (SF and T) MODIL's Phase I producibility demonstration project is presented

A free-piston Stirling cryocooler using metal diaphragms

Science.gov (United States)

Caughley, Alan; Sellier, Mathieu; Gschwendtner, Michael; Tucker, Alan

2016-12-01

A novel concept for a free-piston Stirling cryocooler has been proposed. The concept uses a pair of metal diaphragms to seal and suspend the displacer of a free-piston Stirling cryocooler. The diaphragms allow the displacer to move without rubbing or moving seals, potentially resulting in a long-life mechanism. When coupled to a metal diaphragm pressure wave generator, the system produces a complete Stirling cryocooler with no rubbing parts in the working gas space. Initial modelling of this concept using the Sage modelling tool indicates the potential for a useful cryocooler. A proof-of-concept prototype was constructed and achieved cryogenic temperatures. A second prototype was designed and constructed using the experience gained from the first. The prototype produced 29 W of cooling at 77 K and reached a no-load temperature of 56 K. Sage predicted the macroscopic behaviour of the prototype well but did not provide sufficient insights to improve performance significantly. This paper presents details of the development, modelling and testing of the proof-of-concept prototype and a second, improved prototype.

One-dimensional simulation of a stirling three-stage pulse-tube refrigerator

NARCIS (Netherlands)

Etaati, M.A.; Mattheij, R.M.M.; Tijsseling, A.S.; Waele, de A.T.A.M.

2009-01-01

A one-dimensional mathematical model is derived for a three-stage pulse-tube refrigerator (PTR) that is based on the conservation laws and the ideal gas law. The three-stage PTR is regarded as three separate single-stage PTRs that are coupled via proper junction conditions. At the junctions there

One-dimensional simulation of a Stirling three-stage pulse-tube refrigerator

NARCIS (Netherlands)

Etaati, M.A.; Mattheij, R.M.M.; Tijsseling, A.S.; Waele, de A.T.A.M.

2009-01-01

A one-dimensional mathematical model is derived for a three-stage pulse-tube refrigerator (PTR) that is based on the conservation laws and the ideal gas law. The three-stage PTR is regarded as three separate single-stage PTRs that are coupled via proper junction conditions. At the junctions there

Magnet/cryocooler integration for thermal stability in conduction-cooled systems

Science.gov (United States)

Chang, H.-M.; Kwon, K. B.

2002-05-01

The stability conditions that take into accounts the size of superconducting magnets and the refrigeration capacity of cryocoolers are investigated for the conduction-cooled systems without liquid cryogens. The worst scenario in the superconducting systems is that the heat generation in the resistive state exceeds the refrigeration, causing a rise in the temperature of the magnet winding and leading to burnout. It is shown by an analytical solution that in the continuously resistive state, the temperature may increase indefinitely or a stable steady state may be reached, depending upon the relative size of the magnet with respect to the refrigeration capacity of the cryocooler. The stability criteria include the temperature-dependent properties of the magnet materials and the refrigeration characteristics of the cryocooler. A useful graphical scheme is presented and the design of the stable magnet/cryocooler interface is demonstrated.

Some characteristics of the digitization pulses from high pressure neon-helium flash tubes

International Nuclear Information System (INIS)

Chan, D.S.K.; Leung, S.K.; Ng, L.K.

1979-01-01

Characteristics of the digitization output pulses from high pressure neon-helium flash tubes were studied under various operation conditions using square ultra-high voltage pulses. Properties reported by previous workers were compared. Two discharge mechanisms, the Townsend avalanche discharge and the streamer discharge, were observed to occur in sequence in some events. The output waveforms for both discharge mechanisms were studied in detail. The charge induced on a detecting probe was also estimated from the measured data. (Auth.)

CFD analysis of a diaphragm free-piston Stirling cryocooler

Science.gov (United States)

Caughley, Alan; Sellier, Mathieu; Gschwendtner, Michael; Tucker, Alan

2016-10-01

This paper presents a Computational Fluid Dynamics (CFD) analysis of a novel free-piston Stirling cryocooler that uses a pair of metal diaphragms to seal and suspend the displacer. The diaphragms allow the displacer to move without rubbing or moving seals. When coupled to a metal diaphragm pressure wave generator, the system produces a complete Stirling cryocooler with no rubbing parts in the working gas space. Initial modelling of this concept using the Sage modelling tool indicated the potential for a useful cryocooler. A proof-of-concept prototype was constructed and achieved cryogenic temperatures. A second prototype was designed and constructed using the experience gained from the first. The prototype produced 29 W of cooling at 77 K and reached a no-load temperature of 56 K. The diaphragm's large diameter and short stroke produces a significant radial component to the oscillating flow fields inside the cryocooler which were not modelled in the one-dimensional analysis tool Sage that was used to design the prototypes. Compared with standard pistons, the diaphragm geometry increases the gas-to-wall heat transfer due to the higher velocities and smaller hydraulic diameters. A Computational Fluid Dynamics (CFD) model of the cryocooler was constructed to understand the underlying fluid-dynamics and heat transfer mechanisms with the aim of further improving performance. The CFD modelling of the heat transfer in the radial flow fields created by the diaphragms shows the possibility of utilizing the flat geometry for heat transfer, reducing the need for, and the size of, expensive heat exchangers. This paper presents details of a CFD analysis used to model the flow and gas-to-wall heat transfer inside the second prototype cryocooler, including experimental validation of the CFD to produce a robust analysis.

Dynamic simulation of 10 kW Brayton cryocooler for HTS cable

Science.gov (United States)

Chang, Ho-Myung; Park, Chan Woo; Yang, Hyung Suk; Hwang, Si Dole

2014-01-01

Dynamic simulation of a Brayton cryocooler is presented as a partial effort of a Korean governmental project to develop 1˜3 km HTS cable systems at transmission level in Jeju Island. Thermodynamic design of a 10 kW Brayton cryocooler was completed, and a prototype construction is underway with a basis of steady-state operation. This study is the next step to investigate the transient behavior of cryocooler for two purposes. The first is to simulate and design the cool-down process after scheduled or unscheduled stoppage. The second is to predict the transient behavior following the variation of external conditions such as cryogenic load or outdoor temperature. The detailed specifications of key components, including plate-fin heat exchangers and cryogenic turbo-expanders are incorporated into a commercial software (Aspen HYSYS) to estimate the temporal change of temperature and flow rate over the cryocooler. An initial cool-down scenario and some examples on daily variation of cryocooler are presented and discussed, aiming at stable control schemes of a long cable system.

Dynamic simulation of 10 kW Brayton cryocooler for HTS cable

International Nuclear Information System (INIS)

Chang, Ho-Myung; Park, Chan Woo; Yang, Hyung Suk; Hwang, Si Dole

2014-01-01

Dynamic simulation of a Brayton cryocooler is presented as a partial effort of a Korean governmental project to develop 1∼3 km HTS cable systems at transmission level in Jeju Island. Thermodynamic design of a 10 kW Brayton cryocooler was completed, and a prototype construction is underway with a basis of steady-state operation. This study is the next step to investigate the transient behavior of cryocooler for two purposes. The first is to simulate and design the cool-down process after scheduled or unscheduled stoppage. The second is to predict the transient behavior following the variation of external conditions such as cryogenic load or outdoor temperature. The detailed specifications of key components, including plate-fin heat exchangers and cryogenic turbo-expanders are incorporated into a commercial software (Aspen HYSYS) to estimate the temporal change of temperature and flow rate over the cryocooler. An initial cool-down scenario and some examples on daily variation of cryocooler are presented and discussed, aiming at stable control schemes of a long cable system

Dynamic simulation of 10 kW Brayton cryocooler for HTS cable

Energy Technology Data Exchange (ETDEWEB)

Chang, Ho-Myung; Park, Chan Woo [Hong Ik University, Department of Mechanical Engineering, Seoul, 121-791 (Korea, Republic of); Yang, Hyung Suk; Hwang, Si Dole [KEPCO Research Institute, Daejeon, 305-760 (Korea, Republic of)

2014-01-29

Dynamic simulation of a Brayton cryocooler is presented as a partial effort of a Korean governmental project to develop 1∼3 km HTS cable systems at transmission level in Jeju Island. Thermodynamic design of a 10 kW Brayton cryocooler was completed, and a prototype construction is underway with a basis of steady-state operation. This study is the next step to investigate the transient behavior of cryocooler for two purposes. The first is to simulate and design the cool-down process after scheduled or unscheduled stoppage. The second is to predict the transient behavior following the variation of external conditions such as cryogenic load or outdoor temperature. The detailed specifications of key components, including plate-fin heat exchangers and cryogenic turbo-expanders are incorporated into a commercial software (Aspen HYSYS) to estimate the temporal change of temperature and flow rate over the cryocooler. An initial cool-down scenario and some examples on daily variation of cryocooler are presented and discussed, aiming at stable control schemes of a long cable system.

Corrosion/erosion detection of boiler tubes utilizing pulsed infrared imaging

Science.gov (United States)

Bales, Maurice J.; Bishop, Chip C.

1995-05-01

This paper discusses a new technique for locating and detecting wall thickness reduction in boiler tubes caused by erosion/corrosion. Traditional means for this type of defect detection utilizes ultrasonics (UT) to perform a point by point measurement at given intervals of the tube length, which requires extensive and costly shutdown or `outage' time to complete the inspection, and has led to thin areas going undetected simply because they were located in between the sampling points. Pulsed infrared imaging (PII) can provide nearly 100% inspection of the tubes in a fraction of the time needed for UT. The IR system and heat source used in this study do not require any special access or fixed scaffolding, and can be remotely operated from a distance of up to 100 feet. This technique has been tried experimentally in a laboratory environment and verified in an actual field application. Since PII is a non-contact technique, considerable time and cost savings should be realized as well as the ability to predict failures rather than repairing them once they have occurred.

Cryocooler applications for high-temperature superconductor magnetic bearings

International Nuclear Information System (INIS)

Niemann, R. C.

1998-01-01

The efficiency and stability of rotational magnetic suspension systems are enhanced by the use of high-temperature superconductor (HTS) magnetic bearings. Fundamental aspects of the HTS magnetic bearings and rotational magnetic suspension are presented. HTS cooling can be by liquid cryogen bath immersion or by direct conduction, and thus there are various applications and integration issues for cryocoolers. Among the numerous cryocooler aspects to be considered are installation; operating temperature; losses; and vacuum pumping

Bruce and Darlington power pulse and pressure tube integrity programs -status 1995

Energy Technology Data Exchange (ETDEWEB)

Field, G J [Atomic Energy of Canada Ltd., Mississauga, ON (Canada); Wylie, J [Ontario Hydro, Tiverton, ON (Canada). Bruce Nuclear Generating Station-A

1996-12-31

The optimum solution to pressure tube fretting at the inlet of the Bruce and Darlington channels, a concern which became very serious following inspections in early 1992, is to remove the inlet bundle and operate with a 12 fuel bundle channel. During analysis of this operating mode a `power pulse` was identified which could occur during an inlet header break where all the fuel in the channel moved rapidly to the inlet of the channel. The pulse was unacceptable and the units were derated until solutions could be implemented. A number of solutions were identified and each station has begun implementation of their specific solution. Implementation has not been without problems and this paper provides a status report on the progress to date of the long bundle implementation solution for Bruce B and Darlington and the fuelling with the flow solution being implemented at Bruce A. Both types of solution have a significant impact on the original concern, fretting of the pressure tube. (author). 1 ref., 6 figs.

Development of 1 kW Stirling cryocooler using a linear compressor

International Nuclear Information System (INIS)

Ko, J; Kim, H; Hong, Y J; Yeom, H; In, S; Park, S J

2015-01-01

Cryogenic cooling systems for HTS electric power devices require a reliable and efficient high-capacity cryocooler. A Striling cryocooler with a linear compressor can be a good candidate. It has advantages of low vibration and long maintenance cycle compared with a kinematic-driven Stirling cryocooler. In this study, we developed a dual-opposed linear compressor of 12 kW electric input power with two 6 kW linear motors. Electrical performance of the fabricated linear compressor is verified by experimental measurement of thrust constant. The developed Stirling cryocooler has a gamma-type configuration. The piston and displacer are supported with a flexure spring. A slit-type heat exchanger is adopted for the cold and warm-end, and the generated heat is rejected by cooling water. In the cooling performance test, waveforms of voltage, current, displacement and pressure are obtained and their amplitude and phase difference are analysed. The developed cryocooler reaches 47.8 K within 23.4 min. with no-load. Heat load tests shows a cooling capacity of 440 W at 78.1 K with 6.45 kW of electric input power and 19.4 of % Carnot COP. (paper)

Production and guide tube transmission of very cold neutrons from pulsed cold source

International Nuclear Information System (INIS)

Utsuro, Masahiko; Okumura, Kiyoshi

1982-01-01

The intensity and the energy spectra of Very Cold Neutrons (VCN) transmitted through a curved guide tube were measured by using the time-of-flight method of VCN. In the measurements, the curved guide tube having a characteristic neutron velocity of about 70 m/s is combined to a pulsed cold source of an electron linac in an internal target geometry. A space dependence of the VCN spectra was observed on the radial positions of a detector at the guide tube exit. A simple theoretical analysis on the transmission of VCN in the curved guide tube is also presented with taking into consideration about the effects of a finite size and a finite distance of the VCN-emitting source, and simple analytical formulas for the exit spectra of the guide tube are given. Comparisons between the experimental results and the theoretical calculations show good agreements, and the satisfactory performance of the present VCN guide tube assembly was ascertained. These results present also instructive features for understanding the structures and the space dependence of the exit spectra of a neutron guide tube. The VCN spectra at the guide tube exit can be divided into a few energy regions according to the transmission processes of VCN. Thus, the present study provides useful informations for the preparations of a VCN source with a curved guide tube. (author)

Fatigue stress detection of VIRTIS cryocoolers on board Rosetta

Science.gov (United States)

Giuppi, Stefano; Politi, Romolo; Capria, Maria Teresa; Piccioni, Giuseppe; De Sanctis, Maria Cristina; Erard, Stéphane; Tosi, Federico; Capaccioni, Fabrizio; Filacchione, Gianrico

Rosetta is a planetary cornerstone mission of the European Space Agency (ESA). It is devoted to the study of minor bodies of our solar system and it will be the first mission ever to land on a comet (the Jupiter-family comet 67P/Churyumov-Gerasimenko). VIRTIS-M is a sophisticated imaging spectrometer that combines two data channels in one compact instrument, respectively for the visible and the infrared range (0.25-5.0 μm). VIRTIS-H is devoted to infrared spectroscopy (2.5-5.0 μm) with high spectral resolution. Since the satellite will be inside the tail of the comet during one of the most important phases of the mission, it would not be appropriate to use a passive cooling system, due to the high flux of contaminants on the radiator. Therefore the IR sensors are cooled by two Stirling cycle cryocoolers produced by RICOR. Since RICOR operated life tests only on ground, it was decided to conduct an analysis on VIRTIS onboard Rosetta telemetries with the purpose of study possible differences in the cryocooler performancies. The analysis led to the conclusion that cryocoolers, when operating on board, are subject to a fatigue stress not present in the on ground life tests. The telemetries analysis shows a cyclic variation in cryocooler rotor angular velocity when -M or -H or both channel are operating (it has been also noted an influence of -M channel operations in -H cryocooler rotor angular velocity and vice versa) with frequencies mostly linked to operational parameters values. The frequencies have been calculated for each mission observation applying the Fast Fourier Transform (FFT). In order to evaluate possible hedge effects it has been also applied the Hanning window to compare the results. For a more complete evaluation of cryocoolers fatigue stress, for each mission observation the angular acceleration and the angular jerk have been calculated.

Design of a Two-stage High-capacity Stirling Cryocooler Operating below 30K

Science.gov (United States)

Wang, Xiaotao; Dai, Wei; Zhu, Jian; Chen, Shuai; Li, Haibing; Luo, Ercang

The high capacity cryocooler working below 30K can find many applications such as superconducting motors, superconducting cables and cryopump. Compared to the GM cryocooler, the Stirling cryocooler can achieve higher efficiency and more compact structure. Because of these obvious advantages, we have designed a two stage free piston Stirling cryocooler system, which is driven by a moving magnet linear compressor with an operating frequency of 40 Hz and a maximum 5 kW input electric power. The first stage of the cryocooler is designed to operate in the liquid nitrogen temperature and output a cooling power of 100 W. And the second stage is expected to simultaneously provide a cooling power of 50 W below the temperature of 30 K. In order to achieve the best system efficiency, a numerical model based on the thermoacoustic model was developed to optimize the system operating and structure parameters.

Performance analysis on free-piston Stirling cryocooler based on an idealized mathematical model

Science.gov (United States)

Guo, Y. X.; Chao, Y. J.; Gan, Z. H.; Li, S. Z.; Wang, B.

2017-12-01

Free-piston Stirling cryocoolers have extensive applications for its simplicity in structure and decrease in mass. However, the elimination of the motor and the crankshaft has made its thermodynamic characteristic different from that of Stirling cryocoolers with displacer driving mechanism. Therefore, an idealized mathematical model has been established, and with this model, an attempt has been made to analyse the thermodynamic characteristic and the performance of free-piston Stirling cryocooler. To certify this mathematical model, a comparison has been made between the model and a numerical model. This study reveals that due to the displacer damping force necessary for the production of cooling capacity, the free-piston Stirling cryocooler is inherently less efficient than Stirling cryocooler with displacer driving mechanism. Viscous flow resistance and incomplete heat transfer in the regenerator are the two major causes of the discrepancy between the results of the idealized mathematical model and the numerical model.

Multi-pulsed intense electron beam emission from velvet, carbon fibers, carbon nano-tubes and dispenser cathodes

International Nuclear Information System (INIS)

Xia Liansheng; Yang Anmin; Chen Yi; Zhang Huang; Liu Xingguang; Li Jin; Jiang Xiaoguo; Zhang Kaizhi; Shi Jinshui; Deng Jianjun; Zhang Linwen

2010-01-01

The experimental results of studies of four kinds of cathode emitting intense electron beams are demonstrated under multi-pulsed mode based on an experimental setup including two multi-pulse high voltage sources. The tested cathodes include velvet, carbon fibers, carbon nano-tubes (CNTs) and dispenser cathodes. The results indicate that all four are able to emit multi-pulsed beams. For velvet, carbon fiber and CNTs, the electron induced cathode plasma emission may be the main process and this means that there are differences in beam parameters from pulse to pulse. For dispenser cathodes tested in the experiment, although there is a little difference from pulse to pulse for some reason, thermal-electric field emission may be the main process. (authors)

The effect of low temperature cryocoolers on the development of low temperature superconducting magnets

International Nuclear Information System (INIS)

Green, Michael A.

2000-01-01

The commercial development of reliable 4 K cryocoolers improves the future prospects for magnets made from low temperature superconductors (LTS). The hope of the developers of high temperature superconductors (HTS) has been to replace liquid helium cooled LTS magnets with HTS magnets that operate at or near liquid nitrogen temperature. There has been limited success in this endeavor, but continued problems with HTS conductors have greatly slowed progress toward this goal. The development of cryocoolers that reliably operate below 4 K will allow magnets made from LTS conductor to remain very competitive for many years to come. A key enabling technology for the use of low temperature cryocoolers on LTS magnets has been the development of HTS leads. This report describes the characteristics of LTS magnets that can be successfully melded to low-temperature cryocoolers. This report will also show when it is not appropriate to consider the use of low-temperature cryocoolers to cool magnets made with LTS conductor. A couple of specific examples of LTS magnets where cryocoolers can be used are given

Multi-objective parametric optimization of Inertance type pulse tube refrigerator using response surface methodology and non-dominated sorting genetic algorithm

Science.gov (United States)

Rout, Sachindra K.; Choudhury, Balaji K.; Sahoo, Ranjit K.; Sarangi, Sunil K.

2014-07-01

The modeling and optimization of a Pulse Tube Refrigerator is a complicated task, due to its complexity of geometry and nature. The aim of the present work is to optimize the dimensions of pulse tube and regenerator for an Inertance-Type Pulse Tube Refrigerator (ITPTR) by using Response Surface Methodology (RSM) and Non-Sorted Genetic Algorithm II (NSGA II). The Box-Behnken design of the response surface methodology is used in an experimental matrix, with four factors and two levels. The diameter and length of the pulse tube and regenerator are chosen as the design variables where the rest of the dimensions and operating conditions of the ITPTR are constant. The required output responses are the cold head temperature (Tcold) and compressor input power (Wcomp). Computational fluid dynamics (CFD) have been used to model and solve the ITPTR. The CFD results agreed well with those of the previously published paper. Also using the results from the 1-D simulation, RSM is conducted to analyse the effect of the independent variables on the responses. To check the accuracy of the model, the analysis of variance (ANOVA) method has been used. Based on the proposed mathematical RSM models a multi-objective optimization study, using the Non-sorted genetic algorithm II (NSGA-II) has been performed to optimize the responses.

Operating single quantum emitters with a compact Stirling cryocooler.

Science.gov (United States)

Schlehahn, A; Krüger, L; Gschrey, M; Schulze, J-H; Rodt, S; Strittmatter, A; Heindel, T; Reitzenstein, S

2015-01-01

The development of an easy-to-operate light source emitting single photons has become a major driving force in the emerging field of quantum information technology. Here, we report on the application of a compact and user-friendly Stirling cryocooler in the field of nanophotonics. The Stirling cryocooler is used to operate a single quantum emitter constituted of a semiconductor quantum dot (QD) at a base temperature below 30 K. Proper vibration decoupling of the cryocooler and its surrounding enables free-space micro-photoluminescence spectroscopy to identify and analyze different charge-carrier states within a single quantum dot. As an exemplary application in quantum optics, we perform a Hanbury-Brown and Twiss experiment demonstrating a strong suppression of multi-photon emission events with g((2))(0) Stirling-cooled single quantum emitter under continuous wave excitation. Comparative experiments performed on the same quantum dot in a liquid helium (LHe)-flow cryostat show almost identical values of g((2))(0) for both configurations at a given temperature. The results of this proof of principle experiment demonstrate that low-vibration Stirling cryocoolers that have so far been considered exotic to the field of nanophotonics are an attractive alternative to expensive closed-cycle cryostats or LHe-flow cryostats, which could pave the way for the development of high-quality table-top non-classical light sources.

Operating single quantum emitters with a compact Stirling cryocooler

Energy Technology Data Exchange (ETDEWEB)

Schlehahn, A.; Krüger, L.; Gschrey, M.; Schulze, J.-H.; Rodt, S.; Strittmatter, A.; Heindel, T., E-mail: tobias.heindel@tu-berlin.de; Reitzenstein, S. [Institute of Solid State Physics, Technische Universität Berlin, 10623 Berlin (Germany)

2015-01-15

The development of an easy-to-operate light source emitting single photons has become a major driving force in the emerging field of quantum information technology. Here, we report on the application of a compact and user-friendly Stirling cryocooler in the field of nanophotonics. The Stirling cryocooler is used to operate a single quantum emitter constituted of a semiconductor quantum dot (QD) at a base temperature below 30 K. Proper vibration decoupling of the cryocooler and its surrounding enables free-space micro-photoluminescence spectroscopy to identify and analyze different charge-carrier states within a single quantum dot. As an exemplary application in quantum optics, we perform a Hanbury-Brown and Twiss experiment demonstrating a strong suppression of multi-photon emission events with g{sup (2)}(0) < 0.04 from this Stirling-cooled single quantum emitter under continuous wave excitation. Comparative experiments performed on the same quantum dot in a liquid helium (LHe)-flow cryostat show almost identical values of g{sup (2)}(0) for both configurations at a given temperature. The results of this proof of principle experiment demonstrate that low-vibration Stirling cryocoolers that have so far been considered exotic to the field of nanophotonics are an attractive alternative to expensive closed-cycle cryostats or LHe-flow cryostats, which could pave the way for the development of high-quality table-top non-classical light sources.

A nonproprietary, nonsecret program for calculating Stirling cryocoolers

Science.gov (United States)

Martini, W. R.

1985-01-01

A design program for an integrated Stirling cycle cryocooler was written on an IBM-PC computer. The program is easy to use and shows the trends and itemizes the losses. The calculated results were compared with some measured performance values. The program predicts somewhat optimistic performance and needs to be calibrated more with experimental measurements. Adding a multiplier to the friction factor can bring the calculated rsults in line with the limited test results so far available. The program is offered as a good framework on which to build a truly useful design program for all types of cryocoolers.

Effects of cyclic mean pressure of helium gas on performance of integral crank driven stirling cryocooler

Energy Technology Data Exchange (ETDEWEB)

Hong, Yong Ju; Ko, Jun Seok; Kim, Hyo Bong; Park, Seong Je [Korea Institute of Machinery and Materials, Changwon (Korea, Republic of)

2016-09-15

An integral crank driven Stirling cryocooler is solidly based on concepts of direct IR detector mounting on the cryocooler's cold finger, and the integral construction of the cryocooler and Dewar envelope. Performance factors of the cryocooler depend on operating conditions of the cryocooler such as a cyclic mean pressure of the working fluid, a rotational speed of driving mechanism, a thermal environment, a targeted operation temperature and etc.. At given charging condition of helium gas, the cyclic mean pressure of helium gas in the cryocooler changes with temperatures of the cold end and the environment. In this study, effects of the cyclic mean pressure of helium gas on performances of the Stirling cryocooler were investigated by numerical analyses using the Sage software. The simulation model takes into account thermodynamic losses due to an inefficiency of regenerator, a pressure drop, a shuttle heat transfer and solid conductions. Simulations are performed for the performance variation according to the cyclic mean pressure induced by the temperature of the cold end and the environment. This paper presents P-V works in the compression and expansion space, cooling capacity, contribution of losses in the expansion space.

Effects of cyclic mean pressure of helium gas on performance of integral crank driven stirling cryocooler

International Nuclear Information System (INIS)

Hong, Yong Ju; Ko, Jun Seok; Kim, Hyo Bong; Park, Seong Je

2016-01-01

An integral crank driven Stirling cryocooler is solidly based on concepts of direct IR detector mounting on the cryocooler's cold finger, and the integral construction of the cryocooler and Dewar envelope. Performance factors of the cryocooler depend on operating conditions of the cryocooler such as a cyclic mean pressure of the working fluid, a rotational speed of driving mechanism, a thermal environment, a targeted operation temperature and etc.. At given charging condition of helium gas, the cyclic mean pressure of helium gas in the cryocooler changes with temperatures of the cold end and the environment. In this study, effects of the cyclic mean pressure of helium gas on performances of the Stirling cryocooler were investigated by numerical analyses using the Sage software. The simulation model takes into account thermodynamic losses due to an inefficiency of regenerator, a pressure drop, a shuttle heat transfer and solid conductions. Simulations are performed for the performance variation according to the cyclic mean pressure induced by the temperature of the cold end and the environment. This paper presents P-V works in the compression and expansion space, cooling capacity, contribution of losses in the expansion space

High-resolution X-ray crystal structure of bovine H-protein using the high-pressure cryocooling method

International Nuclear Information System (INIS)

Higashiura, Akifumi; Ohta, Kazunori; Masaki, Mika; Sato, Masaru; Inaka, Koji; Tanaka, Hiroaki; Nakagawa, Atsushi

2013-01-01

Using the high-pressure cryocooling method, the high-resolution X-ray crystal structure of bovine H-protein was determined at 0.86 Å resolution. This is the first ultra-high-resolution structure obtained from a high-pressure cryocooled crystal. Recently, many technical improvements in macromolecular X-ray crystallography have increased the number of structures deposited in the Protein Data Bank and improved the resolution limit of protein structures. Almost all high-resolution structures have been determined using a synchrotron radiation source in conjunction with cryocooling techniques, which are required in order to minimize radiation damage. However, optimization of cryoprotectant conditions is a time-consuming and difficult step. To overcome this problem, the high-pressure cryocooling method was developed (Kim et al., 2005 ▶) and successfully applied to many protein-structure analyses. In this report, using the high-pressure cryocooling method, the X-ray crystal structure of bovine H-protein was determined at 0.86 Å resolution. Structural comparisons between high- and ambient-pressure cryocooled crystals at ultra-high resolution illustrate the versatility of this technique. This is the first ultra-high-resolution X-ray structure obtained using the high-pressure cryocooling method

AIM cryocooler developments for HOT detectors

Science.gov (United States)

Rühlich, I.; Mai, M.; Withopf, A.; Rosenhagen, C.

2014-06-01

Significantly increased FPA temperatures for both Mid Wave and Long Wave IR detectors, i.e. HOT detectors, which have been developed in recent years are now leaving the development phase and are entering real application. HOT detectors allowing to push size weight and power (SWaP) of Integrated Detectors Cooler Assemblies (IDCA's) to a new level. Key component mainly driving achievable weight, volume and power consumption is the cryocooler. AIM cryocooler developments are focused on compact, lightweight linear cryocoolers driven by compact and high efficient digital cooler drive electronics (DCE) to also achieve highest MTTF targets. This technology is using moving magnet driving mechanisms and dual or single piston compressors. Whereas SX030 which was presented at SPIE in 2012 consuming less 3 WDC to operate a typical IDCA at 140K, next smaller cooler SX020 is designed to provide sufficient cooling power at detector temperature above 160K. The cooler weight of less than 200g and a total compressor length of 60mm makes it an ideal solution for all applications with limited weight and power budget, like in handheld applications. For operating a typical 640x512, 15μm MW IR detector the power consumption will be less than 1.5WDC. MTTF for the cooler will be in excess of 30,000h and thus achieving low maintenance cost also in 24/7 applications. The SX020 compressor is based on a single piston design with integrated passive balancer in a new design achieves very low exported vibration in the order of 100mN in the compressor axis. AIM is using a modular approach, allowing the chose between 5 different compressor types for one common Stirling expander. The 6mm expander with a total length of 74mm is now available in a new design that fits into standard dewar bores originally designed for rotary coolers. Also available is a 9mm coldfinger in both versions. In development is an ultra-short expander with around 35mm total length to achieve highest compactness. Technical

Regression analysis of pulsed eddy current signals for inspection of steam generator tube support structures

International Nuclear Information System (INIS)

Buck, J.; Underhill, P.R.; Mokros, S.G.; Morelli, J.; Krause, T.W.; Babbar, V.K.; Lepine, B.

2015-01-01

Nuclear steam generator (SG) support structure degradation and fouling can result in damage to SG tubes and loss of SG efficiency. Conventional eddy current technology is extensively used to detect cracks, frets at supports and other flaws, but has limited capabilities in the presence of multiple degradation modes or fouling. Pulsed eddy current (PEC) combined with principal components analysis (PCA) and multiple linear regression models was examined for the inspection of support structure degradation and SG tube off-centering with the goal of extending results to include additional degradation modes. (author)

New application of plate-fin heat exchanger with regenerative cryocoolers

Science.gov (United States)

Chang, Ho-Myung; Gwak, Kyung Hyun

2015-09-01

A design idea is newly proposed and investigated for the application of plate-fin heat exchanger (PFHX) with regenerative cryocoolers. The role of this heat exchanger is to effectively absorb heat from the stream of coolant and deliver it to the cold-head of a cryocooler. While various types of tubular HX's have been developed so far, a small PFHX could be more useful for this purpose by taking advantage of compactness and design flexibility. In order to confirm the feasibility and effectiveness, a prototype of aluminum-brazed PFHX is designed, fabricated, and tested with a single-stage GM cryocooler in experiments for subcooling liquid nitrogen from 78 K to 65-70 K. The results show that the PFHX is 30-50% more effective in cooling rate than the tubular HX's. Several potential applications of PFHX are presented and discussed with specific design concepts.

Design of a high-pressure single pulse shock tube for chemical kinetic investigations

International Nuclear Information System (INIS)

Tranter, R. S.; Brezinsky, K.; Fulle, D.

2001-01-01

A single pulse shock tube has been designed and constructed in order to achieve extremely high pressures and temperatures to facilitate gas-phase chemical kinetic experiments. Postshock pressures of greater than 1000 atmospheres have been obtained. Temperatures greater than 1400 K have been achieved and, in principle, temperatures greater than 2000 K are easily attainable. These high temperatures and pressures permit the investigation of hydrocarbon species pyrolysis and oxidation reactions. Since these reactions occur on the time scale of 0.5--2 ms the shock tube has been constructed with an adjustable length driven section that permits variation of reaction viewing times. For any given reaction viewing time, samples can be withdrawn through a specially constructed automated sampling apparatus for subsequent species analysis with gas chromatography and mass spectrometry. The details of the design and construction that have permitted the successful generation of very high-pressure shocks in this unique apparatus are described. Additional information is provided concerning the diaphragms used in the high-pressure shock tube

Dynamic Simulation of a Periodic 10 K Sorption Cryocooler

Science.gov (United States)

Bhandari, P.; Rodriguez, J.; Bard, S.; Wade, L.

1994-01-01

A transient thermal simulation model has been developed to simulate the dynamic performance of a multiple-stage 10 K sorption cryocooler for spacecraft sensor cooling applications that require periodic quick-cooldown (under 2 minutes) , negligible vibration, low power consumption, and long life (5 to 10 years). The model was specifically designed to represent the Brilliant Eyes Ten-Kelvin Sorption Cryocooler Experiment (BETSCE), but it can be adapted to represent other sorption cryocooler systems as well. The model simulates the heat transfer, mass transfer, and thermodynamic processes in the cryostat and the sorbent beds for the entire refrigeration cycle, and includes the transient effects of variable hydrogen supply pressures due to expansion and overflow of hydrogen during the cooldown operation. The paper describes model limitations and simplifying assumptions, with estimates of errors induced by them, and presents comparisons of performance predictions with ground experiments. An important benefit of the model is its ability to predict performance sensitivities to variations of key design and operational parameters. The insights thus obtained are expected to lead to higher efficiencies and lower weights for future designs.

A pulse-tube refrigerator using variable-resistance orifice

Science.gov (United States)

Huang, B. J.; Sun, B. W.

2003-01-01

In the present study, we propose a new design of orifice pulse-tube refrigerator (VROPT) using a variable-resistance valve to replace the conventional orifice. The variable-resistance orifice (VRO) is basically a high-speed solenoidal valve similar to the fuel jet device widely used in automobile engines. By changing the frequency and periods of ON and OFF of the valve through an electronic device, we can change the flow resistance of the VRO. This thus provides a possibility for an OPT to be controlled on-line during operation. From the results obtained in the present study, we have shown that VROPT is able to achieve on-line control by regulating the duty cycle d or frequency fv of the VRO. We also show that VROPT will not loss its thermal performance as compared to conventional OPT.

Temperature oscillation suppression of GM cryocooler

Science.gov (United States)

Okidono, K.; Oota, T.; Kurihara, H.; Sumida, T.; Nishioka, T.; Kato, H.; Matsumura, M.; Sasaki, O.

2012-12-01

GM cryocooler is a convenient refrigerator to achieve low temperatures about 4 K, while it is not suitable for precise measurements because of the large temperature oscillation of typically about 0.3 K. To resolve this problem, we have developed an adapter (He-pot) with a simple structure as possible. From the thermodynamic consideration, both heat capacity and thermal conductance should be large in order to reduce the temperature oscillation without compromising cooling power. Optimal structure of the He-pot is a copper cylinder filled with high pressure He-gas at room temperature. This can reduce the temperature oscillation to less than 10 mK below a certain temperature TH without compromising cooling power. TH are 3.8 and 4.5 for filled He-gas pressures of 90 and 60 atm, respectively. By using this He-pot, GM cryocooler can be applied to such as precise physical property measurements and THz detection.

Recent development status of compact 2 K GM cryocoolers

Science.gov (United States)

Bao, Q.; Xu, M. Y.; Tsuchiya, A.; Li, R.

2015-12-01

To meet the growing demand for a compact cooling solution for superconducting electronic devices, we developed a two-stage 2 K GM cryocooler and a cryostat system, which can reach 46.3 K / 2.2 K on the first and second stages under no-load conditions. Nevertheless, with several innovative technologies applied, the total length of the expander cylinder is reduced to under 70% of the smallest conventional 4 K GM cryocooler. In this paper we will present the design method, including material selection and structure design with detailed explanation, which has been confirmed by both simulation and experiment.

Two-Stage, 20 K Pulse Tube Cryocooler for Space Studies

Data.gov (United States)

National Aeronautics and Space Administration — American competitiveness and success are directly correlated with technological innovation and scientific research. NASA is known for its advanced concepts and...

Radial-pulse propagation and impedance characteristics of optically shuttered channel intensifier tubes

International Nuclear Information System (INIS)

Detch, J.L. Jr.; Noel, B.W.

1981-01-01

Electrically gated proximity-focused channel intensifier tubes are often used as optical shutters. Optimum nanosecond shuttering requires both understanding the electrical pulse propagation across the device structure and proper impedance matching. A distributed-transmission-line model is developed that describes analytically the voltage- and current-wave propagation characteristics as functions of time for any point on the surface. The optical gain's spatial uniformity and shutter-open times are shown to depend on the electrical pulse width and amplitude, and on the applied bias. The driving-point impedance is derived from the model and is expressed as a function of an infinite sum of terms in the complex frequency. The synthesis in terms of lumped-constant network elements is realized in first- and second-Foster equivalent circuits. Experimental impedance data are compared with the model's predictions and deviations from the ideal model are discussed

High-resolution X-ray crystal structure of bovine H-protein using the high-pressure cryocooling method.

Science.gov (United States)

Higashiura, Akifumi; Ohta, Kazunori; Masaki, Mika; Sato, Masaru; Inaka, Koji; Tanaka, Hiroaki; Nakagawa, Atsushi

2013-11-01

Recently, many technical improvements in macromolecular X-ray crystallography have increased the number of structures deposited in the Protein Data Bank and improved the resolution limit of protein structures. Almost all high-resolution structures have been determined using a synchrotron radiation source in conjunction with cryocooling techniques, which are required in order to minimize radiation damage. However, optimization of cryoprotectant conditions is a time-consuming and difficult step. To overcome this problem, the high-pressure cryocooling method was developed (Kim et al., 2005) and successfully applied to many protein-structure analyses. In this report, using the high-pressure cryocooling method, the X-ray crystal structure of bovine H-protein was determined at 0.86 Å resolution. Structural comparisons between high- and ambient-pressure cryocooled crystals at ultra-high resolution illustrate the versatility of this technique. This is the first ultra-high-resolution X-ray structure obtained using the high-pressure cryocooling method.

Experimental study of the pressure characteristics in the Stirling refrigerator

International Nuclear Information System (INIS)

Hong, Yong Ju; Park, Seong Je; Kim, Hyo Bong; Koh, Deuk Yong

2001-01-01

The linear compressor have been widely used for pressure wave generation in the Stirling cryocooler and Stirling type pulse tube cryocooler for tactical purpose. The linear compressor has small and compact structure, and long life due to having non-contact sealing mechanism and the pressure drop through regenerator was ver important role in the motion of displacer in the expander of the Stirling cryocooler. In this study, the characteristic of the linear compressor and the pressure drop through regenerator in the expander was experimentally investigated. The results show resonance of the compressor is very important to get maximum performance and the gas spring force in the compression space of the compressor has effect on the characteristic of resonance and the results show the pressure drop through regenerator is very small than operating pressure change

Reaction-time-resolved measurements of laser-induced fluorescence in a shock tube with a single laser pulse

Science.gov (United States)

Zabeti, S.; Fikri, M.; Schulz, C.

2017-11-01

Shock tubes allow for the study of ultra-fast gas-phase reactions on the microsecond time scale. Because the repetition rate of the experiments is low, it is crucial to gain as much information as possible from each individual measurement. While reaction-time-resolved species concentration and temperature measurements with fast absorption methods are established, conventional laser-induced fluorescence (LIF) measurements with pulsed lasers provide data only at a single reaction time. Therefore, fluorescence methods have rarely been used in shock-tube diagnostics. In this paper, a novel experimental concept is presented that allows reaction-time-resolved LIF measurements with one single laser pulse using a test section that is equipped with several optical ports. After the passage of the shock wave, the reactive mixture is excited along the center of the tube with a 266-nm laser beam directed through a window in the end wall of the shock tube. The emitted LIF signal is collected through elongated sidewall windows and focused onto the entrance slit of an imaging spectrometer coupled to an intensified CCD camera. The one-dimensional spatial resolution of the measurement translates into a reaction-time-resolved measurement while the species information can be gained from the spectral axis of the detected two-dimensional image. Anisole pyrolysis was selected as the benchmark reaction to demonstrate the new apparatus.

Performance degradation of space Stirling cryocoolers due to gas contamination

Science.gov (United States)

Liu, Xin-guang; Wu, Yi-nong; Yang, Shao-hua; Zhang, Xiao-ming; Lu, Guo-hua; Zhang, Li

2011-08-01

With extensive application of infrared detective techniques, Stirling cryocoolers, used as an active cooling source, have been developed vigorously in China. After the cooler's cooling performance can satisfy the mission's request, its reliability level is crucial for its application. Among all the possible failure mechanisms, gas contamination has been found to be the most notorious cause of cooler's performance degradation by failure analyses. To analyze the characteristic of gas contamination, some experiments were designed and carried out to quantitatively analyze the relationship between failure and performance. Combined with the test results and the outgassing characteristic of non-metal materials in the cryocooler, a degradation model of cooling performance was given by T(t)=T0+A[1-exp(-t/B)] under some assumptions, where t is the running time, T is the Kelvin cooling temperature, and T0, A, B are model parameters, which can be given by the least square method. Here T0 is the fitting initial cooling temperature, A is the maximum range of performance degradation, and B is the time dependent constant of degradation. But the model parameters vary when a cryocooler is running at different cooling temperature ranges, or it is treated by different cleaning process. In order to verify the applicability of the degradation model, data fit analysis on eight groups of cooler's lifetime test was carried out. The final work indicated this model fit well with the performance degradation of space Stirling cryocoolers due to gas contamination and this model could be used to predict or evaluation the cooler's lifetime. Gaseous contamination will not arouse severe performance degradation until the contaminants accumulate to a certain amount, but it could be fatal when it works. So it is more serious to the coolers whose lifetime is more than 10,000 h. The measures taken to control or minimize its damage were discussed as well. To the long-life cryocooler, internal materials

Low-T, Low-Q Cryocoolers for Science Instruments

Data.gov (United States)

National Aeronautics and Space Administration — The purpose of the planned research is to advance the current space science instruments through the development of light weight and low power cryocoolers. Currently,...

Steady Secondary Flows Generated by Periodic Compression and Expansion of an Ideal Gas in a Pulse Tube

Science.gov (United States)

Lee, Jeffrey M.

1999-01-01

This study establishes a consistent set of differential equations for use in describing the steady secondary flows generated by periodic compression and expansion of an ideal gas in pulse tubes. Also considered is heat transfer between the gas and the tube wall of finite thickness. A small-amplitude series expansion solution in the inverse Strouhal number is proposed for the two-dimensional axisymmetric mass, momentum and energy equations. The anelastic approach applies when shock and acoustic energies are small compared with the energy needed to compress and expand the gas. An analytic solution to the ordered series is obtained in the strong temperature limit where the zeroth-order temperature is constant. The solution shows steady velocities increase linearly for small Valensi number and can be of order I for large Valensi number. A conversion of steady work flow to heat flow occurs whenever temperature, velocity or phase angle gradients are present. Steady enthalpy flow is reduced by heat transfer and is scaled by the Prandtl times Valensi numbers. Particle velocities from a smoke-wire experiment were compared with predictions for the basic and orifice pulse tube configurations. The theory accurately predicted the observed steady streaming.

Small-sized accelerating tube for electron acceleration to 500 keV at pulse duration of 2 ns

International Nuclear Information System (INIS)

Pavlovskaya, N.G.; Ehl'yash, S.L.; Dron', N.A.; Sloeva, G.N.

1978-01-01

The design and characteristics (current, voltage, current density, electron beam structure, energy spectrum, and dose rate) of a soldered small-size two-electrode 600 kV accelerating tube are considered. A six-stage Arkadiev-Marx generator is the pulse high-voltage supply of nanosecond duration. When using a cathode (diameter of 8 mm) made of tantalum foil 0.02 mm thick and with interelectrode gap of 10 mm, the amplitude of the electron beam current beyond the beryllium anode equals to 1040 A under maximum voltage of 490 kV, current pulse duration of 2 ns, number of electrons is 10 13 . The increased electron density on the anode in a spot of 4 mm in diameter is observed; the current density in the spot reaches 1 kA/cm 2 . The electron energy in the beam beyond the anode is as much as 0.6-0.8 J per pulse, and the dose rate near the outer surface of the outlet window is 10 14 -10 15 rad/s. The use of an intensifying oil spark gap is shown to increase radiation hardness. The accelerating tube provides more than 10 5 shots in a single-switching mode

Numerical simulation of a three-stage stirling-type pulse-tube refrigerator

Energy Technology Data Exchange (ETDEWEB)

Etaati, M.A.

2011-06-22

The pulse-tube refrigerator (PTR) is a rather new device for cooling down to extremely low temperatures, i.e. below 4 K. The PTR works by the cyclic compression and expansion of helium that flows through a regenerator made of porous material, a cold heat exchanger, a tube, a hot heat exchanger and an orifice, in series. In a Stirling-type PTR compression and expansion are generated by a piston. The compression increases the temperature of the helium in the tube and makes it flow towards the orifice; the expansion decreases the temperature and makes the helium flow backwards to the regenerator. The net effect of warmer helium flowing in one direction and colder helium in the opposite direction is that of cooling power at the cold heat exchanger. Three PTRs are inter-connected aiming to obtain the desired 4 K lowest temperature. The conservation laws of mass, momentum and energy, and an equation of state, are simplified using asymptotic analysis based on low Mach-numbers. The regenerator is modelled one-dimensionally with Darcy's law for flow resistance. The tube is modelled either one-dimensionally without resistance or two-dimensionally with axisymmetric laminar viscous flow. The heat transfer in the porous medium of the regenerator and in the solid tube wall is taken into account. The gas can be either ideal or real. All the material properties, including viscosity and conductivity, are taken temperature and pressure dependent. Three single-stage PTRs are connected with the regenerators in series and the tubes in parallel and six flow possibilities at the junctions are considered. Three by-passes (double-inlets) are used to enhance and tune the performance. The governing equations are numerically solved with a finite-difference method of nominally second-order accuracy in space and time. Pressure correction, flux limiter, 1D-2D connections and domain decomposition are the keywords here. Special attention is paid to suitable initial conditions, high resolution

Cryogenic Thermal Emittance Measurements on Small-Diameter Stainless Steel Tubing

Science.gov (United States)

Jahromi, Amir E.; Tuttle, James G.; Canavan, Edgar R.

2017-01-01

The Mid Infrared Instrument aboard the James Webb Space Telescope includes a mechanical cryocooler which cools its detectors to their 6 K operating temperature. The refrigerant flows through several meters of 2 mm diameter 304L stainless steel tubing, with some sections gold plated, and some not, which are exposed to their environment. An issue of water freezing onto the tube surfaces is mitigated by running a warm gas through the lines to sublimate the frozen water. To model the effect of this process on nearby instruments, an accurate measure of the tube emittance is needed. Previously we reported the absorptance of the gold plated stainless steel tubing as a function of source temperature (i.e. its environment). In this work the thermal emittance of the uncoated tubing is measured as a function of its temperature between 100 and 280 K. These values lead to an accurate prediction of the minimum length of time required to thermally recycle the system. We report the technique and present the results.

Automated Cryocooler Monitor and Control System Software

Science.gov (United States)

Britchcliffe, Michael J.; Conroy, Bruce L.; Anderson, Paul E.; Wilson, Ahmad

2011-01-01

This software is used in an automated cryogenic control system developed to monitor and control the operation of small-scale cryocoolers. The system was designed to automate the cryogenically cooled low-noise amplifier system described in "Automated Cryocooler Monitor and Control System" (NPO-47246), NASA Tech Briefs, Vol. 35, No. 5 (May 2011), page 7a. The software contains algorithms necessary to convert non-linear output voltages from the cryogenic diode-type thermometers and vacuum pressure and helium pressure sensors, to temperature and pressure units. The control function algorithms use the monitor data to control the cooler power, vacuum solenoid, vacuum pump, and electrical warm-up heaters. The control algorithms are based on a rule-based system that activates the required device based on the operating mode. The external interface is Web-based. It acts as a Web server, providing pages for monitor, control, and configuration. No client software from the external user is required.

A pulsed eddy current probe for inspection of support plates from within Alloy-800 steam generator tubes

International Nuclear Information System (INIS)

Krause, T. W.; Babbar, V. K.; Underhill, P. R.

2014-01-01

Support plate degradation and fouling in nuclear steam generators (SGs) can lead to SG tube corrosion and loss of efficiency. Inspection and monitoring of these conditions can be integrated with preventive maintenance programs, thereby advancing station-life management processes. A prototype pulsed eddy current (PEC) probe, targeting inspection issues associated with SG tubes in SS410 tube support plate structures, has been developed using commercial finite element (FE) software. FE modeling was used to identify appropriate driver and pickup coil configurations for optimum sensitivity to changes in gap and offset for Alloy-800 SG tubes passing through 25 mm thick SS410 support plates. Experimental measurements using a probe that was manufactured based on the modeled configuration, were used to confirm the sensitivity of differential PEC signals to changes in relative position of the tube within the tube support plate holes. Models investigated the effect of shift and tilt of tube with respect to hole centers. Near hole centers and for small shifts, modeled signal amplitudes from the differentially connected coil pairs were observed to change linearly with tube shift. This was in agreement with experimentally measured TEC coil response. The work paves the way for development of a system targeting the inspection and evaluation of support plate structures in steam generators

A pulsed eddy current probe for inspection of support plates from within Alloy-800 steam generator tubes

Science.gov (United States)

Krause, T. W.; Babbar, V. K.; Underhill, P. R.

2014-02-01

Support plate degradation and fouling in nuclear steam generators (SGs) can lead to SG tube corrosion and loss of efficiency. Inspection and monitoring of these conditions can be integrated with preventive maintenance programs, thereby advancing station-life management processes. A prototype pulsed eddy current (PEC) probe, targeting inspection issues associated with SG tubes in SS410 tube support plate structures, has been developed using commercial finite element (FE) software. FE modeling was used to identify appropriate driver and pickup coil configurations for optimum sensitivity to changes in gap and offset for Alloy-800 SG tubes passing through 25 mm thick SS410 support plates. Experimental measurements using a probe that was manufactured based on the modeled configuration, were used to confirm the sensitivity of differential PEC signals to changes in relative position of the tube within the tube support plate holes. Models investigated the effect of shift and tilt of tube with respect to hole centers. Near hole centers and for small shifts, modeled signal amplitudes from the differentially connected coil pairs were observed to change linearly with tube shift. This was in agreement with experimentally measured TEC coil response. The work paves the way for development of a system targeting the inspection and evaluation of support plate structures in steam generators.

Neutron generator tube ion source control

International Nuclear Information System (INIS)

Bridges, J.R.

1982-01-01

A system is claimed for controlling the output of a neutron generator tube of the deuterium-tritium accelerator type and having an ion source to produce sharply defined pulses of neutrons for well logging use. It comprises: means for inputting a relatively low voltage input control pulse having a leading edge and a trailing edge; means, responsive to the input control pulse, for producing a relatively high voltage ion source voltage pulse after receipt of the input pulse; and means, responsive to the input control pulse, for quenching, after receipt of the input pulse, the ion source control pulse, thereby providing a sharply time defined neutron output from the generator tube

Numerical study on transverse asymmetry in the temperature profile of a regenerator in a pulse tube cooler

DEFF Research Database (Denmark)

Andersen, Stig Kildegård; Dietrich, M.; Carlsen, Henrik

2007-01-01

Transverse asymmetry in the temperature profile of the regenerator in a Stirling-type pulse tube cooler as observed in experiments was analysed in a numerical study. The asymmetry was reproduced using a one-dimensional model of the cooler where the regenerator was modelled using two identical...

Operating characteristics of a single-stage Stirling cryocooler capable of providing 700 W cooling power at 77 K

Science.gov (United States)

Xu, Ya; Sun, Daming; Qiao, Xin; Yu, Yan S. W.; Zhang, Ning; Zhang, Jie; Cai, Yachao

2017-04-01

High cooling capacity Stirling cryocooler generally has hundreds to thousands watts of cooling power at liquid nitrogen temperature. It is promising in boil-off gas (BOG) recondensation and high temperature superconducting (HTS) applications. A high cooling capacity Stirling cryocooler driven by a crank-rod mechanism was developed and studied systematically. The pressure and frequency characteristics of the cryocooler, the heat rejection from the ambient heat exchanger, and the cooling performance are studied under different charging pressure. Energy conversion and distribution in the cryocooler are analyzed theoretically. With an electric input power of 10.9 kW and a rotating speed of 1450 r/min of the motor, a cooling power of 700 W at 77 K and a relative Carnot efficiency of 18.2% of the cryocooler have been achieved in the present study, and the corresponding pressure ratio in the compression space reaches 2.46.

An experimental study for the phase shift between piston and displacer in the Stirling cryocooler

International Nuclear Information System (INIS)

Park, S. J.; Hong, Y. J.; Kim, H. B.; Son, H. K.; Yu, B. K.

2002-01-01

The small cryocooler is being widely applied to the areas of infrared detector, superconductor filter, satellite communication, and cryopump. The cryocooler working on the Stirling cycle are characterized by small size, lightweight, low power consumption and high reliability. For these reasons, FPFD (Free Piston Free Displacer) Stirling cryocooler is widely used not only tactical infrared imaging camera but also medical diagnostic apparatus. In this study, Stirling cryocooler actuated by the dual linear motor is designed and manufactured. And, displacement of the piston is measured by LVDTs (Linear Variable Differential Transformers), displacement of the displacer is measured by laser optic method, and phase shift between piston and displacer is discussed. Finally, when the phase shift between displacements of the piston and displacer is 45 .deg., operating frequency is optimum and is decided by resonant frequency of the expander, mass and cross section area of the displacer and constant by friction and flow resistance

An experimental study for the phase shift between piston and displacer in the Stirling cryocooler

Energy Technology Data Exchange (ETDEWEB)

Park, S. J.; Hong, Y. J.; Kim, H. B. [Korea Institute of Machinery and Materials, Taejon (Korea, Republic of); Son, H. K.; Yu, B. K. [Wooyoung Co., Ltd., Seoul (Korea, Republic of)

2002-07-01

The small cryocooler is being widely applied to the areas of infrared detector, superconductor filter, satellite communication, and cryopump. The cryocooler working on the Stirling cycle are characterized by small size, lightweight, low power consumption and high reliability. For these reasons, FPFD (Free Piston Free Displacer) Stirling cryocooler is widely used not only tactical infrared imaging camera but also medical diagnostic apparatus. In this study, Stirling cryocooler actuated by the dual linear motor is designed and manufactured. And, displacement of the piston is measured by LVDTs (Linear Variable Differential Transformers), displacement of the displacer is measured by laser optic method, and phase shift between piston and displacer is discussed. Finally, when the phase shift between displacements of the piston and displacer is 45 .deg., operating frequency is optimum and is decided by resonant frequency of the expander, mass and cross section area of the displacer and constant by friction and flow resistance.

Cryocooled superconducting magnets for high magnetic fields at the HFLSM and future collaboration with the TML

International Nuclear Information System (INIS)

Watanabe, K; Nishijima, G; Awaji, S; Koyama, K; Takahashi, K; Kobayashi, N; Kiyoshi, T

2006-01-01

A hybrid magnet needs a large amount of liquid helium for operation. In order to make an easy-to-operate hybrid magnet system, we constructed a cryocooled 28 T hybrid magnet, consisting of an outer cryocooled 10 T superconducting magnet and an inner traditional water-cooled 19 T resistive magnet. As a performance test, the cryocooled hybrid magnet generated 27.5 T in a 32 mm room temperature experimental bore. As long as Nb3Sn superconducting wires are employed, the expected maximum high field generation in the cryocooled superconducting magnet will be 17 T at 5 K. We adopted the high temperature superconducting insert coil, employing Ag-sheathed Bi 2 Sr 2 Ca 2 Cu 3 O 10 superconducting tape. In combination with the low temperature 16.5 T back-up coil with a 174 mm cold bore, the cryocooled high temperature superconducting magnet successfully generated the total central field of 18.1 T in a 52 mm room temperature bore. As a next step, we start the collaboration with the National Institute for Materials Science for the new developmental works of a 30 T high temperature superconducting magnet and a 50 T-class hybrid magnet

Modified-Collins cryocooler for zero-boiloff storage of cryogenic fuels in space

Science.gov (United States)

Hannon, Charles L.; Krass, Brady; Hogan, Jake; Brisson, John

2012-06-01

Future lunar and planetary explorations will require the storage of cryogenic propellants, particularly liquid oxygen (LOX) and liquid hydrogen (LH2), in low earth orbit (LEO) for periods of time ranging from days to months, and possibly longer. Without careful thermal management, significant quantities of stored liquid cryogens can be lost due to boil-off. Boil-off can be minimized by a variety of passive means including insulation, sun shades and passive radiational cooling. However, it has been shown that active cooling using space cryocoolers has the potential to result in Zero Boil-Off (ZBO) and the launch-mass savings using active cooling exceeds that of passive cooling of LOX for mission durations in LEO of less than 1 week, and for LH2 after about 2 months in LEO. Large-scale DC-flow cryogenic refrigeration systems operate at a fraction of the specific power levels required by small-scale AC-flow cryocoolers. The efficiency advantage of DC-flow cryogenic cycles motivates the current development of a cryocooler based on a modification of the Collins Cycle. The modified Collins cycle design employs piston type expanders that support high operating pressure ratios, electromagnetic valves that enable "floating pistons", and recuperative heat transfer. This paper will describe the design of a prototype Modified-Collins cryocooler for ZBO storage of cryogenic fuels in space.

Performance Characterization of the Astrium 10k Developmental Cryocooler

National Research Council Canada - National Science Library

Bruninghaus, C. H; Kallman, J. P; Tomlinson, B. J., Jr; Myrick, E

2002-01-01

.... Under the technology development program, Astrium (formerly Matra Marconi Space) in Stevenage, United Kingdom, developed a Stirling cycle cryocooler with four Oxford flexure compressors and a two-stage expansion cold end...

Stirling cryocooler test results and design model verification

International Nuclear Information System (INIS)

Shimko, M.A.; Stacy, W.D.; McCormick, J.A.

1990-01-01

This paper reports on progress in developing a long-life Stirling cycle cryocooler for space borne applications. It presents the results from tests on a preliminary breadboard version of the cryocooler used to demonstrate the feasibility of the technology and to validate the regenerator design code used in its development. This machine achieved a cold-end temperature of 65 K while carrying a 1/2 Watt cooling load. The basic machine is a double-acting, flexure-bearing, split Stirling design with linear electromagnetic drives for the expander and compressors. Flat metal diaphragms replace pistons for both sweeping and sealing the machine working volumes. In addition, the double-acting expander couples to a laminar-channel counterflow recuperative heat exchanger for regeneration. A PC compatible design code was developed for this design approach that calculates regenerator loss including heat transfer irreversibilities, pressure drop, and axial conduction in the regenerator walls

Photomultiplier tubes for Low Level Cerenkov Detectors

Energy Technology Data Exchange (ETDEWEB)

Strindehag, O

1965-03-15

Tube backgrounds of several 2-inch photomultiplier types having S11, 'S' , S13 and S20 cathodes are compared by measuring signal and background pulse height distributions at pulse heights corresponding to a few photo-electrons. The reference signal is generated by means of a {beta}-source and a plexiglass radiator. It is found that comparatively good results are obtained with selected tubes of the EMI types 6097B and 9514B having equivalent dark current dc values down to 10{sup -12} input lumens. Special interest is devoted to the correlation between the measured tube backgrounds and the dark current dc values of the tubes, as a good correlation between these parameters simplifies the selection of photomultiplier tubes. The equivalent dark currents of the tested tubes extend over the range 10{sup -12} to 10{sup -9} input lumens. Although the investigation deals with photomultiplier tubes intended for use in low level Cerenkov detectors it is believed that the results could be valuable in other fields where photomultiplier tubes are utilized for the detection of weak light pulses.

Photomultiplier tubes for Low Level Cerenkov Detectors

International Nuclear Information System (INIS)

Strindehag, O.

1965-03-01

Tube backgrounds of several 2-inch photomultiplier types having S11, 'S' , S13 and S20 cathodes are compared by measuring signal and background pulse height distributions at pulse heights corresponding to a few photo-electrons. The reference signal is generated by means of a β-source and a plexiglass radiator. It is found that comparatively good results are obtained with selected tubes of the EMI types 6097B and 9514B having equivalent dark current dc values down to 10 -12 input lumens. Special interest is devoted to the correlation between the measured tube backgrounds and the dark current dc values of the tubes, as a good correlation between these parameters simplifies the selection of photomultiplier tubes. The equivalent dark currents of the tested tubes extend over the range 10 -12 to 10 -9 input lumens. Although the investigation deals with photomultiplier tubes intended for use in low level Cerenkov detectors it is believed that the results could be valuable in other fields where photomultiplier tubes are utilized for the detection of weak light pulses

Sequentially pulsed traveling wave accelerator

Science.gov (United States)

Caporaso, George J [Livermore, CA; Nelson, Scott D [Patterson, CA; Poole, Brian R [Tracy, CA

2009-08-18

A sequentially pulsed traveling wave compact accelerator having two or more pulse forming lines each with a switch for producing a short acceleration pulse along a short length of a beam tube, and a trigger mechanism for sequentially triggering the switches so that a traveling axial electric field is produced along the beam tube in synchronism with an axially traversing pulsed beam of charged particles to serially impart energy to the particle beam.

Engineering model cryocooler test results

International Nuclear Information System (INIS)

Skimko, M.A.; Stacy, W.D.; McCormick, J.A.

1992-01-01

This paper reports that recent testing of diaphragm-defined, Stirling-cycle machines and components has demonstrated cooling performance potential, validated the design code, and confirmed several critical operating characteristics. A breadboard cryocooler was rebuilt and tested from cryogenic to near-ambient cold end temperatures. There was a significant increase in capacity at cryogenic temperatures and the performance results compared will with code predictions at all temperatures. Further testing on a breadboard diaphragm compressor validated the calculated requirement for a minimum axial clearance between diaphragms and mating heads

Highly Effective Thermal Regenerator for Low Temperature Cryocoolers, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Future missions to investigate the structure and evolution of the universe require highly efficient, low-temperature cryocoolers for low-noise detector systems. We...

A 4-Kelvin Pulse-Tube/Reverse-Brayton Hybrid Cryocooler, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — NASA's ability to perform cutting edge space science, including lunar and planetary exploration, requires the use of cryogenically cooled detectors and sensors for...

Miniature Turbine for Pulse-Tube/Reverse-Brayton Hybrid Cryocooler, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Many future advances in NASA's ability to perform cutting edge space science will require improvements in cryogenic system technology, including the development of...

Multimodal tuned dynamic absorber for split Stirling linear cryocooler

Science.gov (United States)

Veprik, A.; Tuito, A.

2017-02-01

Forthcoming low size, weight, power and price split Stirling linear cryocoolers may rely on electro-dynamically driven single-piston compressors and pneumatically driven expanders interconnected by the configurable transfer line. For compactness, compressor and expander units may be placed in a side-by-side manner, thus producing tonal vibration export comprising force and moment components. In vibration sensitive applications, this may result in excessive angular line of sight jitter and translational defocusing affecting the image quality. The authors present Multimodal Tuned Dynamic Absorber (MTDA), having one translational and two tilting modes essentially tuned to the driving frequency. The dynamic reactions (force and moment) produced by such a MTDA are simultaneously counterbalancing force and moment vibration export produced by the cryocooler. The authors reveal the design details, the method of fine modal tuning and outcomes of numerical simulation on attainable performance.

Mechanisms of amplification of ultrashort electromagnetic pulses in gyrotron traveling wave tube with helically corrugated waveguide

International Nuclear Information System (INIS)

Ginzburg, N. S.; Zaslavsky, V. Yu.; Zotova, I. V.; Sergeev, A. S.; Zheleznov, I. V.; Samsonov, S. V.; Mishakin, S. V.

2015-01-01

A time-domain self consistent theory of a gyrotron traveling wave tube with a helically corrugated operating waveguide has been developed. Based on this model, the process of short pulse amplification was studied in regimes of grazing and intersection of the dispersion curves of the electromagnetic wave and the electron beam. In the first case, the possibility of amplification without pulse form distortion was demonstrated for the pulse spectrum width of the order of the gain bandwidth. In the second case, when the electrons' axial velocity was smaller than the wave's group velocity, it was shown that the slippage of the incident signal with respect to the electron beam provides feeding of the signal by “fresh” electrons without initial modulation. As a result, the amplitude of the output pulse can exceed the amplitude of its saturated value for the case of the grazing regime, and, for optimal parameters, the peak output power can be even larger than the kinetic power of the electron beam

Evaluation of machine learning tools for inspection of steam generator tube structures using pulsed eddy current

Science.gov (United States)

Buck, J. A.; Underhill, P. R.; Morelli, J.; Krause, T. W.

2017-02-01

Degradation of nuclear steam generator (SG) tubes and support structures can result in a loss of reactor efficiency. Regular in-service inspection, by conventional eddy current testing (ECT), permits detection of cracks, measurement of wall loss, and identification of other SG tube degradation modes. However, ECT is challenged by overlapping degradation modes such as might occur for SG tube fretting accompanied by tube off-set within a corroding ferromagnetic support structure. Pulsed eddy current (PEC) is an emerging technology examined here for inspection of Alloy-800 SG tubes and associated carbon steel drilled support structures. Support structure hole size was varied to simulate uniform corrosion, while SG tube was off-set relative to hole axis. PEC measurements were performed using a single driver with an 8 pick-up coil configuration in the presence of flat-bottom rectangular frets as an overlapping degradation mode. A modified principal component analysis (MPCA) was performed on the time-voltage data in order to reduce data dimensionality. The MPCA scores were then used to train a support vector machine (SVM) that simultaneously targeted four independent parameters associated with; support structure hole size, tube off-centering in two dimensions and fret depth. The support vector machine was trained, tested, and validated on experimental data. Results were compared with a previously developed artificial neural network (ANN) trained on the same data. Estimates of tube position showed comparable results between the two machine learning tools. However, the ANN produced better estimates of hole inner diameter and fret depth. The better results from ANN analysis was attributed to challenges associated with the SVM when non-constant variance is present in the data.

Study on a high capacity two-stage free piston Stirling cryocooler working around 30 K

Science.gov (United States)

Wang, Xiaotao; Zhu, Jian; Chen, Shuai; Dai, Wei; Li, Ke; Pang, Xiaomin; Yu, Guoyao; Luo, Ercang

2016-12-01

This paper presents a two-stage high-capacity free-piston Stirling cryocooler driven by a linear compressor to meet the requirement of the high temperature superconductor (HTS) motor applications. The cryocooler system comprises a single piston linear compressor, a two-stage free piston Stirling cryocooler and a passive oscillator. A single stepped displacer configuration was adopted. A numerical model based on the thermoacoustic theory was used to optimize the system operating and structure parameters. Distributions of pressure wave, phase differences between the pressure wave and the volume flow rate and different energy flows are presented for a better understanding of the system. Some characterizing experimental results are presented. Thus far, the cryocooler has reached a lowest cold-head temperature of 27.6 K and achieved a cooling power of 78 W at 40 K with an input electric power of 3.2 kW, which indicates a relative Carnot efficiency of 14.8%. When the cold-head temperature increased to 77 K, the cooling power reached 284 W with a relative Carnot efficiency of 25.9%. The influences of different parameters such as mean pressure, input electric power and cold-head temperature are also investigated.

100J-level nanosecond pulsed Yb:YAG cryo-cooled DPSSL amplifier

Science.gov (United States)

Smith, J. M.; Butcher, T. J.; Mason, P. D.; Ertel, K.; Phillips, P. J.; Banerjee, S.; De Vido, M.; Chekhlov, O.; Divoky, M.; Pilar, J.; Shaikh, W.; Hooker, C.; Lucianetti, A.; Hernandez Gomez, C.; Mocek, T.; Edwards, C.; Collier, J. L.

2018-02-01

We report on the successful demonstration of the world's first kW average power, 100 Joule-class, high-energy, nanosecond pulsed diode-pumped solid-state laser (DPSSL), DiPOLE100. Results from the first long-term test for amplification will be presented; the system was operated for 1 hour with 10 ns duration pulses at 10 Hz pulse repetition rate and an average output energy of 105 J and RMS energy stability of approximately 1%. The laser system is based on scalable cryogenic gas-cooled multi-slab ceramic Yb:YAG amplifier technology. The DiPOLE100 system comprises three major sub-systems, a spatially and temporally shaped front end, a 10 J cryo-amplifier and a 100 J cryo-amplifier. The 10 J cryo-amplifier contain four Yb:YAG ceramic gain media slabs, which are diode pumped from both sides, while a multi-pass architecture configured for seven passes enables 10 J of energy to be extracted at 10 Hz. This seeds the 100 J cryo-amplifier, which contains six Yb:YAG ceramic gain media slabs with the multi-pass configured for four passes. Our future development plans for this architecture will be introduced including closed-loop pulse shaping, increased energy, higher repetition rates and picosecond operation. This laser architecture unlocks the potential for practical applications including new sources for industrial materials processing and high intensity laser matter studies as envisioned for ELI [1], HiLASE [2], and the European XFEL [3]. Alternatively, it can be used as a pump source for higher repetition rate PW-class amplifiers, which can themselves generate high-brightness secondary radiation and ion sources leading to new remote imaging and medical applications.

The velocity of the arterial pulse wave: a viscous-fluid shock wave in an elastic tube.

Science.gov (United States)

Painter, Page R

2008-07-29

The arterial pulse is a viscous-fluid shock wave that is initiated by blood ejected from the heart. This wave travels away from the heart at a speed termed the pulse wave velocity (PWV). The PWV increases during the course of a number of diseases, and this increase is often attributed to arterial stiffness. As the pulse wave approaches a point in an artery, the pressure rises as does the pressure gradient. This pressure gradient increases the rate of blood flow ahead of the wave. The rate of blood flow ahead of the wave decreases with distance because the pressure gradient also decreases with distance ahead of the wave. Consequently, the amount of blood per unit length in a segment of an artery increases ahead of the wave, and this increase stretches the wall of the artery. As a result, the tension in the wall increases, and this results in an increase in the pressure of blood in the artery. An expression for the PWV is derived from an equation describing the flow-pressure coupling (FPC) for a pulse wave in an incompressible, viscous fluid in an elastic tube. The initial increase in force of the fluid in the tube is described by an increasing exponential function of time. The relationship between force gradient and fluid flow is approximated by an expression known to hold for a rigid tube. For large arteries, the PWV derived by this method agrees with the Korteweg-Moens equation for the PWV in a non-viscous fluid. For small arteries, the PWV is approximately proportional to the Korteweg-Moens velocity divided by the radius of the artery. The PWV in small arteries is also predicted to increase when the specific rate of increase in pressure as a function of time decreases. This rate decreases with increasing myocardial ischemia, suggesting an explanation for the observation that an increase in the PWV is a predictor of future myocardial infarction. The derivation of the equation for the PWV that has been used for more than fifty years is analyzed and shown to yield

Long-pulse applications of pulse-forming lines for high-power linac application

International Nuclear Information System (INIS)

Hoeberling, R.F.; Tallerico, P.J.

1981-01-01

The ever present demands for high efficiency in the RF power stations for particle accelerators have caused increased interest in longer RF pulses (ten's of microseconds) for linacs such as the Pion Generator for Medical Irradiation (PIGMI) and Free Electron Laser (FEL). For either RF power station, a fundamental decision is whether to use a modulating anode/hard-tube driver or pulsed cathode/line-type pulser configuration. The choices in the extremes of low power for very long pulses or for very-high-power, short pulses are, respectively, a modulated anode/hard tube modulator and pulsed cathode/pulse forming line. However, the demarcation between these two extremes is not clearcut. The criteria (cost, flexibility performance, reliability, efficiency) that resulted in the RF station definition of these two specific systems will be described

Concepts for a low-vibration and cryogen-free tabletop dilution refrigerator

Science.gov (United States)

Uhlig, Kurt

2017-10-01

The purpose of this article is to describe several concepts of how to cool a modern tabletop dilution refrigerator (DR) with a cryogen-free pulse tube cryocooler (PTC). Tabletop DRs have come more and more into the focus of scientists, recently, because they offer easy access to the mixing chamber mounting plate from all directions and because of their very short cooldown times. However, these milli-Kelvin coolers are precooled with LHe which makes their handling inconvenient and often expensive. In the paper it is explained how a cryocooler can be directly coupled to a DR unit making the use of LHe superfluous. Furthermore, concepts are discussed where a tabletop DR is cooled by a remote PTC; PTC and DR are mounted in separate vacuum containers which are connected by a stainless steel bellows tube. This kind of apparatus would offer an extremely low level of vibration at the mixing chamber mounting plate.

RMs1: qualification results of the rotary miniature Stirling cryocooler at Thales Cryogenics

Science.gov (United States)

Martin, Jean-Yves; Seguineau, Cédric; Van-Acker, Sébastien; Sacau, Mikel; Le Bordays, Julien; Etchanchu, Thierry; Vasse, Christophe; Abadie, Christian; Laplagne, Gilles; Benschop, Tonny

2017-05-01

The trend for miniaturized Integrated Dewar and Cooler Assemblies (IDCA) has been confirmed over the past few years with several mentions of a new generation of IR detector working at High Operating Temperature (HOT). This key technology enables the use of cryocooler with reduced needs of cryogenics power. As a consequence, miniaturized IDCA are the combination of a HOT IR detector coupled with a low-size, low-weight and low-power (SWaP) cryocooler. Thales Cryogenics has developed his own line of SWaP products. Qualification results on linear solution where shown last year. The current paper focuses on the latest results obtained on RMs1 prototypes, the new rotary SWaP cryocooler from Thales Cryogenics. Cryogenic performances and induced vibrations are presented. In a second part, progress is discussed on compactness and weight on one side, and on power consumption on the other side. It shows how the trade-off made between weight and power consumption could lead to an optimized solution at system level. At least, an update is made on the qualification status.

Development of a discharge-heated plasma tube

International Nuclear Information System (INIS)

Cha, Byung Heon; Jin, J. T.; Nam, S. M.; Lee, S. M.; Choi, H. L.; Ko, D. K.; Kim, S. H.; Lee, Y. B.; Choi, Y. S.; Lee, J. M.; Lee, C. K.; Lee, H. G.; Lee, H. C.; Jung, S. M.; Kim, Y. J.; Choi, G. S.; Son, N. G.

1999-12-01

A discharge-heated type plasma tube was designed and constructed. The structure of the laser plasma tube was designed to be easy in maintenance. The inside plasma tube was made of a high purity alumina and the thermal insulator tube was made of a porous alumina. The electrode made of tungsten was chosen for the endurance of high discharge voltage. AR coated windows were used as laser windows. A proto-type laser plasma tube was tested with a pulse modulator. An average laser output power was 32 W at the discharge voltage of 28 kV, the electric input power of 4.6 kW, and the pulse repetition rates of 10 kHz. (author)

Space Stirling Cryocooler Contamination Lessons Learned and Recommended Control Procedures

Science.gov (United States)

Glaister, D. S.; Price, K.; Gully, W.; Castles, S.; Reilly, J.

The most important characteristic of a space cryocooler is its reliability over a lifetime typically in excess of 7 years. While design improvements have reduced the probability of mechanical failure, the risk of internal contamination is still significant and has not been addressed in a consistent approach across the industry. A significant fraction of the endurance test and flight units have experienced some performance degradation related to internal contamination. The purpose of this paper is to describe and assess the contamination issues inside long life, space cryocoolers and to recommend procedures to minimize the probability of encountering contamination related failures and degradation. The paper covers the sources of contamination, the degradation and failure mechanisms, the theoretical and observed cryocooler sensitivity, and the recommended prevention procedures and their impact. We begin with a discussion of the contamination sources, both artificial and intrinsic. Next, the degradation and failure mechanisms are discussed in an attempt to arrive at a contaminant susceptibility, from which we can derive a contamination budget for the machine. This theoretical sensitivity is then compared with the observed sensitivity to illustrate the conservative nature of the assumed scenarios. A number of lessons learned on Raytheon, Ball, Air Force Research Laboratory, and NASA GSFC programs are shared to convey the practical aspects of the contamination problem. Then, the materials and processes required to meet the proposed budget are outlined. An attempt is made to present a survey of processes across industry.

Development of bipolar pulse accelerator for intense pulsed ion beam acceleration

International Nuclear Information System (INIS)

Fujioka, Y.; Mitsui, C.; Kitamura, I.; Takahashi, T.; Masugata, K.; Tanoue, H.; Arai, K.

2003-01-01

To improve the purity of an intense pulsed ion beams a new type of pulsed ion beam accelerator named 'bipolar pulse accelerator (BPA)' was proposed. In the accelerator purity of the beam is expected. To confirm the principle of the accelerator experimental system was developed. The system utilizes B y type magnetically insulated acceleration gap and operated with single polar negative pulse. A coaxial gas puff plasma gun placed in the grounded anode was used as an ion source, and source plasma (nitrogen) of current density approx. = 25 A/cm 2 , duration approx. = 1.5 μs was injected into the acceleration gap. The ions are successfully accelerated from the grounded anode to the drift tube by applying negative pulse of voltage 180 kV, duration 60 ns to the drift tube. Pulsed ion beam of current density approx. = 40 A/cm 2 , duration approx. 60 ns was obtained at 42 mm downstream from the anode surface. (author)

Design of a scanning gate microscope for mesoscopic electron systems in a cryogen-free dilution refrigerator.

Science.gov (United States)

Pelliccione, M; Sciambi, A; Bartel, J; Keller, A J; Goldhaber-Gordon, D

2013-03-01

We report on our design of a scanning gate microscope housed in a cryogen-free dilution refrigerator with a base temperature of 15 mK. The recent increase in efficiency of pulse tube cryocoolers has made cryogen-free systems popular in recent years. However, this new style of cryostat presents challenges for performing scanning probe measurements, mainly as a result of the vibrations introduced by the cryocooler. We demonstrate scanning with root-mean-square vibrations of 0.8 nm at 3 K and 2.1 nm at 15 mK in a 1 kHz bandwidth with our design. Using Coulomb blockade thermometry on a GaAs/AlGaAs gate-defined quantum dot, we demonstrate an electron temperature of 45 mK.

A prototype detector using the neutron image intensifier and multi-anode type photomultiplier tube for pulsed neutron imaging

International Nuclear Information System (INIS)

Ishikawa, Hirotaku; Sato, Hirotaka; Hara, Kaoru Y.; Kamiyama, Takashi

2016-01-01

We developed a neutron two-dimensional (2-D) detector for pulsed neutron imaging as a prototype detector, which was composed of a neutron image intensifier and a multi-anode type photomultiplier tube. A neutron transmission spectrum of α-Fe plate was measured by the prototype detector, and compared with the one measured by a typical neutron 2-D detector. The spectrum was in reasonable agreement with the one measured by the typical detector in the neutron wavelength region above 0.15 nm. In addition, a neutron transmission image of a cadmium indicator was obtained by the prototype detector. The usefulness of the prototype detector for pulsed neutron imaging was demonstrated. (author)

Applications concepts of small regenerative cryocoolers in superconducitng magnet systems

NARCIS (Netherlands)

van der Laan, M.T.G.; van der Laan, M.T.G.; Tax, R.B.; ten Kate, Herman H.J.

1992-01-01

Superconducting magnets are in growing use outside laboratories for example MRI scanners in hospitals. Other applications under development are magnet systems for separation, levitated trains and ship propulsion. The application of cryocoolers can make these systems more practical. Interfacing these

Building the better cryocooler

International Nuclear Information System (INIS)

Radebaugh, R.

1992-01-01

This article focuses on the present and future status of small cryocoolers that may be useful for cooling superconducting electronics or magnets no larger than those of Magnetic Resonance Imaging (MRI) systems. In a few cases superconductors have found their way into a large market. The best example is superconducting Super Collider (SSC) and other accelerators use an enormous amount of superconducting wire and require large liquid helium plants for cooling. The costs of these large accelerator systems greatly restricts the number of such installations. Thin film superconducting electronic devices have the potential of being made relatively inexpensively and have a performance advantage over conventional electronic systems. The possible market size for superconducting electronics could be extremely large is one serious problem would simply disappear

Thermal properties of a large-bore cryocooled 10 T superconducting magnet for a hybrid magnet

International Nuclear Information System (INIS)

Ishizuka, M.; Hamajima, T.; Itou, T.; Sakuraba, J.; Nishijima, G.; Awaji, S.; Watanabe, K.

2010-01-01

A cryocooled 10 T superconducting magnet with a 360 mm room temperature bore has been developed for a hybrid magnet. The superconducting magnet cooled by four Gifford-McMahon cryocoolers has been designed to generate a magnetic field of 10 T. Since superconducting wires composed of coils were subjected to large hoop stress over 150 MPa and Nb 3 Sn superconducting wires particularly showed a low mechanical strength due to those brittle property, Nb 3 Sn wires strengthened by NbTi-filaments were developed for the cryocooled superconducting magnet. We have already reported that the hybrid magnet could generate the resultant magnetic field of 27.5 T by adding 8.5 T from the superconducting magnet and 19 T from a water-cooled Bitter resistive magnet, after the water-cooled resistive magnet was inserted into the 360 mm room temperature bore of the cryocooled superconducting magnet. When the hybrid magnet generated the field of 27.5 T, it achieved the high magnetic-force field (B x ∂Bz/∂z) of 4500 T 2 /m, which was useful for magneto-science in high fields such as materials levitation research. In this paper, we particularly focus on the cause that the cryocooled superconducting magnet was limited to generate the designed magnetic field of 10 T in the hybrid magnet operation. As a result, it was found that there existed mainly two causes as the limitation of the magnetic field generation. One was a decrease of thermal conductive passes due to exfoliation from the coil bobbin of the cooling flange. The other was large AC loss due to both a thick Nb 3 Sn layer and its large diameter formed on Nb-barrier component in Nb 3 Sn wires.

Thermodynamic design of 10 kW Brayton cryocooler for HTS cable

Science.gov (United States)

Chang, Ho-Myung; Park, C. W.; Yang, H. S.; Sohn, Song Ho; Lim, Ji Hyun; Oh, S. R.; Hwang, Si Dole

2012-06-01

Thermodynamic design of Brayton cryocooler is presented as part of an ongoing governmental project in Korea, aiming at 1 km HTS power cable in the transmission grid. The refrigeration requirement is 10 kW for continuously sub-cooling liquid nitrogen from 72 K to 65 K. An ideal Brayton cycle for this application is first investigated to examine the fundamental features. Then a practical cycle for a Brayton cryocooler is designed, taking into account the performance of compressor, expander, and heat exchangers. Commercial software (Aspen HYSYS) is used for simulating the refrigeration cycle with real fluid properties of refrigerant. Helium is selected as a refrigerant, as it is superior to neon in thermodynamic efficiency. The operating pressure and flow rate of refrigerant are decided with a constraint to avoid the freezing of liquid nitrogen

Tube Inner Coating of Non-Conductive Films by Pulsed Reactive Coaxial Magnetron Plasma with Outer Anode

Directory of Open Access Journals (Sweden)

Musab Timan Idriss Gasab

2018-03-01

Full Text Available The double-ended coaxial magnetron pulsed plasma (DCMPP method with auxiliary outer anode was introduced in order to achieve the uniform coating of non-conductive thin films on the inner walls of insulator tubes. In this study, titanium (Ti was employed as a cathode (sputtering target, and a glass tube was used as a substrate. In an argon (Ar and oxygen (O2 gas mixture, magnetron plasma was generated. Oxygen gas was introduced to deposit a titanium oxide (TiO2 film. A comparison between films coated with and without an auxiliary outer anode was made. As a result, it was clearly shown that the DCMPP method using an auxiliary outer anode enhanced the uniformity of the deposited non-conductive film compared to the conventional DCMPP method. Moreover, the optimum conditions under which the thin TiO2 film was deposited on the inner wall of the glass tube were revealed. From the results, it was supposed that the auxiliary outer anode contributed to the uniformity of the distributions of deposited negative charge on the non-conductive film and consequently the electric field and the plasma density uniform.

Ceramic accelerating tube of the improved construction

International Nuclear Information System (INIS)

Vasserman, S.B.; Kazarezov, I.V.; Pokhlebenin, E.I.; Shirokov, V.V.

1976-01-01

An improved ceramic accelerating tube is designed. The electrodes are made of copper and covar which provides for maintaining the geometry of the electrodes at thermal-compression welding and obviates the need for machanical treatment of the envelope after welding. Employment of the insulators with a finned surface from the vacuum side by two times increases the electric strength of the accelerating tube, as compared to the insulators with a smooth surface. The accelerating tube envelope can withstand the pulsed voltages of 1.5 MV at a pulse duration of 6 μs and a repetition rate of 100 Hz within two hours

Physics of cryogenics an ultralow temperature phenomenon

CERN Document Server

Zohuri, Bahman

2018-01-01

Physics of Cryogenics: An Ultralow Temperature Phenomenon discusses the significant number of advances that have been made during the last few years in a variety of cryocoolers, such as Brayton, Joule-Thomson, Stirling, pulse tube, Gifford-McMahon and magnetic refrigerators. The book reviews various approaches taken to improve reliability, a major driving force for new research areas. The advantages and disadvantages of different cycles are compared, and the latest improvements in each of these cryocoolers is discussed. The book starts with the thermodynamic fundamentals, followed by the definition of cryogenic and the associated science behind low temperature phenomena and properties. This book is an ideal resource for scientists, engineers and graduate and senior undergraduate students who need a better understanding of the science of cryogenics and related thermodynamics.

Neutron generator tube ion source control apparatus

International Nuclear Information System (INIS)

Bridges, J.R.

1982-01-01

A pulsed neutron well logging system includes a neutron generator tube of the deuterium-tritium accelerator type and an ion source control apparatus providing extremely sharply time-defined neutron pulses. A low voltage control pulse supplied to an input by timing circuits turns a power FET on via a buffer-driver whereby a 2000 volt pulse is produced in the secondary of a pulse transformer and applied to the ion source of the tube. A rapid fall in this ion source control pulse is ensured by a quenching circuit wherein a one-shot responds to the falling edge of the control pulse and produces a 3 microsecond delay to compensate for the propagation delay. A second one-shot is triggered by the falling edge of the output of the first one-shot and gives an 8 microsecond pulse to turn on the power FET which, via an isolation transformer turns on a series-connected transistor to ground the secondary of the pulse transformer and the ion source. (author)

Opposed piston linear compressor driven two-stage Stirling Cryocooler for cooling of IR sensors in space application

Science.gov (United States)

Bhojwani, Virendra; Inamdar, Asif; Lele, Mandar; Tendolkar, Mandar; Atrey, Milind; Bapat, Shridhar; Narayankhedkar, Kisan

2017-04-01

A two-stage Stirling Cryocooler has been developed and tested for cooling IR sensors in space application. The concept uses an opposed piston linear compressor to drive the two-stage Stirling expander. The configuration used a moving coil linear motor for the compressor as well as for the expander unit. Electrical phase difference of 80 degrees was maintained between the voltage waveforms supplied to the compressor motor and expander motor. The piston and displacer surface were coated with Rulon an anti-friction material to ensure oil less operation of the unit. The present article discusses analysis results, features of the cryocooler and experimental tests conducted on the developed unit. The two-stages of Cryo-cylinder and the expander units were manufactured from a single piece to ensure precise alignment between the two-stages. Flexure bearings were used to suspend the piston and displacer about its mean position. The objective of the work was to develop a two-stage Stirling cryocooler with 2 W at 120 K and 0.5 W at 60 K cooling capacity for the two-stages and input power of less than 120 W. The Cryocooler achieved a minimum temperature of 40.7 K at stage 2.

Theoretical study of effect of working fluid on the performance of 77–100 K adsorption cryocooler

International Nuclear Information System (INIS)

Luo, B.J.; Wang, Z.L.; Yan, T.; Hong, G.T.; Li, Y.L.; Liang, J.T.

2015-01-01

Highlights: • Investigate the effects of nitrogen, argon and oxygen on the performance of adsorption cryocooler in the range 77–100 K. • A model of adsorption compressor with a two-stage adsorption compressor is constructed and optimized with genetic algorithm. • Working fluid has larger effects on the adsorption compressor than on the cold stage. • The best selection of working fluid depends on the operating parameters. - Abstract: The aim of this study is to investigate the effects of working fluid (nitrogen, argon and oxygen) on the performance of adsorption cryocooler in the range 77–100 K. A thermodynamic model of adsorption cryocooler with two-stage compressor has been constructed. The model is based on quasi-static conditions without considering the temperature profiles and pressure drops across the compressor. It is then analyzed with an optimization toolbox to determine the optimum operating conditions to obtain the optimum performance of adsorption cryocooler. The Coefficient of Performance (COP) for each working fluid in the range 77–100 K is obtained and compared. It is found that working fluid has larger effects on adsorption compressor than on cold stage, and the optimum selection of working fluid depends on the operating parameters

Effect of counter electric field during the irradiation of pulsed x-ray on the after-pulses of GM counter

International Nuclear Information System (INIS)

Igarashi, Ryuji; Narita, Yuichi; Ozawa, Yasutomo.

1979-01-01

The authors once made it clear by using pulsed radiation that the number of spurious discharge generation in organic gas-quenching type GM counters depends on the intensity of incident radiation. This spurious discharge is peculiar to the organic gas-quenching type GM counters, which the authors named after-pulses. The present study has been carried out to find the experimental conditions to verify the delayed generation mechanism of such after-pulses in bipolar GM tubes and the conditions to give the maximum number of after-pulses generation. For this purpose, a large low electric field region, whose field intensity is variable, should be provided in the tubes. Since it has been generally impossible in the bipolar GM tubes, the provision of that region transiently has been tried. The effect of the intensity of electric field in GM tubes during irradiation on the generation of after-pulses has been investigated by changing radiation intensity, anode voltage, and irradiated position. Consideration of the results has revealed that the number of after-pulse generation can be increased by forming transient low electric field region in the bipolar GM counters of organic gas-quenching type. It was the new knowledge that the transient anode voltage to maximize the after-pulse generating factor was several tens of negative voltage even if the conditions were varied. It seems that this fact depends upon the voltage giving the conditions to maximize the probability of forming after-pulse factors. (Wakatsuki, Y.)

Dose reduction in multi-slice CT of the heart by use of ECG-controlled tube current modulation (''ECG pulsing''): phantom measurements

International Nuclear Information System (INIS)

Poll, L.W.; Cohnen, M.; Brachten, S.; Moedder, U.; Ewen, K.

2002-01-01

To evaluate the effect of ECG-controlled tube current modulation on radiation exposure in retrospectively-ECG-gated multislice CT (MSCT) of the heart. Material and methods: Three different cardiac MSCT protocols with different slice collimation (4 x 1, and 4 x 2.5 mm), and a pitch-factor of 1.5 and 1.8 were investigated at a multi-slice CT scanner Somatom Volume Zoom, Siemens. An anthropomorphic Alderson-Rando phantom was equipped with LiF-Thermoluminescence dosimeters at several organ sites, and effective doses were calculated using ICRP-weighting factors. Scan protocols were performed with ECG-controlled tube current modulation ('ECG pulsing') at two different heart rates (60 and 80 bpm). These data were compared to previous data from MSCT of the heart without use of 'ECG pulsing'. Results: Radiation exposure with (60 bpm) and without tube current modulation using a 2.5 mm collimation was 1.8 mSv and 2.9 mSv for females, and 1.5 mSv and 2.4 mSv for males, respectively. For protocols using a 1 mm collimation with a pitch-factor of 1.5 (1.8), radiation exposure with and without tube current modulation was 5.6 (6.3) mSv and 9.5 (11.2) mSv for females, and 4.6 (5.2) mSv and 7.7 (9.2) mSv for males, respectively. At higher heart rates (80 bpm) radiation exposure is increased from 1.5-1.8 mSv to 1.8-2.1 mSv, using the 2.5 mm collimation, and from 4.6-5.6 mSv to 5.9-7.2 mSv, for protocols using 1 mm collimation. Conclusions: The ECG-controlled tube current modulation allows a dose reduction of 37% to 44% when retrospectively ECG-gated MSCT of the heart is performed. The tube current - as a function over time - and therefore the radiation exposure is dependent on the heart rate. (orig.) [de

Application of a Cryocooler in the Superconducting Magnet Cooling System

International Nuclear Information System (INIS)

Kowalczyk, W.; Malinowski, H.

1998-01-01

The application of the cryocooler working with a OGMS separator was suggested. It is very important to decrease the heat leak into the electromagnet. It was discussed how to reduce the heat leak into the separator's coils. The use of a high temperature superconducting current leads is proposed and calculated. (author)

Advanced, Long-Life Cryocooler Technology for Zero-Boil-Off Cryogen Storage, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — Long-life, high-capacity cryocoolers are a critical need for future space systems utilizing stored cryogens. The cooling requirements for planetary and...

Advanced, Long-Life Cryocooler Technology for Zero-Boil-Off Cryogen Storage, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Long-life, high-capacity cryocoolers are a critical need for future space systems utilizing stored cryogens. The cooling requirements for planetary and...

Estimation of Freezing Point of Hydrocarbon and Hydrofluorocarbon Mixtures for Mixed Refrigerant jt Cryocooler

Science.gov (United States)

Hwang, G.; Lee, J.; Jeong, S.

2010-04-01

Estimating the freezing point of refrigerant is an essential part in designing an MR JT (Mixed refrigerant Joule-Thomson) cryocooler to prevent itself from clogging and to operate with stability. There were researches on estimating freezing point, but some of them resulted in the wrong prediction of clogging. In this paper, the freezing point of the MR is precisely estimated with caution of clogging. The solubility of HC (hydrocarbon) and HFC (hydrofluorocarbon) mixture components are obtained with their activity coefficients, which represent the molecular interaction among the components. The freezing points of the MR JT cryocooler are systematically investigated in the operating temperature range from 70 K to 90 K.

Longitudinally excited CO2 laser with multiple laser tubes

Science.gov (United States)

Uno, Kazuyuki; Akitsu, Tetsuya; Jitsuno, Takahisa

2016-11-01

We developed a longitudinally excited CO2 laser system that was constituted of two or three laser tubes and a single driving circuit. The multiple laser tubes simultaneously produced almost the same short laser pulses with a spike pulse width of about 164 ns and a pulse tail length of about 74 μs with a single driving circuit. The double-tube system was constituted of two 30 cm-long laser tubes with inner diameters of 13 mm and 16 mm and a single driving circuit with an input energy of 2.18 J. The output energy of the 13 mm-tube was 23.3 mJ, and that of the 16 mm-tube was 21.9 mJ at a gas pressure of 4.2 kPa (CO2:N2:He = 1:1:2). The triple-tube system was constituted of three 30 cm-long laser tubes with inner diameters of 9 mm, 13 mm, and 16 mm and a single driving circuit with an input energy of 2.18 J. The output energy of the 9 mm tube was 15.9 mJ, that of the 13 mm tube was 24.1 mJ, and that of the 16 mm tube was 19.2 mJ at a gas pressure of 4.2 kPa. With the same driving circuit and the same input energy, the total output energies of the multitube laser systems were higher than the output energy of a single-tube system.

Development of bipolar-pulse accelerator for intense pulsed ion beam acceleration

Energy Technology Data Exchange (ETDEWEB)

Masugata, Katsumi [Department of Electrical and Electronic System Engineering, Toyama University, 3190 Gofuku, Toyama 930-8555 (Japan)]. E-mail: masugata@eng.toyama-u.ac.jp; Shimizu, Yuichro [Department of Electrical and Electronic System Engineering, Toyama University, 3190 Gofuku, Toyama 930-8555 (Japan); Fujioka, Yuhki [Department of Electrical and Electronic System Engineering, Toyama University, 3190 Gofuku, Toyama 930-8555 (Japan); Kitamura, Iwao [Department of Electrical and Electronic System Engineering, Toyama University, 3190 Gofuku, Toyama 930-8555 (Japan); Tanoue, Hisao [National Institute of Advanced Industry Science and Technology, 1-1-1, Umezono, Tsukuba-shi, Ibaraki 305-8568 (Japan); Arai, Kazuo [National Institute of Advanced Industry Science and Technology, 1-1-1, Umezono, Tsukuba-shi, Ibaraki 305-8568 (Japan)

2004-12-21

To improve the purity of intense pulsed ion beams, a new type of pulsed ion beam accelerator named 'bipolar pulse accelerator' was proposed. To confirm the principle of the accelerator a prototype of the experimental system was developed. The system utilizes By type magnetically insulated acceleration gap and operated with single polar negative pulse. A coaxial gas puff plasma gun was used as an ion source, which was placed inside the grounded anode. Source plasma (nitrogen) of current density {approx}25A/cm2, duration {approx}1.5{mu}s was injected into the acceleration gap by the plasma gun. The ions were successfully accelerated from the grounded anode to the drift tube by applying negative pulse of voltage 240kV, duration 100ns to the drift tube. Pulsed ion beam of current density {approx}40A/cm2, duration {approx}50ns was obtained at 41mm downstream from the anode surface. To evaluate the irradiation effect of the ion beam to solid material, an amorphous silicon thin film of thickness {approx}500nm was used as the target, which was deposited on the glass substrate. The film was found to be poly-crystallized after 4-shots of the pulsed nitrogen ion beam irradiation.

Air Force Research Laboratory Spacecraft Cryocooler Endurance Evaluation Update: FY98-99

National Research Council Canada - National Science Library

Tomlinson, B

1999-01-01

The need for long term endurance evaluation data on space cryocoolers has long been an issue due to the 10-year plus design life of this technology and the absence of any accepted accelerated testing methodology...

Small size neutron tube UNG-1

International Nuclear Information System (INIS)

Bespalov, D.F.; Mints, A.Z.; Shkol'nikov, A.S.

A tube UNG-1 (universal neutron gas-filled) is designed for the use in the well neutron generators IGN-1 and IGN-1-M (a pulse neutron generator). Their serial production in the USSR has been started in 1963. At the same year, the serial production of the tubes UNG-1 has been started. Thus, this tube is the first serial logging accelerating tube in the USSR. A Penning source, equipped with a hot cathode, was selected as an ion source of the tube

Numerical Simulation of Magnetic Field Effect on Cryocooler Regenerators: Temperature Distribution

Directory of Open Access Journals (Sweden)

Rajendra Kumar

2017-01-01

Full Text Available Regenerative types of cryogenic refrigerators (or cryocoolers employ magnetic intermetallic compounds of 3d and 4f elements to work well below 10 K. This paper presents the analysis of temperature distribution in regenerators of such cryocoolers under the influence of magnetic fields of 1 T, 3 T, and 4.3 T. Commercial code of finite element analysis (FEA package, ANSYS (APDL 14.5, is used to investigate the temperature distribution under above-mentioned fields. Er3Ni is selected as regenerator material and the criteria for its selection are discussed in detail. The cold end temperature is varied from 4.2 K to 10 K and hot end temperature is fixed at 20 K. The values obtained from FEA clearly show that the ineffectiveness of Er3Ni is at 8 K and 10 K at 3 T and 4.3 T.

Determination of pseudo multi-pulse production rate in GM counters by correlation analysis between signal pulses

International Nuclear Information System (INIS)

Hashimoto, Kengo; Ueda, Taizou

1996-01-01

A technique, based on the correlation analysis of signal pulses in time sequence, is proposed to determine the production rate of the pseudo multi-pulse in Geiger-Mueller (GM) counter. With a multi-channel scaler initiated by a signal pulse, subsequent pulses are recorded in sequence. The production of the multi-pulse increases the counting probability immediately after the initiation. By examining the deviation of the measured probability from the ideal counting probability, the production rate and the average lag time to produce the multi-pulse can be determined. By the use of the present technique, the production rate and the average lag time were obtained for the various GM tubes. These results indicate that the consumption of the quench gas results in a significant increase in the production rate but little variation in the lag time, and that the lag time strongly depends on the tube diameter. (author)

Improvements in or relating to pulsed X-ray units

International Nuclear Information System (INIS)

Bichenkov, E.I.; Klypin, V.V.; Palchikov, E.I.

1983-01-01

A pulsed X-ray unit comprises a pulsed X-ray tube connected to a discharge capacitor. The discharge capacitor comprises two coaxially arranged cylinders. One cylinder of the discharge capacitor is connected to the X-ray tube and to the high-voltage end of the secondary winding of the pulsed transformer which is shaped as a truncated cone, and is arranged internally of this winding coaxially therewith. The other cylinder of the discharge capacitor is also connected to the X-ray tube and to the low-voltage end of the secondary winding of the pulsed transformer, and is arranged intermediate this winding and the primary winding of the pulsed transformer which is shaped as a hollow cylinder, and connected to the charging device. The cylinders of the discharge capacitor have ports made therein for the passage therethrough of the magnetic flux produced by the windings of the pulsed transformer. (author)

Linear-drive cryocoolers for the Department of Defense standard advanced dewar assembly (SADA)

Science.gov (United States)

Tate, Garin S.

2005-05-01

The Standard Advanced Dewar Assembly (SADA) is the critical module in the Department of Defense (DoD) standardization of scanning second-generation thermal imaging systems. The DoD has established a family of SADAs to fulfill a range of performance requirements for various platforms. The SADA consists of the Infrared Focal Plane Array (IRFPA), Dewar, Command & Control Electronics (C&CE), and the cryogenic cooler, and is used in platforms such as the Apache helicopter, the M1A2 Abrams main battle tank, the M2 Bradley Infantry Fighting Vehicle, and the Javelin Command Launch Unit (CLU). In support of the family of SADAs, the DoD defined a complementary family of tactical linear drive cryocoolers. The Stirling cycle linear drive cryocoolers are utilized to cool the Infrared Focal Plane Arrays (IRFPAs) in the SADAs. These coolers are required to have low input power, a quick cool-down time, low vibration output, low audible noise, and a higher reliability than currently fielded rotary coolers. These coolers must also operate in a military environment with its inherent high vibration level and temperature extremes. This paper will (1) outline the characteristics of each cryocooler, (2) present the status and results of qualification tests, (3) present the status of production efforts, and (4) present the status of efforts to increase linear drive cooler reliability.

Thermal analysis of the cryocooled superconducting magnet for the liquid helium-free hybrid magnet

International Nuclear Information System (INIS)

Ishizuka, Masayuki; Hamajima, Takataro; Itou, Tomoyuki; Sakuraba, Junji; Nishijima, Gen; Awaji, Satoshi; Watanabe, Kazuo

2010-01-01

The liquid helium-free hybrid magnet, which consists of an outer large bore cryocooled superconducting magnet and an inner water-cooled resistive magnet, was developed for magneto-science in high fields. The characteristic features of the cryogen-free outsert superconducting magnet are described in detail in this paper. The superconducting magnet cooled by Gifford-McMahon cryocoolers, which has a 360 mm room temperature bore in diameter, was designed to generate high magnetic fields up to 10 T. The hybrid magnet has generated the magnetic field of 27.5 T by combining 8.5 T generation of the cryogen-free superconducting magnet with 19 T generation of the water-cooled resistive magnet. The superconducting magnet was composed of inner Nb 3 Sn coils and outer NbTi coils. In particular, inner Nb 3 Sn coils were wound using high-strength CuNi-NbTi/Nb 3 Sn wires in consideration of large hoop stress. Although the cryocooled outsert superconducting magnet achieved 9.5 T, we found that the outsert magnet has a thermal problem to generate the designed maximum field of 10 T in the hybrid magnet operation. This problem is associated with unexpected AC losses in Nb 3 Sn wires.

Development of a 77K Reverse-Brayton Cryocooler with Multiple Coldheads, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — RTI will design and optimize an 80 W, 77K cryocooler based on the reverse turbo Brayton cycle (RTBC) with four identical coldheads for distributed cooling. Based on...

High peak power tubes and gate effect Klystrons

International Nuclear Information System (INIS)

Gerbelot, N.; Bres, M.; Faillon, G.; Buzzi, J.M.

1993-01-01

The conventional microwave tubes such as TWTs, Magnetrons, Klystrons... deliver the very high peak powers which are required by radar transmitters but more especially by many particle accelerators. In the range of a few hundred MHz to about 10 GHz, some dozen of MWs per unit are currently obtained and commercially available, according to the frequency and the pulse lengths. But peak power requirements are ever increasing, especially for the expected new linear particle acceleratores, where several hundred MWs per tube would be necessary. Also some special military transmitters begin to request GW pulses, with short pulse lengths - of course - but at nonnegligible repetition rates. Therefore several laboratories and microwave vacuum tube manufacturers have engaged - for several years - studies and development in the field of very high peak microwave power (HPM) toward two main directions: extended operation and extrapolation of the conventional tubes and devices; development of new concepts, among which the most promising are likely the high-current relativistic klystrons - that are also referred to as gate effect klystrons

The 4 K Stirling cryocooler demonstration. Final report No. 8, 1 May 1990-30 April 1992

International Nuclear Information System (INIS)

Stacy, W.D.

1992-09-01

This report briefly summarizes the results and conclusions from an SBIR program intended to demonstrate an innovative Stirling cycle cryocooler concept for efficiently lifting heat from 4 K. Refrigeration at 4 K, a temperature useful for superconductors and sensitive instruments, is beyond the reach of conventional regenerative thermodynamic cycles due to the rapid loss of regenerator matrix heat capacity at temperatures below about 20 K. To overcome this fundamental limit, the cryocooler developed under this program integrated three unique features: recuperative regeneration between the displacement gas flow streams of two independent Stirling cycles operating at a 180 degree phase angle, tailored distortion of the two expander volume waveforms from sinusoidal to perfectly match the instantaneous regenerator heat flux from the two cycles and thereby unload the regenerator, and metal diaphragm working volumes to promote near isothermal expansion and compression processes. Use of diaphragms also provides unlimited operating life potential and eliminates bearings and high precision running seals. A phase 1 proof-of-principle experiment demonstrated that counterflow regenerator operation between 77 K and 4 K increases regenerator effectiveness by minimizing metal temperature transient cycling. In phase 2, a detailed design package for a breadboard cryocooler was completed. Fabrication techniques were successfully developed for manufacturing high precision miniature parallel plate recuperators, and samples were produced and inspected. Process development for fabricating suitably flat diaphragms proved more difficult and expensive than anticipated, and construction of the cryocooler was suspended at a completion level of approximately 75%. Subsequent development efforts on other projects have successfully overcome diaphragm fabrication difficulties

Calorimetric thermal-vacuum performance characterization of the BAe 80K space cryocooler

International Nuclear Information System (INIS)

Kotsubo, V.Y.; Johnson, D.L.; Ross, R.G. Jr.

1992-01-01

This paper on a comprehensive characterization program which is underway at JPL to generate test data on long-life, miniature Stirling-cycle cryocoolers for space application. The key focus of this paper is on the thermal performance of the British Aerospace (BAe) 80K split-Stirling-cycle cryocooler as measured in a unique calorimetric thermal-vacuum test chamber that accurately simulates the heat-transfer interfaces of space. Two separate cooling fluid loops provide precis individual control of the compressor and displacer heatsink temperatures. In addition, heatflow transducers enable calorimetric measurements of the heat rejected separately by the compressor and displacer. Cooler thermal performance has been mapped for coldtip temperatures ranging from below 45 K to above 150 K, for heat-sink temperatures ranging from 280 K to 320 K, and for a wide variety of operational variables including compressor-displacer phase, compressor-displacer stoke, drive frequency, and piston-displacer dc offset

Design of a cryo-cooled artificial channel-cut crystal monochromator for the European XFEL

Energy Technology Data Exchange (ETDEWEB)

Dong, Xiaohao, E-mail: xiaohao.dong@xfel.eu; Sinn, Harald, E-mail: harald.sinn@xfel.eu [European XFEL GmbH, Hamburg, D-22761 (Germany); Shu, Deming, E-mail: shu@aps.anl.gov [Argonne National Laboratory, Argonne, IL 60439, U.S.A (United States)

2016-07-27

An artificial channel-cut crystal monochromator for the hard X-Ray beamlines of SASE 1&2, cryogenically cooled by the so-called pulse tube cooler (cryorefrigerator), is currently under development at the European XFEL ( http://www.xfel.eu/ ). The fabrication is on-going. We present here the crystal optical consideration and the novel cooling configuration, according to the X-Ray FEL pulses proprieties. The mechanical design improvements are pointed out as well to implement such kind of monochromator based on the previous similar design.

Pulsed neutron generator

International Nuclear Information System (INIS)

Bespalov, D.F.; Bykovskii, Yu.A.; Vergun, I.I.; Kozlovskii, K.I.; Kozyrev, Yu.P.; Leonov, R.K.; Simagin, B.I.; Tsybin, A.S.; Shikanov, A.Ie.

1986-03-01

The paper describes a new device for generating pulsed neutron fields, utilized in nuclear geophysics for carrying out pulsed neutron logging and activation analysis under field conditions. The invention employs a sealed-off neutron tube with a laser ion source which increases neutron yield to the level of 10 neutrons per second or higher. 2 refs., 1 fig

Influence of tube volume on measurement uncertainty of GM counters

Directory of Open Access Journals (Sweden)

Stanković Koviljka Đ.

2010-01-01

Full Text Available GM counters are often used in radiation detection since they generate a strong signal which can be easily detected. The working principal of a GM counter is based on the interaction of ionizing radiation with the atoms and molecules of the gas present in the counter's tube. Free electrons created as a result of this interaction become initial electrons, i. e. start an avalanche process which is detected as a pulse of current. This current pulse is independent of the energy imparted on the gas, that being the main difference between a GM counter and the majority of other radiation detectors. In literature, the dependence on the incidence of radiation energy, tube's orientation and characteristics of the reading system are quoted as the main sources of measurement uncertainty of GM counters. The aim of this paper is to determine the dependence of measurement uncertainty of a GM counter on the volume of its counter's tube. The dependence of the pulse current on the size of the counter's tube has, therefore, been considered here, both in radial and parallel geometry. The initiation and expansion of the current pulse have been examined by means of elementary processes of electrical discharge such as the Markov processes, while the changes in the counter's tube volume were put to test by the space - time enlargement law. The random variable known as the 'current pulse in the counter's tube' (i. e. electrical breakdown of the electrode configuration has also been taken into account and an appropriate theoretical distribution statistically determined. Thus obtained theoretical results were then compared to corresponding experimental results established in controlled laboratory conditions.

The role of thermoacoustics in the world of commercial cooling

Science.gov (United States)

Corey, John A.

2005-09-01

The science of thermoacoustics has been with us for nearly 30 years, but as yet few applications have made their way to the marketplace. Acoustic Stirling cryocoolers (also called pulse-tube Stirling or high-frequency pulse-tube coolers) have been the most successful commercial thermoacoustic devices, because they address a region of the cooling market in terms of temperature and cooling power that is not well served by existing technology. This talk will explore how thermoacoustics might fare in attempting to compete with existing technologies in refrigeration and air conditioning, what niche markets make the most sense as entry points, and how thermoacoustics compares to conventional (kinematic or free-piston) Stirling machines. In particular, why there are relatively few commercial Stirling devices in the marketplace (although Stirling cycle machines have been around for over 150 years) will be discussed, and what lessons learned with Stirlings are applicable to thermoacoustics.

Review of the Oxford Cryocooler

International Nuclear Information System (INIS)

Davey, G.

1990-01-01

The Oxford Cryocooler incorporates a linear drive compressor operating close to resonance. All dynamic seals are noncontacting clearance seals maintained by mounting the piston and displacer on mechanical suspension systems with infinite fatigue life. The displacer is pneumatically driven but controlled by a miniature linear motor. The cooler is therefore nonwearing and performance can be maintained even in adverse environments by servo control of piston and displacer strokes and relative phase. Split and integral, single- and two-stage coolers have been produced with operating temperatures between 30 K and 200 K, refrigeration powers between 50 mW and several watts and capable of operating in ambient temperatures from -40 C to 70 C. A current project aims to extend the refrigeration power to 500 watts at 80 K. Experimental optimisation techniques have been devised for rapid development of high efficiency coolers

Wave propagation in spatially modulated tubes

Energy Technology Data Exchange (ETDEWEB)

Ziepke, A., E-mail: ziepke@itp.tu-berlin.de; Martens, S.; Engel, H. [Institut für Theoretische Physik, Hardenbergstraße 36, EW 7-1, Technische Universität Berlin, 10623 Berlin (Germany)

2016-09-07

We investigate wave propagation in rotationally symmetric tubes with a periodic spatial modulation of cross section. Using an asymptotic perturbation analysis, the governing quasi-two-dimensional reaction-diffusion equation can be reduced into a one-dimensional reaction-diffusion-advection equation. Assuming a weak perturbation by the advection term and using projection method, in a second step, an equation of motion for traveling waves within such tubes can be derived. Both methods predict properly the nonlinear dependence of the propagation velocity on the ratio of the modulation period of the geometry to the intrinsic width of the front, or pulse. As a main feature, we observe finite intervals of propagation failure of waves induced by the tube’s modulation and derive an analytically tractable condition for their occurrence. For the highly diffusive limit, using the Fick-Jacobs approach, we show that wave velocities within modulated tubes are governed by an effective diffusion coefficient. Furthermore, we discuss the effects of a single bottleneck on the period of pulse trains. We observe period changes by integer fractions dependent on the bottleneck width and the period of the entering pulse train.

Quasi-static drift-tube accelerating structures for low-speed heavy ions

International Nuclear Information System (INIS)

Faltens, A.; Keefe, D.

1978-01-01

A pulsed drift-tube accelerating structure for use in Heavy Ion Fusion applications is described. Possible arrangements of components in such a structure, the injector design needs, and the influence of the existing state of component technology on drift-tube structure design are considered. It is concluded that the major attractions of the pulsed drift tubes are that they are nonresonant structures and that they appear suitable for accelerating a very high current bunch at low energies. The mechanical tolerances of the nonresonant structure are very loose and the cost per meter should be low; the cost of the transport system is expected to be the major cost. The pulse-power modulators used to drive the drift tubes are inexpensive compared with rf sources of equivalent peak power. The longitudinal emittance of the beam emerging from the structure could be extremely low. (U.K.)

Design and array signal suggestion of array type pulsed eddy current probe for health monitoring of metal tubes

Energy Technology Data Exchange (ETDEWEB)

Shin, Young Kil [Dept. of Electrical Engineering, Kunsan National University, Kunsan (Korea, Republic of)

2015-10-15

An array type probe for monitoring metal tubes is proposed in this paper which utilizes peak value and peak time of a pulsed eddy current(PEC) signal. The probe consists of an array of encircling coils along a tube and the outside of coils is shielded by ferrite to prevent source magnetic fields from directly affecting sensor signals since it is the magnetic fields produced by eddy currents that reflect the condition of metal tubes. The positions of both exciter and sensor coils are consecutively moved automatically so that manual scanning is not necessary. At one position of send-receive coils, peak value and peak time are extracted from a sensor PEC signal and these data are accumulated for all positions to form an array type peak value signal and an array type peak time signal. Numerical simulation was performed using the backward difference method in time and the finite element method for spatial analysis. Simulation results showed that peak value increases and the peak appears earlier as the defect depth or length increases. The proposed array signals are shown to be excellent in reflecting the defect location as well as variations of defect depth and length within the array probe.

Sealed ion accelerator tubes (survey)

International Nuclear Information System (INIS)

Voitsik, L.R.

1985-01-01

The first publications on developing commercial models of small-scale sealed accelerator tubes in which neutrons are generated appeared in the foreign press in 1954 to 1957; they were very brief and were advertising-oriented. The tubes were designed for neutron logging of oil wells instead of ampule neutron sources (Po + Be, Ra + Be). Later, instruments of this type began to be called neutron tubes from the resulting neutron radiation that they gave off. In Soviet Union a neutron tube was developed in 1958 in connection with the development of the pulsed neutron-neutron method of studying the geological profile of oil wells. At that time the tube developed was intended, in the view of its inventors, to replace standard isotope sources with constant neutron yield. A fairly detailed survey of neutron tubes was made in the studies. 8 refs., 8 figs

The Experimental Study about the Effect of Operating Conditions on Multi-tube Pulse Detonation Engine Performance

Science.gov (United States)

Kim, Jung-Min; Han, Hyung-Seok; Choi, Jeong-Yeol

2018-04-01

This study examines a multi-tube pulse detonation engine (PDE) which has a type of constant volume combustion. We designed and made the multi-tube PDE and then conducted an experiment in various operating frequencies and equivalence ratios. First, experiments with operating frequencies of 40, 80, 120, 160, and 200 Hz resulted in an average thrust and specific impulse 23.14 N and 42.34 s. The next experiment resulted in the equivalence ratio varying from 0.81 to 1.38, which resulted in an average thrust and specific impulse 22.36 N and 40.11 s. The average detonation velocity was 8% lower than that calculated according to C-J theory. The incidence ratios of the detonation wave were stable with the exception of the operating frequency of 200 Hz. However, at 200 Hz, the incidence ratio was less than 50%. We assumed that a low fill fraction occurred for this problem. The thrust of the PDE increased with the operating frequency. However, the thrust increase was at a lower rate than in previous studies, because of a lost thrust output result from the slow response time of the load cell amplifier.

Pulsed electron beam generation with fast repetitive double pulse system

Energy Technology Data Exchange (ETDEWEB)

Sharma, Surender Kumar; Deb, Pankaj; Shyam, Anurag, E-mail: surender80@gmail.com [Energetics and Electromagnetics Division, Bhabha Atomic Research Centre, Visakhapatnam (India); Sharma, Archana [Accelerator and Pulse Power Division, Bhabha Atomic Research Centre, Mumbai (India)

2014-07-01

Longer duration high voltage pulse (∼ 100 kV, 260 ns) is generated and reported using helical pulse forming line in compact geometry. The transmission line characteristics of the helical pulse forming line are also used to develop fast repetition double pulse system with very short inter pulse interval. It overcomes the limitations caused due to circuit parameters, power supplies and load characteristics for fast repetitive high voltage pulse generation. The high voltage double pulse of 100 kV, 100 ns with an inter pulse repetition interval of 30 ns is applied across the vacuum field emission diode for pulsed electron beam generation. The electron beam is generated from cathode material by application of negative high voltage (> 100 kV) across the diode by explosive electron emission process. The vacuum field emission diode is made of 40 mm diameter graphite cathode and SS mesh anode. The anode cathode gap was 6 mm and the drift tube diameter was 10 cm. The initial experimental results of pulsed electron beam generation with fast repetitive double pulse system are reported and discussed. (author)

Radiation detection at very low temperature. DRTBT 1999 - Balaruc-les-Bains - Course collection

International Nuclear Information System (INIS)

Chapellier, M.; Ravex, A.; Pari, P.; Bossy, J.; Garoche, P.; Perrin, Nicole; Loidl, M.; Den Hartog, Roland; Navick, Xavier-Francois; Mailly, Dominique; Chardin, Gabriel; Joyez, Philippe; Goyot, M.; Dumoulin, L.; Aprilli, M.; Torre, J.P.; Bouchez, J.; Benoit, Alain

1992-01-01

After four contributions (Introduction to cryogenics, Pulsed tube or recent developments in cryo-coolers, Dilution-based cooling, Adiabatic demagnetisation), the contributions addressed various themes: Low temperature physics (Specific and abnormal heats, Thermal conductivity, Anderson insulator, Superconductors); Physics within bolometers (basic principle of a bolometer, Energy conversion and ionisation, electron-phonon interaction, Edge sensor transition); Example of cryogenic sensors (Sub-millimetre / spider-web, Superconducting Tunnel Junction as photon detectors, ionization-heat massive bolometers); Signal processing (SQUID amplifiers, Elementary statistics, Signal processing and data analysis, Measurement electronics for bolometers, Single electron transistor, Preamplifiers)

Characterization of a pulsed x-ray source for fluorescent lifetime measurements

International Nuclear Information System (INIS)

Blankespoor, S.C.; Derenzo, S.E.; Moses, W.W.; Rossington, C.S.; Ito, M.; Oba, K.

1994-01-01

To search for new, fast, inorganic scintillators, the authors have developed a bench-top pulsed x-ray source for determining fluorescent lifetimes and wavelengths of compounds in crystal or powdered form. This source uses a light-excited x-ray tube which produces x-rays when light from a laser diode strikes its photocathode. The x-ray tube has a tungsten anode, a beryllium exit window, a 30 kV maximum tube bias, and a 50 μA maximum average cathode current. The laser produces 3 x 10 7 photons at 650 nm per ∼100 ps pulse, with up to 10 7 pulses/sec. The time spread for the laser diode, x-ray tube, and a microchannel plate photomultiplier tube is less than 120 ps fwhm. The mean x-ray energy at tube biases of 20, 25, and 30 kV is 9.4, 10.3, and 11.1 keV, respectively. The authors measured 140, 230, and 330 x-ray photons per laser diode pulse per steradian, at tube biases of 20, 25, and 30 kV, respectively. Background x-rays due to dark current occur at a rate of 1 x 10 6 and 3 x 10 6 photons/sec/steradian at biases of 25 and 30 kV, respectively. Data characterizing the x-ray output with an aluminum filter in the x-ray beam are also presented

SLAC pulsed X-ray facility

Science.gov (United States)

Ipe, N. E.; McCall, R. C.; Baker, E. D.

1986-05-01

The Stanford Linear Accelerator Center (SLAC) operates a high energy (up to 33 GeV) linear accelerator delivering pulses up to a few microseconds wide. The pulsed nature of the electron beam creates problems in the detection and measurement of radiation both from the accelerator beam and the klystrons that provide the RF power for the accelerator. Hence, a pulsed X-ray facility has been built at SLAC mainly for the purpose of testing the response of different radiation detection instruments to pulsed radiation fields. The X-ray tube consists of an electron gun with a control grid. This provides a stream of pulsed electrons that can be accelerated towards a confined target-window. The window is made up of aluminum 0.051 cm (20 mils) thick, plated on the vacuum side with a layer of gold 0.0006 cm (1/4 mil) thick. The frequency of electron pulses can be varied by an internal pulser from 60 to 360 pulses per second with pulse widths of 360 ns to 5 ms. The pulse amplitude can be varied over a wide range of currents. An external pulser can be used to obtain other frequencies or special pulse shapes. The voltage across the gun can be varied from 0 to 100 kV. The major part of the X-ray tube is enclosed in a large walk-in-cabinet made of 1.9 cm (3/4 in) plywood and lined with 0.32 cm (1/8 in) lead to make a very versatile facility.

SLAC pulsed x-ray facility

International Nuclear Information System (INIS)

Ipe, N.E.; McCall, R.C.; Baker, E.D.

1986-05-01

The Stanford Linear Accelerator Center (SLAC) operates a high energy (up to 33 GeV) linear accelerator delivering pulses up to a few microseconds wide. The pulsed nature of the electron beam creates problems in the detection and measurement of radiation both from the accelerator beam and the klystrons that provide the rf power for the accelerator. Hence, a pulsed x-ray facility has been built at SLAC mainly for the purpose of testing the response of different radiation detection instruments to pulsed radiation fields. The x-ray tube consists of an electron gun with a control grid. This provides a stream of pulsed electrons that can be accelerated towards a confined target-window. The window is made up of aluminium 0.051 cm (20 mils) thick, plated on the vacuum side with a layer of gold 0.0006 cm (1/4 mil) thick. The frequency of electron pulses can be varied by an internal pulser from 60 to 360 pulses per second with pulse widths of 360 ns to 5 μs. The pulse amplitude can be varied over a wide range of currents. An external pulser can be used to obtain other frequencies or special pulse shapes. The voltage across the gun can be varied from 0 to 100 kV. The major part of the x-ray tube is enclosed in a large walk-in-cabinet made of 1.9 cm (3/4 in) plywood and lined with 0.32 cm (1/8 in) lead to make a very versatile facility. 3 refs., 5 figs

Vibration-induced electrical noise in a cryogen-free dilution refrigerator: Characterization, mitigation, and impact on qubit coherence

Energy Technology Data Exchange (ETDEWEB)

Kalra, Rachpon; Laucht, Arne; Dehollain, Juan Pablo; Bar, Daniel; Freer, Solomon; Simmons, Stephanie; Muhonen, Juha T.; Morello, Andrea, E-mail: a.morello@unsw.edu.au [Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney NSW 2052 (Australia)

2016-07-15

Cryogen-free low-temperature setups are becoming more prominent in experimental science due to their convenience and reliability, and concern about the increasing scarcity of helium as a natural resource. Despite not having any moving parts at the cold end, pulse tube cryocoolers introduce vibrations that can be detrimental to the experiments. We characterize the coupling of these vibrations to the electrical signal observed on cables installed in a cryogen-free dilution refrigerator. The dominant electrical noise is in the 5–10 kHz range and its magnitude is found to be strongly temperature dependent. We test the performance of different cables designed to diagnose and tackle the noise, and find triboelectrics to be the dominant mechanism coupling the vibrations to the electrical signal. Flattening a semi-rigid cable or jacketing a flexible cable in order to restrict movement within the cable, successfully reduces the noise level by over an order of magnitude. Furthermore, we characterize the effect of the pulse tube vibrations on an electron spin qubit device in this setup. Coherence measurements are used to map out the spectrum of the noise experienced by the qubit, revealing spectral components matching the spectral signature of the pulse tube.

L-band pulsed klystron for the JHP

International Nuclear Information System (INIS)

Fukuda, S.; Takeuchi, Y.; Hisamatsu, H.; Anami, S.; Kihara, M.; Takahashi, A.

1994-01-01

An L-band high-power klystron for the JHP (6 MW output power and 600 μsec pulse width) was designed at KEK. High-power tests of the test diodes were performed up to a beam voltage of 140 kV, a pulse width of 600 μsec and a repetition rate of 50 pps. The capability to meet the specifications of the gun and the collector was confirmed. High-power tests of the rf window were also performed up to rf powers of 4 MW (600 μsec pulse width) and 5 MW (375 μsec pulse width). We obtained good results for an rf window using high-purity alumina (99.7%). The design considerations and manufacturing process are also described. Manufacturing a prototype tube has been completed and the tube is undergoing the high-power tests. (author)

Methods for tube attachment in a heat exchange equipment

International Nuclear Information System (INIS)

Shilin, O.V.; Vasil'ev, V.B.

1984-01-01

Two main ways of attaching tubes to tube panels in heat exchange equipment are analyzed: expanding and pulse method (by explosion, for instance). Labour-consumption and cost price for the fastening of brass, perlitic and corrosion-resistant tubes for both of the methods are presented. The extent of fitting out with equipment for tube fixing and ways of testing the joints for attachment are evaluated. Measures for improving the joint quality and introduction of the advanced technology are suggested

Cryogen free low temperature sample environment for neutron scattering experiments

International Nuclear Information System (INIS)

Kirichek, O; Evans, B E; Down, R B E; Bowden, Z A

2009-01-01

Recent increase in liquid helium cost caused by global helium supply problems rose significant concern about affordability of conventional cryogenic equipment. Luckily the progress in cryo-cooler technology offers a new generation of cryogenic systems with significantly reduced consumption and in some cases nearly complete elimination of cryogens. These cryogen-free systems also offer the advantage of operational simplicity and require less space than conventional cryogen-cooled systems. The ISIS facility carries on an internal development program intended to substitute gradually all conventional cryogenic systems with cryogen free systems preferably based on pulse tube refrigerators. A unique feature of this cryo-cooler is the absence of cold moving parts. This considerably reduces vibrations and increases the reliability of the cold head. The program includes few development projects which are aiming to deliver range of cryogen free equipment including top-loading cryostat, superconducting magnets and dilution refrigerators. Here we are going to describe the design of these systems and discuss the results of prototypes testing.

A numerical and experimental investigation of the thermal control performance of a spaceborne compressor assembly

Science.gov (United States)

Oh, Hyun-Ung; Lee, Min-Kyu; Shin, Somin; Hong, Joo-Sung

2011-09-01

Spaceborne pulse tube type cryocoolers are widely used for providing cryogenic temperatures for sensitive infrared, gamma-ray and X-ray detectors. Thermal control for the compressor of the cryocooler is one of the important technologies for the cooling performance, mission life time, and jitter stability of the cooler. The thermal design of the compressor assembly proposed in this study is basically composed of a heat pipe, a radiator, and a heater. In the present work, a method for heat pipe implementation is proposed and investigated to ensure the jitter stability of the compressor under the condition that one heat pipe is not working. An optimal design of the radiator that uses ribs for effective use by minimizing the temperature gradient on the radiator and reducing its weight is introduced. The effectiveness of the thermal design of the compressor assembly is demonstrated by on-orbit thermal analysis using the correlated thermal model obtained from the thermal balance test that is performed under a space simulating environment.

Application of smart structure concepts to vibration suppression of a cryocooler coldfinger

International Nuclear Information System (INIS)

Glaser, R.J.; Kuo, Chinpo, Garba, J.A.

1993-01-01

A flight experiment demonstrating vibration suppression using smart structure technology is being flown on a small British satellite in late 1993. Piezo actuators are used to suppress motion of the tip of a cryocooler coldfinger in three dimensions. Two actuation methods are being demonstrated: low voltage piezo translators and applique ceramics. The applique ceramics stretch the coldfinger to cancel the tip motion and is discussed in detail in a companion paper. Commercially available piezo translators displace the entire cryocooler to cancel the motion of the tip of the coldfinger as measured by three eddy current transducers. Two types of control systems are being demonstrated: a real time analog control system using position feedback, and a digital feed forward controller that updates it's waveform every second or so. The flight experiment is a technology demonstration. The coldfinger is not being used to cool an operational sensor. Instead, the cooler vibration experiment will demonstrate that this class of hardware can be flown successfully. This includes qualification of the piezos for launch, and for the space environment; the design and qualification of low-power flight piezo drivers; and design and implementation of the control systems

Design of high–order HTS dual–band bandpass filters with receiver subsystem for future mobile communication systems

Energy Technology Data Exchange (ETDEWEB)

Sekiya, N., E-mail: nsekiya@yamanashi.ac.jp

2016-08-15

Highlights: • We have developed two high-order HTS dual-band BPFs with a receiver subsystem for future mobile communication systems. • We developed a method for flexibly adjusting the coupling coefficient for the two passbands. • We demonstrated an HTS dual-band BPF receiver subsystem that uses a pulse tube cryocooler and a wideband LNA. • The proposed BPF is evaluated by simulation and measurement with good agreement. - Abstract: We have developed two high-order high-temperature superconducting (HTS) dual-band bandpass filters (BPFs) with a receiver subsystem for future mobile communication systems. They feature stub-loaded hair-pin resonators with two types of microstrip lines between them. One has a six-pole design, and the other has an eight-pole design. Both were designed to operate at 2.15 GHz with a 43-MHz (2%) bandwidth for the lower passband and at 3.50 GHz with a 70-MHz (2%) bandwidth for the upper one. They were fabricated using YBa{sub 2}Cu{sub 3}O{sub y} thin film on a CeO{sub 2}-bufferd r-Al{sub 2}O{sub 3} substrate. The measured results for both filters agree well with the simulated ones. The HTS dual-band BPF receiver subsystem uses a pulse tube cryocooler and a wideband low noise amplifier (LNA). We measured the frequency response of the six-pole dual-band BPF with and without a wideband LNA with a gain of 10 dB. The measured return losses were close.

Pulsed neutron generator for mass flow measurement using the pulsed neutron activation technique

International Nuclear Information System (INIS)

Rochau, G.E.; Hornsby, D.R.; Mareda, J.F.; Riggan, W.C.

1980-01-01

A high-output, transportable neutron generator has been developed to measure mass flow velocities in reactor safety tests using the Pulsed Neutron Activation (PNA) Technique. The PNA generator produces >10 10 14 MeV D-T neutrons in a 1.2 millisecond pulse. The Millisecond Pulse (MSP) Neutron Tube, developed for this application, has an expected operational life of 1000 pulses, and it limits the generator pulse repetition rate to 12 pulses/minute. A semiconductor neutron detector is included in the generator package to monitor the neutron output. The control unit, which can be operated manually or remotely, also contains a digital display with a BCD output for the neutron monitor information. The digital logic of the unit controls the safety interlocks and rejects transient signals which could accidently fire the generator

Physical design of 9 MeV travelling wave electron linac accelerating tube

International Nuclear Information System (INIS)

Chen Huaibi; Ding Xiaodong; Lin Yuzheng

2000-01-01

An accelerating tube is described. It is a part of an accelerator used for inspection of vehicle cargoes in rail cars, trucks, shipping containers, or airplanes in customs. A klystron with power of 4 MW and frequency of 2856 MHz will be applied to supply microwave power. The electrons can be accelerated by a travelling wave in the accelerating tube about 220 cm long, with a buncher whose capture efficiency is more than 80%. Energy of electrons after travelling through the tube can reach 9 MeV (pulse current intensity 170 mA) or 6 MeV (pulse current intensity 300 mA). Physical design of the accelerating tube, including the calculations of longitudinal particle dynamics, structure parameter and working character is carried out

Maximization of bremsstrahlung and K-series production efficiencies in flash x-ray tubes

International Nuclear Information System (INIS)

Krehl, P.

1986-01-01

Historically, x-ray output of flash x-ray tubes was maximized empirically by changing the electrode geometry and varying the capacitance of the pulse generator. With the advent of high-voltage, low-impedance transmission lines, short-duration, high-current pulses could be generated with ease. An appropriate line scaling should assure that dose maximization is not reached at the expense of pulse prolongation which would reduce stop motion capability, but rather that dose rate should be maximized. Additionally, anode evaporation in the arc phase should be minimized to enhance tube life

Characterization of the frictional losses and heat transfer of oscillatory viscous flow through wire-mesh regenerators

Directory of Open Access Journals (Sweden)

A.A. Boroujerdi

2015-12-01

Full Text Available In this paper, new relations for calculating heat transfer and pressure drop characteristics of oscillatory flow through wire-mesh screen regenerator such as Darcy permeability, Forchheimer’s inertial coefficient, and heat transfer area per unit volume, as a function of the wire diameter are presented. According to the derived relations, thinner wires have higher pressure drop and higher heat transfer rate. The relations are applicable for all regenerative cryocoolers. Embedding the new relations into a numerical model, three Stirling-type orifice pulse tube cryocoolers with three regenerators different in length and diameter but same volume in a variety of wire diameters, have been modeled. The results achieved by the model reveal that the local heat transfer coefficient decreases with increase of the wire diameter and the length-to-diameter ratio. In addition, it was shown that the mean absolute gas–solid wire temperature difference is a linear function of wire diameter in the range investigated. The results show that for larger length-to-diameter ratios, Forchheimer’s effect will dominate frictional losses, and the variations of the frictional losses are proportional to the inverse of the wire diameter. Wire diameter has been optimized to maximize the coefficient of performance of the cryocooler. Shorter regenerators have thinner optimum wires.

Streak tube development

International Nuclear Information System (INIS)

Hinrichs, C.K.; Estrella, R.M.

1979-01-01

A research program for the development of a high-speed, high-resolution streak image tube is described. This is one task in the development of a streak camera system with digital electronic readout, whose primary application is for diagnostics in underground nuclear testing. This program is concerned with the development of a high-resolution streak image tube compatible with x-ray input and electronic digital output. The tube must be capable of time resolution down to 100 psec and spatial resolution to provide greater than 1000 resolution elements across the cathode (much greater than presently available). Another objective is to develop the capability to make design changes in tube configurations to meet different experimental requirements. A demountable prototype streak tube was constructed, mounted on an optical bench, and placed in a vacuum system. Initial measurements of the tube resolution with an undeflected image show a resolution of 32 line pairs per millimeter over a cathode diameter of one inch, which is consistent with the predictions of the computer simulations. With the initial set of unoptmized deflection plates, the resolution pattern appeared to remain unchanged for static deflections of +- 1/2-inch, a total streak length of one inch, also consistent with the computer simulations. A passively mode-locked frequency-doubled dye laser is being developed as an ultraviolet pulsed light source to measure dynamic tube resolution during streaking. A sweep circuit to provide the deflection voltage in the prototype tube has been designed and constructed and provides a relatively linear ramp voltage with ramp durations adjustable between 10 and 1000 nsec

Life-test results on the Zetatron tube, transformer and the tube-transformer assembly

International Nuclear Information System (INIS)

Shope, L.A.

1983-01-01

In the development of the PFN probe it became evident that some considerable life testing of the neutron tube, high-voltage pulse transformer, and the tube-transformer assembly (TTA) were needed to (1) identify life limiting mechanisms, (2) estimate performance degradation, and (3) provide a data base for end-of-life predictions. Initial results had shown clearly that testing monitored by technicians would be much too costly. Consequently, a computer-controlled and monitored test was developed. This paper describes the test, summarizes the records, and discusses the results. Also presented are early results of actual probe life testing now underway

The Ricor K508 cryocooler operational experience on Mars

Energy Technology Data Exchange (ETDEWEB)

Johnson, Dean L.; Lysek, Mark J.; Morookian, John Michael [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

2014-01-29

The Mars Science Laboratory (Curiosity) landed successfully on Mars on August 5, 2012, eight months after launch. The chosen landing site of Gale Crater, located at 4.5 degrees south latitude, 137.4 degrees east longitude, has provided a much more benign environment than was originally planned for during the critical design and integration phases of the MSL Project when all possible landing sites were still being considered. The expected near-surface atmospheric temperatures at the Gale Crater landing site during Curiosity's primary mission (1 Martian year or 687 Earth days) are from −90°C to 0°C. However, enclosed within Curiosity's thermal control fluid loops the Chemistry and Mineralogy (CheMin) instrument is maintained at approximately +20°C. The CheMin instrument uses X-ray diffraction spectroscopy to make precise measurements of mineral constituents of Mars rocks and soil. The instrument incorporated the commercially available Ricor K508 Stirling cycle cryocooler to cool the CCD detector. After several months of brushing itself off, stretching and testing out its subsystems, Curiosity began the exploration of the Mars surface in October 2012. The CheMin instrument on the Mars Science Laboratory (MSL) received its first soil sample from Curiosity on October 24, and successfully analyzed its first soil sample. After a brief review of the rigorous Ricor K508 cooler qualification tests and life tests based on the original MSL environmental requirements this paper presents final pre-launch instrument integration and testing results, and details the operational data of the CheMin cryocooler, providing a snapshot of the resulting CheMin instrument analytical data.

The Ricor K508 cryocooler operational experience on Mars

International Nuclear Information System (INIS)

Johnson, Dean L.; Lysek, Mark J.; Morookian, John Michael

2014-01-01

The Mars Science Laboratory (Curiosity) landed successfully on Mars on August 5, 2012, eight months after launch. The chosen landing site of Gale Crater, located at 4.5 degrees south latitude, 137.4 degrees east longitude, has provided a much more benign environment than was originally planned for during the critical design and integration phases of the MSL Project when all possible landing sites were still being considered. The expected near-surface atmospheric temperatures at the Gale Crater landing site during Curiosity's primary mission (1 Martian year or 687 Earth days) are from −90°C to 0°C. However, enclosed within Curiosity's thermal control fluid loops the Chemistry and Mineralogy (CheMin) instrument is maintained at approximately +20°C. The CheMin instrument uses X-ray diffraction spectroscopy to make precise measurements of mineral constituents of Mars rocks and soil. The instrument incorporated the commercially available Ricor K508 Stirling cycle cryocooler to cool the CCD detector. After several months of brushing itself off, stretching and testing out its subsystems, Curiosity began the exploration of the Mars surface in October 2012. The CheMin instrument on the Mars Science Laboratory (MSL) received its first soil sample from Curiosity on October 24, and successfully analyzed its first soil sample. After a brief review of the rigorous Ricor K508 cooler qualification tests and life tests based on the original MSL environmental requirements this paper presents final pre-launch instrument integration and testing results, and details the operational data of the CheMin cryocooler, providing a snapshot of the resulting CheMin instrument analytical data

Validation of accelerated ageing of Thales rotary Stirling cryocoolers for the estimation of MTTF

Science.gov (United States)

Seguineau, C.,; Cauquil, J.-M.; Martin, J.-Y.; Benschop, T.

2016-05-01

The cooled IR detectors are used in a wide range of applications. Most of the time, the cryocoolers are one of the components dimensioning the lifetime of the system. The current market needs tend to reliability figures higher than 15,000hrs in "standard conditions". Field returns are hardly useable mostly because of the uncertain environmental conditions of use, or the differences in user profiles. A previous paper explains how Thales Cryogenics has developed an approach based on accelerated ageing and statistical analysis [1]. The aim of the current paper is to compare results obtained on accelerated ageing on one side, and on the other side, specific field returns where the conditions of use are well known. The comparison between prediction and effective failure rate is discussed. Moreover, a specific focus is done on how some new applications of cryocoolers (continuous operation at a specific temperature) can increase the MTTF. Some assumptions are also exposed on how the failure modes, effects and criticality analysis evolves for continuous operation at a specific temperature and compared to experimental data.

Chemical kinetics studies at high temperatures using shock tubes

OpenAIRE

Rajakumar, B; Anandraj, D; Reddy, KPJ; Arunan, E

2002-01-01

Shock tube is an unique facility to create temperature gradients exceeding million degrees Kelvin per second. We have established two shock tubes for measuring the kinetic reaction rates at high temperatures with two different but complementary detection techniques. The first one is a single pulse shock tube, in which the reflected shock is used to heat the molecules. The equilibrated products are analyzed by gas chromatograph and infrared spectrometer. The second one uses laser-schlieren sys...

A 1 T, 0.33 m bore superconducting magnet operating with cryocoolers at 12 K

NARCIS (Netherlands)

van der Laan, M.T.G.; van der Laan, M.T.G.; Tax, R.B.; ten Kate, Herman H.J.; van de Klundert, L.J.M.

1992-01-01

The application of small cryocoolers to cooling a superconducting magnet at 12 K has important advantages, especially for small and medium-size magnets. Simple construction and a helium-free magnet system were obtained. The demonstration magnet developed is a six-coil system with a volume of 75 L

Design of High Voltage Electrical Breakdown Strength measuring system at 1.8K with a G-M cryocooler

Science.gov (United States)

Li, Jian; Huang, Rongjin; Li, Xu; Xu, Dong; Liu, Huiming; Li, Laifeng

2017-09-01

Impregnating resins as electrical insulation materials for use in ITER magnets and feeder system are required to be radiation stable, good mechanical performance and high voltage electrical breakdown strength. In present ITER project, the breakdown strength need over 30 kV/mm, for future DEMO reactor, it will be greater than this value. In order to develop good property insulation materials to satisfy the requirements of future fusion reactor, high voltage breakdown strength measurement system at low temperature is necessary. In this paper, we will introduce our work on the design of this system. This measuring system has two parts: one is an electrical supply system which provides the high voltage from a high voltage power between two electrodes; the other is a cooling system which consists of a G-M cryocooler, a superfluid chamber and a heat switch. The two stage G-M cryocooler pre-cool down the system to 4K, the superfluid helium pot is used for a container to depress the helium to superfluid helium which cool down the sample to 1.8K and a mechanical heat switch connect or disconnect the cryocooler and the pot. In order to provide the sufficient time for the test, the cooling system is designed to keep the sample at 1.8K for 300 seconds.

New model of universal gas-filled neutron tube

International Nuclear Information System (INIS)

Bespalov, D.F.; Bessarabskii, I.G.; Voitsik, L.R.; Mints, A.Z.

1985-01-01

The UNG-1 gas-filled neutron tube is serially produced. In type UNG neutron generators, the tube operates in the pulsed mode in the high voltage doubling circuit arrangement. During extended operation, its advantages were discovered: long operating time, fairly stable neutron yield, and simplicity of use and operation. However, the mean neutron yield (approx.10 7 s -1 ) generated by the tube in the optimal mode at the present time proved to be inadequate in solving numerous geophysical problems. So a model of a neutron tube, model UNG-2, was designed, ensuring an enhanced neutron yield of 10 8 s -1 in the continuous-operating mode. When the tube is connected to the high voltage doubling circuit, the mean neutron yield is only somewhat in excess of the neutron yield from the UNG-1 tube

Impulse generation by detonation tubes

Science.gov (United States)

Cooper, Marcia Ann

Impulse generation with gaseous detonation requires conversion of chemical energy into mechanical energy. This conversion process is well understood in rocket engines where the high pressure combustion products expand through a nozzle generating high velocity exhaust gases. The propulsion community is now focusing on advanced concepts that utilize non-traditional forms of combustion like detonation. Such a device is called a pulse detonation engine in which laboratory tests have proven that thrust can be achieved through continuous cyclic operation. Because of poor performance of straight detonation tubes compared to conventional propulsion systems and the success of using nozzles on rocket engines, the effect of nozzles on detonation tubes is being investigated. Although previous studies of detonation tube nozzles have suggested substantial benefits, up to now there has been no systematic investigations over a range of operating conditions and nozzle configurations. As a result, no models predicting the impulse when nozzles are used exist. This lack of data has severely limited the development and evaluation of models and simulations of nozzles on pulse detonation engines. The first experimental investigation measuring impulse by gaseous detonation in plain tubes and tubes with nozzles operating in varying environment pressures is presented. Converging, diverging, and converging-diverging nozzles were tested to determine the effect of divergence angle, nozzle length, and volumetric fill fraction on impulse. The largest increases in specific impulse, 72% at an environment pressure of 100 kPa and 43% at an environment pressure of 1.4 kPa, were measured with the largest diverging nozzle tested that had a 12° half angle and was 0.6 m long. Two regimes of nozzle operation that depend on the environment pressure are responsible for these increases and were first observed from these data. To augment this experimental investigation, all data in the literature regarding

Vibration-free stirling cryocooler for high definition microscopy

Science.gov (United States)

Riabzev, S. V.; Veprik, A. M.; Vilenchik, H. S.; Pundak, N.; Castiel, E.

2009-12-01

The normal operation of high definition Scanning Electronic and Helium Ion microscope tools often relies on maintaining particular components at cryogenic temperatures. This has traditionally been accomplished by using liquid coolants such as liquid Nitrogen. This inherently limits the useful temperature range to above 77 K, produces various operational hazards and typically involves elevated ownership costs, inconvenient logistics and maintenance. Mechanical coolers, over-performing the above traditional method and capable of delivering required (even below 77 K) cooling to the above cooled components, have been well-known elsewhere for many years, but their typical drawbacks, such as high purchasing cost, cooler size, low reliability and high power consumption have so far prevented their wide-spreading. Additional critical drawback is inevitable degradation of imagery performance originated from the wideband vibration export as typical for the operation of the mechanical cooler incorporating numerous movable components. Recent advances in the development of reliable, compact, reasonably priced and dynamically quiet linear cryogenic coolers gave rise to so-called "dry cooling" technologies aimed at eventually replacing the traditional use of outdated liquid Nitrogen cooling facilities. Although much improved these newer cryogenic coolers still produce relatively high vibration export which makes them incompatible with modern high definition microscopy tools. This has motivated further research activity towards developing a vibration free closed-cycle mechanical cryocooler. The authors have successfully adapted the standard low vibration Stirling cryogenic refrigerator (Ricor model K535-LV) delivering 5 W@40 K heat lift for use in vibration-sensitive high definition microscopy. This has been achieved by using passive mechanical counterbalancing of the main portion of the low frequency vibration export in combination with an active feed-forward multi

X-ray tube transformer

International Nuclear Information System (INIS)

1980-01-01

An X-ray generator is described which comprises a transmission line transformer including an electrical conductor with a cavity and a second electrical conductor including helical windings disposed along a longitudinal axis within the cavity of the first conductor. The windings have a pitch which varies per unit length along the axis. There is dielectric material in the cavity for insulation and to couple electromagnetically the two conductors in response to an electric current flowing through the conductors, which have an impedance between them; this varies with distance along the axis of the helix of the second conductor. An X-ray tube is disposed along the longitudinal axis within the cavity, for radiating X-rays. The invention increases the voltage of applied voltage pulses at the remote tube-head with a transformer formed by using a spiral delay line geometry to give a tapered-impedance coaxial high voltage multiplier for pulse voltage operation. This transformer is smaller and lighter than previous designs for the same high peak voltage and power ratings. This is important because the penetration capabilities of Flash X-ray equipment increase with voltage, particularly in heavy materials such as steel. (U.K.)

Quasi-static drift-tube accelerating structures for low-speed heavy ions

International Nuclear Information System (INIS)

Faltens, A.; Keefe, D.

1977-01-01

The major attractions of the pulsed drift-tubes are that they are non-resonant structures and that they appear suitable for accelerating a very high current bunch at low energies. The mechanical tolerances of the non-resonant structure are very loose and the cost per meter should be low; the cost of the transport system is expected to be the major cost. The pulse power modulators used to drive the drift-tubes are inexpensive compared to r.f. sources with equivalent peak-power. The longitudinal emittance of the beam emerging from the structure could be extremely low

900-L liquid xenon cryogenic system operation for the MEG experiment

CERN Document Server

Haruyama, T; Mihara, S; Hisamatsu, Y; Iawamoto, W; Mori, T; Nishiguchi, H; Otani, W; Sawada, R; Uchiyama, Y; Nishitani, T

2009-01-01

A cryogenic system for the MEG (muon rare decay) experiment has started operation at the Paul Sherrer Institute in Zurich. The main part of the MEG detector is the 900-L liquid xenon calorimeter for gamma ray detection, equipped with 850 photo multipliers directly immersed in liquid xenon. A 200 W pulse tube cryocooler enabled LN2-free operation of this calorimeter. A liquid purification system; using a liquid pump and a zero boil-off 1000-L cryogenic buffer dewar is also included in the system. The first entire engineering run was carried out in November-December 2007 and satisfactory cryogenic performances were confirmed.

Studies of cryocooler based cryosorption pump with activated carbon panels operating at 11K

International Nuclear Information System (INIS)

Kasthurirengan, S; Behera, Upendra; Gangradey, Ranjana; Udgata, Swarup; Krishnamoorthy, V

2012-01-01

Cryosorption pump is the only solution for pumping helium and hydrogen in fusion reactors. It is chosen because it offers highest pumping speed as well as the only suitable pump for the harsh environments in a tokamak. Towards the development of such cryosorption pumps, the optimal choice of the right activated carbon panels is essential. In order to characterize the performance of the panels with indigenously developed activated carbon, a cryocooler based cryosorption pump with scaled down sizes of panels is experimented. The results are compared with the commercial cryopanel used in a CTI cryosorption (model: Cryotorr 7) pump. The cryopanel is mounted on the cold head of the second stage GM cryocooler which cools the cryopanel down to 11K with first stage reaching about ∼50K. With no heat load, cryopump gives the ultimate vacuum of 2.1E-7 mbar. The pumping speed of different gases such as nitrogen, argon, hydrogen, helium are tested both on indigenous and commercial cryopanel. These studies serve as a bench mark towards the development of better cryopanels to be cooled by liquid helium for use with tokamak.

Pulsed power supply system for neutron well logging

International Nuclear Information System (INIS)

Hopkinson, E.C.

1975-01-01

A variable D. C. power supply and a variable A. C. power supply are coupled onto the upper end of a single conductor cable at the earth's surface and from the lower end of said cable to a well logging instrument. The A. C. voltage is used to provide filament power for the ion source accelerator tube. The D. C. voltage is used to provide power to fixed D. C. loads maintained constant by regulators once a threshold is reached. The D. C. voltage is raised above the threshold to control the pulsed acceleration voltage and hence neutron output by first feeding into a unijunction relaxation oscillator in combination with an SCR output which output is transformer coupled into a voltage multiplier circuit. An antilatch feature is provided for the SCR by transformer coupling the pulses on the SCR anode back to the base of a transistor in series with the cathode of the SCR. Two outputs of the voltage multiplier circuit are connected to the cathode and anode, respectively, of an ion source accelerator tube, the cathode being connected through a resistor to retard the ripple pulsing of the cathode to allow ionization of the accelerator tube

Tactical versus space cryocoolers: a comparision

Science.gov (United States)

Arts, R.; Mullié, J.; Leenders, H.; de Jonge, G.; Benschop, T.

2017-05-01

In recent years, several space cryocooler developments have been performed in parallel at Thales Cryogenics. On one end of the spectrum are research programmes such as the ESA-funded 30-50 K system developed in cooperation with CEA and Absolut System and the LPT6510 cooler developed in cooperation with Absolut System. On the other end of the spectrum are commercial designs adapted for space applications, such as the LPT9310 commercial coolers delivered for JPL's ECOSTRESS instrument and the LSF9199/30 SADA-compatible cooler delivered for various space programmes at Sofradir. In this paper, an overview is presented of the latest developments regarding these coolers. Initial performance results of the 30-50K cooler are discussed, pending developments for the LPT6510 cooler are presented, and the synergies between COTS and space are reviewed, such as design principles from space coolers being applied to an upgraded variant of the COTS LPT9310, as well as design principles from COTS coolers being applied to the LPT6510 for improved manufacturability.

Simulation of thermal processes in superconducting pancake coils cooled by GM cryocooler

International Nuclear Information System (INIS)

Lebioda, M; Rymaszewski, J; Korzeniewska, E

2014-01-01

This article presents the thermal model of a small scale superconducting magnetic energy storage system with the closed cycle helium cryocooler. The authors propose the use of contact-cooled coils with maintaining the possibility of the system reconfiguring. The model assumes the use of the second generation superconducting tapes to make the windings in the form of flat discs (pancakes). The paper presents results for a field model of the single pancake coil and the winding system consisting of several coils.

Exploring the polymerization of bioactive nano-cones on the inner surface of an organic tube by an atmospheric pressure pulsed micro-plasma jet

Science.gov (United States)

Xu, H. M.; Yu, J. S.; Chen, G. L.; Qiu, X. P.; Hu, W.; Chen, W. X.; Bai, H. Y.

2015-12-01

In this paper, the successful deposition of acrylic acid polymer (PAA) nano-cones on the inner surface of a polyvinyl chloride (PVC) tube using an atmospheric pressure pulsed plasma jet (APPJ) with acrylic acid (AA) monomer is presented. Optical emission spectroscopy (OES) measurements indicated that various reactive radicals, such as rad OH and rad O, existed in the plasma jet. Moreover, the pulsed current proportionally increased with the increase in the applied voltage. The strengthened stretching vibration of the carbonyl group (Cdbnd O) at 1700 cm-1, shown in the ATR-FTIR spectra, clearly indicated that the PAA was deposited on the PVC surface. The maximum height of the PAA nano-cones deposited by this method ranged from 150 to 200 nm. FTIR and XPS results confirmed the enhanced exposure of the carboxyl groups on the modified PVC surface, which was considered highly beneficial for successfully immobilizing a high density of biomolecules. The XPS data showed that the carbon ratios of the Csbnd OH/R and COOH/R groups increased from 7.03% and 2.6% to 18.69% and 6.81%, respectively (more than doubled) when an Ar/O2 plasma with AA monomer was applied to treat the inner surface of the PVC tube. Moreover, the enhanced attachment density of MC3T3-E1 bone cells was observed on the PVC inner surface coated with PAA nano-cones.

Hollow-core fibers for high power pulse delivery

DEFF Research Database (Denmark)

Michieletto, Mattia; Lyngsø, Jens K.; Jakobsen, Christian

2016-01-01

We investigate hollow-core fibers for fiber delivery of high power ultrashort laser pulses. We use numerical techniques to design an anti-resonant hollow-core fiber having one layer of non-touching tubes to determine which structures offer the best optical properties for the delivery of high power...... picosecond pulses. A novel fiber with 7 tubes and a core of 30 mu m was fabricated and it is here described and characterized, showing remarkable low loss, low bend loss, and good mode quality. Its optical properties are compared to both a 10 mu m and a 18 mu m core diameter photonic band gap hollow......-core fiber. The three fibers are characterized experimentally for the delivery of 22 picosecond pulses at 1032nm. We demonstrate flexible, diffraction limited beam delivery with output average powers in excess of 70W. (C) 2016 Optical Society of America...

Mathematical model and simulation of the hydrodynamic of air-pulsed sieve plate columns

International Nuclear Information System (INIS)

Hannappel, J.; Pfeifer, W.; Rathjen, E.

1979-02-01

In this work the dynamic flow events in an air pulsed sieve plate column are described by a simulation model. The model consists of a system of differential equations. The pressure built up by the pulsed air is brought to equilibrium with the pressure losses of the oscillating liquid column in the pulsation tube and in the column. In case of definition of the a) column geometry, b) integral holdup of the column, c) density of the participating phases, d) control times of the pulsed air valves, e) pulse repetition frequency and pulsed air reservoir pressure the height of oscillation and hence the intensity of pulsation are calculated. It is shown by a concrete example that 1) the oscillation of the liquid column in the pulsation tube and in the column is sinusoidal in all cases; 2) generation of a defined pulsation is restricted to the range between 0.3 and 3 Hz; 3) the amount of air needed for pulsation depends on the geometry of the column and in the intensity of pulsation. It can be optimized by appropriate selection of the diameter of the pulsation tube. (orig.) [de

Development of New Cryocooler Regenerator Materials-Ductile Intermetallic Compounds

International Nuclear Information System (INIS)

Gschneidner, K.A.; Pecharsky, A.O.; Pecharsky, V.K.

2004-01-01

The volumetric heat capacities of a number of binary and ternary Er- and Tm-based intermetallic compounds, which exhibited substantial ductilities, were measured from ∼3 to ∼350 K. They have the RM stoichiometry (where R = Er or Tm, and M is a main group or transition metal) and crystallize in the CsCl-type structure. The heat capacities of the Tm-based compounds are in general larger than the corresponding Er-based materials. Many of them have heat capacities which are significantly larger than those of the low temperature ( 2 , Er 3 Ni and ErNi. Utilization of the new materials as regenerators in the various cryocoolers should improve the performance of these refrigeration units for cooling below 15 K

Methodology of Accelerated Life-Time Tests For Stirling-Type "Bae-Co"-Made Cryocoolers Against Displacer-Blockage by Cryo-Pollutant Deposits

National Research Council Canada - National Science Library

Getmanits, Vladimir

2000-01-01

...: The contractor will investigate techniques for accelerated testing of cryocooler technology. During this phase of the effort the contractor will perform a detailed design of the equipment needed to conduct accelerated testing...

The effect of applied electric field on pulsed radio frequency and pulsed direct current plasma jet array

International Nuclear Information System (INIS)

Hu, J. T.; Liu, X. Y.; Liu, J. H.; Xiong, Z. L.; Liu, D. W.; Lu, X. P.; Iza, F.; Kong, M. G.

2012-01-01

Here we compare the plasma plume propagation characteristics of a 3-channel pulsed RF plasma jet array and those of the same device operated by a pulsed dc source. For the pulsed-RF jet array, numerous long life time ions and metastables accumulated in the plasma channel make the plasma plume respond quickly to applied electric field. Its structure similar as “plasma bullet” is an anode glow indeed. For the pulsed dc plasma jet array, the strong electric field in the vicinity of the tube is the reason for the growing plasma bullet in the launching period. The repulsive forces between the growing plasma bullets result in the divergence of the pulsed dc plasma jet array. Finally, the comparison of 309 nm and 777 nm emissions between these two jet arrays suggests the high chemical activity of pulsed RF plasma jet array.

Study of reverse Brayton cryocooler with Helium-Neon mixture for HTS cable

Science.gov (United States)

Dhillon, A. K.; Ghosh, P.

2017-12-01

As observed in the earlier studies, helium is more efficient than neon as a refrigerant in a reverse Brayton cryocooler (RBC) from the thermodynamic point of view. However, the lower molecular weight of helium leads to higher refrigerant inventory as compared to neon. Thus, helium is suitable to realize the high thermodynamic efficiency of RBC whereas neon is appropriate for the compactness of the RBC. A binary mixture of helium and neon can be used to achieve high thermodynamic efficiency in the compact reverse Brayton cycle (RBC) based cryocooler. In this paper, an attempt has been made to analyze the thermodynamic performance of the RBC with a binary mixture of helium and neon as the working fluid to provide 1 kW cooling load for high temperature superconductor (HTS) power cables working with a temperature range of 50 K to 70 K. The basic RBC is simulated using Aspen HYSYS V8.6®, a commercial process simulator. Sizing of each component based on the optimized process parameters for each refrigerant is performed based on a computer code developed using Engineering Equation Solver (EES-V9.1). The recommendation is provided for the optimum mixture composition of the refrigerant based on the trade-off factors like thermodynamic efficiency such as the exergy efficiency and equipment considerations. The outcome of this study may be useful for recommending a suitable refrigerant for the RBC operating at a temperature level of 50 K to 70 K.

Use of charge storage tube in the building of a buffer memory; Application des tubes a memoire a la realisation d'une memoire tampon

Energy Technology Data Exchange (ETDEWEB)

Marcovici, C [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1964-07-01

The apparatus manufactured is a buffer memory to be located between a detector and a multichannel pulse height analyser which received the pulses at regular times. The buffer memory and the detector have the same order of dead time, then the whole is equivalent to a detector plus an analyser without dead time, but that is true only if the mean time between two consecutive pulses from the detector is greater than the analyser time resolution. The apparatus used two electrostatic barrier grid tubes; the first one stores temporarily the data from the detector during the time necessary to analyse the data recorded on the other one. At the end of the analysis, the roles of the two tubes are permuted. The advantage on similar other apparatus is the uninterrupted recording of the pulse height informations from the detector and the uninterrupted analysis. In addition, the transistorization is interesting for reliability and maintainability. The document presents principles and data on the barrier grid storage tube, considers its conventional uses in nuclear electronics studies statistically the reduction of counting losses. It describes the test equipment and the tests which permits the screening of the best cathode ray storage tube for this application. Finally, it describes the item and gives the wave shapes in various points of the buffer memory. (author) [French] Le dispositif realise est une memoire tampon destinee a etre placee entre un detecteur et un selecteur d'amplitude multicanaux. Elle permet a ce dernier de recevoir et analyser les impulsions a intervalles de temps reguliers. Son temps de resolution est comparable a celui du detecteurs, l'ensemble est donc equivalent a un systeme constitue d'un detecteur suivi d'un selecteur sans temps mort, mais ceci n'est valable que tant que l'intervalle de temps moyen entre deux impulsions issues du detecteur est superieur au temps d'analyse necessite par le selecteur. Ce dispositif est constitue de deux tubes a memoire

Boreside rotating ultrasonic tester for wastage determination of LMFBR-type steam generator tubes

International Nuclear Information System (INIS)

Neely, H.H.; Renger, H.L.

1979-01-01

Large sodium-water reaction (SWR) leak tests are being run in near-prototypic steam generators at prototypic plant conditions of the Liquid Metal Fast Breeder Reactor (LMFBR). These tests simulate various types of steam tube failure at predetermined locations. A SWR results in a highly energetic-exothermic-caustic reaction which erodes neighboring tubes. A boreside-rotating ultrasonic inspection device was developed to measure wall thickness and inside diameter of the 2/one quarter/Cr-1 Mo, 10.1 mm I.D. steam tubes. Rotation of the UT beam yields a complimentary scan of the full tube in a single pass. The UT system was designed with a 15 MHz transducer in pulse-echo compression-wave mode at a pulse rate of 10,000/second. The UT beam is rotated at 20 r/s on a 1.27 mm pitch. System outputs are diameter, wall thickness, attitude, and axial position. Measurements are processed, then fed to a CRT and computer for later retrieval and plotting

Application of the pulsed magnetic welding process to nuclear breeder reactor fuel pin end closures

International Nuclear Information System (INIS)

Brown, W.F.

1984-01-01

The pulsed magnetic welding process is a solid state welding process in which metallurgical bonding is effected by impacting metal or alloy parts against each other at high velocity by use of controlled high frequency, high intensity pulsed magnetic fields. This process is similar to the explosive welding process except that magnetic energy is used for impacting the parts together instead of using explosive energy. The pulsed magnetic welding (PMW) process is readily applied to the welding of cylindrical plugs to small diameter tubes. Although breeder reactor fuel pin design may vary in size, the application described here consisted of cladding tubes approximately 6.4 mm in diameter by 244 cm long with a wall thickness of 0.38 mm. After the cladding tubes are filled with fuel pellets and associated metal hardware, tapered end plugs are inserted into the end of the tubes and welded. A typical setup for PMW is described

Effects of MHD slow shocks propagating along magnetic flux tubes in a dipole magnetic field

Directory of Open Access Journals (Sweden)

N. V. Erkaev

2002-01-01

Full Text Available Variations of the plasma pressure in a magnetic flux tube can produce MHD waves evolving into shocks. In the case of a low plasma beta, plasma pressure pulses in the magnetic flux tube generate MHD slow shocks propagating along the tube. For converging magnetic field lines, such as in a dipole magnetic field, the cross section of the magnetic flux tube decreases enormously with increasing magnetic field strength. In such a case, the propagation of MHD waves along magnetic flux tubes is rather different from that in the case of uniform magnetic fields. In this paper, the propagation of MHD slow shocks is studied numerically using the ideal MHD equations in an approximation suitable for a thin magnetic flux tube with a low plasma beta. The results obtained in the numerical study show that the jumps in the plasma parameters at the MHD slow shock increase greatly while the shock is propagating in the narrowing magnetic flux tube. The results are applied to the case of the interaction between Jupiter and its satellite Io, the latter being considered as a source of plasma pressure pulses.

Small high cooling power space cooler

Energy Technology Data Exchange (ETDEWEB)

Nguyen, T. V.; Raab, J.; Durand, D.; Tward, E. [Northrop Grumman Aerospace Systems Redondo Beach, Ca, 90278 (United States)

2014-01-29

The small High Efficiency pulse tube Cooler (HEC) cooler, that has been produced and flown on a number of space infrared instruments, was originally designed to provide cooling of 10 W @ 95 K. It achieved its goal with >50% margin when limited by the 180 W output ac power of its flight electronics. It has also been produced in 2 stage configurations, typically for simultaneously cooling of focal planes to temperatures as low as 35 K and optics at higher temperatures. The need for even higher cooling power in such a low mass cryocooler is motivated by the advent of large focal plane arrays. With the current availability at NGAS of much larger power cryocooler flight electronics, reliable long term operation in space with much larger cooling powers is now possible with the flight proven 4 kg HEC mechanical cooler. Even though the single stage cooler design can be re-qualified for those larger input powers without design change, we redesigned both the linear and coaxial version passive pulse tube cold heads to re-optimize them for high power cooling at temperatures above 130 K while rejecting heat to 300 K. Small changes to the regenerator packing, the re-optimization of the tuned inertance and no change to the compressor resulted in the increased performance at 150 K. The cooler operating at 290 W input power achieves 35 W@ 150 K corresponding to a specific cooling power at 150 K of 8.25 W/W and a very high specific power of 72.5 W/Kg. At these powers the cooler still maintains large stroke, thermal and current margins. In this paper we will present the measured data and the changes to this flight proven cooler that were made to achieve this increased performance.

34 GHz, 45 MW pulsed magnicon

International Nuclear Information System (INIS)

Nezhevenko, Oleg A.; LaPointe, Michael A.; Yakovlev, Vyacheslav P.; Hirshfield, Jay L.; Serdobintsev, Gennady V.; Kuznetsov, Gennady I.; Persov, Boris Z.; Fix, Alexander

2002-01-01

A high efficiency, high power magnicon at 34.272 GHz has been designed and built as a microwave source to develop RF technology for a future multi-TeV electron-positron linear collider. The tube is designed to provide a peak output power of ∼45 MW in a 1 microsecond pulse, with a gain of 55 dB, using a 500 kV, 220 A, 1 mm-diameter electron beam. The status of the tube itself as well as the near-term experimental program is presented

Analysis of defect tubes of fast reactor heat exchanger

International Nuclear Information System (INIS)

Rukhlyada, N.Ya.

2014-01-01

The experimental Auger electron spectroscopy and X-ray diffraction microanalysis data of laboratory investigations of defect tubes of heat exchanger with sodium coolant are presented. Element distribution through depth of corrosion layers form on the side of coolant (sodium) and on the surface contacting with steam in heat exchanger tube is studied. Sodium presence through all thickness of the tube is determined. It is shown that treatment of 12Cr18N9 steel surface by plasma pulses decreases intergranular corrosion susceptibility. It is related with structural changes of surface layer (∼ 20 μm), its enrichment by chromium and formation of chromium oxide protective film [ru

Laser-excited atomic-fluorescence spectrometry with electrothermal tube atomization.

Science.gov (United States)

Vera, J A; Leong, M B; Stevenson, C L; Petrucci, G; Winefordner, J D

1989-12-01

The performance of graphite-tube electrothermal atomizers is evaluated for laser-excited atomic-fluorescence spectrometry for several elements. Three pulsed laser systems are used to pump tunable dye lasers which subsequently are used to excite Pb, Ga, In, Fe, Ir, and Tl atoms in the hot graphite tube. The dye laser systems used are pumped by nitrogen, copper vapour and Nd:YAG lasers. Detection limits in the femtogram and subfemtogram range are typically obtained for all elements. A commercial graphite-tube furnace is important for the successful utilization of the laser-based method when the determination of trace elements is intended, especially when complicated matrices may be present.

Survey of high-voltage pulse technology suitable for large-scale plasma source ion implantation processes

International Nuclear Information System (INIS)

Reass, W.A.

1994-01-01

Many new plasma processes ideas are finding their way from the research lab to the manufacturing plant floor. These require high voltage (HV) pulse power equipment, which must be optimized for application, system efficiency, and reliability. Although no single HV pulse technology is suitable for all plasma processes, various classes of high voltage pulsers may offer a greater versatility and economy to the manufacturer. Technology developed for existing radar and particle accelerator modulator power systems can be utilized to develop a modern large scale plasma source ion implantation (PSII) system. The HV pulse networks can be broadly defined by two classes of systems, those that generate the voltage directly, and those that use some type of pulse forming network and step-up transformer. This article will examine these HV pulse technologies and discuss their applicability to the specific PSII process. Typical systems that will be reviewed will include high power solid state, hard tube systems such as crossed-field ''hollow beam'' switch tubes and planar tetrodes, and ''soft'' tube systems with crossatrons and thyratrons. Results will be tabulated and suggestions provided for a particular PSII process

In vitro optical detection of simulated blood pulse in a human tooth pulp model.

Science.gov (United States)

Niklas, A; Hiller, K-A; Jaeger, A; Brandt, M; Putzger, J; Ermer, C; Schulz, I; Monkman, G; Giglberger, S; Hirmer, M; Danilov, S; Ganichev, S; Schmalz, G

2014-01-01

Noninvasive optical methods such as photoplethysmography, established for blood pulse detection in organs, have been proposed for vitality testing of human dental pulp. However, no information is available on the mechanism of action in a closed pulp chamber and on the impairing influence of other than pulpal blood flow sources. Therefore, the aim of the present in vitro study was to develop a device for the optical detection of pulpal blood pulse and to investigate the influence of different parameters (including gingival blood flow [GBF] simulation) on the derived signals. Air, Millipore water, human erythrocyte suspensions (HES), non-particulate hemoglobin suspension (NPHS), and lysed hemoglobin suspension (LHES) were pulsed through a flexible (silicone) or a rigid (glass) tube placed within an extracted human molar in a tooth-gingiva model. HES was additionally pulsed through a rigid tube around the tooth, simulating GBF alone or combined with the flow through the tooth by two separate peristaltic pumps. Light from high-power light-emitting diodes (625 nm (red) and 940 nm (infrared [IR]); Golden Dragon, Osram, Germany) was introduced to the coronal/buccal part of the tooth, and the signal amplitude [∆U, in volts] of transmitted light was detected by a sensor at the opposite side of the tooth. Signal processing was carried out by means of a newly developed blood pulse detector. Finally, experiments were repeated with the application of rubber dam (blue, purple, pink, and black), aluminum foil, and black antistatic plastic foil. Nonparametric statistical analysis was applied (n = 5; α = 0.05). Signals were obtained for HES and LHES, but not with air, Millipore water, or NPHS. Using a flexible tube, signals for HES were higher for IR compared to red light, whereas for the rigid tube, the signals were significantly higher for red light than for IR. In general, significantly less signal amplitude was recorded for HES with the rigid glass tube than with the

Water nucleation : wave tube experiments and theoretical considerations

NARCIS (Netherlands)

Holten, V.

2009-01-01

This work is an experimental and theoretical study of the condensation of water. Condensation consists of nucleation – the formation of droplets – and the subsequent growth of those droplets. In our expansion tube setup, these processes are separated in time with the nucleation pulse principle, in

Study of general digital DC/pulse neutron generator

International Nuclear Information System (INIS)

Li Gang; Liu Zheng; Li Wensheng; Liu Hanlin; Liu Linmao

2014-01-01

Preliminary experimental results of digital DC/pulse neutron generator based on a ceramic drive-in target neutron tube for explosives detection are presented. The generator is a portable and on-off neutron source, and it can be controlled by remote PC. The generator can produce DC neutrons, pulse neutrons and multiple pulse neutrons. The maximum neutron yield is about 2 × 10"8 n/s, the minimum pulse width is 10 μs and the maximum pulse frequency is 10 kHz. Neutron yield and time-spectrum is measured in China Academy of Engineering Physics. The generator is suitable for explosive detection with PFTNA technology, and it can be used in other areas such as reactor measurements and on-line industrial test systems. (authors)

Drift Tube Linac Conditioning of Tank1

CERN Document Server

Shafqat, N; Toor, W A

2014-01-01

Tank1 of the Drift Tube Linac (DTL) of the Linac4 has been conditioned at the Linac4 tunnel. The tank was tuned for resonance at 352.2 MHz, and stable operation has been achieved with 725 µs long RF pulses at a repetition rate of 1 Hz. The maximum RF level that has been reached is 810 kW with a pulse width of 600 µs. Since this was the first RF structure exclusively conditioned in the Linac4 tunnel with the operation and control software of Linac4, some related issues and limitations had to be taken into account.

Thermal characterization of rods, tubes and spheres using pulsed infrared thermography

International Nuclear Information System (INIS)

Apinaniz, E; Mendioroz, A; Madariaga, N; Oleaga, A; Celorrio, R; Salazar, A

2008-01-01

In this work we analyse the accuracy of an extension of the flash method to measure the thermal diffusivity of rods, tubes and spheres, which was recently proposed by the authors. We have performed measurements in a wide set of calibrated samples of different sizes and we have found that a lower limiting size of the radius can be established for the validity of the method. On the other hand, a procedure to retrieve the thermal conductivity of tubes, based on filling them with a contrast liquid (water), is proposed. Moreover, the thermal contact resistance between the two layers of coated cylinders is also obtained. Measurements on calibrated samples confirm the validity of the two latest methods

Observation of quantized vortices by cryocooler-based scanning Hall probe microscope

Energy Technology Data Exchange (ETDEWEB)

Tokunaga, Y.; Konishi, Y.; Tokunaga, M.; Tamegai, T

2004-10-01

We have developed a scanning Hall probe microscope (SHPM) system utilizing closed-cycle cryocooler. The Hall probe used in this system is fabricated from a GaAs/GaAlAs two-dimensional electron gas. A stepping-motor-driven XYZ translator is used with a resolution better than 0.1 {mu}m and maximum scan range of 20 x 20 mm{sup 2}. The spatial resolution of the system is about 5 {mu}m and magnetic resolution is about 100 mG. By using this system, we have successfully resolved the quantized vortices on the cleaved surface of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+y} single crystal.

Modeling Photo-multiplier Gain and Regenerating Pulse Height Data for Application Development

Science.gov (United States)

Aspinall, Michael D.; Jones, Ashley R.

2018-01-01

Systems that adopt organic scintillation detector arrays often require a calibration process prior to the intended measurement campaign to correct for significant performance variances between detectors within the array. These differences exist because of low tolerances associated with photo-multiplier tube technology and environmental influences. Differences in detector response can be corrected for by adjusting the supplied photo-multiplier tube voltage to control its gain and the effect that this has on the pulse height spectra from a gamma-only calibration source with a defined photo-peak. Automated methods that analyze these spectra and adjust the photo-multiplier tube bias accordingly are emerging for hardware that integrate acquisition electronics and high voltage control. However, development of such algorithms require access to the hardware, multiple detectors and calibration source for prolonged periods, all with associated constraints and risks. In this work, we report on a software function and related models developed to rescale and regenerate pulse height data acquired from a single scintillation detector. Such a function could be used to generate significant and varied pulse height data that can be used to integration-test algorithms that are capable of automatically response matching multiple detectors using pulse height spectra analysis. Furthermore, a function of this sort removes the dependence on multiple detectors, digital analyzers and calibration source. Results show a good match between the real and regenerated pulse height data. The function has also been used successfully to develop auto-calibration algorithms.

Titanium condenser tubes--problems and their solutions for wider application to large surface condensers

Energy Technology Data Exchange (ETDEWEB)

Sato, S; Sugiyama, Y; Nagata, K; Namba, K; Shimono, M

1978-01-01

To meet the demand for high reliability condensers for thermal and nuclear power plants, especially for PWR plants, the condensers installed entirely with titanium tubes have been investigated and used. Some difficulties from conventional copper alloy tubes exist. Further investigations are necessary on three items: (1) tube vibration; (2) joining tubes to tube plate; (3) fouling (bio-fouling) control. Literature survey on the tube vibration suggests that the probability of tube vibration due to decreased stiffness of titanium tubes in comparison with conventional copper alloy tubes can be decreased by designing the proper span length between supports. Experiments on seal welding of tubes to a tube plate have successfully proved that pulsed TIG arc welding is applicable to get reliable and strong joints, even on site, by suitable countermeasures. Experiments on the fouling (bio-fouling) of titanium tubes in marine application reveal that the increased fouling of titanium tubes could be controlled by proper application of sponge ball cleaning.

Performance of the hybrid photomultiplier tube (HPMT)

Energy Technology Data Exchange (ETDEWEB)

Schomaker, R.J. [B.V. Delft Electronische Producten, Roden (Netherlands)

1995-12-31

The HPMT, which may be an alternative for PhotoMultiplier Tubes (PMT`s) in many applications, is a vacuum tube in which the latest technologies of photocathodes and photodiodes are combined. Photo-electrons are accelerated and bombarding a reversely biased PIN diode, where they create many electron-hole-pairs. The resulting charge pulse can be amplified and further processed. The HPMT shows many superior characteristics compared to regular PMT`s, because it does not suffer the statistical fluctuations common for electron multiplication processes. An energy resolution of up to 14 photo-electrons will be presented, together with striking figures for dynamic range and timing behavior.

Ultrasonic inspection of inpile tubes

International Nuclear Information System (INIS)

Boyd, D.M.; Bossi, H.

1985-01-01

The in-service inspection (ISI) of inpile tubes can be performed accurately and safely with a semiautomatic ultrasonic inspection system. The ultrasonic technique uses a set of multiple transducers to detect and size cracks, voids, and laminations radially and circumferentially. Welds are also inspected for defects. The system is designed to inspect stainless steel and Inconel tubes ranging from 53.8 mm (2.12 in.) to 101.6 mm (4 in.) inner diameter with wall thickness on the order of 5 mm. The inspection head contains seven transducers mounted in a surface-following device. Six angle-beam transducers generate shear waves in the tubes. Two of the six are oriented to detect circumferential cracks, and two detect axial cracks. Although each of these four transducers is used in the pulse-echo mode, they are oriented in aligned sets so pitch-catch operation is possible if desired. The remaining angle-beam transducers are angulated to detect flaws that are off axial or circumferential orientation. The seventh transducer is used for longitudinal inspection and detects and sizes laminar-type defects

At site qualification of accelerating tube dynodes

International Nuclear Information System (INIS)

Rajan, Rehim N.; Dewangan, S.; Sharma, D.K.

2015-01-01

A dc electron beam accelerator rated for 3 MeV encountered numerous vacuum side discharges at terminal voltage levels of 1800 kV. The cumulative rating of the accelerating tube in the system is 3350 kV. Pulsed currents in the order of 50 mA has been observed at the beam collector during these events along with voltage dips in terminal voltage. As dynode to dynode arcing is suspected to be the primary cause of this behaviour, it is desired to test the voltage withstanding capacity of each pair of dynodes. The accelerating tubes are rated for 335 kV at 6 kg/cm 2 SF 6 environment. However working at these pressures and testing of individual pairs of dynodes are impractical for qualification of dynodes of the 10 sets of accelerating tubes mounted in the accelerator. This problem has been overcome by using atmospheric pressure SF 6 and solid dielectrics. Experience of at site testing of the accelerating tube dynodes are described in this paper. (author)

Progress with the slotted-tube pulsed microwiggler

International Nuclear Information System (INIS)

Warren, R.W.

1991-01-01

A pulsed microwiggler can produce a wiggler field of unusually short period and high strength. A period of a few millimeters and a field of 5 appear possible. A satisfactory design is hard to realize, however, for many reasons: the high current, the current nonuniformities caused by the skin effect, thermal stresses in the parts, the high precision, etc. In addition, measuring the field with adequate resolution in the time domain, as well as in all three spatial coordinates, is challenging, particularly inside the small bore of a microwiggler. This paper presents recent design modifications that illustrate new solutions to these problems, and details of the construction, testing, and performance of wigglers already built. 6 refs., 5 figs

''High-power microwave'' tubes: In the laboratory and on-line

International Nuclear Information System (INIS)

Caryotakis, G.

1994-01-01

The possibility of incapacitating the electronic circuits of hostile equipment with high-energy microwave pulses has created a demand for microwave tubes capable of very high peak pulsed powers. Experimentalists, primarily from the plasma physics community, have been working in this field, dubbed High-Power Microwave or HPM. Separately, research in high-energy physics requires electron-positron colliders with energies approaching 1 trillion electron-volts (1 terra-electron-volt, or TeV). Such accelerators must be powered by microwave sources that are very similar to some that are proposed for the HPM application. The paper points out that for these tubes to be used on-line in the manner intended, they must be designed and built to operate at a very high internal vacuum, which is not the case for many of the HPM laboratory projects. The development of a particular klystron at the Stanford Linear Accelerator Center is described in detail in order to illustrate the need for special facilities and strong Quality Control. Should the Defense requirements for HPM survive the end of the cold war, an effort should be made to coordinate the tube development activities serving these two widely disparate applications

Development of a Gas-Fed Pulse Detonation Research Engine

Science.gov (United States)

Litchford, Ron J.; Hutt, John (Technical Monitor)

2001-01-01

In response to the growing need for empirical data on pulse detonation engine performance and operation, NASA Marshall Space Flight Center has developed and placed into operation a low-cost gas-fed pulse detonation research engine. The guiding design strategy was to achieve a simple and flexible research apparatus, which was inexpensive to build and operate. As such, the engine was designed to operate as a heat sink device, and testing was limited to burst-mode operation with run durations of a few seconds. Wherever possible, maximum use was made of standard off-the-shelf industrial or automotive components. The 5-cm diameter primary tube is about 90-cm long and has been outfitted with a multitude of sensor and optical ports. The primary tube is fed by a coaxial injector through an initiator tube, which is inserted directly into the injector head face. Four auxiliary coaxial injectors are also integrated into the injector head assembly. All propellant flow is controlled with industrial solenoid valves. An automotive electronic ignition system was adapted for use, and spark plugs are mounted in both tubes so that a variety of ignition schemes can be examined. A microprocessor-based fiber-optic engine control system was developed to provide precise control over valve and ignition timing. Initial shakedown testing with hydrogen/oxygen mixtures verified the need for Schelkin spirals in both the initiator and primary tubes to ensure rapid development of the detonation wave. Measured pressure wave time-of-flight indicated detonation velocities of 2.4 km/sec and 2.2 km/sec in the initiator and primary tubes, respectively. These values implied a fuel-lean mixture corresponding to an H2 volume fraction near 0.5. The axial distribution for the detonation velocity was found to be essentially constant along the primary tube. Time-resolved thrust profiles were also acquired for both underfilled and overfilled tube conditions. These profiles are consistent with previous time

Fabrication of Multi-Harmonic Buncher for Pulsed Proton Beam Generation

Energy Technology Data Exchange (ETDEWEB)

Kim, H. S.; Kwon, H. J.; Cho, Y. S. [Korea Multipurpose Accelerator Complex, Gyeongju (Korea, Republic of)

2015-05-15

Fast neutrons with a broad spectrum can be generated by irradiating the proton beams on target materials. To measure the neutron energy by time of flight (TOF) method, the short pulse width of the proton beam is preferred because the neutron energy uncertainty is proportional to the pulse width. In addition, the pulse repetition rate should be low enough to extend the lower limit of the available neutron energy. Pulsed proton beam generation system is designed based on an electrostatic deflector and slit system as shown in Fig. 1. In a simple deflector with slit system, most of the proton beam is blocked by slit, especially when the beam pulse width is short. The ideal field pattern inside the buncher cavity is saw-tooth wave. To make the field pattern similar to the saw-tooth waveform, we adopted a multi-harmonic buncher (MHB). The design for the multi-harmonic buncher including 3D electromagnetic calculation has been performed. Based on the design, a multi-harmonic buncher cavity was fabricated. It consists of two resonators, two drift tubes and a vacuum chamber. The resonator is a quarter-wave coaxial resonator type. The drift tube is connected to the resonator by using a coaxial vacuum feedthrough. Design summary and detailed fabrication method of the multi-harmonic buncher is presented in this paper. A multi-harmonic buncher for a proton beam chopper system to generate a short pulse neutron beam was designed, fabricated and assembled.

Treatment of Dye Wastewater by Using a Hybrid Gas/Liquid Pulsed Discharge Plasma Reactor

International Nuclear Information System (INIS)

Lu Na; Li Jie; Wu Yan; Masayuki, Sato

2012-01-01

A hybrid gas/liquid pulsed discharge plasma reactor using a porous ceramic tube is proposed for dye wastewater treatment. High voltage pulsed discharge plasma was generated in the gas phase and simultaneously the plasma channel was permeated through the tiny holes of the ceramic tube into the water phase accompanied by gas bubbles. The porous ceramic tube not only separated the gas phase and liquid phase but also offered an effective plasma spreading channel. The effects of the peak pulse voltage, additive gas varieties, gas bubbling rate, solution conductivity and TiO 2 addition were investigated. The results showed that this reactor was effective for dye wastewater treatment. The decoloration efficiency of Acid Orange II was enhanced with an increase in the power supplied. Under the studied conditions, 97% of Acid Orange II in aqueous solution was effectively decolored with additive oxygen gas, which was 51% higher than that with argon gas, and the increasing O 2 bubbling rate also benefited the decoloration of dye wastewater. Water conductivity had a small effect on the level of decoloration. Catalysis of TiO 2 could be induced by the pulsed discharge plasma and addition of TiO 2 aided the decoloration of Acid Orange II.

Preliminary test Results for a 25K Sorption Cryocooler Designed for the UCSB Long Duration Balloon Cosmic Microwave Background Radiation Experiment

Science.gov (United States)

Wade, L. A.; Levy, A. R.

1996-01-01

A continuous operation, vibration-free, long-life 25K sorption cryocooler has been built and is now in final integration and performance testing. This cooler wil be flown on the University of California at Santa Barbara (UCSB) Long Duration Balloon (LDB) Cosmic Microwave Background Radiation Experiment.

Numerical investigation of transient behaviour of the recuperative heat exchanger in a MR J-T cryocooler using different heat transfer correlations

Science.gov (United States)

Damle, R. M.; Ardhapurkar, P. M.; Atrey, M. D.

2016-12-01

In J-T cryocoolers operating with mixed refrigerants (nitrogen-hydrocarbons), the recuperative heat exchange takes place under two-phase conditions. Simultaneous boiling of the low pressure stream and condensation of the high pressure stream results in higher heat transfer coefficients. The mixture composition, operating conditions and the heat exchanger design are crucial for obtaining the required cryogenic temperature. In this work, a one-dimensional transient algorithm is developed for the simulation of the two-phase heat transfer in the recuperative heat exchanger of a mixed refrigerant J-T cryocooler. Modified correlation is used for flow boiling of the high pressure fluid while different condensation correlations are employed with and without the correction for the low pressure fluid. Simulations are carried out for different mixture compositions and numerical predictions are compared with the experimental data. The overall heat transfer is predicted reasonably well and the qualitative trends of the temperature profiles are also captured by the developed numerical model.

A vacuum-sealed, gigawatt-class, repetitively pulsed high-power microwave source

Science.gov (United States)

Xun, Tao; Fan, Yu-wei; Yang, Han-wu; Zhang, Zi-cheng; Chen, Dong-qun; Zhang, Jian-de

2017-06-01

A compact L-band sealed-tube magnetically insulated transmission line oscillator (MILO) has been developed that does not require bulky external vacuum pump for repetitive operations. This device with a ceramic insulated vacuum interface, a carbon fiber array cathode, and non-evaporable getters has a base vacuum pressure in the low 10-6 Pa range. A dynamic 3-D Monte-Carlo model for the molecular flow movement and collision was setup for the MILO chamber. The pulse desorption, gas evolution, and pressure distribution were exactly simulated. In the 5 Hz repetition rate experiments, using a 600 kV diode voltage and 48 kA beam current, the average radiated microwave power for 25 shots is about 3.4 GW in 45 ns pulse duration. The maximum equilibrium pressure is below 4.0 × 10-2 Pa, and no pulse shortening limitations are observed during the repetitive test in the sealed-tube condition.

Pulsed dose rate brachytherapy (PDR): an analysis of the technique at 2 years

Energy Technology Data Exchange (ETDEWEB)

Thienpont, M [Ghent Rijksuniversiteit (Belgium). Kliniek voor Radiotherapie en Kerngeneeskunde; Van Eijkeren, M; Van Hecke, H; Boterberg, T; De Neve, W

1995-12-01

A total of 154 applications was analysed using a pulsed dose brachytherapy technique for 138 patients over a 2 year period with emphasis on technical aspects influencing the overall treatment time. Vaginal ovoids were used in 59 cases, plastic tubes in 52, a Fletcher-type in 18, vaginal cylinders in 14 and a perineal template in 11 cases. Pulses were given at hourly intervals with a median dose rate of 0.6 Gy per pulse (range 0.4 to 3 Gy). The number of pulses per application varied from 3 to 134 (median 32). The number of dwell positions varied from 1 to 542 over 1 to 18 catheters. Patient related problems were few. The room was entered almost every 77 minutes. We noted 561 status codes in 147 applications. Of the 25 different codes, the most frequent one was due to the door left open when a pulse had to be given (35%) or due to constriction of the plastic catheters at the transfer tube junction (26%). However, the median total treatment time was increased by only 5 minutes. With pulsed dose rate brachytherapy at hourly pulses we can treat our patients within the planned time despite frequent room entrance and occurrence of an appreciable number of status codes. This technique seems to fulfill its promise to replace low dose rate brachytherapy.

Optimisation of the Read-out Electronics of Muon Drift-Tube Chambers for Very High Background Rates at HL-LHC and Future Colliders

CERN Document Server

Nowak, Sebastian; Gadow, Philipp; Ecker, Katharina; Fink, David; Fras, Markus; Kortner, Oliver; Kroha, Hubert; Müller, Felix; Richter, Robert; Schmid, Clemens; Schmidt-Sommerfeld, Korbinian; Zhao, Yazhou

2016-01-01

In the ATLAS Muon Spectrometer, Monitored Drift Tube (MDT) chambers and sMDT chambers with half of the tube diameter of the MDTs are used for precision muon track reconstruction. The sMDT chambers are designed for operation at high counting rates due to neutron and gamma background irradiation expected for the HL-LHC and future hadron colliders. The existing MDT read-out electronics uses bipolar signal shaping which causes an undershoot of opposite polarity and same charge after a signal pulse. At high counting rates and short electronics dead time used for the sMDTs, signal pulses pile up on the undershoot of preceding background pulses leading to a reduction of the signal amplitude and a jitter in the drift time measurement and, therefore, to a degradation of drift tube efficiency and spatial resolution. In order to further increase the rate capability of sMDT tubes, baseline restoration can be used in the read-out electronics to suppress the pile-up effects. A discrete bipolar shaping circuit with baseline...

Microcrystallography, high-pressure cryocooling and BioSAXS at MacCHESS

Energy Technology Data Exchange (ETDEWEB)

Englich, Ulrich, E-mail: ue22@cornell.edu; Kriksunov, Irina A. [MacCHESS (Macromolecular Diffraction Facility at CHESS), Cornell University, Ithaca, NY 14853 (United States); Cerione, Richard A. [MacCHESS (Macromolecular Diffraction Facility at CHESS), Cornell University, Ithaca, NY 14853 (United States); Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853 (United States); Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, NY 14853 (United States); Cook, Michael J.; Gillilan, Richard [MacCHESS (Macromolecular Diffraction Facility at CHESS), Cornell University, Ithaca, NY 14853 (United States); Gruner, Sol M. [Field of Biophysics, Cornell University, Ithaca, NY 14853 (United States); Physics Department, Cornell University, Ithaca, NY 14853 (United States); Huang, Qingqui; Kim, Chae Un; Miller, William; Nielsen, Soren; Schuller, David; Smith, Scott; Szebenyi, Doletha M. E. [MacCHESS (Macromolecular Diffraction Facility at CHESS), Cornell University, Ithaca, NY 14853 (United States)

2011-01-01

Three research initiatives pursued by the Macromolecular Diffraction Facility at the Cornell High Energy Synchrotron Source (MacCHESS) are presented. The Macromolecular Diffraction Facility at the Cornell High Energy Synchrotron Source (MacCHESS) is a national research resource supported by the National Center for Research Resources of the US National Institutes of Health. MacCHESS is pursuing several research initiatives designed to benefit both CHESS users and the wider structural biology community. Three initiatives are presented in further detail: microcrystallography, which aims to improve the collection of diffraction data from crystals a few micrometers across, or small well diffracting regions of inhomogeneous crystals, so as to obtain high-resolution structures; pressure cryocooling, which can stabilize transient structures and reduce lattice damage during the cooling process; and BioSAXS (small-angle X-ray scattering on biological solutions), which can extract molecular shape and other structural information from macromolecules in solution.

X-Ray Flare Oscillations Track Plasma Sloshing along Star-disk Magnetic Tubes in the Orion Star-forming Region

Science.gov (United States)

Reale, Fabio; Lopez-Santiago, Javier; Flaccomio, Ettore; Petralia, Antonino; Sciortino, Salvatore

2018-03-01

Pulsing X-ray emission tracks the plasma “echo” traveling in an extremely long magnetic tube that flares in an Orion pre-main sequence (PMS) star. On the Sun, flares last from minutes to a few hours and the longest-lasting ones typically involve arcades of closed magnetic tubes. Long-lasting X-ray flares are observed in PMS stars. Large-amplitude (∼20%), long-period (∼3 hr) pulsations are detected in the light curve of day-long flares observed by the Advanced CCD Imaging Spectrometer on-board Chandra from PMS stars in the Orion cluster. Detailed hydrodynamic modeling of two flares observed on V772 Ori and OW Ori shows that these pulsations may track the sloshing of plasma along a single long magnetic tube, triggered by a sufficiently short (∼1 hr) heat pulse. These magnetic tubes are ≥20 solar radii long, enough to connect the star with the surrounding disk.

Modeling fluid forces and response of a tube bundle in cross-flow induced vibrations

International Nuclear Information System (INIS)

Khushnood, Shahab; Khan, Zaffar M.; Malik, M. Afzaal; Koreshi, Zafarullah; Khan, Mahmood Anwar

2003-01-01

Flow induced vibrations occur in process heat exchangers, condensers, boilers and nuclear steam generators. Under certain flow conditions and fluid velocities, the fluid forces result in tube vibrations and possible damage of tube, tube sheet or baffle due to fretting and fatigue. Prediction of these forces is an important consideration. The characteristics of vibration depend greatly on the fluid dynamic forces and structure of the tube bundle. It is undesirable for the tube bundles to vibrate excessively under normal operating conditions because tubes wear and eventual leakage can occur leading to costly shutdowns. In this paper modeling of fluid forces and vibration response of a tube in a heat exchanger bundle has been carried out. Experimental validation has been performed on an existing refinery heat exchanger tube bundle. The target tube has been instrumented with an accelerometer and strain gages. The bundle has been studied for pulse, sinusoidal and random excitations. Natural frequencies and damping of the tubes have also been computed. Experimental fluid forces and response shows a reasonable agreement with the predictions. (author)

Gastrostomy Tube (G-Tube)

Science.gov (United States)

... any of these problems: a dislodged tube a blocked or clogged tube any signs of infection (including redness, swelling, or warmth at the tube site; discharge that's yellow, green, or foul-smelling; fever) excessive bleeding or drainage from the tube site severe abdominal pain lasting ...

An efficient high-voltage power supply for a photomultiplier tube

NARCIS (Netherlands)

Ainutdinov, VM; Vonsovskii, NN; Kompaniets, KG; Kozyr, AI; Mikhailov, YV

2003-01-01

An adjustable power supply for a photomultiplier tube operating in the pulsed spectrometric mode with a wide range of linearity is described. The power consumed by the source is 50 mW. The output voltage is varied from 800 to 2000 V. The maximum ripple amplitude is 2.5 mV.

50 MW C-band pulse klystron; 50MW C band pulse klystron

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-03-01

C-band pulse klystron E3746 with an output of 50 MW class was developed jointly with the High-Energy Accelerator Research Organization in the Ministry of Education as the klystron for a linear accelerator. For a large-sized linear accelerator in the next generation, a klystron with higher operating frequency has been required to obtain a compact and efficient accelerator. In E3746, the problem of power resistance during high-frequency operation was solved by mounting a traveling-wave multi-cell output circuit. Moreover, stable operation in the pulse width of 2.5 {mu}s and the output of 54 MW was performed at the same operation efficiency (44%) as the conventional S-band tube by using the frequency (in a C-band frequency band) that is two times as high as the conventional general accelerator. (translated by NEDO)

The density and velocity of plasma bullets propagating along one dielectric tube

Directory of Open Access Journals (Sweden)

Longfei Ji

2015-08-01

Full Text Available This study shows that the propagation of plasma bullets along one dielectric tube is strongly affected by many discharge parameters, such as the waveform of applied voltage (AC or pulsed DC, peak voltage, He flow rate, and the frequency of AC voltage. Analysis indicates that the density and velocity of plasma bullets are mainly determined by the electric field at the front of plasma bullets. These discharge parameters may significantly influence the distribution of plasma potential along the tube, thus control the electric field at the front of plasma bullets and their propagation. An increase in the pulsed DC voltage with its rise time of <40-50 ns can lead to an obvious improvement in the electric field at the front of plasma bullets, resulting in generation of a plasma in the high density gas and a fast propagation of plasma bullets. He flowing through the tube can contribute to the surface diffusion of charged species, and greatly increase the electric field at the front of plasma bullets. During the propagation of plasma bullets, their density is decreased due to the surface recombination of charged species, such as electrons and ions.

In-vitro model for evaluation of pulse oximetry

Science.gov (United States)

Vegfors, Magnus; Lindberg, Lars-Goeran; Lennmarken, Claes; Oberg, P. Ake

1991-06-01

An in vitro model with blood circulating in a silicon tubing system and including an artificial arterial bed is an important tool for evaluation of the pulse oximetry technique. The oxygen saturation was measured on an artificial finger using a pulse oximeter (SpO2) and on blood samples using a hemoximeter (SaO2). Measurements were performed at different blood flows and at different blood hematocrits. An increase in steady as well as in pulsatile blood flow was followed by an increase in pulse oximeter readings and a better agreement between SpO2 and SaO2 readings. After diluting the blood with normal saline (decreased hematocrit) the agreement was further improved. These results indicate that the pulse oximeter signal is related to blood hematocrit and the velocity of blood. The flow-related dependance of SpO2 was also evaluated in a human model. These results provided evidence that the pulse oximeter signal is dependent on vascular changes.

A novel time-to-pulse height converter for fast-neutron time-of-flight techniques

International Nuclear Information System (INIS)

Christiansen, J.

1962-01-01

An electronic time-to-pulse height converter is described which uses a multiplicative method instead of the usual one of adding overlapping pulses. This is achieved by a coincidence of a linear sawtooth and a sharply clipped needle-pulse. The sawtooth is fed to the grid of a beam-deflecting tube (E80T) and the needle-pulse is applied to the deflecting plates and opens the tube only during a time-interval of about 5.10 -9 s. The plate gets a charge proportional to the time-difference between the start of the sawtooth and the needle pulse. The plate-pulse is stretched and amplified and its height represents a measurement of the time-difference. With this method we got a time resolution of 2τ = 7 x 10 -12 s with artificial pulses, 2τ = 3 x 10 -10 s with Co 60 γ-coincidences by using NE 102 plastic crystals and 2τ = 1.4 x 10 -9 s with 511-keV γ-coincidences using NaI(Te) crystals. The method was also used with pulsed beam techniques. In this case we got from the pulsing RF an 8-Mc, sharply-peaked pulse-sequence, which was fed to the E80T plates. We had a time-resolution of 2τ = 1.1 x 10 -9 s with 4-MeV neutrons using plastic crystals 0.7 in long. Normally the region of linear response was 30 ns but it was possible to go up to 120 ns. (author) [fr

Modelling of a stirling cryocooler regenerator under steady and steady - periodic flow conditions using a correlation based method

Science.gov (United States)

Kishor Kumar, V. V.; Kuzhiveli, B. T.

2017-12-01

The performance of a Stirling cryocooler depends on the thermal and hydrodynamic properties of the regenerator in the system. CFD modelling is the best technique to design and predict the performance of a Stirling cooler. The accuracy of the simulation results depend on the hydrodynamic and thermal transport parameters used as the closure relations for the volume averaged governing equations. A methodology has been developed to quantify the viscous and inertial resistance terms required for modelling the regenerator as a porous medium in Fluent. Using these terms, the steady and steady - periodic flow of helium through regenerator was modelled and simulated. Comparison of the predicted and experimental pressure drop reveals the good predictive power of the correlation based method. For oscillatory flow, the simulation could predict the exit pressure amplitude and the phase difference accurately. Therefore the method was extended to obtain the Darcy permeability and Forchheimer’s inertial coefficient of other wire mesh matrices applicable to Stirling coolers. Simulation of regenerator using these parameters will help to better understand the thermal and hydrodynamic interactions between working fluid and the regenerator material, and pave the way to contrive high performance, ultra-compact free displacers used in miniature Stirling cryocoolers in the future.

Comparative simulation of Stirling and Sibling cycle cryocoolers with two codes

International Nuclear Information System (INIS)

Mitchell, M.P.; Wilson, K.J.; Bauwens, L.

1989-01-01

The authors present a comparative analysis of Stirling and Sibling Cycle cryocoolers conducted with two different computer simulation codes. One code (CRYOWEISS) performs an initial analysis on the assumption of isothermal conditions in the machines and adjusts that result with decoupled loss calculations. The other code (MS*2) models fluid flows and heat transfers more realistically but ignores significant loss mechanisms, including flow friction and heat conduction through the metal of the machines. Surprisingly, MS*2 is less optimistic about performance of all machines even though it ignores losses that are modelled by CRYOWEISS. Comparison between constant-bore Stirling and Sibling machines shows that their performance is generally comparable over a range of temperatures, pressures and operating speeds. No machine was consistently superior or inferior according to both codes over the whole range of conditions studied

Pulsed rf operation analysis

International Nuclear Information System (INIS)

Puglisi, M.; Cornacchia, M.

1981-01-01

The need for a very low final amplifier output impedance, always associated with class A operation, requires a very large power waste in the final tube. The recently suggested pulsed rf operation, while saving a large amount of power, increases the inherent final amplifier non linearity. A method is presented for avoiding the large signal non linear analysis and it is shown how each component of the beam induced voltage depends upon all the beam harmonics via some coupling coefficients which are evaluated

Electron emitter pulsed-type cylindrical IEC

International Nuclear Information System (INIS)

Miley, G.H.; Gu, Y.; Stubbers, R.; Zich, R.; Anderl, R.; Hartwell, J.

1997-01-01

A cylindrical version of the single grid Inertial Electrostatic Confinement (IEC) device (termed the C-device) has been developed for use as a 2.5-MeV D-D fusion neutron source for neutron activation analysis. The C-device employs a hollow-tube type cathode with similar anodes backed up by ''reflector'' dishes. The resulting discharge differs from a conventional hollow cathode discharge, by creating an explicit ion beam which is ''pinched'' in the cathode region. Resulting fusion reactions generate ∼10 6 neutron/s. A pulsed version is under development for applications requiring higher fluxes. Several pulsing techniques are under study, including an electron emitter (e-emitter) assisted discharge in a thorated tungsten wire emitter located behind a slotted area in the reflector dishes. Pulsing is initiated after establishing a low power steady-state discharge by pulsing the e-emitter current using a capacitor switch type circuit. The resulting electron jet, coupled with the discharge by the biased slot array, creates a strong pulse in the pinched ion beam. The pulse length/repetition rate are controlled by the e-emitter pulse circuit. Typical parameters in present studies are ∼30micros, 10Hz and 1-amp ion current. Corresponding neutron measurements are an In-foil type activation counter for time averaged rates. Results for a wide variety of operating conditions are presented

Copper bromide vapour laser with an output pulse duration of up to 320 ns

International Nuclear Information System (INIS)

Gubarev, F A; Fedorov, K V; Evtushenko, G S; Fedorov, V F; Shiyanov, D V

2016-01-01

We report the development of a copper bromide vapour laser with an output pulse duration of up to 320 ns. To lengthen the pulse, the discharge current was limited using a compound switch comprising a pulsed hydrogen thyratron and a tacitron. This technique permits limiting the excitation of the working levels at the initial stage of the discharge development to lengthen the inversion lifetime. The longest duration of a laser pulse was reached in tubes 25 and 50 mm in diameter for a pulse repetition rate of 2 – 4 kHz. (lasers and laser beams)

High-intensity focused ultrasound ablation around the tubing.

Science.gov (United States)

Siu, Jun Yang; Liu, Chenhui; Zhou, Yufeng

2017-01-01

High-intensity focused ultrasound (HIFU) has been emerging as an effective and noninvasive modality in cancer treatment with very promising clinical results. However, a small vessel in the focal region could be ruptured, which is an important concern for the safety of HIFU ablation. In this study, lesion formation in the polyacrylamide gel phantom embedded with different tubing (inner diameters of 0.76 mm and 3 mm) at varied flow speeds (17-339 cm/s) by HIFU ablation was photographically recorded. Produced lesions have decreased length (~30%) but slightly increased width (~6%) in comparison to that without the embedded tubing. Meanwhile, bubble activities during the exposures were measured by passive cavitation detection (PCD) at the varied pulse repetition frequency (PRF, 10-30 Hz) and duty cycle (DC, 10%-20%) of the HIFU bursts. High DC and low flow speed were found to produce stronger bubble cavitation whereas no significant influence of the PRF. In addition, high-speed photography illustrated that the rupture of tubing was produced consistently after the first HIFU burst within 20 ms and then multiple bubbles would penetrate into the intraluminal space of tubing through the rupture site by the acoustic radiation force. Alignment of HIFU focus to the anterior surface, middle, and posterior surface of tubing led to different characteristics of vessel rupture and bubble introduction. In summary, HIFU-induced vessel rupture is possible as shown in this phantom study; produced lesion sizes and shapes are dependent on the focus alignment to the tubing, flow speed, and tubing properties; and bubble cavitation and the formation liquid jet may be one of the major mechanisms of tubing rupture as shown in the high-speed photography.

Dynamic range studies of the RCA streak tube in the LLL streak camera

International Nuclear Information System (INIS)

Thomas, S.W.; Phillips, G.E.

1979-01-01

As indicated by tests on several cameras, the dynamic range of the Lawrence Livermore Laboratory streak-camera system appears to be about two orders of magnitude greater than those reported for other systems for 10- to 200-ps pulses. The lack of a fine mesh grid in the RCA streak tube used in these cameras probably contributes to a lower system dynamic noise and therefore raises the dynamic range. A developmental tube with a mesh grid was tested and supports this conjecture. Order-of-magnitude variations in input slit width do not affect the spot size on the phosphor or the dynamic range of the RCA tube. (author)

Tritium application: self-luminous glass tube(SLGT)

International Nuclear Information System (INIS)

Kim, K.; Lee, S.K.; Chung, E.S.; Kim, K.S.; Kim, W.S.; Nam, G.J.

2005-01-01

To manufacture SLGTs (self-luminous glass tubes), 4 core technologies are needed: coating technology, tritium injection technology, laser sealing/cutting technology and tritium handling technology. The inside of the glass tubes is coated with greenish ZnS phosphor particles with sizes varying from 4∝5 [μm], and Cu, and Al as an activator and a co-dopant, respectively. We also found that it would be possible to produce a phosphor coated glass tube for the SLGT using the well established cold cathode fluorescent lamp (CCFL) bulb manufacturing technology. The conceptual design of the main process loop (PL) is almost done. A delicate technique will be needed for the sealing/cutting of the glass tubes. Instead of the existing torch technology, a new technology using a pulse-type laser is under investigation. The design basis of the tritium handling facilities is to minimize the operator's exposure to tritium uptake and the emission of tritium to the environment. To fulfill the requirements, major tritium handling components are located in the secondary containment such as the glove boxes (GBs) and/or the fume hoods. The tritium recovery system (TRS) is connected to a GB and PL to minimize the release of tritium as well as to remove the moisture and oxygen in the GB. (orig.)

Cryogenic system with GM cryocooler for krypton, xenon separation from hydrogen-helium purge gas

Energy Technology Data Exchange (ETDEWEB)

Chu, X. X.; Zhang, D. X.; Qian, Y.; Liu, W. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800 (China); Zhang, M. M.; Xu, D. [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190 (China)

2014-01-29

In the thorium molten salt reactor (TMSR), fission products such as krypton, xenon and tritium will be produced continuously in the process of nuclear fission reaction. A cryogenic system with a two stage GM cryocooler was designed to separate Kr, Xe, and H{sub 2} from helium purge gas. The temperatures of two stage heat exchanger condensation tanks were maintained at about 38 K and 4.5 K, respectively. The main fluid parameters of heat transfer were confirmed, and the structural heat exchanger equipment and cold box were designed. Designed concentrations after cryogenic separation of Kr, Xe and H{sub 2} in helium recycle gas are less than 1 ppb.

Experience with pulsed tig-welding at UKAEA Springfields

International Nuclear Information System (INIS)

Taylor, A.F.

1973-01-01

Welding investigations at Springfields are primarily concerned with development of jointing procedures for nuclear fuel elements, where high standards of integrity are required. Equipment and work which developed from a pulsed TIG-welding technique, set up in 1963 for welding of 0.4 mm thick tubing are described. A computer based control system, which is illustrated, can provide direct digital control of continuous or pulsed TIG or plasma welding. The work has been mainly concerned with stainless and low alloy steel between 0.4 and 4 mm thick. Some applications are mentioned. Tentative conclusions are drawn and it is felt that because of development at Springfields in continuous TIG-welding there is no advantage in using pulsed TIG on materials thinner than about 2 mm. (U.K.)

CIAE 600 kV ns pulse neutron generator

International Nuclear Information System (INIS)

Shen Guanren; Guan Xialing; Chen Hongtao

2001-01-01

The overall composition of CIAE 600 kV ns Pulse Neutron Generator (CPNG) are introduced, and its characteristic, main technological performance and application were also given. CPNG consists of high voltage power supply with highest output voltage 600 kV, direct current 15 mA, stability and ripple ≤0.1%, 2214 mm x 1604 mm x 1504 mm stainless steel high voltage electrode, built in head equipment uniform field accelerating tube, ns pulsed installation, turbomolecular vacuum pump system and drift pipes at 0 degree and 45 degree. Its characteristics are: (1) high current beam; (2) high current beam ns pulsed installation made use of low energy for chopper and high energy for buncher; (3) compactly laid out and simple in structure

A conduction-cooled, 680-mm-long warm bore, 3-T Nb3Sn solenoid for a Cerenkov free electron laser

OpenAIRE

Wessel, Wilhelm A.J.; den Ouden, A.; Krooshoop, Hendrikus J.G.; ten Kate, Herman H.J.; Wieland, J.; van der Slot, Petrus J.M.

1999-01-01

A compact, cryocooler cooled Nb3Sn superconducting magnet system for a Cerenkov free electron laser has been designed, fabricated and tested. The magnet is positioned directly behind the electron gun of the laser system. The solenoidal field compresses and guides a tube-shaped 100 A, 500 kV electron beam. A two-stage GM cryocooler, equipped with a first generation ErNi5 regenerator, cools the epoxy impregnated solenoid down to the operating temperature of about 7.5 K. This leaves a conservati...

BANSHEE: High-voltage repetitively pulsed electron-beam driver

International Nuclear Information System (INIS)

VanHaaften, F.

1992-01-01

BANSHEE (Beam Accelerator for a New Source of High-Energy Electrons) this is a high-voltage modulator is used to produce a high-current relativistic electron beam for high-power microwave tube development. The goal of the BANSHEE research is first to achieve a voltage pulse of 700--750 kV with a 1-μs pulse width driving a load of ∼100 Ω, the pulse repetition frequency (PRF) of a few hertz. The ensuing goal is to increase the pulse amplitude to a level approaching 1 MV. We conducted tests using half the modulator with an output load of 200 Ω, up to a level of ∼650 kV at a PRF of 1 Hz and 525 kV at a PRF of 5 Hz. We then conducted additional testing using the complete system driving a load of ∼100 Ω

Characterization of irradiated fuel rods using pulsed eddy current techniques

International Nuclear Information System (INIS)

Martin, M.R.; Francis, W.C.

1975-11-01

A number of irradiated fuel rods and unfueled zircaloy cladding tubes (''water tubes'') were obtained from the Saxton reactor through arrangements with the Westinghouse Electric Corporation for use in subsequent irradiation effects and fuel behavior programs. A comprehensive nondestructive and corroborative destructive characterization program was undertaken on these fuel rods and tubes by ANC to provide baseline data on their characteristics prior to further testing and for comparison against post-post data. This report deals primarily with one portion of the NDT program performed remotely in the hot cells. The portion of interest in this paper is the pulsed eddy current inspection used in the nondestructive phase of the work. 6 references

A high-voltage resonant converter for pulsed magnets

International Nuclear Information System (INIS)

Rafael, F.S.; Lira, A.C.; Apfelbaum, J.; Pomilio, J.A.

1992-01-01

A 500-W, 25-kV, parallel-loaded resonant converter has been built in order to feed the LNLS ring kicker magnets. The use of high frequency permits reduction of the transformer and filter sizes. The tank components are the transformer leakage inductance and winding capacitance. The switching frequency is 20 kHz, limited by the tank circuit characteristic. The load is an LC Pulse-Forming Network, which is discharged on the load by a thyratron tube. The current pulse rise and fall times are about 100 ns and the flat top is 200 ns, at 800 A. (author) 3 refs.; 7 figs

Sensitive and ultra-fast species detection using pulsed cavity ringdown spectroscopy

KAUST Repository

Alquaity, Awad

2015-01-01

Pulsed cavity ringdown spectroscopy (CRDS) is used to develop a novel, ultra-fast, high-sensitivity diagnostic for measuring species concentrations in shock tube experiments. The diagnostic is demonstrated by monitoring trace concentrations of ethylene in the mid-IR region near 949.47 cm-1. Each ringdown measurement is completed in less than 1 μs and the time period between successive pulses is 10 μs. The high sensitivity diagnostic has a noise-equivalent detection limit of 1.08 x 10-5 cm-1 which enables detection of 15 ppm ethylene at fuel pyrolysis conditions (1845 K and 2 bar) and 294 ppb ethylene under ambient conditions (297 K and 1 bar). To our knowledge, this is the first successful application of the cavity ringdown method to the measurement of species time-histories in a shock tube. © 2015 OSA.

Characterization of image converter tubes and photodiodes in the infrared region

International Nuclear Information System (INIS)

Fleurot, N.; Nail, M.; Verrecchia, R.; Clement, G.

1979-01-01

The detection of near infrared picosecond luminous events is of the highest interest in the laser fusion research. The temporal profile of the 1.06 μm laser pulse, has to be carefully measured with S1 streak cameras which present limitations in the picosecond range. We have undertaken measurement on S1 photodiodes to situate their fatigue threshold and try to understand the limitations of image converter tubes we also present the work undertaken at R.T.C./L.E.P. to produce stable and highly sensitive image converter tubes in the micron range with the ''transfer sensitization method''. (author)

Peak potential meter applied to X-ray tubes in mammal radiography systems

International Nuclear Information System (INIS)

Schiabel, Homero; Frere, Annie F.; Andreeta, Jose P.

1989-01-01

It is of a great importance to identify accurately the real peak potential (or simply, KVp) applied to a X-ray tube purposed to medical diagnosis, since it defines the beam energetic quality in terms of photons penetration power. Mainly in mammographic systems. it is of fundamental relevance the KVp accurate measurement because the soft tissues involved in this kind of examination provides different absorption - and, hence, clear contrast on mammographic film - just in a very restrict energetic range. Thus a device to measure KVp with adequate accuracy in mammographic units, using the basic principles of scintillation detection, was developed. This system is therefore composed of a NaI(Tl) crystal which is a X-ray sensor - replacing radiographic films which usually are a source of errors in these measurements - , a photo multiplier tube and changed into amplified electric pulses. Finally the electronic circuit, after adequate pulses treatment, shows instantaneously the actual KVp value in the test on displays. (author)

PULSE COLUMN

Science.gov (United States)

Grimmett, E.S.

1964-01-01

This patent covers a continuous countercurrent liquidsolids contactor column having a number of contactor states each comprising a perforated plate, a layer of balls, and a downcomer tube; a liquid-pulsing piston; and a solids discharger formed of a conical section at the bottom of the column, and a tubular extension on the lowest downcomer terminating in the conical section. Between the conical section and the downcomer extension is formed a small annular opening, through which solids fall coming through the perforated plate of the lowest contactor stage. This annular opening is small enough that the pressure drop thereacross is greater than the pressure drop upward through the lowest contactor stage. (AEC)

Three-stage linear, split-Stirling cryocooler for 1 to 2K magnetic cold stage

International Nuclear Information System (INIS)

Longsworth, R.C.

1993-08-01

A long-life, linear, high efficiency 8K split Stirling cycle cryocooler was designed, built, and tested. The refrigerator is designed for cooling a 50 mW, 1.5K magnetic cold stage. Dual opposed piston compressors are driven by moving-coil linear motors. The three stage expander, although not completed, is also driven by a linear motor and is designed to produce 1 SW at 60K, 4W at 16K, and 1.2W at 8K. The cold regenerator employs a parallel gap construction for high efficiency. The key technology areas addressed include warm and cold flexible suspension bearings and a new cold regenerator geometry for high efficiency at 8K

Transthoracic Doppler echocardiography to predict optimal tube pulsing window for coronary artery CT angiography

Energy Technology Data Exchange (ETDEWEB)

Sun, Gang, E-mail: cjr.sungang@vip.163.com [Department of Medical Imaging, Jinan Military General Hospital, No. 25, Shifan Road, Jinan, Shandong Province 250031 (China); Li, Min, E-mail: limin22000@yahoo.com.cn [Department of Medical Imaging, Jinan Military General Hospital, No. 25, Shifan Road, Jinan, Shandong Province 250031 (China); Jiang, Xiang-sen, E-mail: jiangxiangsen123@126.com [Department of Medical Imaging, Jinan Military General Hospital, No. 25, Shifan Road, Jinan, Shandong Province 250031 (China); Li, Li, E-mail: leely1976@yahoo.com.cn [Department of Medical Imaging, Jinan Military General Hospital, No. 25, Shifan Road, Jinan, Shandong Province 250031 (China); Peng, Zhao-hui, E-mail: zhaohuipeng_R@163.com [Department of Medical Imaging, Jinan Military General Hospital, No. 25, Shifan Road, Jinan, Shandong Province 250031 (China); Mu, Nan-nan, E-mail: munannan22000@sohu.com [Department of Medical Imaging, Jinan Military General Hospital, No. 25, Shifan Road, Jinan, Shandong Province 250031 (China)

2012-09-15

Rationale and objective: To evaluate the feasibility of transthoracic Doppler echocardiography to determine the optimal pulsing windows for CT coronary angiography to narrow the pulsing windows further, especially in higher heart rate. Materials and methods: Doppler was performed on 135 patients before CT scanning. For Doppler, the intervals with minimal motion were evaluated during both systole and diastole integrating electrocardiogram (ECG) intervals. For CT scanning, the retrospective ECG-gating was applied and the optimal reconstruction intervals were determined. The accuracy of Doppler analysis to predict the optimal reconstruction intervals was tested. The predicted length of pulsing windows was compared between Doppler analysis and traditional prospective ECG-gating protocol (heart rate ≦ 65 bpm, 60–76%; 66–79 bpm, 30–77%; ≧80 bpm, 31–47%). Results: According to Doppler analysis, the mean length of intervals with minimal motion in systole was 106.4 ± 39.2 ms and 125.2 ± 92.0 ms in diastole. When the intervals with minimal motion during diastole > 90 ms, the optimal reconstruction intervals were located at diastole; otherwise, at systole (P < 0.001). The optimal reconstruction intervals in 93.8% (132/135) patients could be predicted accurately by Doppler analysis. If the optimal reconstruction intervals predicted by Doppler were applied as the exposure windows, the mean length of pulsing windows should has been 105.2 ± 69.4 ms (range: 26.9–510.3 ms), which was significantly shorter than that of traditional prospective ECG-gating protocol (232.0 ± 120.2 ms, range: 93.2–427.3 ms, P < 0.001). Conclusion: Doppler can help detecting the optimal pulsing windows accurately. Prospective ECG-gating incorporating Doppler analysis may narrow pulsing windows significantly while maintaining image quality.

Transthoracic Doppler echocardiography to predict optimal tube pulsing window for coronary artery CT angiography

International Nuclear Information System (INIS)

Sun, Gang; Li, Min; Jiang, Xiang-sen; Li, Li; Peng, Zhao-hui; Mu, Nan-nan

2012-01-01

Rationale and objective: To evaluate the feasibility of transthoracic Doppler echocardiography to determine the optimal pulsing windows for CT coronary angiography to narrow the pulsing windows further, especially in higher heart rate. Materials and methods: Doppler was performed on 135 patients before CT scanning. For Doppler, the intervals with minimal motion were evaluated during both systole and diastole integrating electrocardiogram (ECG) intervals. For CT scanning, the retrospective ECG-gating was applied and the optimal reconstruction intervals were determined. The accuracy of Doppler analysis to predict the optimal reconstruction intervals was tested. The predicted length of pulsing windows was compared between Doppler analysis and traditional prospective ECG-gating protocol (heart rate ≦ 65 bpm, 60–76%; 66–79 bpm, 30–77%; ≧80 bpm, 31–47%). Results: According to Doppler analysis, the mean length of intervals with minimal motion in systole was 106.4 ± 39.2 ms and 125.2 ± 92.0 ms in diastole. When the intervals with minimal motion during diastole > 90 ms, the optimal reconstruction intervals were located at diastole; otherwise, at systole (P < 0.001). The optimal reconstruction intervals in 93.8% (132/135) patients could be predicted accurately by Doppler analysis. If the optimal reconstruction intervals predicted by Doppler were applied as the exposure windows, the mean length of pulsing windows should has been 105.2 ± 69.4 ms (range: 26.9–510.3 ms), which was significantly shorter than that of traditional prospective ECG-gating protocol (232.0 ± 120.2 ms, range: 93.2–427.3 ms, P < 0.001). Conclusion: Doppler can help detecting the optimal pulsing windows accurately. Prospective ECG-gating incorporating Doppler analysis may narrow pulsing windows significantly while maintaining image quality

Tritium application: self-luminous glass tube(SLGT)

Energy Technology Data Exchange (ETDEWEB)

Kim, K.; Lee, S.K.; Chung, E.S.; Kim, K.S.; Kim, W.S. [Nuclear Power Lab., Korea Electric Power Research Inst. (KEPRI), Daejeon (Korea); Nam, G.J. [Engineering Information Technology Center, Inst. for Advanced Engineering (IAE), Kyonggi-do (Korea)

2005-07-01

To manufacture SLGTs (self-luminous glass tubes), 4 core technologies are needed: coating technology, tritium injection technology, laser sealing/cutting technology and tritium handling technology. The inside of the glass tubes is coated with greenish ZnS phosphor particles with sizes varying from 4{proportional_to}5 [{mu}m], and Cu, and Al as an activator and a co-dopant, respectively. We also found that it would be possible to produce a phosphor coated glass tube for the SLGT using the well established cold cathode fluorescent lamp (CCFL) bulb manufacturing technology. The conceptual design of the main process loop (PL) is almost done. A delicate technique will be needed for the sealing/cutting of the glass tubes. Instead of the existing torch technology, a new technology using a pulse-type laser is under investigation. The design basis of the tritium handling facilities is to minimize the operator's exposure to tritium uptake and the emission of tritium to the environment. To fulfill the requirements, major tritium handling components are located in the secondary containment such as the glove boxes (GBs) and/or the fume hoods. The tritium recovery system (TRS) is connected to a GB and PL to minimize the release of tritium as well as to remove the moisture and oxygen in the GB. (orig.)

Cryocooled wideband digital channelizing radio-frequency receiver based on low-pass ADC

International Nuclear Information System (INIS)

Vernik, Igor V; Kirichenko, Dmitri E; Dotsenko, Vladimir V; Miller, Robert; Webber, Robert J; Shevchenko, Pavel; Talalaevskii, Andrei; Gupta, Deepnarayan; Mukhanov, Oleg A

2007-01-01

We have demonstrated a digital receiver performing direct digitization of radio-frequency signals over a wide frequency range from kilohertz to gigahertz. The complete system, consisting of a cryopackaged superconductor all-digital receiver (ADR) chip followed by room-temperature interface electronics and a field programmable gate array (FPGA) based post-processing module, has been developed. The ADR chip comprises a low-pass analog-to-digital converter (ADC) delta modulator with phase modulation-demodulation architecture together with digital in-phase and quadrature mixer and a pair of digital decimation filters. The chip is fabricated using a 4.5 kA cm -2 process and is cryopackaged using a commercial-off-the-shelf cryocooler. Experimental results in HF, VHF, UHF and L bands and their analysis, proving consistent operation of the cryopackaged ADR chip up to 24.32 GHz clock frequency, are presented and discussed

Laser plasma generation of hydrogen-free diamond-like carbon thin films on Zr-2.5Nb CANDU pressure tube materials and silicon wafers with a pulsed high-power CO2 laser

International Nuclear Information System (INIS)

Ebrahim, N.A.; Mouris, J.F.; Hoffmann, C.R.J.; Davis, R.W.

1995-06-01

We report the first experiments on the laser plasma deposition of hydrogen-free, diamond-like carbon (DLC) films on Zr-2.5Nb CANDU pressure-tube materials and silicon substrates, using the short-pulse, high-power, CO 2 laser in the High-Power Laser Laboratory at Chalk River Laboratories. The films were (AFM). The thin films show the characteristic signature of DLC films in the Raman spectra obtained using a krypton-ion (Kr + ) laser. The Vickers ultra-low-load microhardness tests show hardness of the coated surface of approximately 7000 Kg force mm -2 , which is consistent with the hardness associated with DLC films. AFM examination of the film morphology shows diamond-like crystals distributed throughout the film, with film thicknesses of up to 0.5 μm generated with 50 laser pulses. With significantly more laser pulses, it is expected that very uniform diamond-like films would be produced. These experiments suggest that it should be possible to deposit hydrogen-free, diamond-like films of relevance to nuclear reactor components with a high-power and high-repetition-rate laser facility. (author). 7 refs., 2 tabs., 15 figs

Nondestructive examination of irradiated fuel rods by pulsed eddy current techniques

International Nuclear Information System (INIS)

Francis, W.C.; Quapp, W.J.; Martin, M.R.; Gibson, G.W.

1976-02-01

A number of fuel rods and unfueled zircaloy cladding tubes which had been irradiated in the Saxton reactor have undergone extensive nondestructive and corroborative destructive examinations by Aerojet Nuclear Company as part of the Water Reactor Safety Research Program, Irradiation Effects Test Series. This report discusses the pulsed eddy current (PEC) nondestructive examinations on the fuel rods and tubing and the metallography results on two fuel rods and one irradiated zircaloy tube. The PEC equipment, designed jointly by Argonne National Laboratory and Aerojet, performed very satisfactorily the functions of diameter, profile, and wall thickness measurements and OD and ID surface defect detection. The destructive examination provided reasonably good confirmation of ''defects'' detected in the nondestructive examination

Development of High Power Vacuum Tubes for Accelerators and Plasma Heating

International Nuclear Information System (INIS)

Srivastava, Vishnu

2012-01-01

High pulsed power magnetrons and klystrons for medical and industrial accelerators, and high CW power klystrons and gyrotrons for plasma heating in tokamak, are being developed at CEERI. S-band 2.0MW pulsed tunable magnetrons of centre frequency 2856MHz and 2998 MHz were developed, and S-band 2.6MW pulsed tunable magnetron is being developed for medical LINAC, and 3MW pulsed tunable magnetron is being developed for industrial accelerator. S-band (2856MHz), 5MW pulsed klystron was developed for particle accelerator, and S-band 6MW pulsed klystron is under development for 10MeV industrial accelerator. 350MHz, 100kW (CW) klystron is being developed for proton accelerator, and C-band 250kW (CW) klystron is being developed for plasma heating. 42GHz, 200kW (CW/Long pulse) gyrotron is under development for plasma heating. Plasma filled tubes are also being developed for switching. 25kV/1kA and 40kV/3kA thyratrons were developed for high voltage high current switching in pulse modulators for magnetrons and klystrons. 25kV/3kA Pseudospark switch of current rise time of 1kA/|a-sec and pulse repetition rate of 500Hz is being developed. Plasma assisted high power microwave device is also being investigated.

Development of High Power Vacuum Tubes for Accelerators and Plasma Heating

Science.gov (United States)

Srivastava, Vishnu

2012-11-01

High pulsed power magnetrons and klystrons for medical and industrial accelerators, and high CW power klystrons and gyrotrons for plasma heating in tokamak, are being developed at CEERI. S-band 2.0MW pulsed tunable magnetrons of centre frequency 2856MHz and 2998 MHz were developed, and S-band 2.6MW pulsed tunable magnetron is being developed for medical LINAC, and 3MW pulsed tunable magnetron is being developed for industrial accelerator. S-band (2856MHz), 5MW pulsed klystron was developed for particle accelerator, and S-band 6MW pulsed klystron is under development for 10MeV industrial accelerator. 350MHz, 100kW (CW) klystron is being developed for proton accelerator, and C-band 250kW (CW) klystron is being developed for plasma heating. 42GHz, 200kW (CW/Long pulse) gyrotron is under development for plasma heating. Plasma filled tubes are also being developed for switching. 25kV/1kA and 40kV/3kA thyratrons were developed for high voltage high current switching in pulse modulators for magnetrons and klystrons. 25kV/3kA Pseudospark switch of current rise time of 1kA/|a-sec and pulse repetition rate of 500Hz is being developed. Plasma assisted high power microwave device is also being investigated.

Development of NDT techniques for the inspection of WSGHWR pressure tubes

International Nuclear Information System (INIS)

Gray, B.S.; Highmore, P.J.; Rudlin, J.R.; Cooper, A.G.

1979-01-01

The fuel for the Steam Generating Heavy Water Reactor at Winfrith Heath is contained in vertical Zircaloy pressure tubes and is cooled by boiling light water. This paper describes the development of NDT techniques for the inservice examination of the pressure tubes to provide continuing assurance of the absence of axial crack-like defects. The resultant equipment has to operate in water-filled tubes in the presence of the radiation field due to the irradiated fuel elements in adjacent tubes. Also, a layer of surface oxide on the inside of the tubes has been found to significantly affect the behaviour of a prototype inspection device. To provide adequate sensitivity in these conditions, without the occurrence of unnecessary spurious indications, a combination of techniques has been developed. This involves the use of ultrasonics in both pulse-echo and 'pitch and catch' mode together with a single frequency eddy current technique. Laboratory work using artificial defects is described and also how the development programme was modified to accommodate the results of in-reactor tests using a prototype device. Reference is also made to the development of CCTV equipment to provide a supplementary visual examination. (author)

Pulsed neutron sources for epithermal neutrons

International Nuclear Information System (INIS)

Windsor, C.G.

1978-01-01

It is shown how accelerator based neutron sources, giving a fast neutron pulse of short duration compared to the neutron moderation time, promise to open up a new field of epithermal neutron scattering. The three principal methods of fast neutron production: electrons, protons and fission boosters will be compared. Pulsed reactors are less suitable for epithermal neutrons and will only be briefly mentioned. The design principle of the target producing fast neutrons, the moderator and reflector to slow them down to epithermal energies, and the cell with its beam tubes and shielding will all be described with examples taken from the new Harwell electron linac to be commissioned in 1978. A general comparison of pulsed neutron performance with reactors is fraught with difficulties but has been attempted. Calculation of the new pulsed source fluxes and pulse widths is now being performed but we have taken the practical course of basing all comparisons on extrapolations from measurements on the old 1958 Harwell electron linac. Comparisons for time-of-flight and crystal monochromator experiments show reactors to be at their best at long wavelengths, at coarse resolution, and for experiments needing a specific incident wavelength. Even existing pulsed sources are shown to compete with the high flux reactors in experiments where the hot neutron flux and the time-of-flight methods can be best exploited. The sources under construction can open a new field of inelastic neutron scattering based on energy transfer up to an electron volt and beyond

Superfluid stirling refrigerator: A new method for cooling below 1 Kelvin

International Nuclear Information System (INIS)

Kotsubo, V.; Swift, G.W.

1990-01-01

We have invented and built a new type of cryocooler, which we call the superfluid Stirling refrigerator (SSR). The first prototype reached 0.6 K from a starting temperature of 1.2 K. The working fluid of the SSR is the 3 He solute in a superfluid 3 He-- 4 He solution. At low temperatures, the superfluid 4 He is in its quantum ground state, and therefore is thermodynamically inert, while the 3 He solute has the thermodynamic properties of a dense ideal gas. Thus, in principle, any refrigeration cycle that can use an ideal gas can also use the 3 He solute as working fluid. In our SSR prototype, bellows-sealed superleak pistons driven by a room-temperature camshaft work on the 3 He solute. Ultimately, we anticipate elimination of moving parts by analogy with pulse-tube refrigeration. 15 refs., 6 figs

MAPLE Fabricated Fe3O4@Cinnamomum verum Antimicrobial Surfaces for Improved Gastrostomy Tubes

Directory of Open Access Journals (Sweden)

Alina Georgiana Anghel

2014-06-01

Full Text Available Cinnamomum verum-functionalized Fe3O4 nanoparticles of 9.4 nm in size were laser transferred by matrix assisted pulsed laser evaporation (MAPLE technique onto gastrostomy tubes (G-tubes for antibacterial activity evaluation toward Gram positive and Gram negative microbial colonization. X-ray diffraction analysis of the nanoparticle powder showed a polycrystalline magnetite structure, whereas infrared mapping confirmed the integrity of C. verum (CV functional groups after the laser transfer. The specific topography of the deposited films involved a uniform thin coating together with several aggregates of bio-functionalized magnetite particles covering the G-tubes. Cytotoxicity assays showed an increase of the G-tube surface biocompatibility after Fe3O4@CV treatment, allowing a normal development of endothelial cells up to five days of incubation. Microbiological assays on nanoparticle-modified G-tube surfaces have proved an improvement of anti-adherent properties, significantly reducing both Gram negative and Gram positive bacteria colonization.

Experimental study of a diod with magnetic insulation at the pulse duration more or equal to 10-5 s

International Nuclear Information System (INIS)

Rojfe, I.M.; Burtsev, V.A.; Vasilevskij, M.A.; Ehngel'ko, V.I.

1980-01-01

Results of the experimental investigation of a heavy-current diod with magnetic insulation are presented. Diod characteristics dependence on magnetic field distribution and magnitude in the accelerating interval has been studied. It is noted that the magnetic insulation of the accelerating tube has permitted to obtain the pulse duration of > or approximately 10 sub(s)sup(-5) at the voltage of > or approximately 400 kV in the tube and electron beam current of 3-4 kA. Maximum insulating magnetic field is 2.5 kOe. It is shown that the pulse duration of electron current in diods with magnetic insulation is limitted by break-down development along the accelerating tube surface. When magnetic field on the cathode is approximately 5kOe thre is a time interval of 4-5μs when the impedance is constant. The difference of diod impedance behaviour in time in these two cases are defined by a distinct expansion of cathode plasma at low magnetic fields. Cathode lateral surface plays a significant role in the process of plasma expantion. When the interelectrode gap is 3-5 cm and the voltage amplitude - < or approximately 400 kV it is possible to obtain tubular electron beams with the pulse duration of 10-15 μs, beam energy of 5-6 kJat a relatively small (approximately equal to 5kOe) magnitudes of magnetic field on the cathode. A possibility is shown to use multipoint graphite cathodes with a large area for obtaining tubular beams. The tubular electron beam of approximately equal to 400 A with the pulse duration of 25 μs have been obtained in the first experiments with such cathode at the voltage amplitude of < or approximately 150 kV. The conclusion is made that the tube magnetic isolation permits to increase considerably the pulse duration

Intense pulsed heavy ion beam technology

International Nuclear Information System (INIS)

Masugata, Katsumi; Ito, Hiroaki

2010-01-01

Development of intense pulsed heavy ion beam accelerator technology is described for the application of materials processing. Gas puff plasma gun and vacuum arc discharge plasma gun were developed as an active ion source for magnetically insulated pulsed ion diode. Source plasma of nitrogen and aluminum were successfully produced with the gas puff plasma gun and the vacuum arc plasma gun, respectively. The ion diode was successfully operated with gas puff plasma gun at diode voltage 190 kV, diode current 2.2 kA and nitrogen ion beam of ion current density 27 A/cm 2 was obtained. The ion composition was evaluated by a Thomson parabola spectrometer and the purity of the nitrogen ion beam was estimated to be 86%. The diode also operated with aluminum ion source of vacuum arc plasma gun. The ion diode was operated at 200 kV, 12 kA, and aluminum ion beam of current density 230 A/cm 2 was obtained. The beam consists of aluminum ions (Al (1-3)+ ) of energy 60-400 keV, and protons (90-130 keV), and the purity was estimated to be 89%. The development of the bipolar pulse accelerator (BPA) was reported. A double coaxial type bipolar pulse generator was developed as the power supply of the BPA. The generator was tested with dummy load of 7.5 ohm, bipolar pulses of -138 kV, 72 ns (1st pulse) and +130 kV, 70 ns (2nd pulse) were successively generated. By applying the bipolar pulse to the drift tube of the BPA, nitrogen ion beam of 2 A/cm 2 was observed in the cathode, which suggests the bipolar pulse acceleration. (author)

Experimental study on vapor explosion induced by pressure pulse in coarse mixing of hot molten metal and water

International Nuclear Information System (INIS)

Inoue, A.; Tobita, Y.; Aritomi, M.; Takahashi, M.; Matsuzaki, M.

2004-01-01

An experimental study was done to investigate characteristics of metal-water interaction, when a mount of hot liquid metal is injected into the water. The test section is a vertical shock tube of 60mm in inner diameter and 1200mm in length. A special injector which is designed to inject hot metal of controlled volume and flow rate is attached at the top of the tube. When the hot metal is injected in the water and comes down at a position of the test vessel, a trigger pressure pulse is generated at the bottom of the test tube. Local transient pressures along the tube are measured by piezo pressure transducers. The following items were investigated in the experiment; 1) The criteria to cause a vapor explosion, 2) Transient behaviors and propagation characteristics of pressure wave in the mixing region. 3) Effects of triggering pulse, injection temperature and mass of hot molten metal on the peak pressure. The probability of the vapor explosion jumped when the interface temperature at the molten metal-water direct contact is higher than the homogeneous nucleation temperature of water and the triggering pulse becomes larger than 0.9MPa. Two types of the pressure propagation modes are observed, one is the detonative mode with a sharp rise and other is usual pressure mode with a mild rise. (author)

Experimental Investigation of a Multi-Cycle Single-Tube Pulse Detonation Rocket Engine with a Coaxial Rotary Valve

Science.gov (United States)

Matsuoka, Ken; Esumi, Motoki; Ikeguchi, Ken Bryan; Kasahara, Jiro; Matsuo, Akiko; Funaki, Ikkoh

We developed a novel coaxial rotary valve for a multi-tube PDE. Since this single valve can supply three different gases (fuel, oxidizer and purge gas) into a combustor, the unification of the valve systems for three different gases is possible by using our newly designed valve. A PDRE system can be simple and lightweight by using this valve, and thus its thrust-weight ratio can be increased. We proposed the design of a multi-tube rotary-valved PDRE system by this rotary valve. Moreover, in preparation for a multi-tube rotary-valved PDRE, we carried out the multi-cycle operation experiment by the single-tube rotary-valved PDRE system. The combustion wave velocity was measured to confirm the operation of the PDRE system. Deflagration-to-detonation transition (DDT) was confirmed and DDT distance decreased under the condition of high operation frequency. In addition, a maximum operation frequency was 159 Hz.

Nuclear magnetic resonance in pulse radiolysis. Chemically induced dynamic nuclear polarization

International Nuclear Information System (INIS)

Trifunac, A.D.; Johnson, K.W.; Lowers, R.H.

1976-01-01

Nuclear magnetic resonance and chemically induced dynamic nuclear polarization (CIDNP) were applied to the study of pulse radiolysis. Samples were irradiated with a 3-MeV electron beam from the Argonne Van de Graaff accelerator in an EPR magnet (approximately 4000 G) which had axial holes for beam access. A fast flow system transferred the irradiated solution to the rotating 5-mm NMR sample tube. The NMR spectra of mixtures of sodium acetate and methanol were presented to demonstrate the features of the CIDNP in pulse radiolysis

Polarizing beam-splitter device at a pulsed neutron source

International Nuclear Information System (INIS)

Itoh, Shinichi; Takeda, Masayasu.

1996-01-01

A polarizing beam-splitter device was designed using Fe/Si supermirrors in order to obtain two polarized neutron beam lines, from one unpolarized neutron beam line, with a practical beam size for investigating the properties of condensed matter. This device was mounted after a guide tube at a pulsed neutron source, and its performance was investigated. (author)

Experimental study of the processes accompanying argon breakdown in a long discharge tube at a reduced pressure

Energy Technology Data Exchange (ETDEWEB)

Meshchanov, A. V.; Ionikh, Yu. Z., E-mail: y.ionikh@spbu.ru; Shishpanov, A. I.; Kalinin, S. A. [St. Petersburg State University (Russian Federation)

2016-10-15

Results are presented from experimental studies of the breakdown stage of a low-pressure discharge (1 and 5 Torr) in a glass tube the length of which (75 cm) is much larger than its diameter (2.8 cm). Breakdowns occurred under the action of positive voltage pulses with an amplitude of up to 9.4 kV and a characteristic rise time of 2–50 μs. The discharge current in the steady-state mode was 10–120 mA. The electrode voltage, discharge current, and radiation from the discharge gap were detected simultaneously. The dynamic breakdown voltage was measured, the prebreakdown ionization wave was recorded, and its velocity was determined. The dependence of the discharge parameters on the time interval between voltage pulses (the socalled “memory effect”) was analyzed. The memory effect manifests itself in a decrease or an increase in the breakdown voltage and a substantial decrease in its statistical scatter. The time interval between pulses in this case can reach 0.5 s. The effect of illumination of the discharge tube with a light source on the breakdown was studied. It is found that the irradiation of the anode region of the tube by radiation with wavelengths of ≤500 nm substantially reduces the dynamic breakdown voltage. Qualitative explanations of the obtained results are offered.

IEEE Conference Record of 1978 Thirteenth Pulse Power Modulator Symposium, Buffalo, New York, 20-22 June 1978.

Science.gov (United States)

1978-01-01

tubes must be made to fire simultane- ously. As the rising edge of the output pulse becomes faster, jitter and drift in_____ turn become more important...S. In separate tests this oil In combination with mylar - The jetting action from the perforations in the tube copper windings had a breakdown strength...173 SESSIO VuI - SWITCHES Wni AN I~RMW CAPAB~LY’ A 100-kY W0A Long-Pukse Switch Tube , £6.L MeNera, EIMAC Division of Varian

Control of laser pulse waveform in longitudinally excited CO2 laser by adjustment of excitation circuit

Science.gov (United States)

Uno, Kazuyuki; Jitsuno, Takahisa

2018-05-01

In a longitudinally excited CO2 laser that had a 45 cm-long discharge tube with a 1:1:2 mixture of CO2/N2/He gas at a pressure of 3.0 kPa, we realized the generation of a short laser pulse with a spike pulse width of about 200 ns and a pulse tail length of several tens of microseconds, control of the energy ratio of the spike pulse part to the pulse tail part in the short laser pulse, the generation of a long laser pulse with a pulse width of several tens of microseconds, and control of the pulse width in the long laser pulse, by using four types of excitation circuits in which the capacitance was adjusted. In the short laser pulse, the energy ratio was in the range 1:14-1:112. In the long laser pulse, the pulse width was in the range 25.7-82.7 μs.

Time fluctuations in the response of photomultiplier tubes Dario 56 AVP, XP 1021, XP 1210

International Nuclear Information System (INIS)

Breuze, G.; Sawine, P.

1969-01-01

The authors have studied experimentally the intrinsic time resolving power of 3 photomultiplier tubes, Dario 56 AVP, XP 1021, XP 1210 at various excitation levels produced by a source of short light pulses. They show, in agreement with present theories, that there exists an optimal resolving power for a certain trigger threshold, and they check the law governing the variations of this resolving power with the average number of photo-electrons emitted by light pulse, up to the limiting case of a single photo-electron. The results obtained show the progress which has been made by the constructor between the 56 AVP and the XP 1210 models: for 100 photo-electrons per pulse, for example, the times of resolution are 260 x 10 -12 s and 75 x 10 -12 s respectively; whereas the rise time for the anode pulses decreases from 2,3 to 1,2 x 10 -9 s. The intermediate tube XP 1021 has also a particularly good performance with respect to the 56 AVP, which it resembles very much both in its price and by its outer aspect. The authors stress finally the difficulties encountered in measuring with accuracy the time characteristics of PM as fast as the XP 1210, and in particular the limitation imposed by the light source. (author) [fr

Management of in-tube projectiles using acoustic channel

Science.gov (United States)

Kostina, M. A.; Bortalevich, S. I.; Loginov, E. L.; Shinyakov, Y. A.; Sukhorukov, M. P.

2018-03-01

The article describes the method of measuring the distance from the operator's console installed outside the pipe to the in-tube projectile. A method for measuring distance in the absence of an echo signal is proposed. To do this, two identical ultrasonic locators operating at different frequencies were installed inside and outside the pipeline. The change in the duration of an acoustic pulse propagating in a circular waveguide with rigid walls is shown, which leads to a decrease in the data transfer rate.

Annular pulse column development studies

International Nuclear Information System (INIS)

Benedict, G.E.

1980-01-01

The capacity of critically safe cylindrical pulse columns limits the size of nuclear fuel solvent extraction plants because of the limited cross-sectional area of plutonium, U-235, or U-233 processing columns. Thus, there is a need to increase the cross-sectional area of these columns. This can be accomplished through the use of a column having an annular cross section. The preliminary testing of a pilot-plant-scale annular column has been completed and is reported herein. The column is made from 152.4-mm (6-in.) glass pipe sections with an 89-mm (3.5-in.) o.d. internal tube, giving an annular width of 32-mm (1.25-in.). Louver plates are used to swirl the column contents to prevent channeling of the phases. The data from this testing indicate that this approach can successfully provide larger-cross-section critically safe pulse columns. While the capacity is only 70% of that of a cylindrical column of similar cross section, the efficiency is almost identical to that of a cylindrical column. No evidence was seen of any non-uniform pulsing action from one side of the column to the other

50 mm Diameter digital DC/pulse neutron generator for subcritical reactor test

International Nuclear Information System (INIS)

Li Gang; Zhang Zhongshuai; Chi Qian; Liu Linmao

2012-01-01

A 50 mm diameter digital DC/pulse neutron generator was developed with 25 mm ceramic drive-in target neutron tube. It was applied in the subcritical reactor test of China Institute of Atomic Energy (CIAE). The generator can produce neutron in three modes: DC, pulse and multiple pulse. The maximum neutron yield of the generator is 1 × 10 8 n/s, while the maximum pulse frequency is 10 kHz, and the minimum pulse width is 10 μs. As a remote controlled generator, it is small in volume, easy to be connected and controlled. The tested results indicate that penning ion source has the feature of delay time in glow discharge, and it is easier for glow discharge to happen when switching the DC voltage of penning ion source into pulse. According to these two characteristics, the generator has been modified. This improved generator can be used in many other areas including Prompt Gamma Neutron Activation Analysis (PGNAA), neutron testing and experiment.

50 mm Diameter digital DC/pulse neutron generator for subcritical reactor test

Energy Technology Data Exchange (ETDEWEB)

Li Gang; Zhang Zhongshuai [Northeast Normal University, Changchun 130024 (China); Chi Qian [Guang Hua College of Chang Chun University, Changchun 130117 (China); Liu Linmao, E-mail: ll888@nenu.edu.cn [Northeast Normal University, Changchun 130024 (China)

2012-11-01

A 50 mm diameter digital DC/pulse neutron generator was developed with 25 mm ceramic drive-in target neutron tube. It was applied in the subcritical reactor test of China Institute of Atomic Energy (CIAE). The generator can produce neutron in three modes: DC, pulse and multiple pulse. The maximum neutron yield of the generator is 1 Multiplication-Sign 10{sup 8} n/s, while the maximum pulse frequency is 10 kHz, and the minimum pulse width is 10 {mu}s. As a remote controlled generator, it is small in volume, easy to be connected and controlled. The tested results indicate that penning ion source has the feature of delay time in glow discharge, and it is easier for glow discharge to happen when switching the DC voltage of penning ion source into pulse. According to these two characteristics, the generator has been modified. This improved generator can be used in many other areas including Prompt Gamma Neutron Activation Analysis (PGNAA), neutron testing and experiment.

Magnetic swirls and associated fast magnetoacoustic kink waves in a solar chromospheric flux tube

Science.gov (United States)

Murawski, K.; Kayshap, P.; Srivastava, A. K.; Pascoe, D. J.; Jelínek, P.; Kuźma, B.; Fedun, V.

2018-02-01

We perform numerical simulations of impulsively generated magnetic swirls in an isolated flux tube that is rooted in the solar photosphere. These swirls are triggered by an initial pulse in a horizontal component of the velocity. The initial pulse is launched either (a) centrally, within the localized magnetic flux tube or (b) off-central, in the ambient medium. The evolution and dynamics of the flux tube are described by three-dimensional, ideal magnetohydrodynamic equations. These equations are numerically solved to reveal that in case (a) dipole-like swirls associated with the fast magnetoacoustic kink and m = 1 Alfvén waves are generated. In case (b), the fast magnetoacoustic kink and m = 0 Alfvén modes are excited. In both these cases, the excited fast magnetoacoustic kink and Alfvén waves consist of a similar flow pattern and magnetic shells are also generated with clockwise and counter-clockwise rotating plasma within them, which can be the proxy of dipole-shaped chromospheric swirls. The complex dynamics of vortices and wave perturbations reveals the channelling of sufficient amount of energy to fulfil energy losses in the chromosphere (˜104 W m-1) and in the corona (˜102 W m-1). Some of these numerical findings are reminiscent of signatures in recent observational data.

Spatio-temporal dynamics of a pulsed microwave argon plasma: ignition and afterglow

International Nuclear Information System (INIS)

Carbone, Emile; Sadeghi, Nader; Vos, Erik; Hübner, Simon; Van Veldhuizen, Eddie; Van Dijk, Jan; Nijdam, Sander; Kroesen, Gerrit

2015-01-01

In this paper, a detailed investigation of the spatio-temporal dynamics of a pulsed microwave plasma is presented. The plasma is ignited inside a dielectric tube in a repetitively pulsed regime at pressures ranging from 1 up to 100 mbar with pulse repetition frequencies from 200 Hz up to 500 kHz. Various diagnostic techniques are employed to obtain the main plasma parameters both spatially and with high temporal resolution. Thomson scattering is used to obtain the electron density and mean electron energy at fixed positions in the dielectric tube. The temporal evolution of the two resonant and two metastable argon 4s states are measured by laser diode absorption spectroscopy. Nanosecond time-resolved imaging of the discharge allows us to follow the spatio-temporal evolution of the discharge with high temporal and spatial resolution. Finally, the temporal evolution of argon 4p and higher states is measured by optical emission spectroscopy. The combination of these various diagnostics techniques gives deeper insight on the plasma dynamics during pulsed microwave plasma operation from low to high pressure regimes. The effects of the pulse repetition frequency on the plasma ignition dynamics are discussed and the plasma-off time is found to be the relevant parameter for the observed ignition modes. Depending on the delay between two plasma pulses, the dynamics of the ionization front are found to be changing dramatically. This is also reflected in the dynamics of the electron density and temperature and argon line emission from the plasma. On the other hand, the (quasi) steady state properties of the plasma are found to depend only weakly on the pulse repetition frequency and the afterglow kinetics present an uniform spatio-temporal behavior. However, compared to continuous operation, the time-averaged metastable and resonant state 4s densities are found to be significantly larger around a few kHz pulsing frequency. (paper)

Evaluation of the adhesive layer of blast tube using ultrasound

Energy Technology Data Exchange (ETDEWEB)

Park, Joon Soo; Song, Sung Jin; Kim, Young Hwan; Cho, Hyun [Dept. of Machanical Engineering, Sungkyunkwan University, Seoul (Korea, Republic of); Lim, Soo Yong; Yun, Nam Gyun [Agency for Defense Development, Daejeon (Korea, Republic of); Lee, Jeong Ki [Korea Inspection and Engineering Co., Ltd, Seoul (Korea, Republic of); Park, Young Joo [Hankuk Fiber Group, Milyang (Korea, Republic of)

2003-05-15

Ultrasonic testing method has been developed to evaluate adhesive layers in blast tube for the reliability of the rocket. The main objective of the present work was to find debonding and uncharged state between steel and FRP layers. We distinguish the debonding and uncharged state using the resonance method in the adhesive layers. It was found that the higher magnitude of ultrasound is reflected for the uncharged area in frequency domain, and shown good agreements with experimental results. The traditional ultrasonic pulse-echo method offers good implements for the distinction debonding area. The nondestructive testing results were compared with the micrography of destructive testing. As results, ultrasonic testing could be utilized for the evaluation of adhesive layer in the blast tube.

A copper bromide vapour laser with a high pulse repetition rate

International Nuclear Information System (INIS)

Shiyanov, D V; Evtushenko, Gennadii S; Sukhanov, V B; Fedorov, V F

2002-01-01

The results of an experimental study of a copper bromide vapour laser with a discharge-channel diameter above 2.5 cm and a high pump-pulse repetition rate are presented. A TGU1-1000/25 high-power tacitron used as a switch made it possible to obtain for the first time a fairly high output radiation power for pump-pulse repetition rates exceeding 200 kHz. At a maximum pump-pulse repetition rate of 250 kHz achieved in a laser tube 2.6 cm in diameter and 76 cm long, the output power was 1.5 W. The output powers of 3 and 10.5 W were reached for pump-pulse repetition rates of 200 and 100 kHz, respectively. These characteristics were obtained without circulating a buffer gas and (or) low-concentration active impurities through the active volume. (active media. lasers)

Lifetime prediction and reliability estimation methodology for Stirling-type pulse tube refrigerators by gaseous contamination accelerated degradation testing

Science.gov (United States)

Wan, Fubin; Tan, Yuanyuan; Jiang, Zhenhua; Chen, Xun; Wu, Yinong; Zhao, Peng

2017-12-01

Lifetime and reliability are the two performance parameters of premium importance for modern space Stirling-type pulse tube refrigerators (SPTRs), which are required to operate in excess of 10 years. Demonstration of these parameters provides a significant challenge. This paper proposes a lifetime prediction and reliability estimation method that utilizes accelerated degradation testing (ADT) for SPTRs related to gaseous contamination failure. The method was experimentally validated via three groups of gaseous contamination ADT. First, the performance degradation model based on mechanism of contamination failure and material outgassing characteristics of SPTRs was established. Next, a preliminary test was performed to determine whether the mechanism of contamination failure of the SPTRs during ADT is consistent with normal life testing. Subsequently, the experimental program of ADT was designed for SPTRs. Then, three groups of gaseous contamination ADT were performed at elevated ambient temperatures of 40 °C, 50 °C, and 60 °C, respectively and the estimated lifetimes of the SPTRs under normal condition were obtained through acceleration model (Arrhenius model). The results show good fitting of the degradation model with the experimental data. Finally, we obtained the reliability estimation of SPTRs through using the Weibull distribution. The proposed novel methodology enables us to take less than one year time to estimate the reliability of the SPTRs designed for more than 10 years.

Pulse shaping for fast coincidence with NaI(Tl) detectors

International Nuclear Information System (INIS)

Bose, S.; Sinha, B.K.; Bhattacharya, R.

1983-01-01

The effect of multiple limiting of the anode pulses of the photomultiplier tubes on the resolving time of an NaI(Tl)-NaI(Tl) fast coincidence set up is investigated with the help of a simple transistored limiter circuit. The performance of the set up for different energy ranges selected in the side channels is also investigated. (orig.)

High-Power Plasma Switch for 11.4 GHz Microwave Pulse Compressor

International Nuclear Information System (INIS)

Hirshfield, Jay L.

2010-01-01

Results obtained in several experiments on active RF pulse compression at X-band using a magnicon as the high-power RF source are presented. In these experiments, microwave energy was stored in high-Q TE01 and TE02 modes of two parallel-fed resonators, and then discharged using switches activated with rapidly fired plasma discharge tubes. Designs and high-power tests of several versions of the compressor are described. In these experiments, coherent pulse superposition was demonstrated at a 5-9 MW level of incident power. The compressed pulses observed had powers of 50-70 MW and durations of 40-70 ns. Peak power gains were measured to be in the range of 7:1-11:1 with efficiency in the range of 50-63%.

Pulsed White Spectrum Neutron Generator for Explosive Detection

International Nuclear Information System (INIS)

King, Michael J.; Miller, Gill T.; Reijonen, Jani; Ji, Qing; Andresen, Nord; Gicquel, Frederic; Kavlas, Taneli; Leung, Ka-Ngo; Kwan, Joe

2008-01-01

Successful explosive material detection in luggage and similar sized containers is a critical issue in securing the safety of all airline passengers. Tensor Technology Inc. has recently developed a methodology that will detect explosive compounds with pulsed fast neutron transmission spectroscopy. In this scheme, tritium beams will be used to generate neutrons with a broad energy spectrum as governed by the T(t,2n)4He fission reaction that produces 0-9 MeV neutrons. Lawrence Berkeley National Laboratory (LBNL), in collaboration with Tensor Technology Inc., has designed and fabricated a pulsed white-spectrum neutron source for this application. The specifications of the neutron source are demanding and stringent due to the requirements of high yield and fast pulsing neutron emission, and sealed tube, tritium operation. In a unique co-axial geometry, the ion source uses ten parallel rf induction antennas to externally couple power into a toroidal discharge chamber. There are 20 ion beam extraction slits and 3 concentric electrode rings to shape and accelerate the ion beam into a titanium cone target. Fast neutron pulses are created by using a set of parallel-plate deflectors switching between +-1500 volts and deflecting the ion beams across a narrow slit. The generator is expected to achieve 5 ns neutron pulses at tritium ion beam energies between 80-120 kV. First experiments demonstrated ion source operation and successful beam pulsing

Use of genetic algorithm to identify thermophysical properties of deposited fouling in heat exchanger tubes

International Nuclear Information System (INIS)

Adili, Ali; Ben Salah, Mohieddine; Kerkeni, Chekib; Ben Nasrallah, Sassi

2009-01-01

At high temperature, the circulation of fluid in heat exchangers provides a tendency for fouling accumulation to take place on the internal surface of tubes. This paper shows an experimental process of thermophysical properties estimation of the fouling deposited on internal surface of a heat exchanger tube using genetic algorithms (GAs). The genetic algorithm is used to minimize an objective function containing calculated and measured temperatures. The experimental bench using a photothermal method with a finite width pulse heat excitation is used and the estimated parameters are obtained with high accuracy

Binary rf pulse compression experiment at SLAC

International Nuclear Information System (INIS)

Lavine, T.L.; Spalek, G.; Farkas, Z.D.; Menegat, A.; Miller, R.H.; Nantista, C.; Wilson, P.B.

1990-06-01

Using rf pulse compression it will be possible to boost the 50- to 100-MW output expected from high-power microwave tubes operating in the 10- to 20-GHz frequency range, to the 300- to 1000-MW level required by the next generation of high-gradient linacs for linear for linear colliders. A high-power X-band three-stage binary rf pulse compressor has been implemented and operated at the Stanford Linear Accelerator Center (SLAC). In each of three successive stages, the rf pulse-length is compressed by half, and the peak power is approximately doubled. The experimental results presented here have been obtained at low-power (1-kW) and high-power (15-MW) input levels in initial testing with a TWT and a klystron. Rf pulses initially 770 nsec long have been compressed to 60 nsec. Peak power gains of 1.8 per stage, and 5.5 for three stages, have been measured. This corresponds to a peak power compression efficiency of about 90% per stage, or about 70% for three stages, consistent with the individual component losses. The principle of operation of a binary pulse compressor (BPC) is described in detail elsewhere. We recently have implemented and operated at SLAC a high-power (high-vacuum) three-stage X-band BPC. First results from the high-power three-stage BPC experiment are reported here

Comparison of oxygen liquefaction methods for use on the Martian surface

Science.gov (United States)

Johnson, W. L.; Hauser, D. M.; Plachta, D. W.; Wang, X.-Y. J.; Banker, B. F.; Desai, P. S.; Stephens, J. R.; Swanger, A. M.

2018-03-01

In order to use oxygen that is produced on the surface of Mars from In-Situ production processes in a chemical propulsion system, the oxygen must first be converted from vapor phase to liquid phase and then stored within the propellant tanks of the propulsions system. There are multiple ways that this can be accomplished, from simply attaching a liquefaction system onto the propellant tanks to carrying separate tanks for liquefaction and storage of the propellant and loading just prior to launch (the way that traditional rocket launches occur on Earth). A study was done into these various methods by which the oxygen (and methane) could be liquefied and stored on the Martian surface. Five different architectures or cycles were considered: Tube-on-Tank (also known as Broad Area Cooling or Distributed Refrigeration), Tube-in-Tank (also known as Integrated Refrigeration and Storage), a modified Linde open liquefaction/refrigeration cycle, the direct mounting of a pulse tube cryocooler onto the tank, and an in-line liquefier at ambient pressure. Models of each architecture were developed to give insight into the performance and losses of each of the options. The results were then compared across eight categories: Mass, Power (both input and heat rejection), Operability, Cost, Manufacturability, Reliability, Volume-ility, and Scalability. The result was that Tube-on-Tank and Tube-in-Tank architectures were the most attractive solutions, with NASA's engineering management choosing to pursue tube on tank development rather than further differentiate the two. As a result NASA is focusing its Martian surface liquefaction activities and technology development on Tube-on-Tank liquefaction cycles.

Plasma immersion ion implantation (and deposition) inside metallic tubes of different dimensions and configurations

Science.gov (United States)

Ueda, M.; Silva, C.; Santos, N. M.; Souza, G. B.

2017-10-01

There is a strong need for developing methods to coat or implant ions inside metallic tubes for many practical contemporary applications, both for industry and science. Therefore, stainless steel tubes with practical diameters of 4, 11 and 16 cm, but short lengths of 20 cm, were internally treated by nitrogen plasma immersion ion implantation (PIII). Different configurations as tube with lid in one of the ends or both sides open were tested for better PIII performance, in the case of smallest diameter tube. Among these PIII tests in tubes, using the 4 cm diameter one with a lid, it was possible to achieve tube temperatures of more than 700 °C in 15 min and maintain it during the whole treatment time (typically 2 h). Samples made of different materials were placed at the interior of the tube, as the monitors for posterior analysis, and the tube was solely pulsed by high voltage pulser producing high voltage glow discharge and hollow cathode discharge both driven by a moderate power source. In this experiment, samples of SS 304, pure Ti, Ti6Al4V and Si were used for the tests of the above methods. Results on the analysis of the surface of these nitrogen PIII treated materials, as well as on their processing methods, are presented and discussed in the paper.

A Thin detector with ionization tubes for high energy electrons and photons

International Nuclear Information System (INIS)

Amatuni, Ts. A.; Denisov, S.P.; Krasnokutsky, R.N.; Lebedenko, V.N.; Shuvalov, R.S.

1981-01-01

A possibility to measure the energy of electrons and photons with a simple detector, consisting of a lead convertor and ionization tubes filled with pure argon, has been studied. The measurements have been performed in a 26.6 GeV electron beam. The best energy resolution approximately 16% was achieved for the convertor thickness 40 mm and argon pressure > 20 atm. The performance of the detector in magnetic field up to 16 kGs has been also studied. It turned out that the mean pulse height rises approximately linearly with increasing magnetic field and becomes flat at H approximately 10 kGs. This behaviour is the same for magnetic field perpendicular and parallel with respect to the ionization tubes. The energy resolution depends weakly on the magnetic field. Ionization tubes filled with argon or xenon under high pressure may be used for minimum ionizing particle detection [ru

21 CFR 868.5800 - Tracheostomy tube and tube cuff.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Tracheostomy tube and tube cuff. 868.5800 Section... (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5800 Tracheostomy tube and tube cuff. (a) Identification. A tracheostomy tube and tube cuff is a device intended to be placed into a...

The effect of external visible light on the breakdown voltage of a long discharge tube

Science.gov (United States)

Shishpanov, A. I.; Ionikh, Yu. Z.; Meshchanov, A. V.

2016-06-01

The breakdown characteristics of a discharge tube with a configuration typical of gas-discharge light sources and electric-discharge lasers (a so-called "long discharge tube") filled with argon or helium at a pressure of 1 Torr have been investigated. A breakdown has been implemented using positive and negative voltage pulses with a linear leading edge having a slope dU/ dt ~ 10-107 V/s. Visible light from an external source (halogen incandescent lamp) is found to affect the breakdown characteristics. The dependences of the dynamic breakdown voltage of the tube on dU/ dt and on the incident light intensity are measured. The breakdown voltage is found to decrease under irradiation of the high-voltage anode of the tube in a wide range of dU/ dt. A dependence of the effect magnitude on the light intensity and spectrum is obtained. Possible physical mechanisms of this phenomenon are discussed.

Tube plug

International Nuclear Information System (INIS)

Zafred, P. R.

1985-01-01

The tube plug comprises a one piece mechanical plug having one open end and one closed end which is capable of being inserted in a heat exchange tube and internally expanded into contact with the inside surface of the heat exchange tube for preventing flow of a coolant through the heat exchange tube. The tube plug also comprises a groove extending around the outside circumference thereof which has an elastomeric material disposed in the groove for enhancing the seal between the tube plug and the tube

Ultrasonic inspection of tube to tube plate welds

International Nuclear Information System (INIS)

Telford, D.W.; Peat, T.S.

1985-01-01

To monitor the deterioration of a weld between a tube and tube plate which has been repaired by a repair sleeve inside the tube and brazed at one end to the tube, ultrasound from a crystal at the end of a rod is launched, in the form of Lamb-type waves, into the tube through the braze and allowed to travel along the tube to the weld and be reflected back along the tube. The technique may also be used for the type of heat exchanger in which, during construction, the tubes are welded to the tube plate via external sleeves in which case the ultrasound is used in a similar manner to inspect the sleeve/tube plate weld. an electromagnetic transducer may be used to generate the ultrasound. The ultrasonic head comprising the crystal and an acoustic baffle is mounted on a Perspex (RTM) rod which may be rotated by a stepping motor. Echo signals from the region of deterioration may be isolated by use of a time gate in the receiver. The device primarily detects circumferentially orientated cracks, and may be used in heat exchangers in nuclear power plants. (author)

Evaluation of the adhesive layer of blast tube by using ultrasound

Energy Technology Data Exchange (ETDEWEB)

Park, Joon Soo; Song, Sung Jin; Kim, Young H.; Cho, Hyun [Sungkyunkwan University, Seoul (Korea, Republic of); Lim, Soo Yong; Yun, Nam Gyun [Agency Defence Development, Daejeon (Korea, Republic of); Lee, Jeong Ki [Korea Inspection and Engineering Co., LTD, Daejeon (Korea, Republic of); Park, Young Joo [Hankuk Fiber Co., LTD, Milyang (Korea, Republic of)

2003-07-01

Ultrasonic testing method has been developed to evaluated adhesive layers in blast tube for the reliability of the rocket. The main objective of the present work was to find debonding and uncharged state between steel and FRP layers. We distinguish the debonding and uncharged state using the resonance method in the adhesive layers. It was found that the higher magnitude of ultrasound is reflected for the uncharged area in frequency domain, and shown good agreements with experimental results. The traditional ultrasonic pulse-echo method offers good implements for the distinction debonding area. The nondestructive testing results were compared with the micrography of destructive testing. As results, ultrasonic testing could be utilized for the evaluation of adhesive layer in the blast tube.

Domain wall manipulation in magnetic nanotubes induced by electric current pulses

International Nuclear Information System (INIS)

Otálora, J A; López-López, J A; Landeros, P; Núñez, A S

2012-01-01

We propose that the injection of electric currents can be used to independently manipulate the position and chirality of vortex-like domain walls in metallic ferromagnetic nanotubes. We support this proposal upon theoretical and numerical assessment of the magnetization dynamics driven by such currents. We show that proper interplay between the tube geometry, magnitude of the electric current and the duration of a current pulse, can be used to manipulate the position, velocity and chirality of a vortex domain wall. Our calculations suggest that domain wall velocities greater than 1 km s -1 can be achieved for tube diameters of the order of 30 nm and increasing with it. We also find that the transition from steady to precessional domain wall motion occurs for very high electric current densities, of the order of 10 13 A m -2 . Furthermore, the great stability displayed by such chiral magnetic configurations, and the reduced Ohmic loses provided by the current pulses, lead to highly reproducible and efficient domain wall reversal mechanisms.

Characterization of the pulse plasma source

International Nuclear Information System (INIS)

Milosavljevic, V; Karkari, S K; Ellingboe, A R

2007-01-01

Characterization of the pulse plasma source through the determination of the local thermodynamic equilibrium (LTE) threshold is described. The maximum electron density measured at the peak in discharge current is determined by the width of the He II Paschen alpha spectral line, and the electron temperature is determined from the ratios of the relative intensities of spectral lines emitted from successive ionized stages of atoms. The electron density and temperature maximum values are measured to be 1.3 x 10 17 cm -3 and 19 000 K, respectively. These are typical characteristics for low-pressure, pulsed plasma sources for input energy of 15.8 J at 130 Pa pressure in helium-argon mixture. The use of LTE-based analysis of the emission spectra is justified by measurement of the local plasma electron density at four positions in the discharge tube using a floating hairpin resonance probe. The hairpin resonance probe data are collected during the creation and decay phases of the pulse. From the spatio-temporal profile of the plasma density a 60 μs time-window during which LTE exists throughout the entire plasma source is determined

Heat Exchanger Tube to Tube Sheet Joints Corrosion Behavior

Directory of Open Access Journals (Sweden)

M. Iancu

2013-03-01

Full Text Available Paper presents the studies made by the authors above the tube to tube sheet fittings of heat exchanger with fixed covers from hydrofining oil reforming unit. Tube fittings are critical zones for heat exchangers failures. On a device made from material tube and tube sheet at real joints dimensions were establish axial compression force and traction force at which tube is extracted from expanded joint. Were used two shapes joints with two types of fittings surfaces, one with smooth hole of tube sheet and other in which on boring surface we made a groove. From extracted expanded tube zones were made samples for corrosion tests in order to establish the corrosion rate, corrosion potential and corrosion current in working mediums such as hydrofining oil and industrial water at different temperatures. The corrosion rate values and the temperature influence are important to evaluate joints durability and also the results obtained shows that the boring tube sheet shape with a groove on hole tube shape presents a better corrosion behavior then the shape with smooth hole tube sheet.

Liquid Nitrogen Zero Boiloff Testing

Science.gov (United States)

Plachta, David; Feller, Jeffrey; Johnson, Wesley; Robinson, Craig

2017-01-01

Cryogenic propellants such as liquid hydrogen (LH2) and liquid oxygen (LO2) are a part of NASAs future space exploration due to their high specific impulse for rocket motors of upper stages suitable for transporting 10s to 100s of metric tons of payload mass to destinations outside of low earth orbit and for their return. However, the low storage temperatures of LH2 and LO2 cause substantial boil-off losses for missions with durations greater than several months. These losses can be eliminated by incorporating high performance cryocooler technology to intercept heat load to the propellant tanks and modulating the cryocooler to control tank pressure. The active thermal control technology being developed by NASA is the reverse turbo-Brayton cycle cryocooler and its integration to the propellant tank through a distributed cooling tubing network coupled to the tank wall. This configuration was recently tested at NASA Glenn Research Center, in a vacuum chamber and cryo-shroud that simulated the essential thermal aspects of low Earth orbit, its vacuum and temperature. Testing consisted of three passive tests with the active cryo-cooler system off, and 7 active tests, with the cryocooler powered up. The test matrix included zero boil-off tests performed at 90 full and 25 full, and several demonstrations at excess cooling capacity and reduced cooling capacity. From this, the tank pressure response with varied cryocooler power inputs was determined. This test series established that the active cooling system integrated with the propellant tank eliminated boil-off and robustly controlled tank pressure.

Numerical Investigation of Pulse Wave Propagation in Arteries Using Fluid Structure Interaction Capabilities

Directory of Open Access Journals (Sweden)

Hisham Elkenani

2017-01-01

Full Text Available The aim of this study is to present a reliable computational scheme to serve in pulse wave velocity (PWV assessment in large arteries. Clinicians considered it as an indication of human blood vessels’ stiffness. The simulation of PWV was conducted using a 3D elastic tube representing an artery. The constitutive material model specific for vascular applications was applied to the tube material. The fluid was defined with an equation of state representing the blood material. The onset of a velocity pulse was applied at the tube inlet to produce wave propagation. The Coupled Eulerian-Lagrangian (CEL modeling technique with fluid structure interaction (FSI was implemented. The scaling of sound speed and its effect on results and computing time is discussed and concluded that a value of 60 m/s was suitable for simulating vascular biomechanical problems. Two methods were used: foot-to-foot measurement of velocity waveforms and slope of the regression line of the wall radial deflection wave peaks throughout a contour plot. Both methods showed coincident results. Results were approximately 6% less than those calculated from the Moens-Korteweg equation. The proposed method was able to describe the increase in the stiffness of the walls of large human arteries via the PWV estimates.

Tube spacer grid for a heat-exchanger tube bundle

International Nuclear Information System (INIS)

Scheidl, H.

1976-01-01

A tube spacer grid for a heat-exchanger tube bundle is formed by an annular grid frame having a groove formed in its inner surface in which the interspaced grid bars have their ends positioned and held in interspaced relationship by short sections of tubes passed through holes axially formed in the grid frame so that the tubes are positioned between the ends of the grid bars in the grooves. The tube sections may be cut from the same tubes used to form the tube bundle. 5 claims, 3 drawing figures

Pulsed dose rate brachytherapy – is it the right way?

Directory of Open Access Journals (Sweden)

Janusz Skowronek

2010-10-01

Full Text Available Pulsed dose rate (PDR-BT treatment is a brachytherapy modality that combines physical advantages of high-doserate (HDR-BT technology (isodose optimization, radiation safety with the radiobiological advantages of low-dose-rate (LDR-BT brachytherapy. Pulsed brachytherapy consists of using stronger radiation source than for LDR-BT and producing series of short exposures of 10 to 30 minutes in every hour to approximately the same total dose in the sameoverall time as with the LDR-BT. Modern afterloading equipment offers certain advantages over interstitial or intracavitaryinsertion of separate needles, tubes, seeds or wires. Isodose volumes in tissues can be created flexibly by a combinationof careful placement of the catheter and the adjustment of the dwell times of the computerized stepping source.Automatic removal of the radiation sources into a shielded safe eliminates radiation exposures to staff and visitors.Radiation exposure is also eliminated to the staff who formerly loaded and unloaded multiplicity of radioactive sources into the catheters, ovoids, tubes etc. This review based on summarized clinical investigations, analyses the feasibility and the background to introduce this brachytherapy technique and chosen clinical applications of PDR-BT.

Evaluation of stomach tubes and gastric lavage for sampling diets from blue catfish and flathead catfish

Science.gov (United States)

Waters, D.S.; Kwak, T.J.; Arnott, J.B.; Pine, William E.

2004-01-01

We compared the ability to extract all stomach contents by using stomach tubes or gastric lavage to sample diets from blue catfish Ictalurus furcatus and flathead catfish Pylodictus olivarus. Pulsed gastric lavage (PGL) removed a significantly greater proportion of stomach content mass (95.6%) from blue catfish than did stomach tubes (14.6%). Percent mass of flathead catfish contents removed with PGL (96.0%) was not significantly different from that removed with stomach tubes (86.9%). Based on the greater effectiveness of PGL for blue catfish, combined with a shorter mean time required per sample (69 versus 118 s) and the better preservation of extracted diet material, we recommend using PGL as a nonlethal technique to collect diet samples from large catfishes.

A study on integrity of LMFBR secondary cooling system to hypothetical tube failure propagation in the steam generator

International Nuclear Information System (INIS)

Yoshihisa Shindo; Kazuo Haga

2005-01-01

Full text of publication follows: A fundamental safety issue of liquid-metal-cooled fast breeder reactor (LMFBR) is to maintain the integrity of the secondary cooling system components against violent chemical sodium-water reaction caused by the water leak from the heat transfer tube of steam generators (SG). The produced sodium-water reaction jet would attack more severely surrounding tubes and would cause other tube failures (tube failure propagation), if it was assumed that the water leak was not detected by function-less detectors and proper operating actions to mitigate the tube failure propagation, such as isolations of the SG from the secondary cooling system and turbine water/steam system, and blowing water and steam inside tubes in the SG, were not taken. This study has been made focusing on the affection of large-scale water leak enlarged due to SG tube failure propagation to the structural integrity of the secondary cooling system because the generated pressure pulse caused by a large-scale sodium-water reaction might break heat transfer tubes of the intermediate heat exchanger (IHX). The present work has been made as one part of the study of probabilistic safety assessment (PSA) of LMFBR, because if the heat-transfer tubes of IHX were failed, the reactor core may be affected by the pressure pulse and/or by the sodium-water reaction products transported through the primary cooling system. As tools for PSA of the water leak incident of SG, we have developed QUARK-LP Version 4 code that mainly analyzes the high temperature rupture phenomena and estimates the number of failed tubes during the middle-scale water leak. The pressure pulse behavior generated by sodium-water reaction in the failure SG and the pressure propagation in the secondary cooling system are calculated by using the SWAAM-2 code developed by ANL. Furthermore, the quasi-steady state high pressure and temperature of the secondary cooling system in a long term is estimated by using the SWAAM

Cycle Design of Reverse Brayton Cryocooler for HTS Cable Cooling Using Exergy Analysis

Science.gov (United States)

Gupta, Sudeep Kumar; Ghosh, Parthasarathi

2017-02-01

The reliability and price of cryogenic refrigeration play an important role in the successful commercialization of High Temperature Superconducting (HTS) cables. For cooling HTS cable, sub-cooled liquid nitrogen (LN2) circulation system is used. One of the options to maintain LN2 in its sub-cooled state is by providing refrigeration with the help of Reverse Brayton Cryo-cooler (RBC). The refrigeration requirement is 10 kW for continuously sub-cooling LN2 from 72 K to 65 K for cooling 1 km length of HTS cable [1]. In this paper, a parametric evaluation of RBC for sub-cooling LN2 has been performed using helium as a process fluid. Exergy approach has been adopted for this analysis. A commercial process simulator, Aspen HYSYS® V8.6 has been used for this purpose. The critical components have been identified and their exergy destruction and exergy efficiency have been obtained for a given heat load condition.

Resolution and Efficiency of the ATLAS Muon Drift-Tube Chambers at High Background Rates

CERN Document Server

Deile, M.; Horvat, S.; Kortner, O.; Kroha, H.; Manz, A.; Mohrdieck-Mock, S.; Rauscher, F.; Richter, Robert; Staude, A.; Stiller, W.

2016-01-01

The resolution and efficiency of a precision drift-tube chamber for the ATLAS muon spectrometer with final read-out electronics was tested at the Gamma Irradiation Facility at CERN in a 100 GeV muon beam and at photon irradiation rates of up to 990 Hz/square cm which corresponds to twice the highest background rate expected in ATLAS. A silicon strip detector telescope was used as external reference in the beam. The pulse-height measurement of the read-out electronics was used to perform time-slewing corrections which lead to an improvement of the average drift-tube resolution from 104 microns to 82 microns without irradiation and from 128 microns to 108 microns at the maximum expected rate. The measured drift-tube efficiency agrees with the expectation from the dead time of the read-out electronics up to the maximum expected rate.

Manufacturing tungsten monocrystal tubes by electro-spark machining and study of machined surface structure

International Nuclear Information System (INIS)

Abdukarimov, Eh.T.; Ismailov, L.R.; Krakhmalev, V.A.; Fershtat, L.N.

1981-01-01

A technique to manufacture tubes from tungsten monocrystals with low consumption of electrodes has been developed. Regimes of obtaining deep and through holes of different diameters with the productivity of 1 mm/min and with the minimum deviation from cylindrical shape are worked out using a specially designed electric pulse installation. X-ray and metallographical analyses have shown that as a result of electrospark machining a cold hardened layer is formed up to hundreds micrometers thick, pierced by the network of microcracks. Simultaneous use of electrospark and electrochemical machining permitted to manufacture tubes from tungsten monocrystals with non-distorted monocrystal surface and without a network of microcracks

A long-pulse repetitive operation magnetically insulated transmission line oscillator

International Nuclear Information System (INIS)

Fan, Yu-Wei; Zhong, Hui-Huang; Zhang, Jian-De; Shu, Ting; Liu, Jin Liang

2014-01-01

The improved magnetically insulated transmission line oscillator (MILO) is a gigawatt-class L-band high power microwave tube. It has allowed us to generate 3.1 GW pulse of 40 ns duration in the single-pulse operation and 500 MW pulse of 25 ns duration in the repetition rate operation. However, because of the severe impedance mismatch, the power conversion efficiency is only about 4% in the repetition rate operation. In order to eliminate the impedance mismatch and obtain repetitive long-pulse high-power microwave (HPM), a series of experiments are carried out and the recent progress is presented in this paper. In the single-pulse operation, when the diode voltage is 466 kV and current is 41.6 kA, the radiated microwave power is above 2.2 GW, the pulse duration is above 102 ns, the microwave frequency is about 1.74 GHz, and the power conversion efficiency is about 11.5%. In the repetition rate operation, under the condition of the diode voltage about 400 kV, beam current about 38 kA, the radiated microwave power is about 1.0 GW, the pulse duration is about 85 ns. Moreover, the radiated microwave power and the pulse duration decline little by little when the shot numbers increase gradually. The experimental results show that the impedance matching is a vital factor for HPM systems and one of the major technical challenges is to improve the cathode for the repetition rate operation MILO

A long-pulse repetitive operation magnetically insulated transmission line oscillator

Energy Technology Data Exchange (ETDEWEB)

Fan, Yu-Wei; Zhong, Hui-Huang; Zhang, Jian-De; Shu, Ting; Liu, Jin Liang [College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

2014-05-15

The improved magnetically insulated transmission line oscillator (MILO) is a gigawatt-class L-band high power microwave tube. It has allowed us to generate 3.1 GW pulse of 40 ns duration in the single-pulse operation and 500 MW pulse of 25 ns duration in the repetition rate operation. However, because of the severe impedance mismatch, the power conversion efficiency is only about 4% in the repetition rate operation. In order to eliminate the impedance mismatch and obtain repetitive long-pulse high-power microwave (HPM), a series of experiments are carried out and the recent progress is presented in this paper. In the single-pulse operation, when the diode voltage is 466 kV and current is 41.6 kA, the radiated microwave power is above 2.2 GW, the pulse duration is above 102 ns, the microwave frequency is about 1.74 GHz, and the power conversion efficiency is about 11.5%. In the repetition rate operation, under the condition of the diode voltage about 400 kV, beam current about 38 kA, the radiated microwave power is about 1.0 GW, the pulse duration is about 85 ns. Moreover, the radiated microwave power and the pulse duration decline little by little when the shot numbers increase gradually. The experimental results show that the impedance matching is a vital factor for HPM systems and one of the major technical challenges is to improve the cathode for the repetition rate operation MILO.

A long-pulse repetitive operation magnetically insulated transmission line oscillator.

Science.gov (United States)

Fan, Yu-Wei; Zhong, Hui-Huang; Zhang, Jian-De; Shu, Ting; Liu, Jin Liang

2014-05-01

The improved magnetically insulated transmission line oscillator (MILO) is a gigawatt-class L-band high power microwave tube. It has allowed us to generate 3.1 GW pulse of 40 ns duration in the single-pulse operation and 500 MW pulse of 25 ns duration in the repetition rate operation. However, because of the severe impedance mismatch, the power conversion efficiency is only about 4% in the repetition rate operation. In order to eliminate the impedance mismatch and obtain repetitive long-pulse high-power microwave (HPM), a series of experiments are carried out and the recent progress is presented in this paper. In the single-pulse operation, when the diode voltage is 466 kV and current is 41.6 kA, the radiated microwave power is above 2.2 GW, the pulse duration is above 102 ns, the microwave frequency is about 1.74 GHz, and the power conversion efficiency is about 11.5%. In the repetition rate operation, under the condition of the diode voltage about 400 kV, beam current about 38 kA, the radiated microwave power is about 1.0 GW, the pulse duration is about 85 ns. Moreover, the radiated microwave power and the pulse duration decline little by little when the shot numbers increase gradually. The experimental results show that the impedance matching is a vital factor for HPM systems and one of the major technical challenges is to improve the cathode for the repetition rate operation MILO.

Pulsed eddy currents: principle and applications

International Nuclear Information System (INIS)

Bernard, A.; Coutanceau, N.

1993-04-01

Eddy currents are widely used as a non destructive testing technique specially for heat exchanger testing. The specificities of pulsed eddy current testing are analyzed in terms of probe design and signal processing. The specific applications are detailed. They are divided in two parts. First part, deals with the two main applications of the high peak energy supplied to the probe. One concerns the design of focused probes used for the detection of small defects in irradiated fuel rods. The other concerns the saturation of ferromagnetic materials in order to test the full thickness of the exchanger tubes. Second part, deals with applications of the wide and low frequency spectrum generated by the pulse source. It enables the testing of thick materials, and the detection of sub-surface defects. It has been tested on austenitic steel (nuclear pressure vessel nozzle), multilayered structures of aluminium alloys (aeronautics) and sleeved structures (nuclear pressure vessel head penetrations through thermal sleeves)

Report on the performance and operating characteristics of the Burle C83061E QUANTACON trademark photomultiplier tube

International Nuclear Information System (INIS)

Sandberg, V.D.; Thompson, T.N.; Helvy, F.A.

1989-01-01

The Burle C83061E QUANTACON trademark is a 10.4 inch diameter photomultiplier tube with improved photoelectron collection optics. We report here on the first tests of this newly developed tube. We find the single photoelectron charge resolution to be excellent, with a peak to (noise) valley ratio exceeding 3 and with a transit time spread of less than 2.3 ns (FWHM) for full photocathode illumination at the single photoelectron level. A design for a fast anode pulse base is also presented. 11 refs., 8 figs

Investigations of single-electron avalanches in a proportional drift tube

International Nuclear Information System (INIS)

Anderson, W.S.; Armitage, J.C.; Chevreau, P.; Heinrich, J.G.; Lu, C.; McDonald, I.; McDonald, K.T.; Miller, B.; Secrest, D.; Weckel, J.

1990-01-01

Detailed information on single-electron drift and avalanche behavior has a basic interest in an investigation of gas-chamber performance. Its timing, avalanche distribution, attachment by the working gas mixtures, etc., provide various criteria for choosing the best suitable gas mixture under a specific experimental circumstance. Investigations of single-electron avalanches in a proportional drift tube have been carried out with a pulsed N 2 laser. The study consists of two aspects: timing properties, and fluctuations in the gas avalanche

A conduction-cooled, 680-mm-long warm bore, 3-T Nb3Sn solenoid for a Cerenkov free electron laser

NARCIS (Netherlands)

Wessel, Wilhelm A.J.; den Ouden, A.; Krooshoop, Hendrikus J.G.; ten Kate, Herman H.J.; Wieland, J.; van der Slot, Petrus J.M.

1999-01-01

A compact, cryocooler cooled Nb3Sn superconducting magnet system for a Cerenkov free electron laser has been designed, fabricated and tested. The magnet is positioned directly behind the electron gun of the laser system. The solenoidal field compresses and guides a tube-shaped 100 A, 500 kV electron

Picosecond ion pulses from an EN tandem created by a femtosecond Ti:sapphire laser

International Nuclear Information System (INIS)

Carnes, K.D.; Cocke, C.L.; Chang, Z.; Ben-Itzhak, I.; Needham, H.V.; Rankin, A.

2007-01-01

As the James R. Macdonald Laboratory at Kansas State University continues its transformation from an ion collisions facility to an ultrafast laser/ion collisions facility, we are looking for novel ways to combine our traditional accelerator expertise with our new laser capabilities. One such combination is to produce picosecond pulses of stripping gas ions in the high energy accelerating tube of our EN tandem by directing ∼100 fs, sub-milliJoule laser pulses up the high energy end of the tandem toward a focusing mirror at the terminal. Ion pulses from both stripping and residual gas have been produced and identified, with pulse widths thus far on the order of a nanosecond. This width represents an upper limit, as it is dominated by pulse-to-pulse jitter in the ion time-of-flight (TOF) and is therefore not a true representation of the actual pulse width. In this paper, we describe the development process and report on the results to date. Conditions limiting the minimum temporal pulse width, such as tandem terminal ripple, thermal motion of the gas and space charge effects, are also outlined

Tube holding system

International Nuclear Information System (INIS)

Cunningham, R.C.

1978-01-01

A tube holding rig is described for the lateral support of tubes arranged in tight parcels in a heat exchanger. This tube holding rig includes not less than two tube supporting assemblies, with a space between them, located crosswise with respect to the tubes, each supporting assembly comprising a first set of parallel components in contact with the tubes, whilst a second set of components is also in contact with the tubes. These two sets of parts together define apertures through which the tubes pass [fr

Effects of previous ionization and excitation on the ionization wave propagation along the dielectric tube

International Nuclear Information System (INIS)

Xia, Yang; Liu, Dongping; Bi, Zhenhua; Wang, Xueyang; Niu, Jinhai; Ji, Longfei; Song, Ying; Qi, Zhihua; Wang, Wenchun

2016-01-01

In this paper, by using a high precision synchronization system, the ignition time, velocity, and propagation properties of the ionization waves (IWs) have been investigated in detail from the 1st high voltage (HV) pulse to the sequential ones over a large range of the pulse-off time. In order to clarify the effects of previous ionization and excitation on the IW propagation, the density of the residual charges are controlled by varying the pulse-off time from 199 μs to 15 μs. The results show that the formation and propagation of IWs can be strongly affected by previous discharge. For a longer pulse-off time (100 μs–190 μs), the propagation velocity of plasma bullets are decreased from the 1st to the 10th HV pulse, then increased after the 10th pulse, and finally become stable after about 500 pulses. When the pulse-off time is reduced to 15 μs, the propagation velocity of plasma bullets will rapidly increase and become stable after the 1st HV pulse. The ignition voltage is significantly reduced after the 1st HV pulse with the decrease in pulse-off time. Consequently, the generation and propagation of IWs in the tube are strongly affected by the accumulation of long-lived metastable helium (He) species and residual charges from previous discharges, which is important for understanding the plasma bullet behavior. (paper)

Compact field programmable gate array-based pulse-sequencer and radio-frequency generator for experiments with trapped atoms

Energy Technology Data Exchange (ETDEWEB)

Pruttivarasin, Thaned, E-mail: thaned.pruttivarasin@riken.jp [Quantum Metrology Laboratory, RIKEN, Wako-shi, Saitama 351-0198 (Japan); Katori, Hidetoshi [Quantum Metrology Laboratory, RIKEN, Wako-shi, Saitama 351-0198 (Japan); Innovative Space-Time Project, ERATO, JST, Bunkyo-ku, Tokyo 113-8656 (Japan); Department of Applied Physics, Graduate School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656 (Japan)

2015-11-15

We present a compact field-programmable gate array (FPGA) based pulse sequencer and radio-frequency (RF) generator suitable for experiments with cold trapped ions and atoms. The unit is capable of outputting a pulse sequence with at least 32 transistor-transistor logic (TTL) channels with a timing resolution of 40 ns and contains a built-in 100 MHz frequency counter for counting electrical pulses from a photo-multiplier tube. There are 16 independent direct-digital-synthesizers RF sources with fast (rise-time of ∼60 ns) amplitude switching and sub-mHz frequency tuning from 0 to 800 MHz.

HF electronic tubes. Technologies, grid tubes and klystrons

International Nuclear Information System (INIS)

Lemoine, Th.

2009-01-01

This article gives an overview of the basic technologies of electronic tubes: cathodes, electronic optics, vacuum and high voltage. Then the grid tubes, klystrons and inductive output tubes (IOT) are introduced. Content: 1 - context and classification; 2 - electronic tube technologies: cathodes, electronic optics, magnetic confinement (linear tubes), periodic permanent magnet (PPM) focussing, collectors, depressed collectors; 3 - vacuum technologies: vacuum quality, surface effects and interaction with electrostatic and RF fields, secondary emission, multipactor effect, thermo-electronic emission; 4 - grid tubes: operation of a triode, tetrodes, dynamic operation and classes of use, 'common grid' and 'common cathode' operation, ranges of utilisation and limitations, operation of a tetrode on unadjusted load, lifetime of a tetrode, uses of grid tubes; 5 - klystrons: operation, impact of space charge, multi-cavity klystrons, interaction efficiency, extended interaction klystrons, relation between interaction efficiency, perveance and efficiency, ranges of utilization and power limitations, multi-beam klystrons and sheet beam klystrons, operation on unadjusted load, klystron band pass and lifetime, uses; 6 - IOT: principle of operation, ranges of utilisation and limitations, interaction efficiency and depressed collector IOT, IOT lifetime and uses. (J.S.)

Repeated pulsed x-ray emission equipment

International Nuclear Information System (INIS)

Terauchi, Hikaru; Iida, Satoshi

1982-01-01

X-ray diffraction technique has been applied to determine the spatial positions of atoms which compose a material, and it is needless to say that the technique is a fundamental means regardless of the fields of research. However, the application of X-ray diffraction to the research on physical properties has been so far limited to know the spatial positions of atoms or molecules under thermal equilibrium condition. The addition of time element to the conventional technique, that is, the analysis of material structure including the time-varying processes under non-equilibrium conditions, is considered to approach the elucidation of the essence of materials. The authors call this dynamic structural analysis. The authors have planned to analyze X-ray diffraction intensity which has the resolution of about 10 -8 s in the real time which is conjugate with energy. However, present pulsed X-ray sources are not suitable for diffraction experiment because the pulse width is too long or X-ray wavelength is too short. Accordingly, the authors have made for trial a pulsed X-ray source for diffraction experiment. Its specifications are: diode voltage (X-ray tube voltage) from 200 to 300 kV, diode current from 2 to 5 kA, pulse width of about 30ns, maximum repetition frequency 10 pps, and X-ray focus size of 2 mm diameter. One of the features of this source is the repeated generation of pulsed X-ray. This is the first trial in the world, and is indispensable to the dynamic structural analysis described above. The quality of the emitted X-ray is also written. (Wakatsuki, Y.)

Estimation of Pulse Transit Time as a Function of Blood Pressure Using a Nonlinear Arterial Tube-Load Model.

Science.gov (United States)

Gao, Mingwu; Cheng, Hao-Min; Sung, Shih-Hsien; Chen, Chen-Huan; Olivier, Nicholas Bari; Mukkamala, Ramakrishna

2017-07-01

pulse transit time (PTT) varies with blood pressure (BP) throughout the cardiac cycle, yet, because of wave reflection, only one PTT value at the diastolic BP level is conventionally estimated from proximal and distal BP waveforms. The objective was to establish a technique to estimate multiple PTT values at different BP levels in the cardiac cycle. a technique was developed for estimating PTT as a function of BP (to indicate the PTT value for every BP level) from proximal and distal BP waveforms. First, a mathematical transformation from one waveform to the other is defined in terms of the parameters of a nonlinear arterial tube-load model accounting for BP-dependent arterial compliance and wave reflection. Then, the parameters are estimated by optimally fitting the waveforms to each other via the model-based transformation. Finally, PTT as a function of BP is specified by the parameters. The technique was assessed in animals and patients in several ways including the ability of its estimated PTT-BP function to serve as a subject-specific curve for calibrating PTT to BP. the calibration curve derived by the technique during a baseline period yielded bias and precision errors in mean BP of 5.1 ± 0.9 and 6.6 ± 1.0 mmHg, respectively, during hemodynamic interventions that varied mean BP widely. the new technique may permit, for the first time, estimation of PTT values throughout the cardiac cycle from proximal and distal waveforms. the technique could potentially be applied to improve arterial stiffness monitoring and help realize cuff-less BP monitoring.

Development of a compact superconducting magnet with a GdBCO magnetic lens

International Nuclear Information System (INIS)

Zhang, Z Y; Matsumoto, S; Kiyoshi, T; Teranishi, R

2013-01-01

Concentration of a magnetic field has been achieved using a Gd–Ba–Cu–O (GdBCO) magnetic lens. A conduction-cooled compact high-field superconducting magnet with a GdBCO magnetic lens was developed. The magnet possessed a 10-mm room-temperature bore and consisted of two Nb–Ti solenoid coils and a GdBCO magnetic lens, which was installed at the center of the Nb–Ti coils in order to concentrate the background field generated by the Nb–Ti coils. The Nb–Ti coils and the GdBCO magnetic lens were cooled using a two-stage pulse-tube cryocooler. A concentrated magnetic field of 10.3 T was obtained at a background field of 5.6 T provided by the Nb–Ti coils. No degradation was found in the magnet during repeat excitation. The large field gradient generated by the GdBCO magnetic lens is expected to be used for the levitation of diamagnetic materials. (paper)

New generation of cryogen free advanced superconducting magnets for neutron scattering experiments

International Nuclear Information System (INIS)

Kirichek, O; Adroja, D T; Manuel, P; Bewley, R I; Brown, J; Kouzmenko, G; Wotherspoon, R

2012-01-01

Recent advances in superconducting technology and cryocooler refrigeration have resulted in a new generation of advanced superconducting magnets for neutron beam applications. These magnets have outstanding parameters such as high homogeneity and stability at highest magnetic fields possible, a reasonably small stray field, low neutron scattering background and larger exposure to neutron detectors. At the same time the pulse tube refrigeration technology provides a complete re-condensing regime which allows to minimise the requirements for cryogens without introducing additional noise and mechanical vibrations. The magnets can be used with dilution refrigerator insert which expands the temperature range from 20mK to 300K. Here we are going to present design, test results and the operational data of the 14T magnet for neutron diffraction and the 9T wide angle chopper magnet for neutron spectroscopy developed by Oxford Instruments in collaboration with ISIS neutron source. First scientific results obtained from the neutron scattering experiments with these magnets are also going to be discussed.

A digital miniature x-ray tube with a high-density triode carbon nanotube field emitter

International Nuclear Information System (INIS)

Jeong, Jin-Woo; Kang, Jun-Tae; Choi, Sungyoul; Kim, Jae-Woo; Song, Yoon-Ho; Ahn, Seungjoon

2013-01-01

We have fabricated a digital miniature x-ray tube (6 mm in diameter and 32 mm in length) with a high-density triode carbon nanotube (CNT) field emitter for special x-ray applications. The triode CNT emitter was densely formed within a diameter of below 4 mm with the focusing-functional gate. The brazing process enables us to obtain and maintain a desired vacuum level for the reliable electron emission from the CNT emitters after the vacuum packaging. The miniature x-ray tube exhibited a stable and reliable operation over 250 h in a pulse mode at an anode voltage of above 25 kV.

The System of Nanosecond 280-KeV He+ Pulsed Beam

International Nuclear Information System (INIS)

Junphong, P.; Ano, V.; Lekprasert, B.; Suwannakachorn, D.; Thongnopparat, N.; Vilaithong, T.; Chiang Mai U.; Wiedemann, H.; SLAC/SLAC, SSRL

2006-01-01

At Fast Neutron Research Facility, the 150 kV-pulses neutron generator is being upgraded to a 280-kV-pulsed-He beam for time-of-flight Rutherford backscattering spectrometry. It involves replacing the existing beam line elements by a multicusp ion source, a 400-kV accelerating tube, 45-double focusing dipole magnet and quadrupole lens. The multicusp ion source is a compact filament-driven of 2.6 cm in diameter and 8 cm in length. The current extracted is 20.4 μ A with 13 kV of extraction voltage and 8.8 kV of Einzel lens voltage. The beam emittance has found to vary between 6-12 mm mrad. The beam transport system has to be redesigned based on the new elements. The important part of a good pulsed beam depends on the pulsing system. The two main parts are the chopper and buncher. An optimized geometry for the 280 keV pulsed helium ion beam will be presented and discussed. The PARMELA code has been used to optimize the space charge effect, resulting in pulse width of less than 2 ns at a target. The calculated distance from a buncher to the target is 4.6 m. Effects of energy spread and phase angle between chopper and buncher have been included in the optimization of the bunch length

Tube to tube excursive instability - sensitivities and transients

International Nuclear Information System (INIS)

Brown, M.; Layland, M.W.

1980-01-01

A simple basic analysis of excursive instability in a boiler tube shows how it depends upon operating conditions and physical properties. A detailed mathematical model of an AGR boiler is used to conduct a steady state parameter sensitivity survey. It is possible from this basis to anticipate the effects of changes in operating conditions and changes in design parameters upon tube to tube stability. Dynamic responses of tubes operating near the stability threshold are examined using a mathematical model. Simulated excursions are triggered by imparting small abrupt pressure changes on the boiler inlet pressure. The influences of the magnitude of the pressure change, waterside friction factor and gas side coupling between tubes are examined. (author)

Design of a New Acceleration System for High-Current Pulsed Proton Beams from an ECR Source

Science.gov (United States)

Cooper, Andrew L.; Pogrebnyak, Ivan; Surbrook, Jason T.; Kelly, Keegan J.; Carlin, Bret P.; Champagne, Arthur E.; Clegg, Thomas B.

2014-03-01

A primary objective for accelerators at TUNL's Laboratory for Experimental Nuclear Astrophysics (LENA) is to maximize target beam intensity to ensure a high rate of nuclear events during each experiment. Average proton target currents of several mA are needed from LENA's electron cyclotron resonance (ECR) ion source because nuclear cross sections decrease substantially at energies of interest tube structures; and provide better heat dissipation by using deionized water to provide the current drain needed to establish the accelerating tube's voltage gradient. Details of beam optical modeling calculations, proposed accelerating tube design, and initial beam pulsing tests will be described. Work supported in part by USDOE Office of HE and Nuclear Physics.

Tube-support response to tube-denting evaluation. Volume 1. Final report

International Nuclear Information System (INIS)

Anderson, P.L.; Hall, J.F.; Shah, P.K.; Wills, R.L.

1983-05-01

The response of the tube supports is one of the important considerations of tube denting in a steam generator. Investigations have indicated that damaged tube supports have the potential to distort and damage tubes. This investigation considers the response to tube denting of the Combustion Engineering type tube supports. Drilled support plates and eggcrate tube supports are tested in a model steam generator in which tube denting is induced. The experimental data is used to verify and refine analytical predictor models developed using finite element techniques. It was found that analytical models underpredicted the deformations of the tube supports and appropriate modifications to enhance the predictive capability are identified. Non-destructive examination methods are evaluated for application to operating steam generators. It was found that the standard eddy current and profilometry techniques are acceptable methods for determining tube deformations, but these techniques are not adequate to assess tube support damage. Radiography is judged to be the best available means of determining the extent and progression of damage in tube supports

Digital pulse shape discrimination

International Nuclear Information System (INIS)

Miller, L. F.; Preston, J.; Pozzi, S.; Flaska, M.; Neal, J.

2007-01-01

Pulse-shape discrimination (PSD) has been utilised for about 40 years as a method to obtain estimates for dose in mixed neutron and photon fields. Digitizers that operate close to GHz are currently available at a reasonable cost, and they can be used to directly sample signals from photomultiplier tubes. This permits one to perform digital PSD rather than the traditional, and well-established, analogous techniques. One issue that complicates PSD for neutrons in mixed fields is that the light output characteristics of typical scintillators available for PSD, such as BC501A, vary as a function of energy deposited in the detector. This behaviour is more easily accommodated with digital processing of signals than with analogous signal processing. Results illustrate the effectiveness of digital PSD. (authors)

Condenser tube buckling within tube-tubesheet joints

International Nuclear Information System (INIS)

Willertz, L.E.; Kalnins, A.; Updike, D.P.

1991-01-01

The problem of the appearance of protrusions, or bumps, in the interior of roller-expanded tubes within a tubesheet is addressed. Such bumps have been observed in condensers of power plants. A brief history of the reported occurrences of the bumps is given. The hypothesis is advanced that the mechanics of the formation of the bumps is similar to a buckling problem that has 'bifurcation at infinity'. Following this hypothesis, a two-dimensional physical model is developed, and the application of this model to study a three-dimensional bump is proposed. It is proposed in this paper that an initial deviation from the circular shape of the tube required to produce a bump. It is shown that without such a deviation the tubes cannot buckle. An experiment with short tube segments has been performed that verifies some of the features of the observed condenser tube bumps. Exactly what force produced the initial deviation for the observed bumps is still unknown. Available evidence implicates the hydro-laser jet that is used in the cleaning of tubes and tubesheets. A scenario of how a bump could have been produced by the hydro-laser jet is proposed. (author)

Development of a sealed-accelerator-tube neutron generator

Science.gov (United States)

Verbeke; Leung; Vujic

2000-10-01

Sealed-accelerator-tube neutron generators are being developed in Lawrence Berkeley National Laboratory (LBNL) for applications ranging from neutron radiography to boron neutron capture therapy and neutron activation analysis. The new generation of high-output neutron generators is based on the D-T fusion reaction, producing 14.1-MeV neutrons. The main components of the neutron tube--the ion source, the accelerator and the target--are all housed in a sealed metal container without external pumping. Thick-target neutron yield computations are performed in this paper to estimate the neutron yield of titanium and scandium targets. With an average deuteron beam current of 1 A and an energy of 120 keV, a time-averaged neutron production of approximately 10(14) n/s can be estimated for a tritiated target, for both pulsed and cw operations. In mixed deuteron/triton beam operation, a beam current of 2 A at 150 keV is required for the same neutron output. Recent experimental results on ion sources and accelerator columns are presented and discussed.

High-power rf pulse compression with SLED-II at SLAC

International Nuclear Information System (INIS)

Nantista, C.

1993-04-01

Increasing the peak rf power available from X-band microwave tubes by means of rf pulse compression is envisioned as a way of achieving the few-hundred-megawatt power levels needed to drive a next-generation linear collider with 50--100 MW klystrons. SLED-II is a method of pulse compression similar in principal to the SLED method currently in use on the SLC and the LEP injector linac. It utilizes low-los resonant delay lines in place of the storage cavities of the latter. This produces the added benefit of a flat-topped output pulse. At SLAC, we have designed and constructed a prototype SLED-II pulse-compression system which operates in the circular TE 01 mode. It includes a circular-guide 3-dB coupler and other novel components. Low-power and initial high-power tests have been made, yielding a peak power multiplication of 4.8 at an efficiency of 40%. The system will be used in providing power for structure tests in the ASTA (Accelerator Structures Test Area) bunker. An upgraded second prototype will have improved efficiency and will serve as a model for the pulse compression system of the NLCTA (Next Linear Collider Test Accelerator)

Reduction of radiation exposure while maintaining high-quality fluoroscopic images during interventional cardiology using novel x-ray tube technology with extra beam filtering.

Science.gov (United States)

den Boer, A; de Feyter, P J; Hummel, W A; Keane, D; Roelandt, J R

1994-06-01

Radiographic technology plays an integral role in interventional cardiology. The number of interventions continues to increase, and the associated radiation exposure to patients and personnel is of major concern. This study was undertaken to determine whether a newly developed x-ray tube deploying grid-switched pulsed fluoroscopy and extra beam filtering can achieve a reduction in radiation exposure while maintaining fluoroscopic images of high quality. Three fluoroscopic techniques were compared: continuous fluoroscopy, pulsed fluoroscopy, and a newly developed high-output pulsed fluoroscopy with extra filtering. To ascertain differences in the quality of images and to determine differences in patient entrance and investigator radiation exposure, the radiated volume curve was measured to determine the required high voltage levels (kVpeak) for different object sizes for each fluoroscopic mode. The fluoroscopic data of 124 patient procedures were combined. The data were analyzed for radiographic projections, image intensifier field size, and x-ray tube kilovoltage levels (kVpeak). On the basis of this analysis, a reference procedure was constructed. The reference procedure was tested on a phantom or dummy patient by all three fluoroscopic modes. The phantom was so designed that the kilovoltage requirements for each projection were comparable to those needed for the average patient. Radiation exposure of the operator and patient was measured during each mode. The patient entrance dose was measured in air, and the operator dose was measured by 18 dosimeters on a dummy operator. Pulsed compared with continuous fluoroscopy could be performed with improved image quality at lower kilovoltages. The patient entrance dose was reduced by 21% and the operator dose by 54%. High-output pulsed fluoroscopy with extra beam filtering compared with continuous fluoroscopy improved the image quality, lowered the kilovoltage requirements, and reduced the patient entrance dose by 55% and

Preliminary research results for parameter diagnostics of intense pulsed ion beams

International Nuclear Information System (INIS)

Yang Hailiang; Qiu Aici; Sun Jianfeng; He Xiaoping; Tang Junping; Wang Haiyang; Li Jingya; Ren Shuqing; Huang Jianjun; Zhang Jiasheng; Peng Jianchang; Ouyang Xiaoping; Zhang Guoguang; Li Hongyu

2004-01-01

The preliminary experimental results for parameter diagnostics of intense pulsed ion beams from the FLASH II accelerator were reported. The ion number of an intense pulsed ion beam were experimentally determined by monitoring delayed radioactivity from protons induced nuclear reactions in a 12 C target. The prompt γ-rays and diode Bremsstrahlung X-rays were measured with PIN semi-conductor detector and a ST401 plastic scintillator detector. The Bremsstrahlung distribution outside of the drift tube was detected with a thermoluminescent detector and the shielding design was also determined. The current densities of beam were measured with biased ion collector array. The ion beams were also recorded with a CR-39 detector. (author)

A space-qualified experiment integrating HTS digital circuits and small cryocoolers

International Nuclear Information System (INIS)

Silver, A.; Akerling, G.; Auten, R.

1996-01-01

High temperature superconductors (HTS) promise to achieve electrical performance superior to that of conventional electronics. For application in space systems, HTS systems must simultaneously achieve lower power, weight, and volume than conventional electronics, and meet stringent space qualification and reliability requirements. Most effort to date has focused on passive RF/microwave applications. However, incorporation of active microwave components such as amplifiers, mixers, and phase shifters, and on-board high data rate digital signal processing is limited by the power and weight of their spacecraft electronic and support modules. Absence of data on active HTS components will prevent their utilization in space. To validate the feasibility in space of HTS circuits and components based on Josephson junctions, one needs to demonstrate HTS circuits and critical supporting technologies, such as space-qualified packaging and interconnects, closed-cycle cryocooling, and interface electronics. This paper describes the packaging, performance, and space test plan of an integrated, space-qualified experimental package consisting of HTS Josephson junction circuits and all the supporting components for NRL's high temperature superconductor space experiment (HTSSE-II). Most of the technical challenges and approaches are equally applicable to passive and active RF/microwave and digital electronic components, and this experiment will provide valuable validation data

Development of a hermetically sealed brushless DC motor for a J-T cryocooler

Science.gov (United States)

Joscelyn, Edwin; Hochler, Irwin; Ferri, Andrew; Rott, Heinz; Soukaris, Ted

1996-01-01

This development was sponsored by Ball Aerospace for the Cryogenic On-Orbit LongLife Active Refrigerator (COOLLAR) program. The cryocooler is designed to cool objects to 65 K and operate in space for at least 7 years. The system also imports minimal impact to the spacecraft in terms of vibration and heat. The basic Joule-Thompson cycle involves compressing a working fluid, nitrogen in this case, at near-constant temperature from 17.2 KPa to 6.89 MPa. The nitrogen is then expanded through a Joule-Thompson valve. The pure nitrogen gas must be kept clean; therefore, any contamination from motor organic materials must be eliminated. This requirement drove the design towards sealing of the motor within a titanium housing without sacrificing motor performance. It is estimated that an unsealed motor would have contributed 1.65 g of contaminants, due to the organic insulation and potting materials, over the 7-year life. This paper describes the motor electrical and mechanical design, as well as the sealing difficulties encountered, along with their solutions.

PULSE COMBUSTOR DESIGN QUALIFICATION TEST AND CLEAN COAL FEEDSTOCK TEST - VOLUME I AND VOLUME II

Energy Technology Data Exchange (ETDEWEB)

Unknown

2002-02-08

For this Cooperative Agreement, the pulse heater module is the technology envelope for an indirectly heated steam reformer. The field of use of the steam reformer pursuant to this Cooperative Agreement with DOE is for the processing of sub-bituminous coals and lignite. The main focus is the mild gasification of such coals for the generation of both fuel gas and char--for the steel industry is the main focus. An alternate market application for the substitution of metallurgical coke is also presented. This project was devoted to qualification of a 253-tube pulse heater module. This module was designed, fabricated, installed, instrumented and tested in a fluidized bed test facility. Several test campaigns were conducted. This larger heater is a 3.5 times scale-up of the previous pulse heaters that had 72 tubes each. The smaller heater has been part of previous pilot field testing of the steam reformer at New Bern, North Carolina. The project also included collection and reduction of mild gasification process data from operation of the process development unit (PDU). The operation of the PDU was aimed at conditions required to produce char (and gas) for the Northshore Steel Operations. Northshore Steel supplied the coal for the process unit tests.

Pulsed neutron uranium borehole logging with prompt fission neutrons

International Nuclear Information System (INIS)

Bivens, H.M.; Smith, G.W.; Jensen, D.H.

1976-01-01

The gross count natural gamma log normally used for uranium borehole logging is seriously affected by disequilibrium. Methods for the direct measurement of uranium, such as neutron logging, which are not affected by disequilibrium have been the object of considerable effort in recent years. This paper describes a logging system for uranium which uses a small accelerator to generate pulses of 14 MeV neutrons to detect and assay uranium by the measurement of prompt fission neutrons in the epithermal energy range. After an initial feasibility study, a prototype logging probe was built for field evaluation which began in January 1976. Physical and operational characteristics of the prototype probe, the neutron tube-transformer assembly, and the neutron tube are described. In logging operations, only the epithermal prompt fission neutrons detected between 250 microseconds to 2500 microseconds following the excitation neutron pulse are counted. Comparison of corrected neutron logs with the conventional gross count natural gamma logs and the chemical assays of cores from boreholes are shown. The results obtained with this neutron probe clearly demonstrate its advantages over the gross count natural gamma log, although at this time the accuracy of the neutron log assay is not satisfactory under some conditions. The necessary correction factors for various borehole and formation parameters are being determined and, when applied, should improve the assay accuracy

Study the Effect of the Flow on the Performance of a shell and Tube Type Heat Exchanger using Experimental Design Technique

Directory of Open Access Journals (Sweden)

Zuher Hassan Abdullah

2016-10-01

Full Text Available In the current research an experimental study was done to show the effect of pulse flow on the effectiveness of shell and tube type heat exchanger. the study was in the case of steady and pulse flows with a changing mass flow rate of hot water flowing inside the pipes of the heat exchanger for the range between (0.0273-0.0819 kg / s  at fix mass flow rate of cold water that flows through the shell and on the outer surface of the pipes when (0.0416 kg / s, to obtain pulsing a used was solenoid valve. The research aims to measure the percentage effect of independent factors which were presenting the mass flow rate of hot water, flow type and the surrounding environment conditions of the experimental side upon shell and tube type heat exchanger performance using experimental design technique at the significant level (0.05.The results derived from the experimental tests showed that pulse flow leads to increase internal heat transfer coefficient (hi comparing with its value in the steady flow and the highest increase was by (9.75% at a mass flow rate of hot water (0.0416 kg / s and increases the overall heat transfer coefficient (U, where the highest percentage was by 4.68% at a mass flow rate of hot water (0.0416kg/s. The results also showed increasing both the number of transmitted units (NTU and the effectiveness of the shell and tube type heat exchanger ( in the case of pulse flow of its value in the steady flow and the highest percentage of increase occurring was (4.75% and (1.85%, respectively, and at the mass flow rate of hot water (0.0416 kg / s. Percentage effect of mass flow rate of hot water was (97%, 97.42%, 95.5%, 99.48% and the percentage effect of each flow type and the errors were (2.8%, 2.25%, 2.44%, 0.4% and (0. 2, 0.33%, 2.06%, 0.12 respectively

Chest tube insertion

Science.gov (United States)

Chest drainage tube insertion; Insertion of tube into chest; Tube thoracostomy; Pericardial drain ... Be careful there are no kinks in your tube. The drainage system should always sit upright and be placed ...

Vibro-impact responses of a tube with tube--baffle interaction

International Nuclear Information System (INIS)

Shin, Y.S.; Sass, D.E.; Jendrzejczyk, J.A.

1978-01-01

The relatively small, inherent tube-to-baffle hole clearances associated with manufacturing tolerances in heat exchangers affect the vibrational characteristics and the response of the tube. Numerical studies were made to predict the vibro-impact response of a tube with tube-baffle interaction. The finite element method has been employed with a non-linear elastic contact spring-dashpot to model the effect of the relative approach between the tube and the baffle plate. The coupled equations of motion are directly integrated with a proportional system damping represented by a linear combination of mass and stiffness. Lumped mass approach with explicit time integration scheme was found to be a suitable choice for tube-baffle impacting analysis. Fourier analyses indicate that the higher mode contributions to the tube response are significant for strong tube-baffle impacting. The contact damping forces are negligible compared with the contact spring forces. The numerical analysis results are in reasonably good agreement with those of the experiments

Signal propagation in straw tubes with resistive cathodes

International Nuclear Information System (INIS)

Marzec, J.; Zaremba, K.; Pawlowski, Z.; Konarzewski, B.

2000-01-01

The analysis presented in this paper is part of the research performed by the authors for the COMPASS experiment at CERN. They have developed a theoretical model of the signal transmission in a straw tube. In contrast to commonly used simplified models, their approach takes into account the energy losses in the cathode resistance. This model allows determination of the main electrical parameters, such as characteristic impedance and signal attenuation, as well as a detailed simulation of the pulse shape dependent on the point of the charge injection. Simulation results have been compared with the results of experimental measurements of different types of the straw detectors

Signal propagation in straw tubes with resistive cathodes

Energy Technology Data Exchange (ETDEWEB)

Marzec, J.; Zaremba, K.; Pawlowski, Z.; Konarzewski, B.

2000-02-01

The analysis presented in this paper is part of the research performed by the authors for the COMPASS experiment at CERN. They have developed a theoretical model of the signal transmission in a straw tube. In contrast to commonly used simplified models, their approach takes into account the energy losses in the cathode resistance. This model allows determination of the main electrical parameters, such as characteristic impedance and signal attenuation, as well as a detailed simulation of the pulse shape dependent on the point of the charge injection. Simulation results have been compared with the results of experimental measurements of different types of the straw detectors.

Signal propagation in straw tubes with resistive cathode

CERN Document Server

Marzec, J; Pawlowski, Z; Konarzewski, B

2000-01-01

The analysis presented in this paper is part of the research performed by the authors for the COMPASS experiment at CERN. We have developed a theoretical model of the signal transmission in a straw tube. In contrast to commonly used simplified models, our approach takes into account the energy losses in the cathode resistance. This model allows determination of the main electrical parameters, such as characteristic impedance and signal attenuation, as well as a detailed simulation of the pulse shape dependent on the point of the charge injection. Simulation results have been compared with the results of experimental measurements of different types of the straw detectors. (7 refs).

Pulse shape discrimination of plastic scintillator EJ 299-33 with radioactive sources

Science.gov (United States)

Pagano, E. V.; Chatterjee, M. B.; De Filippo, E.; Russotto, P.; Auditore, L.; Cardella, G.; Geraci, E.; Gnoffo, B.; Guazzoni, C.; Lanzalone, G.; De Luca, S.; Maiolino, C.; Martorana, N. S.; Pagano, A.; Papa, M.; Parsani, T.; Pirrone, S.; Politi, G.; Porto, F.; Quattrocchi, L.; Rizzo, F.; Trifirò, A.; Trimarchi, M.

2018-05-01

The present study has been carried out in order to investigate about the possibility of using EJ 299-33 scintillator in a multi-detector array to detect neutrons along with light charged particles. In a reaction induced by stable and exotic heavy-ions beams, where copious production of neutrons and other light charged particles occurs, discrimination with low identification threshold of these particles are of great importance. In view of this, EJ 299-33 scintillator having dimension of 3 cm × 3 cm × 3 cm backed by a photomultiplier tube was tested and used under vacuum to detect neutrons, gamma-rays and alpha particles emitted by radioactive sources. Anode pulses from the photomultiplier tube were digitized through GET electronics, recorded and stored in a data acquisition system for the purpose of an off-line analysis. The measurements, under vacuum and low background conditions, show good pulse shape discrimination properties characterized by low identification threshold for neutrons, gamma-rays and alpha particles. The Figures of Merit for neutron-gamma and alpha particles-gamma discriminations have been evaluated together with the energy resolution for gamma-ray and alpha particles.

Performance estimation of an oil-free linear compressor unit for a new compact 2K Gifford-McMahon cryocooler

Science.gov (United States)

Hiratsuka, Y.; Bao, Q.; Y Xu, M.

2017-12-01

Since 2012, a new, compact Gifford-McMahon (GM) cryocooler for cooling superconducting single photon detectors (SSPD) has been developed and reported by Sumitomo Heavy Industries, Ltd. (SHI). Also, it was reported that National Institute of Information and Communications Technology (NICT) developed a multi-channel, conduction-cooled SSPD system. However, the size and power consumption reduction becomes indispensable to apply such a system to the optical communication of AdHoc for a mobile system installed in a vehicle. The objective is to reduce the total height of the expander by 33% relative to the existing RDK-101 GM expander and to reduce the total volume of the compressor unit by 50% relative to the existing CNA-11 compressor. In addition, considering the targeted cooling application, we set the design cooling capacity targets of the first and the second stages 1 W at 60 K and 20 mW at 2.3 K respectively. In 2016, Hiratsuka et al. reported that an oil-free compressor was developed for a 2K GM cryocooler. The cooling performance of a 2K GM expander driven by an experimental unit of the linear compressor was measured. No-load temperature less than 2.1 K and the cooling capacity of 20 mW at 2.3 K were successfully achieved with an electric input power of only 1.1 kW. After that, the compressor capsule and the heat exchanger, etc. were assembled into one enclosure as a compressor unit. The total volume of the compressor unit and electrical box was significantly reduced to about 38 L, which was close to the target of 35 L. Also, the sound noise, vibration characteristics, the effect of the compressor unit inclination and the ambient temperature on the cooling performance, were evaluated. The detailed experimental results are discussed in this paper.

Innovation on high-power long-pulse gyrotrons

International Nuclear Information System (INIS)

Litvak, Alexander; Sakamoto, Keishi; Thumm, Manfred

2011-01-01

Progress in the worldwide development of high-power gyrotrons for magnetic confinement fusion plasma applications is described. After technology breakthroughs in research on gyrotron components in the 1990s, significant progress has been achieved in the last decade, in particular, in the field of long-pulse and continuous wave (CW) gyrotrons for a wide range of frequencies. At present, the development of 1 MW-class CW gyrotrons has been very successful; these are applicable for self-ignition experiments on fusion plasmas and their confinement in the tokamak ITER, for long-pulse confinement experiments in the stellarator Wendelstein 7-X (W7-X) and for EC H and CD in the future tokamak JT-60SA. For this progress in the field of high-power long-pulse gyrotrons, innovations such as the realization of high-efficiency stable oscillation in very high order cavity modes, the use of single-stage depressed collectors for energy recovery, highly efficient internal quasi-optical mode converters and synthetic diamond windows have essentially contributed. The total tube efficiencies are around 50% and the purity of the fundamental Gaussian output mode is 97% and higher. In addition, activities for advanced gyrotrons, e.g. a 2 MW gyrotron using a coaxial cavity, multi-frequency 1 MW gyrotrons and power modulation technology, have made progress.

Pressure tube reactor

International Nuclear Information System (INIS)

Susuki, Akira; Murata, Shigeto; Minato, Akihiko.

1993-01-01

In a pressure tube reactor, a reactor core is constituted by arranging more than two units of a minimum unit combination of a moderator sealing pipe containing a calandria tube having moderators there between and a calandria tube and moderators. The upper header and a lower header of the calandria tank containing moderators are communicated by way of the moderator sealing tube. Further, a gravitationally dropping mechanism is disposed for injecting neutron absorbing liquid to a calandria gas injection portion. A ratio between a moderator volume and a fuel volume is defined as a function of the inner diameter of the moderator sealing tube, the outer diameter of the calandria tube and the diameter of fuel pellets, and has no influence to intervals of a pressure tube lattice. The interval of the pressure tube lattice is enlarged without increasing the size of the pressure tube, to improve production efficiency of the reactor and set a coolant void coefficient more negative, thereby enabling to improve self controllability and safety. Further, the reactor scram can be conducted by injecting neutron absorbing liquid. (N.H.)

Numerical investigation of combustion phenomena in pulse detonation engine with different fuels

Science.gov (United States)

Alam, Noor; Sharma, K. K.; Pandey, K. M.

2018-05-01

The effects of different fuel-air mixture on the cyclic operation of pulse detonation engine (PDE) are numerically investigated. The present simulation is to be consider 1200 mm long straight tube combustor channel and 60 mm internal diameter, and filled with stoichiometric ethane-air and ethylene-air (C2H6-air & C2H4) fuel mixture at atmospheric pressure and temperature of 0.1 MPa and 300 K respectively. The obstacles of blockage ratio (BR) 0.5 and having 60 mm spacing among them are allocated inside the combustor tube. There are realizable k-ɛ turbulence model used to analyze characteristic of combustion flame. The objective of present simulation is to analyze the variation in combustion mechanism for two different fuels with one-step reduced chemical reaction model. The obstacles were creating perturbation inside the PDE tube. Therefore, flame surface area increases and reduces deflagration-to-detonation transition (DDT) run-up length.

Time-dependent flux from pulsed neutrons revealed by superconducting Nb current-biased kinetic inductance detector with "1"0B converter operated at 4 K

International Nuclear Information System (INIS)

Miyajima, Shigeyuki; Narukami, Yoshito; Shishido, Hiroaki; Yoshioka, Naohito; Ishida, Takekazu; Fujimaki, Akira; Hidaka, Mutsuo; Oikawa, Kenichi; Harada, Masahide; Oku, Takayuki; Arai, Masatoshi

2015-01-01

We have demonstrated a new superconducting detector for a neutron based on Nb superconductor meanderline with a "1"0B conversion layer. We use a current-biased kinetic inductance detector (CB-KID), which is composed of a meanderline, for detection of a neutron with high spatial resolution and fast response. The thickness of Nb meanderlines is 40 nm and widths are 3 μm, 1 μm, and 0.6 μm. The CB-KIDs are fabricated at the center of the Si chip of the size 22 mm × 22 mm and the total area of CB-KIDs covers 8 mm × 8 mm. The chip was cooled to a temperature lower than 4 K below the transition temperature of Nb using a Gifford-McMahon (GM) cryocooler. The Nb CB-KIDs with a "1"0B conversion layer output the voltage by irradiating pulsed neutrons at the material life science experimental facility (MLF) of Japan Proton Accelerator Research Complex (J-PARC) center. The response time of CB-KIDs is about a few tens ns. We have also obtained the time dependence of neutron flux generated from pulsed neutrons using a CB-KID. Experimental results were in good agreement with the simulated results. (author)

Vertical steam generator with slab-type tube-plate with even tube bundle washing

International Nuclear Information System (INIS)

Manek, O.; Masek, V.; Motejl, V.; Quitta, R.

1980-01-01

A shielding plate supporting the tubes attached to the tube plate of a vertical steam generator is mounted above the tube plate. Tube sleeves are designed with a dimensional tolerance relative to the heat transfer tubes and the sleeve end and the tube plate end. A separate space is thus formed above the tube plate in which circulation or feed water is introduced to flow between the branch and the heat transfer tube. This provides intensive washing of heat transfer tubes at a critical point and prevents deposit formation, thus excluding heat transfer tube failures. (J.B.)

Pulsed Nd-YAG laser welding of Prototype Fast Breeder Reactor fuel elements

International Nuclear Information System (INIS)

Suresh Varma, P.V.; Gupta, Amit; Amit, K.; Bhatt, R.B.; Afzal, Mohd.; Panakkal, J.P.; Kamath, H.S.

2009-02-01

End plug welding of Prototype Fast Breeder Reactor (PFBR) fuel elements involves welding of fully Austenitic Stainless Steel (ASS) of grade D9 clad tube with 316M end plug. Pulsed Gas Tungsten Arc Welding (GTAW) is being used for the production of PFBR fuel elements at Advanced Fuel Fabrication Facility (AFFF). GTAW is an established process for end plug welding and hence adopted by many countries. GTAW has got certain limitations like heat input, arc gap sensitivity and certain sporadic defects like tungsten inclusion. Experiments have been carried out at AFFF to use Laser Beam Welding (LBW) technique as LBW offers a number of advantages over the former process. This report mainly deals with the optimization of laser parameters for welding of PFBR fuel elements. To facilitate pulsed Nd-YAG laser spot welding, parameters like peak power, pulse duration, pulse energy, frequency and defocusing of laser beam on to the work piece have been optimized. On the basis of penetration requirement laser welding parameters have been optimized. (author)

Digital PIV Measurements of Acoustic Particle Displacements in a Normal Incidence Impedance Tube

Science.gov (United States)

Humphreys, William M., Jr.; Bartram, Scott M.; Parrott, Tony L.; Jones, Michael G.

1998-01-01

Acoustic particle displacements and velocities inside a normal incidence impedance tube have been successfully measured for a variety of pure tone sound fields using Digital Particle Image Velocimetry (DPIV). The DPIV system utilized two 600-mj Nd:YAG lasers to generate a double-pulsed light sheet synchronized with the sound field and used to illuminate a portion of the oscillatory flow inside the tube. A high resolution (1320 x 1035 pixel), 8-bit camera was used to capture double-exposed images of 2.7-micron hollow silicon dioxide tracer particles inside the tube. Classical spatial autocorrelation analysis techniques were used to ascertain the acoustic particle displacements and associated velocities for various sound field intensities and frequencies. The results show that particle displacements spanning a range of 1-60 microns can be measured for incident sound pressure levels of 100-130 dB and for frequencies spanning 500-1000 Hz. The ability to resolve 1 micron particle displacements at sound pressure levels in the 100 dB range allows the use of DPIV systems for measurement of sound fields at much lower sound pressure levels than had been previously possible. Representative impedance tube data as well as an uncertainty analysis for the measurements are presented.

Analysis of microwave amplifier and frequency multiplier tube with a multipactor electron gun

International Nuclear Information System (INIS)

Yokoo, Kuniyoshi; Ono, Shoichi; Tai, Dong-Zhe.

1983-01-01

The performance analysis was made for a multipactor microwave tube with the aim of realizing a microwave amplifier or a frequency multiplier tube with a multipactor cathode with high efficiency and high power. The possibility for producing the multipactor tube with high efficiency and high power was shown by using effectively the characteristics of the multipactor cathode which emits pulsed electron current with narrow band, synchronizing with high frequency period. As the operating conditions for the multipactor cathode, it was shown that the wide spacing of the cathode was needed for the operation in high operating power, and the narrow spacing was needed for the operation in high efficiency and for reducing power consumption. It was also shown that there were the best values of the high-frequency voltage for the cathode operation. The study by the simulation for the multipactor cathode and for the acceleration zone of electron current was also performed to examine the possible performance for a microwave amplifier and a frequency multiplier tube. For the use of the multipactor cathode with a spacing of 1 mm, the conversion efficiency for d. c. input power was 86, 56 and 31 % for the primary, the secondary and the tertiary harmonic wave amplifications, respectively. (Asami, T.)

Use of CATHENA to model calandria-tube/moderator heat transfer after pressure-tube/calandria-tube ballooning contact

International Nuclear Information System (INIS)

Fan, H.Z.; Bilanovic, Z.; Nitheanandan, T.

2004-01-01

A study was performed to assess the effect of the calandria-tube/moderator heat transfer after pressure-tube/calandria tube ballooning contact using CATHENA. Results of this study indicated that the analytical tool, CATHENA, can be applied for pool boiling heat transfer on the external surface of a large diameter tube, such as the calandria tube used in CANDU reactors. The methodology in such CANDU-generic study can be used to simulate the tube surface with multiple boiling regimes and to assess the benefits of closely coupling thermalhydraulics modelling and fuel/fuel channel behaviour modelling. CATHENA (Canadian Algorithm for THErmalhydraulic Network Analysis) is a one-dimensional, two-fluid thermalhydraulic simulation code designed by AECL to analyse two-phase flow and heat transfer in piping networks. The detailed heat transfer package in CATHENA allows a connection to be established from the multiple solid surfaces of tubes to the surrounding large amount of moderator water, which acts as a heat sink during a postulated loss of coolant event. The generalized heat transfer package within CATHENA allows the tube walls to be divided into several layers in the radial direction and several sectors in the circumferential direction, to account for heat transfer conditions in these two directions. The CATHENA code with the generalized heat transfer package is capable of capturing key pool-boiling phenomena such as nucleate, transition and film boiling heat transfer as well as an ability to model the rewet phenomenon to some extent. A CATHENA input model was generated and used in simulations of selected contact boiling experiment test cases. The transient wall temperatures have been calculated in different portions of the calandria tube. By using this model an adequate agreement was achieved between CATHENA calculation and experimental measurement The CATHENA code enables one to investigate the transient and local thermal-mechanical behaviour of the calandria tube

PULSE COMBUSTOR DESIGN QUALIFICATION TEST AND CLEAN COAL FEEDSTOCK TEST - VOLUME I AND VOLUME II; FINAL

International Nuclear Information System (INIS)

Unknown

2002-01-01

For this Cooperative Agreement, the pulse heater module is the technology envelope for an indirectly heated steam reformer. The field of use of the steam reformer pursuant to this Cooperative Agreement with DOE is for the processing of sub-bituminous coals and lignite. The main focus is the mild gasification of such coals for the generation of both fuel gas and char-for the steel industry is the main focus. An alternate market application for the substitution of metallurgical coke is also presented. This project was devoted to qualification of a 253-tube pulse heater module. This module was designed, fabricated, installed, instrumented and tested in a fluidized bed test facility. Several test campaigns were conducted. This larger heater is a 3.5 times scale-up of the previous pulse heaters that had 72 tubes each. The smaller heater has been part of previous pilot field testing of the steam reformer at New Bern, North Carolina. The project also included collection and reduction of mild gasification process data from operation of the process development unit (PDU). The operation of the PDU was aimed at conditions required to produce char (and gas) for the Northshore Steel Operations. Northshore Steel supplied the coal for the process unit tests

Pulsed klystrons with feedback controlled mod-anode modulators

Energy Technology Data Exchange (ETDEWEB)

Reass, William A [Los Alamos National Laboratory; Baca, David M [Los Alamos National Laboratory; Jerry, Davis L [Los Alamos National Laboratory; Rees, Daniel E [Los Alamos National Laboratory

2009-01-01

This paper describes a fast rise and fall, totem-pole mod-anode modulators for klystron application. Details of these systems as recently installed utilizing a beam switch tube ''on-deck'' and a planar triode ''off-deck'' in a grid-catch feedback regulated configuration will be provided. The grid-catch configuration regulates the klystron mod-anode voltage at a specified set-point during switching as well as providing a control mechanism that flat-top regulates the klystron beam current during the pulse. This flat-topped klystron beam current is maintained while the capacitor bank droops. In addition, we will review more modern on-deck designs using a high gain, high voltage planar triode as a regulating and switching element. These designs are being developed, tested, and implemented for the Los Alamos Neutron Science Center (LANSCE) accelerator refurbishment project, ''LANSCE-R''. An advantage of the planar triode is that the tube can be directly operated with solid state linear components and provides for a very compact design. The tubes are inexpensive compared to stacked semiconductor switching assemblies and also provide a linear control capability. Details of these designs are provided as well as operational and developmental results.

Development of 700 pps high-duty-cycle line-type pulse modulator

Energy Technology Data Exchange (ETDEWEB)

Baba, H.; Satoh, K.; Miura, A. [NIHON KOSHUHA Co., LTD., Yokohama, Kanagawa (Japan)] [and others

1997-04-01

The high-duty-cycle line-type pulse modulator has been developed to drive the 5.5 MW S-band klystron at the 700 pps maximum repetition-rate and the 14 {mu}sec flat-top pulse-width. To keep an enough recovery time to the thyratron-tube, the command charging scheme was adopted. To do this, a charging SCR-bank has been developed, which is capable of handling the peak charging current of 50 A. The system achieved the world wide highest average output-power of 205 kW. Two modulators have been installed in a new high-duty-cycle electron linear accelerator, which has been started its business operation in March 1996 as an electron-beam-sterilization facility. (J.P.N)

Improvement of pump tubes for gas guns and shock tube drivers

Science.gov (United States)

Bogdanoff, D. W.

1990-01-01

In a pump tube, a gas is mechanically compressed, producing very high pressures and sound speeds. The intensely heated gas produced in such a tube can be used to drive light gas guns and shock tubes. Three concepts are presented that have the potential to allow substantial reductions in the size and mass of the pump tube to be achieved. The first concept involves the use of one or more diaphragms in the pump tube, thus replacing a single compression process by multiple, successive compressions. The second concept involves a radical reduction in the length-to-diameter ratio of the pump tube and the pump tube piston. The third concept involves shock heating of the working gas by high explosives in a cyclindrical geometry reusable device. Preliminary design analyses are performed on all three concepts and they appear to be quite feasible. Reductions in the length and mass of the pump tube by factors up to about 11 and about 7, respectively, are predicted, relative to a benchmark conventional pump tube.

Computer analysis of an adiabatic Stirling cryocooler using a two-phase two-component working fluid

International Nuclear Information System (INIS)

Renfroe, D.A.; Cheung, C.M.

1992-01-01

This paper describes the performance and behavior of a Stirling cyrocooler incorporating a working fluid composed of helium and nitrogen. At the operating temperature of the cryocooler (80 K), the nitrogen component will condense in the freezer section. It is shown that the phase change in the working fluid increased the heat lifted for a given size and weight of machine and the coefficient of performance. The magnitude of these effects was dependent on the mass ratio of nitrogen to helium, phase angle between the compression and expansion processes, and the ratio of the compression space volume to the expansion space volume. The optimum heat lifted performance was obtained for a mass ratio of four parts of nitrogen to one part of helium, a phase angle of approximately 100 degrees, and a volume ratio of two which resulted in a heat lifted increase of 75% over the single phase, 90 degree phase angle configuration. The coefficient of performance showed a 20% improvement

In Vitro Comparison of Holmium Lasers: Evidence for Shorter Fragmentation Time and Decreased Retropulsion Using a Modern Variable-pulse Laser.

Science.gov (United States)

Bell, John Roger; Penniston, Kristina L; Nakada, Stephen Y

2017-09-01

To compare the performance of variable- and fixed-pulse lasers on stone phantoms in vitro. Seven-millimeter stone phantoms were made to simulate calcium oxalate monohydrate stones using BegoStone plus. The in vitro setting was created with a clear polyvinyl chloride tube. For each trial, a stone phantom was placed at the open end of the tubing. The Cook Rhapsody H-30 variable-pulse laser was tested on both long- and short-pulse settings and was compared to the Dornier H-20 fixed-pulse laser; 5 trials were conducted for each trial arm. Fragmentation was accomplished with the use of a flexible ureteroscope and a 273-micron holmium laser fiber using settings of 1 J × 12 Hz. The treatment time (in minute) for complete fragmentation was recorded as was the total retropulsion distance (in centimeter) during treatment. Laser fibers were standardized for all repetitions. The treatment time was significantly shorter with the H-30 vs the H-20 laser (14.3 ± 2.5 vs 33.1 ± 8.9 minutes, P = .008). There was no difference between the treatment times using the long vs short pulse widths of the H-30 laser (14.4 ± 3.4 vs 14.3 ± 1.7 minutes, P = .93). Retropulsion differed by laser type and pulse width, H-30 long pulse (15.8 ± 5.7 cm), H-30 short pulse (54.8 ± 7.1 cm), and H-20 (33.2 ± 12.5 cm) (P laser fragmented stone phantoms in half the time of the H-20 laser regardless of the pulse width. Retropulsion effects differed between the lasers, with the H-30 causing the least retropulsion. Longer pulse widths result in less stone retropulsion. Copyright © 2017 Elsevier Inc. All rights reserved.

The development of long pulse high voltage power supply for MNI-1U neutral beam injector

International Nuclear Information System (INIS)

Detai Wang

1989-01-01

A high power long pulse high voltage power supply (HVPS) for MNI- 1 U neutral beam injector (NBI) is described. This HVPS is used as a switching regulator with a duty cycle of 1/100, the specifications of circuit are as follows, output pulse voltage 50kv, pulse current 30A, pulse width 50ms, rise-time and fall-time of the voltage are less than 25 μs, stability of the pulse flat is better than 0.5%, regulation response time of the pulse voltage less than 30 μs can be attained. It is also used as a stable DC HVPS, output voltage is 1 to 100kv, current is 1 to 5A. If regulation tube is shunted with high power resistor in parallel, the current can be extended to 10 A, stability of the output voltage or current is better than 0.1%. Now, the HVPS has been put into operation for MNI- 1 U NBI and PIG ion source made in French. 3 refs., 5 figs

Vibro-impact responses of a tube with tube--baffle interaction. [LMFBR

Energy Technology Data Exchange (ETDEWEB)

Shin, Y S; Sass, D E; Jendrzejczyk, J A

1978-01-01

The relatively small, inherent tube-to-baffle hole clearances associated with manufacturing tolerances in heat exchangers affect the vibrational characteristics and the response of the tube. Numerical studies were made to predict the vibro-impact response of a tube with tube-baffle interaction. The finite element method has been employed with a non-linear elastic contact spring-dashpot to model the effect of the relative approach between the tube and the baffle plate. The coupled equations of motion are directly integrated with a proportional system damping represented by a linear combination of mass and stiffness. Lumped mass approach with explicit time integration scheme was found to be a suitable choice for tube-baffle impacting analysis. Fourier analyses indicate that the higher mode contributions to the tube response are significant for strong tube-baffle impacting. The contact damping forces are negligible compared with the contact spring forces. The numerical analysis results are in reasonably good agreement with those of the experiments.

Experimental study of single taylor bubbles rising in stagnant liquid mixtures inside of vertical tubes

International Nuclear Information System (INIS)

Azevedo, Marcos B. de; Faccini, Jose L.H.; Su, Jian

2015-01-01

The present work reports an experimental study of single Taylor bubbles rising in vertical tubes filled with water-glycerin mixtures by using the pulse-echo ultrasonic technique. A 2m long acrylic tube with inner diameter of 24 mm was used in the experiments. Initially, the tube was sealed at the ends and filled partially with the liquid mixtures to leave an air pocket of length L 0 at the top end. A Taylor bubble was formed by the inversion of the tube. The rising bubbles were detected by ultrasonic transducers located at the upper part of the tube. The velocity, the length and the pro le of the bubbles and the thickness of the liquid lm around them were obtained from the ultrasonic signals processing. The liquid lm thickness in the vertical tube was also determined by a graphic method that relates the bubble length L b with the initial length of the air pocket L 0 . It was observed that the bubble velocity decreased with increasing viscosity, while the lm thickness increased. It was shown that the liquid lm thickness determined by the graphic method fitted well the higher viscosities data, but overestimated the lower viscosities data. Additionally, the results indicated that some correlations developed to estimate the thickness of liquid films falling down inside/outside of tubes and down a plane surface could be applied to estimate the thickness of liquid films falling around Taylor bubbles in an Inverse Viscosity Number (N f ) range different to those considered in the literature. (author)

Bender/Coiler for Tubing

Science.gov (United States)

Stoltzfus, J. M.

1983-01-01

Easy-to-use tool makes coils of tubing. Tubing to be bend clamped with stop post. Die positioned snugly against tubing. Operator turns handle to slide die along tubing, pushing tubing into spiral groove on mandrel.

Air pulse deformation measurement: a preliminary method for noninvasive vocal fold pliability analysis.

Science.gov (United States)

Larsson, Hans; Lindestad, P Å; Hertegård, S

2011-01-01

A new method, air pulse pliability measurement, is presented, with which the pliability and elasticity of the vocal folds was measured in vitro and in vivo using air pulses. The size of the mucosal movements induced by air pulse stimulation was measured with a laser-based technique. The air pulses fed via a 2-mm tubing, introduced through the working channel of a flexible endoscope. Both in vitro and in vivo tests were performed. Nine normal, vocally healthy subjects were examined by air pulse stimulations of the vocal folds, of the skin (cheek and dorsum of the hand) and of the inside of the lips. The in vitro tests showed a coefficient of variation of 5% within a range of 1-5 mm from the probe to the surface. The elasticity data showed no differences between vocal folds, lips or cheek. The hand data showed a significantly higher stiffness as compared to the other 3 measuring points (p measuring points, but in ideal conditions on skin it was 9%. The results show that the technique allows automatic, quantitative, noninvasive vocal fold pliability measurements on awake subjects. Copyright © 2010 S. Karger AG, Basel.

Long pulse, plasma cathode E-gun

International Nuclear Information System (INIS)

Goebel, D.M.; Schumacher, R.W.; Watkins, R.M.

1993-01-01

A unique, long-pulse E-gun has been developed for high-power tube applications. The Hollow-Cathode-Plasma (HCP) E-gun overcomes the limitations of conventional thermionic-cathode guns that have limited current density (typically ≤ 10 A/cm 2 ) or field-emission guns that offer high current density but suffer from short pulsewidth capability (typically 50 A/cm 2 ), long-pulse operation without gap closure, and also requires no cathode-heater power. The gun employs a low-pressure glow discharge inside a hollow cathode (HC) structure to provide a stable, uniform plasma surface from which a high current-density electron beam can be extracted. The plasma density is controlled by a low-voltage HC discharge pulser to produce the desired electron current density at the first grid of a multi-grid accelerator system. A dc high-voltage electron-beam supply accelerates the electrons across the gap, while the HC pulser modulates the beam current to generate arbitrary pulse waveforms. The electron accelerator utilizes a multi-aperture array that produces a large area, high perveance (>35 μpervs) beam consisting initially of many individual beamlets. The E-beam is normally operated without an applied magnetic field in the ion-focused regime, where the plasma produced by beam ionization of a background gas space-charge neutralizes the beam, and the Bennett self-pinch compresses the beamlets and increases the current density. The self-pinched beam has been observed to propagate over a meter without beam breakup or instabilities. The HCP E-gun has been operated at voltages up to 150 kV, currents up to 750 A, and pulse lengths of up to 120 μsec

Steam generator tube extraction

International Nuclear Information System (INIS)

Delorme, H.

1985-05-01

To enable tube examination on steam generators in service, Framatome has now developed a process for removing sections of steam generator tubes. Tube sections can be removed without being damaged for treating the tube section expanded in the tube sheet

Automated Cryocooler Monitor and Control System

Science.gov (United States)

Britcliffe, Michael J.; Hanscon, Theodore R.; Fowler, Larry E.

2011-01-01

A system was designed to automate cryogenically cooled low-noise amplifier systems used in the NASA Deep Space Network. It automates the entire operation of the system including cool-down, warm-up, and performance monitoring. The system is based on a single-board computer with custom software and hardware to monitor and control the cryogenic operation of the system. The system provides local display and control, and can be operated remotely via a Web interface. The system controller is based on a commercial single-board computer with onboard data acquisition capability. The commercial hardware includes a microprocessor, an LCD (liquid crystal display), seven LED (light emitting diode) displays, a seven-key keypad, an Ethernet interface, 40 digital I/O (input/output) ports, 11 A/D (analog to digital) inputs, four D/A (digital to analog) outputs, and an external relay board to control the high-current devices. The temperature sensors used are commercial silicon diode devices that provide a non-linear voltage output proportional to temperature. The devices are excited with a 10-microamp bias current. The system is capable of monitoring and displaying three temperatures. The vacuum sensors are commercial thermistor devices. The output of the sensors is a non-linear voltage proportional to vacuum pressure in the 1-Torr to 1-millitorr range. Two sensors are used. One measures the vacuum pressure in the cryocooler and the other the pressure at the input to the vacuum pump. The helium pressure sensor is a commercial device that provides a linear voltage output from 1 to 5 volts, corresponding to a gas pressure from 0 to 3.5 MPa (approx. = 500 psig). Control of the vacuum process is accomplished with a commercial electrically operated solenoid valve. A commercial motor starter is used to control the input power of the compressor. The warm-up heaters are commercial power resistors sized to provide the appropriate power for the thermal mass of the particular system, and

Water-cooled U-tube grids for continuously operated neutral-beam injectors

International Nuclear Information System (INIS)

Hoffman, M.A.; Duffy, T.J.

1979-01-01

A design for water-cooled extractor grids for long-pulse and continuously operated ion sources for neutral-beam injectors is described. The most serious design problem encountered is that of minimizing the thermal deformation (bowing) of these slender grid rails, which have typical overall spans of 150 mm and diameters on the order of 1 mm. A unique U-tube design is proposed that offers the possibility of keeping the thermal bowing down to about 0.05 mm (about 2.0 mils). However, the design requires high-velocity cooling water at a Reynolds number of about 3 x 10 4 and an inlet pressure on the order of 4.67 x 10 6 Pa (677 psia) in order to keep the axial and circumferential temperature differences small enough to achieve the desired small thermal bowing. It appears possible to fabricate and assemble these U-tube grids out of molybdenum with high precision and with a reasonably small number of brazes

Propagating Structure Of A Microwave Driven Shock wave Inside A Tube

International Nuclear Information System (INIS)

Shimada, Yutaka; Shibata, Teppei; Yamaguchi, Toshikazu; Komurasaki, Kimiya; Oda, Yasuhisa; Kajiwara, Ken; Takahashi, Koji; Kasugai, Atsushi; Sakamoto, Keishi; Arakawa, Yoshihiro

2010-01-01

The thrust generation process of a microwave rocket is similar to a pulse detonation engine, and understanding the interactions between microwave plasma and shock waves is important. Shadowgraph images of the microwave plasma generated in a tube under atmospheric air were taken. The observed plasma and shock wave were propagating one-dimensionally at constant velocity inside the tube. In order to understand the flow field inside the rocket, one-dimensional CFD analysis was conducted. With the change of microwave power density, the structure of the flow field was classified into two regimes: Microwave Supported Combustion (MSC), and Microwave Supported Detonation (MSD). The structure of the MSD was different from the structure of a chemical detonation, which implied the existence of a preheating in front of the shock wave. Furthermore, the flight performance was estimated by calculating the momentum coupling coefficient. It was confirmed that the efficiency was nearly constant in the MSD regime, with the increase of microwave power density.

Development of high-current pulsed heavy-ion-beam technology for applications to materials processing

Energy Technology Data Exchange (ETDEWEB)

Ito, Hiroaki; Ochiai, Yasushi; Masugata, Katsumi [University of Toyama, Toyama (Japan)

2011-12-15

Development of intense pulsed heavy ion beam technology for applications to materials processing is described. We have developed a magnetically insulated ion diode for the generation of intense pulsed metallic ion beams in which a vacuum arc plasma gun is used as the ion source. When the ion diode was successfully operated at a diode voltage of 220 kV and a diode current of 10 kA, an ion beam with an ion current density of >200 A/cm{sup 2} and a pulse duration of 40 ns was obtained. The ion composition was evaluated by using a Thomson parabola spectrometer, and the ion beam consisted of aluminum ions (Al{sup (1-3)+}) with an energy of 140 - 740 keV and protons with an energy of 160 - 190 keV; the purity was estimated to be 89%, which was much higher than that of the pulsed ion beam produced in a conventional ion diode. The development of a bipolar pulse accelerator (BPA) was reported in order to improve the purity of intense pulsed ion beams. A double coaxial type bipolar pulse generator was developed as the power supply of the BPA. When a bipolar pulse with a voltage of {+-}90 kV and a pulse duration of about 65 ns was applied to the drift tube of the BPA, the ion beam with an ion current density of 2 A/cm{sup 2} and a pulse duration of 30 ns was observed 25 mm downstream from the cathode surface, which suggested bipolar pulse acceleration.

Pulsed TIG welding in the fabrication of nuclear components and structures

International Nuclear Information System (INIS)

Lucas, W.; Males, B.O.

1979-01-01

TIG welding is an important welding technique in nuclear plant fabrication for the welding of critical components and structures where a high level of weld integrity is demanded. Whilst the process is ideally suited to precision welding, since the arc is a small intense heat source, it has proved to be somewhat intolerant to production variations in 'difficult' applications, such as tube to tube plate welding and orbital tube welding with tube in the fixed position. Whilst the problems directly associated with this intolerance (of the welding process) are less frequently observed when used manually, difficulties are experienced in fully mechanised welding operations particularly when welding to a relatively rigid approved procedure. Pulsing of the welding current was developed as a technique to achieve greater control of the behaviour of the weld pool. Instead of moving the weld pool in a continuous motion around the joint, welding was conducted intermittently in the form of overlapping spots. This technique, which offers significant advantages over continuous current welding has been exploited in nuclear fabrication for welding those components which demand a high level of weld quality. In this paper, the essential features of this technique are described and, in indicating its advantages, examples have been drawn from recent experiences on the welding of two types of joint for the Advanced Gas Cooled Reactor, a tube sheet and a butt joint in the G Position. (author)

Design and development of micro pulse lidar for cloud and aerosol studies

Science.gov (United States)

Dubey, P. K.; Arya, B. C.; Ahammed, Y. Nazeer; Kumar, Arun; Kulkarni, P. S.; Jain, S. L.

2008-12-01

A micro pulse lidar (MPL) has been indigenously designed and developed at the National Physical Laboratory, New Delhi using a 532 nm, 500 pico second pulsed laser having average power of 50mW (at 7.5 KHz PRR). Photon counting technique has been incorporated using the conventional optics, multichannel scaler (Stanford Research Systems SR430) and high sensitive photomultiplier tube. The sensitivity, range and bin etc are computer controlled in the present system. The interfacing between MPL and computer has been achieved by serial (RS232) and parallel printer port. The necessary software and graphical user interface has been developed using visual basic. In addition to this the telescope cover status sensing circuit has been incorporated to avoid conflict between dark count and background acquisition. The micro pulse lidar will be used for the aerosol, boundary layer and the cloud studies at a bin resolution of 6 meters. In the present communication the details of the system and preliminary results will be presented.

Review of the hybrid photo diode tube (HPD) an advanced light detector for physics

International Nuclear Information System (INIS)

Anzivino, G.; Baillon, P.; Benetti, P.; Boskma, L.; Burger, P.; Contin, A.; DeSalvo, R.; Gorodetzky, P.; Grassi, D.; Hao, W.; He, H.; Liu, L.; Lundin, M.; Mondardini, M.R.; Paolucci, S.; Rossella, M.; Santiard, J.C.; Schomaker, R.; You, K.; Wang, K.; Wang, Y.; Xia, X.; Xu, C.; Yang, C.; Zhao, M.

1995-01-01

The HPD is a nonmultiplicative light detector with typical gain of 1000 to 5000. Its development project, mainly supported by the CERN LAA project and by the INFN group V, was originally intended to find a replacement for the photo multiplier (PM) tubes for scintillating fibre calorimeter readout. After five years of development the HPD has become a versatile light detector, commercially available for everyday use, that can outperform PM tubes in photon counting efficiency and resolution, multi tesla magnetic field operation, uniformity of response, fast pulse dynamic range, and gain stability. The HPD has also a wide edge on PMs on pixelization potential and it is getting more and more competitive on timing properties. A review of the HPD performances and its latest advances are reported. (orig.)

Review of the hybrid photo diode tube (HPD) an advanced light detector for physics

Energy Technology Data Exchange (ETDEWEB)

Anzivino, G. [Istituto Nazionale di Fisica Nucleare, Frascati (Italy). Lab. Nazionale di Frascati; Arnaudon, H. [Universite` L. Pasteur, 4, rue B. Pascal, F-67000 Strasbourg (France); Baillon, P. [CERN, CH-1211 Geneva 23 (Switzerland); Benetti, P. [INFN Sezione di Pavia and Universita` di Pavia, via A. Bassi 6, I-27100 Pavia (Italy); Boskma, L. [DEP, P.O. box 60, NL-9300 AB Roden (Netherlands); Burger, P. [Canberra, Lammerdries 25, B-2250 Olen (Belgium); Contin, A. [CERN, CH-1211 Geneva 23 (Switzerland)]|[INFN Sezione di Bologna and Universita` di Bologna, via Irnerio 46, I-40126 Bologna (Italy); DeSalvo, R. [CERN, CH-1211 Geneva 23 (Switzerland); Gorodetzky, P. [CNRS, Strasbourg (France); Grassi, D. [INFN Sezione di Pavia and Universita` di Pavia, via A. Bassi 6, I-27100 Pavia (Italy); Hao, W. [IHEP, Beijing (China); He, H. [IHEP, Beijing (China); Liu, L. [IHEP, Beijing (China); Lundin, M. [Cornell University, Ithaca, NY 14853 (United States); Mondardini, M.R. [Cornell University, Ithaca, NY 14853 (United States); Paolucci, S. [INFN Sezione di Pavia and Universita` di Pavia, via A. Bassi 6, I-27100 Pavia (Italy); Rossella, M. [INFN Sezione di Pavia and Universita` di Pavia, via A. Bassi 6, I-27100 Pavia (Italy); Santiard, J.C. [CERN, CH-1211 Geneva 23 (Switzerland); Schomaker, R. [DEP, P.O. box 60, NL-9300 AB Roden (Netherlands); You, K. [IHEP, Beijing (China); Wang, K. [IHEP, Beijing (China); Wang, Y. [IHEP, Beijing (China); Xia, X. [IHEP, Beijing (China); Xu, C. [IHEP, Beijing (China); Yang, C. [IHEP, Beijing (China); Zhao, M. [IHEP, Beijing (China)

1995-11-01

The HPD is a nonmultiplicative light detector with typical gain of 1000 to 5000. Its development project, mainly supported by the CERN LAA project and by the INFN group V, was originally intended to find a replacement for the photo multiplier (PM) tubes for scintillating fibre calorimeter readout. After five years of development the HPD has become a versatile light detector, commercially available for everyday use, that can outperform PM tubes in photon counting efficiency and resolution, multi tesla magnetic field operation, uniformity of response, fast pulse dynamic range, and gain stability. The HPD has also a wide edge on PMs on pixelization potential and it is getting more and more competitive on timing properties. A review of the HPD performances and its latest advances are reported. (orig.).

Feeding tube - infants

Science.gov (United States)

... this page: //medlineplus.gov/ency/article/007235.htm Feeding tube - infants To use the sharing features on this page, please enable JavaScript. A feeding tube is a small, soft, plastic tube placed ...

Analogue saturation limit of single and double 10 mm microchannel plate photomultiplier tubes

Energy Technology Data Exchange (ETDEWEB)

Milnes, J. S., E-mail: james.milnes@photek.co.uk; Conneely, T. M. [Photek Ltd., 26 Castleham Road, St Leonards on Sea, East Sussex TN38 9NS (United Kingdom); Horsfield, C. J. [AWE Aldermaston, Reading, Berkshire RG7 4PR (United Kingdom)

2016-11-15

Photek are a well-established supplier of microchannel plate (MCP) photomultiplier tubes (PMTs) to the inertial confinement fusion community. The analogue signals produced at the major inertial confinement fusion facilities cover many orders of magnitude, therefore understanding the upper saturation limit of MCP-PMTs to large low rate signals takes on a high importance. Here we present a study of a single and a double MCP-PMT with 10 mm diameter active area. The saturation was studied for a range of optical pulse widths from 4 ns to 100 ns and at a range of electron gain values: 10{sup 3} to 10{sup 4} for the single and 10{sup 4} to 10{sup 6} for the double. We have shown that the saturation level of ∼1.2 nC depends only on the integrated charge of the pulse and is independent of pulse width and gain over this range, but that the level of charge available in deep saturation is proportional to the operating gain.

Pulse height non-linearity in LaBr3:Ce crystal for gamma ray spectrometry and imaging

International Nuclear Information System (INIS)

Pani, R.; Cinti, M.N.; Pellegrini, R.; Bennati, P.; Ridolfi, S.; Scafe, R.; Orsolini Cencelli, V.; De Notaristefani, F.; Fabbri, A.; Navarria, F.L.; Lanconelli, N.; Moschini, G.; Boccaccio, P.

2011-01-01

In this paper the response in term of pulse height linearity of two Hamamatsu photomultipliers is investigated, when coupled to a LaBr 3 :Ce scintillation crystal. The two photodetectors have high quantum efficiency and in particular 30% for R6231-01 and 42% for R7600-200 tube. The substantial difference is in the dynode structure, linear focused and metal channel for R6231 and R7600 respectively. In this work in order to verify the non-linearity effects on the pulse height distribution, due principally to the high and fast light production of LaBr 3 :Ce scintillator, we propose a 'peak by peak' procedure to calibrate the pulse height distribution. Utilizing a specific fragmentation of the calibration curve in subsets, the calculated energy values are very similar for both PMTs. This result confirmed the potentiality of the procedure to highlight the non-linearity effects on pulse height distribution.

Kinetics of the Thermal Decomposition of Tetramethylsilane behind the Reflected Shock Waves in a Single Pulse Shock Tube (SPST) and Modeling Study

Science.gov (United States)

Parandaman, A.; Sudhakar, G.; Rajakumar, B.

Thermal reactions of Tetramethylsilane (TMS) diluted in argon were studied behind the reflected shock waves in a single-pulse shock tube (SPST) over the temperature range of 1085-1221 K and pressures varied between 10.6 and 22.8 atm. The stable products resulting from the decomposition of TMS were identified and quantified using gas chromatography and also verified with Fourier Transform Infrared (FTIR) spectrometer. The major reaction products are methane (CH4) and ethylene (C2H4). The minor reaction products are ethane (C2H6) and propylene (C3H6). The initiation of mechanism in the decomposition of TMS takes plays via the Si-C bond scission by ejecting the methyl radicals (CH3) and trimethylsilyl radicals ((CH3)3Si). The measured temperature dependent rate coefficient for the total decomposition of TMS was to be ktotal = 1.66 ×1015 exp (-64.46/RT) s-1 and for the formation of CH4 reaction channel was to be k = 2.20 × 1014 exp (-60.15/RT) s-1, where the activation energies are given in kcal mol-1. A kinetic scheme containing 17 species and 28 elementary reactions was used for the simulation using chemical kinetic simulator over the temperature range of 1085-1221 K. The agreement between the experimental and simulated results was satisfactory.

Eustachian tube patency

Science.gov (United States)

Eustachian tube patency refers to how much the eustachian tube is open. The eustachian tube runs between the middle ear and the throat. It controls the pressure behind the eardrum and middle ear space. This helps keep ...

Effect of tube-support interaction on the dynamic responses of heat exchanger tubes

International Nuclear Information System (INIS)

Shin, Y.S.; Jendrzejczyk, J.A.; Wambsganss, M.W.

1977-01-01

Operating heat exchangers have experienced tube damages due to excessive flow-induced vibration. The relatively small inherent tube-to-baffle hole clearances associated with manufacturing tolerances in heat exchangers affect the tube vibrational characteristics. In attempting a theoretical analysis, questions arise as to the effects of tube-baffle impacting on dynamic responses. Experiments were performed to determine the effects of tube-baffle impacting in vertical/horizontal tube orientation, and in air/water medium on the vibrational characteristics (resonant frequencies, mode shapes, and damping) and displacement response amplitudes of a seven-span tube model. The tube and support conditions were prototypic, and overall length approximately one-third that of a straight tube segment of the steam generator designed for the CRBR. The test results were compared with the analytical results based on the multispan beam with ''knife-edge'' supports