Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Helium cooling”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRS2012

James Webb Space Telescope Integrated Science Instrument Module Calibration and Verification of High-Accuracy Instrumentation to Measure Heat Flow in Cryogenic Testing

The James Webb Space Telescope (JWST) is an upcoming flagship observatory mission scheduled to be launched in 2018, Three of the four science instruments are passively cooled to their operational temperature range of 36K to 40K, and the fourth instrument is actively cooled to its operational temperature of approximately 6K. The requirement for multiple thermal zones results in the instruments being thermally connected to five external radiators via individual high purity aluminum heat straps. Thermal-vacuum and thermal balance testing of the flight instruments at the Integrated Science Instrument Module (ISIM) element level will take place within a newly constructed shroud cooled by gaseous helium inside Goddard Space Flight Center's (GSFC) Space Environment Simulator (SES). The flight external radiators are not available during ISIM-Ievel thermal vacuum/thermal testing, so they will be replaced in test with stable and adjustable thermal boundaries with identical physical interfaces to the flight radiators. Those boundaries are provided on specially designed test hardware which measures the heat flow within each of the five heat straps to an accuracy of less than 2 m W, which is less than 5% of the minimum predicted heat flow values. This is essential to ISIM thermal model correlation, since thermal models are more accurately correlated when temperature data is supplemented by accurate knowledge of heat flows. Devices that measure heat flow in this manner have historically been referred to as "Q-meters". Perhaps the most important feature of the design of the Q-meters is that it does not depend on the absolute accuracy of its temperature sensors, but rather on a difference in heater power, for which a table is empirically developed during a calibration campaign in a small chamber at GSFC. This paper discusses the Q-meter calibration procedure including calibration chamber modifications and accommodations, the handling of differing conditions between calibration and usage, the calibration process itself, and the results of the tests used to determine if the calibration is successful.

Comber, Brian↗
NASA NTRS2012

James Webb Space Telescope Integrated Science Instrument Module Calibration and Verification of High-Accuracy Instrumentation to Measure Heat Flow in Cryogenic Testing

The James Webb Space Telescope (JWST) is an upcoming flagship observatory mission scheduled to be launched in 2018. Three of the four science instruments are passively cooled to their operational temperature range of 36K to 40K, and the fourth instrument is actively cooled to its operational temperature of approximately 6K. The requirement for multiple thermal zoned results in the instruments being thermally connected to five external radiators via individual high purity aluminum heat straps. Thermal-vacuum and thermal balance testing of the flight instruments at the Integrated Science Instrument Module (ISIM) element level will take place within a newly constructed shroud cooled by gaseous helium inside Goddard Space Flight Center's (GSFC) Space environment Simulator (SES). The flight external radiators are not available during ISIM-level thermal vacuum/thermal testing, so they will be replaced in test with stable and adjustable thermal boundaries with identical physical interfaces to the flight radiators. Those boundaries are provided by specially designed test hardware which also measures the heat flow within each of the five heat straps to an accuracy of less than 2 mW, which is less than 5% of the minimum predicted heat flow values. Measurement of the heat loads to this accuracy is essential to ISIM thermal model correlation, since thermal models are more accurately correlated when temperature data is supplemented by accurate knowledge of heat flows. It also provides direct verification by test of several high-level thermal requirements. Devices that measure heat flow in this manner have historically been referred to a "Q-meters". Perhaps the most important feature of the design of the JWST Q-meters is that it does not depend on the absolute accuracy of its temperature sensors, but rather on knowledge of precise heater power required to maintain a constant temperature difference between sensors on two stages, for which a table is empirically developed during a calibration campaign in a small chamber at GSFC. This paper provides a brief review of Q-meter design, and discusses the Q-meter calibration procedure including calibration chamber modifications and accommodations, handling of differing conditions between calibration and usage, the calibration process itself, and the results of the tests used to determine if the calibration is successful.

Comber, Brian↗
NASA NTRS1982

Superfluid-supercritical helium tradeoff analysis for the Shuttle Infrared Telescope Facility (SIRTF)

A comparative study is made of three methods for obtaining the required cooling of the SIRTF. The first is a supercritical helium system in which the 2 K temperatures are obtained by a Joule-Thomson expander; the second is a superfluid (He II) helium system; and the third is a hybrid system in which supercritical helium provides the major cooling and small He II reservoirs supply specific detector cooling. The superfluid helium system is found to offer superior performance; it would be the system to use if funding were available. The comparative study gives equal weight to performance, operations, and cost. From this point of view, the hybrid system is selected as the best compromise to obtain an operational SIRTF.

Gier, H. L.↗
NASA NTRS1983

Vapor-liquid phase separator studies

Porous plugs serve as both entropy rejection devices and phase separation components separating the vapor phase on the downstream side from liquid Helium 2 upstream. The liquid upstream is the cryo-reservoir fluid needed for equipment cooling by means of Helium 2, i.e Helium-4 below its lambda temperature in near-saturated states. The topics outlined are characteristic lengths, transport equations and plug results.

Yuan, S. W. K.↗
NASA NTRS1990

Emerging applications of high temperature superconductors for space communications

Proposed space missions require longevity of communications system components, high input power levels, and high speed digital logic devices. The complexity of these missions calls for a high data bandwidth capacity. Incorporation of high temperature superconducting (HTS) thin films into some of these communications system components may provide a means of meeting these requirements. Space applications of superconducting technology has previously been limited by the requirement of cooling to near liquid helium temperatures. Development of HTS materials with transition temperatures above 77 K along with the natural cooling ability of space suggest that space applications may lead the way in the applications of high temperature superconductivity. In order for HTS materials to be incorporated into microwave and millimeter wave devices, the material properties such as electrical conductivity, current density, surface resistivity and others as a function of temperature and frequency must be well characterized and understood. The millimeter wave conductivity and surface resistivity were well characterized, and at 77 K are better than copper. Basic microwave circuits such as ring resonators were used to determine transmission line losses. Higher Q values than those of gold resonator circuits were observed below the transition temperature. Several key HTS circuits including filters, oscillators, phase shifters and phased array antenna feeds are feasible in the near future. For technology to improve further, good quality, large area films must be reproducibly grown on low dielectric constant, low loss microwave substrates.

Heinen, Vernon O.↗
DOE OSTI2023

Cryogenic Plant Integration for the Colossus milli-Kelvin Platform at Fermilab

The Colossus platform at Fermilab will be the largest and most powerful 3He/4He dilution-cooled cryogenic system constructed to-date. Perhaps its primary innovation will be in the integration of a liquid helium cryogenics plant to cool the stages typically cooled by mechanical cryocoolers in commercially available cryogen-free dilution refrigerators. This design shift carries with it important implications for the future of cryogenics associated with quantum computing due to the inherently greater efficiencies of helium cryogenic plants when compared to the use of multitude of independent mechanical cryocoolers. Construction of Colossus is expected to begin in 2023 with a target of commencing operations in 2025.

Tatkowski, G.↗
DOE OSTI2025

Operation of helium sub-atmospheric multistage cryogenic centrifugal compressor trains: Part 1 – Steady state modeling and speed ratio selection

Helium cryogenic systems which can provide cooling below the normal boiling point of helium (approximately 4.2 K) are often required by superconducting radio-frequency niobium resonators utilized in modern high-energy particle accelerators. Achieving temperatures below 4.2 K generally involves operating a cryogenic vessel with liquid helium under sub-atmospheric conditions, thereby lowering the saturation pressure and corresponding saturation temperature. Over the last several decades, multi-stage cryogenic centrifugal compressor trains (CC’s) have been operated efficiently and reliably within large-scale cryogenic systems to continuously evacuate helium vapor generated by a device within the vessel, maintaining sub-atmospheric conditions in the vessel while pressurizing the return vapor to above atmospheric conditions. Traditionally, these CC systems have been operated using empirically derived control philosophies and insight gathered from previous operational experience. Recent efforts at the Facility for Rare Isotope Beams (FRIB) have been aimed at the development of a theoretical basis to characterize the operation of multi-stage cryogenic centrifugal compressor train and utilizing predictive model results to generate control parameters. The objective of this research was identifying operational points which adequately balance cryogenic system efficiency, stability, and overall ease of operation. Furthermore, this manuscript provides an overview of the predictive model development, characterization of the FRIB cryogenic centrifugal compressors and implementation of the predicted performance results during steady-state system operation.

Compressor train control↗
NASA NTRS2007

The Hottest Horizontal-Branch Stars in Omega Centauri: Late Hot Flasher vs. Helium Enrichment

UV observations of some massive globular clusters uncovered a significant population of very hot stars below the hot end of the horizontal branch (HB), the so-called blue hook stars. This feature might be explained either by the late hot flasher scenario here stars experience the helium flash while on the white dwarf cooling curve or by the helium-rich sub-population recently postulated to exist in some clusters. Spectroscopic analyses of blue hook stars in omega Cen and NGC 2808 support the late hot flasher scenario, but the stars contain much less helium than expected and the predicted C, N enrichment could not be verified from existing data. We want to determine effective temperatures, surface gravities and abundances of He, C, N in blue hook and canonical extreme horizontal branch (EHB) star candidates. Moderately high resolution spectra of stars at the hot end of the blue horizontal branch in the globular cluster omega Cen were analysed for atmospheric parameters (T(sub eff), log g) and abundances using LTE and Non-LTE model atmospheres. In the temperature range 30,000 K to 50,000 K we find that 37% of our stars are helium-poor (log nHe/nH less than -2), 49% have solar helium abundance within a factor of 3 (-1.5 less than or equal to log nHe/nH less than or equal to -0.5) and 14% are helium rich (log nHe/nH greater than -0.4). We also find carbon enrichment in step with helium enrichment, with a maximum carbon enrichment of 3% by mass. At least 30% of the hottest HB stars in omega Centauri show helium abundances well above the predictions from the helium enrichment scenario (Y = 0.42 corresponding to log nHe/nH approximately equal to -0.74). In addition the most helium-rich stars show strong carbon enrichment as predicted by the late hot flasher scenario. We conclude that the helium-rich HB stars in omega Cen cannot be explained solely by the helium-enrichment scenario invoked to explain the blue main sequence.

Moehler, S.↗
NASA NTRS2003

Continuous Cooling from 10 K to 4 K Using a Toroidal ADR

Future large infrared space telescopes will require cooling to 4K to achieve background limited performance for submillimeter wavelengths. These observatories will require lifetimes of many years and will have relatively large cooling requirements making stored helium dewars impractical. We have designed and are building an adiabatic demagnetization refrigerator (ADR) for use in cooling relatively large loads (10- 100 mW) at 4K and rejecting that heat to a cryocooler operating at 1 OK. Cryocoolers below 1 OK have poor thermodynamic efficiency and ADRs can operate in this temperature range with an efficiency of 75% of Carnot or better. Overall, this can save as much as 2/3 of the input power required to operate a 4K cryocooler. The ADR magnet consists of 8 short coils wired in series and arranged in a toroid to provide self shielding of its magnetic field. This will save mass (about 30% of the mass or about 1.5 kg in our small version, higher percentages in higher cooling power, larger versions) that would have been used for passive or active shields in an ordinary solenoid. The toroid has a 100 mm outer diameter and will produce an approximately 3T average field. In the initial demonstration model the toroid coils will be wound with ordinary NbTi wire and operated at 4K. A second version will then use Nb3Sn wire to provide complete 10K operation. As a refrigerant for this temperature range we will use either GdLiF4 or GdF3 crystals, pending tests of these crystals' cooling capacity per field and thermal conductance. Preliminary indications are that these materials are superior to GGG. We will use gas gap heat switches to alternately connect the toroid to the cold load and the warm heat sink. A small continuous stage will maintain the cold end at 4K while the main toroid is recycled.

DiPirro, Michael J.↗
DOE OSTI2024

Nested Pebble Bed Blanket (NesPeB)

Recent advances in magnetic confinement fusion technology have attracted billions of dollars of investments in startups from venture capitals and corporations, resulting in the development of devices aiming to demonstrate net energy gain in a self-heated burning plasma, such as SPARC (under construction) and others. However, future fusion power plants must operate in regimes that will require technologies far beyond current experience. According to a National Academies of Science, Engineering, and Medicine report, to have nuclear fusion power plants contributing in a timely manner to the planned reduction of atmospheric carbon dioxide, a pilot plant should be built by 2035, and it should demonstrate fusion power production and the performance of the tritium fuel system (requiring a high enough tritium breeding) by 2040. A recognized key technology gap by [26] is the fusion first wall and blanket since no current blanket concept is considered satisfactory or has been built and proven. The first wall and blanket in magnetic fusion reactors form a vital and complex system, as it must satisfy different functions such as power extraction, tritium breeding, plasma containment, radiation shielding, and safety. The list of design requirements is even longer: high enough tritium production for fusion self-sufficiency, low material activation, decay heat and shutdown dose rates, high thermal efficiency, high-capacity factor, high magnets-divertor-vacuum vessel-first wall life, low corrosion, low cost, and intrinsically safe (requiring minimal licensing). Despite fifty-plus years of research, the first wall and blanket concepts proposed suffer from fundamental technical problems and immaturity (TRL=2-3) that jeopardize the timely delivery of a commercial fusion power plant. A fusion first-wall blanket has never been built nor tested, and a "winning", practical functioning design requires enough engineering margins (high enough tritium breeding considering the uncertainty, etc.), manufacturing simplicity, ease of continuous operation, maintenance, and low cost. A new, groundbreaking blanket concept called "Nested Pebble Bed Blanket" (NesPeB) was developed at ORNL under the successful ARPA-E GAMOW FERMI project (patent application allowed by the USPTO). The NesPeB blanket concept addresses current blanket concepts' shortcomings and technical immaturity, paving the way for accelerated delivery of fusion power plants. NesPeB is based on nested pebbles, which are binary-sized lithium-ceramic pebbles enclosed in "Beryllide" perforated and coated spherical shells, which are also binary-sized, stacked on top of each other, forming a "bed" and cooled by Nitrogen gas also "sweeping" the Helium and Tritium generated by the neutron irradiation of Lithium; the vacuum vessel plasma facing material is Molybdenum-96 and -97 with the first wall cooled by Helium while the divertor armor is made of Tungsten. The simulations of the NesPeB blanket using Fusion Reactors Models Integrator (FERMI) are encouraging as they estimate a tritium breeding ratio (TBR) greater than 1.2 using natural Lithium, acceptable pressure drop, and excellent heat transfer properties. Furthermore, the NesPeB blanket is not limited by magneto-hydro-dynamics (MHD) effects, is designed for online refueling, relies on existing tritium extraction technologies, has a simple construction, and limits the corrosion and chemical reactivity problems. NesPeB has the potential to be transformational and disruptive since it can solve all the main, challenging technical problems of fusion device blankets and accelerate a pilot plant delivery for 10 or more years.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1989

Thermal Analysis Of Reluctant Glass Formers

Thermocouple holds sample and monitors temperature during cooling. Ellipsoidal furnace provides controlled cooling rates for studies of thermal properties of reluctant glass formers. Glass tube inserted into furnace and used to blow helium on specimen to cool rapidly. Cooling curve analyzed to determine rate of cooling and such properties of sample as nucleation and recalescence temperatures at cooling rate. Continuous-cooling-crystallization boundaries determined empirically from plots of nucleation time vs. nucleation temperature from runs at large number of different rates of cooling. Apparatus used to examine glass-formation ability of material and critical cooling rate to form glass.

Ethridge, Edwin C.↗
DOE OSTI2020

Multi-metallic conduction cooled superconducting radio-frequency cavity with high thermal stability

Superconducting radio-frequency cavities are commonly used in modern particle accelerators for applied and fundamental research. Such cavities are typically made of high-purity, bulk Nb and with cooling by a liquid helium bath at a temperature of ~2 K. The size, cost and complexity of operating a particle accelerator with a liquid helium refrigerator make the current cavity technology not favorable for use in industrial-type accelerators. We have developed a multi-metallic 1.495 GHz elliptical cavity conductively cooled by a cryocooler. The cavity has a ~2 µm thick layer of Nb 3 Sn on the inner surface, exposed to the rf field, deposited on a ~3 mm thick bulk Nb shell and a bulk Cu shell, of thickness $\geqslant\! 5$ mm deposited on the outer surface by electroplating. A bolt-on Cu plate 1.27 cm thick was used to thermally connect the cavity equator to the second stage of a Gifford-McMahon cryocooler with a nominal capacity of 2 W at 4.2 K. The cavity was tested initially in liquid helium at 4.3 K and reached a peak surface magnetic field of ~36 mT with a quality factor of 2 × 10 9 . The cavity cooled by the cryocooler achieved a peak surface magnetic field of ~29 mT, equivalent to an accelerating gradient of 6.5 MV m –1 . The conduction-cooled cavity could be operated in continuous-wave with as high as 5 W dissipation in the cavity for 1 h without any thermal breakdown, because of the Cu outer layer with high thermal conductivity. This result represents a paradigm shift in the technology of superconducting accelerator cavities.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS2004

A Continuous Adiabatic Demagnetization Refrigerator for Far-IR/Sub-mm Astronomy

We report on recent progress in the development of a continuous adiabatic demagnetization refrigerator (CADR). Continuous operation avoids the constraints of long hold times and short recycle times that lead to the generally large mass of single-shot ADRs, allowing us to achieve an order of magnitude larger cooling power per unit mass. Our current design goal is 10 microW of cooling at 50 mK using a 6-10 K heat sink. The estimated mass is less than 10 kg, including magnetic shielding of each stage. The relatively high heat rejection capability allows it to operate with a mechanical cryocooler as part of a cryogen-free, low temperature cooling system. This has the advantages of long mission life and reduced complexity and cost. We have assembled a three-stage CADR and have demonstrated continuous cooling using a superfluid helium bath as the heat sink. The temperature stability is 8 microK rms or better over the entire cycle, and the cooling power is 2.5 microW at 60 mK rising to 10 microW at 100 mK.

Shirron, Peter↗
NASA NTRS1994

Experimental studies of transpiration cooling with shock interaction in hypersonic flow, part B

This report describes the result of experimental studies conducted to examine the effects of the impingement of an oblique shock on the flowfield and surface characteristics of a transpiration-cooled wall in turbulent hypersonic flow. The principal objective of this work was to determine whether the interaction between the oblique shock and the low-momentum region of the transpiration-cooled boundary layer created a highly distorted flowfield and resulted in a significant reduction in the cooling effectiveness of the transpiration-cooled surface. As a part of this program, we also sought to determine the effectiveness of transpiration cooling with nitrogen and helium injectants for a wide range of blowing rates under constant-pressure conditions in the absence of shock interaction. This experimental program was conducted in the Calspan 48-Inch Shock Tunnel at nominal Mach numbers of 6 and 8, for a Reynolds number of 7.5 x 10(exp 6). For these test conditions, we obtained fully turbulent boundary layers upstream of the interaction regions over the transpiration-cooled segment of the flat plate. The experimental program was conducted in two phases. In the first phase, we examined the effects of mass-addition level and coolant properties on the cooling effectiveness of transpiration-cooled surfaces in the absence of shock interaction. In the second phase of the program, we examined the effects of oblique shock impingement on the flowfield and surface characteristics of a transpiration-cooled surface. The studies were conducted for a range of shock strengths with nitrogen and helium coolants to examine how the distribution of heat transfer and pressure and the characteristics of the flowfield in the interaction region varied with shock strength and the level of mass addition from the transpiration-cooled section of the model. The effects of the distribution of the blowing rate along the interaction regions were also examined for a range of blowing rates through the transpiration-cooled panels. The regions of shockwave/boundary layer interaction examined in these studies were induced by oblique shocks generated with a sharp, flat plate, inclined to the freestream at angles of 5 degrees, 7.5 degrees, and 10 degrees. It was found that, in the absence of an incident shock, transpiration cooling was a very effective method for reducing both the heat transfer and the skin friction loads on the surface. The helium coolant was found to be significantly more effective than nitrogen, because of its low molecular weight and high specific heat. The studies of shock-wave/transpiration-cooled surface interaction demonstrated that the interaction region between the incident shock and the low-momentum transpiration-cooled boundary layer did not result in a significant increase in the size of attached or separated interaction regions, and did not result in significant flowfield distortions above the interaction region. The increase in heating downstream of the shock-impingement point could easily be reduced to the values without shock impingement by a relatively small increase in the transpiration cooling in this region. Surprisingly, this increase in cooling rate did not result in a significant increase in size of the region ahead of the incident shock or create a significantly enlarged interaction region with a resultant increase in the distortion level in the inviscid flow. Thus, transpiration cooling appears to be a very effective technique to cool the internal surfaces of scramjet engines, where shocks in the engine would induce large local increases in wall heating and create viscous/inviscid interactions that could significantly disturb the smooth flow through the combustor. However, if hydrogen is used as the coolant, burning upstream of shock impingement might result in localized hot spots. Clearly, further research is needed in this area.

Holden, Michael S.↗
NASA NTRS2002

Progress in the Development of a Continuous Adiabatic Demagnetization Refrigerator

We report on recent progress in the development of a continuous adiabatic demagnetization refrigerator (CADR). Continuous operation avoids the constraints of long hold times and short recycle times that lead to the generally large mass of single-shot ADRs, allowing us to achieve an order of magnitude larger cooling power per unit mass. Our current design goal is 10 micro W of cooling at 50 mK using a 6-10 K heat sink. The estimated mass is less than 10 kg, including magnetic shielding of each stage. The relatively high heat rejection capability allows it to operate with a mechanical cryocooler as part of a cryogen-free, low temperature cooling system. This has the advantages of long mission life and reduced complexity and cost. We have assembled a three-stage CADR and have demonstrated continuous cooling using a superfluid helium bath as the heat sink. The temperature stability is 8 micro K rms or better over the entire cycle, and the cooling power is 2.5 micro W at 60 mK rising to 10 micro W at 100 mK.

Shirron, Peter↗
DOE OSTI2024

LCLS-II Helium Refrigeration System Commissioning Results

SLAC National Accelerator Laboratory has upgraded to LCLS-II, featuring a 4 GeV superconducting linear accelerator composed of 37 cryomodules and two large helium refrigeration systems with a cooling capacity of 4 kW at 2.0 K. The LCLS-II Helium Refrigeration System (HRS) consists of two compressor stations, each with a power of approximately 4.5 MW, two 4.5 K cold boxes, each with a power of 18 kW equivalent at 4.5 K, and two sets of cold compressors that can each produce a flow of 230 g/s at 31 mbar (2.0K). Performance tests of the HRS were meticulously planned and successfully carried out, with results demonstrating that it exceeded the process requirements for LCLS-II operations. This paper provides a detailed presentation of the LCLS-II HRS performance and the challenges encountered during the commissioning phase.

42 ENGINEERING↗
NASA NTRS1990

Silicon Detectors For Helium Liquid And Vapor

Simple electrical-resistance devices made of silicon indicate whether helium liquid or helium vapor present. Devices designed primarily for use in outer space, were tested and found to operate in normal Earth gravity. Silicon cubes supported by stainless-steel wires and strips. Voltage across each cube at fixed current indicates whether immersed in helium liquid or vapor. Liquid cools more than vapor does, resulting in greater electrical resistance. Such helium-liquid/vapor detectors incorporated into ducts or containers of laboratory equipment, and used to infer locations of liquid/vapor interfaces in order to measure quantities of liquid and vapor or to control refill operations.

Di Pirro, M. J.↗