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At least 55 records · Page 3

Benchmarking the design of the cryogenics system for the underground argon in DarkSide-20k

DarkSide-20k (DS-20k) is a dark matter detection experimentunder construction at the Laboratori Nazionali del Gran Sasso (LNGS)in Italy. It utilises ∼ 100 t of low radioactivity argon from anunderground source (UAr) in its inner detector, with half serving astarget in a dual-phase time projection chamber (TPC). The UArcryogenics system must maintain stable thermodynamic conditionsthroughout the experiment's lifetime of over10 years. Continuous removal ofimpurities and radon from the UAr is essential for maximising signalyield and mitigating background. We are developing an efficient andpowerful cryogenics system with a gas purification loop with atarget circulation rate of1000 slpm. Central to itsdesign is a condenser operated with liquid nitrogen which is pairedwith a gas heat exchanger cascade, delivering a combined coolingpower of more than 8 kW. Here wepresent the design choices in view of the DS-20k requirements, inparticular the condenser's working principle and the coolingcontrol, and we show test results obtained with a dedicatedbenchmarking platform at CERN and LNGS. We find that the thermalefficiency of the recirculation loop, defined in terms of nitrogenconsumption per argon flow rate, is95 % and the pressure in the testcryostat can be maintained within±(0.1–0.2) mbar. Wefurther detail a 5-day cool-down procedure of the test cryostat,maintaining a cooling rate typically within-2 K/h, as required for theDS-20k inner detector. Additionally, we assess the circuit's flowresistance, and the heat transfer capabilities of two heat exchangergeometries for argon phase change, used to provide gas forrecirculation. We conclude by discussing how our findings influencethe finalisation of the system design, including necessarymodifications to meet requirements and ongoing testing activities.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Design of the PIXIE Cryogenic System

The Primordial Inflation Explorer (PIXIE) is a proposed m1ss1on to study the polarization of the remnant cosmic microwave background with the goal of finding and understanding primordial gravity waves. The instrument has been designed to capture this information across the entire sky by rejecting foreground signals and suppressing systematic error by multiple differencing methods. The instrument operates at a temperature very close to the Cosmic Microwave Background of 2.7 K, while the detectors operate at 0.1 K. The PIXIE cryogenic system provides this in low Earth orbit by making use of 3 subsystems. Lightweight, simply deployed shields provide protection against the Earth and Sun while passively cooling wiring and instrument supports at 150 K. A mechanical cryocooler precools wires and supports at 68, 17, and 4.5 K while its compressors operate at room temperature. And finally two adiabatic demagnetization refrigerators cool the instrument from 4.5 to 2.7 K and cool the detectors to 0.1 K. Staged cooling in this manner allows a thermodynamically efficient use of relatively mature technologies that can be fully demonstrated before flight..

DiPirro, Michael↗

Liquid-Vapor Equilibrium of Multicomponent Cryogenic Systems

Liquid-vapor and solid-vapor equilibria at low to moderate pressures and low temperatures are important in many solar system environments, including the surface and clouds of Titan, the clouds of Uranus and Neptune, and the surfaces of Mars and Triton. The familiar cases of ideal behavior are limiting cases of a general thermodynamic representation for the vapor pressure of each component in a homogeneous multicomponent system. The fundamental connections of laboratory measurements to thermodynamic models are through the Gibbs-Duhem relation and the Gibbs-Helmholtz relation. Using laboratory measurements of the total pressure, temperature, and compositions of the liquid and vapor phases at equilibrium, the values of these parameters can be determined. The resulting model for vapor-liquid equilibrium can then conveniently and accurately be used to calculate pressures, compositions, condensation altitudes, and their dependencies on changing climatic conditions. A specific system being investigated is CH4-C2H6-N2, at conditions relevant to Titan's surface and atmosphere. Discussed are: the modeling of existing data on CH4-N2, with applications to the composition of Titan's condensate clouds; some new measurements on the CH4-C2H6 binary, using a high-precision static/volumetric system, and on the C2H6-N2 binary, using the volumetric system and a sensitive cryogenic flow calorimeter; and describe a new cryogenic phase-equilibrium vessel with which we are beginning a detailed, systematic study of the three constituent binaries and the ternary CH4-C2H6-N2 system at temperatures ranging from 80 to 105 K and pressures from 0.1 to 7 bar.

Thompson, W. Reid↗

Design of the cryogenic system for the SAFIRE instrument

One of the primary goals of the NASA Mission to Planet Earth is to improve understanding of the ozone chemistry of the atmosphere over an extended period of time. The Spectroscopy of the Atmosphere using Far Infrared Emission (SAFIRE) instrument is being developed to conduct, for the first time, global measurements of the key ozone chemistry constituents in both the mid- and far-infrared spectral regions. Such remote, long-term observations are made possible by the recent development of compact long-life hybrid cryogenic dewars which are necessary to cool the sensitive detectors to the 3-4 K range. The success of this hybrid concept is based on the use of long-life Stirling cycle cryocoolers to intercept parasitic heat from the internal radiation shields of the superfluid helium dewar. Extensive system trade studies are required to optimize the mass, power, and lifetime of these space-borne cryogenic systems. The SAFIRE Cryogenic Subsystem is described, including the thermal performance trades leading to the chosen system configuration and the important dewar/cryocooler interface issues.

Lee, J. H.↗

Lessons from commissioning and operations of the ICARUS cryogenic system at Fermilab

Results and lessons from three years of commissioning and operations of the cryogenic and purificationsystems of the ICARUS neutrino detector installed at the Fermilab are described. The detector uses liquid argon stored in two separate containers of about 275 m 3 each. The liquid argon must be kept in very stable thermal conditions, and the contamination of electronegative impurities must be consistently kept at small fractions of parts per billion. Since its fill in early 2020, the detector has been commissioned and then operated in neutrino beams at Fermilab for the search of sterile neutrinos and measurements of neutrino-argon cross sections. The results of operating the cryogenic and purification systems and lessons learned, including challenges in reaching the design electron lifetime in argon bath, operating and servicing liquid nitrogen and argon circulation pumps, argon condensers and purifiers, are described. Plans for future operations and list of recommendations are presented.

43 PARTICLE ACCELERATORS↗

Investigation of Vapor Cooling Enhancements for Applications on Large Cryogenic Systems

The need to demonstrate and evaluate the effectiveness of heat interception methods for use on a relevant cryogenic propulsion stage at a system level has been identified. Evolvable Cryogenics (eCryo) Structural Heat Intercept, Insulation and Vibration Evaluation Rig (SHIIVER) will be designed with vehicle specific geometries (SLS Exploration Upper Stage (EUS) as guidance) and will be subjected to simulated space environments. One method of reducing structure-born heat leak being investigated utilizes vapor-based heat interception. Vapor-based heat interception could potentially reduce heat leak into liquid hydrogen propulsion tanks, increasing potential mission length or payload capability. Due to the high number of unknowns associated with the heat transfer mechanism and integration of vapor-based heat interception on a realistic large-scale skirt design, a sub-scale investigation was developed. The sub-project effort is known as the Small-scale Laboratory Investigation of Cooling Enhancements (SLICE). The SLICE aims to study, design, and test sub-scale multiple attachments and flow configuration concepts for vapor-based heat interception of structural skirts. SLICE will focus on understanding the efficiency of the heat transfer mechanism to the boil-off hydrogen vapor by varying the fluid network designs and configurations. Various analyses were completed in MATLAB, Excel VBA, and COMSOL Multiphysics to understand the optimum flow pattern for heat transfer and fluid dynamics. Results from these analyses were used to design and fabricate test article subsections of a large forward skirt with vapor cooling applied. The SLICE testing is currently being performed to collect thermal mechanical performance data on multiple skirt heat removal designs while varying inlet vapor conditions necessary to intercept a specified amount of heat for a given system. Initial results suggest that applying vapor-cooling provides a 50 heat reduction in conductive heat transmission along the skirt to the tank. The information obtained by SLICE will be used by the SHIIVER engineering team to design and implement vapor-based heat removal technology into the SHIIVER forward skirt hardware design.

small scale testing↗

LTF/Fluid and Cryogenic Systems Branch

Functions of the Branch: Cross-Cutting Fluids Engineering; Research and Technology Development of Cryogenic Fluid Management (CFM) Systems; Component and System level; Design, Development Test and Evaluation (DDT&E) for Fluid, CFM, Propellant and Gaseous Systems; Fluid Component Specification and Selection; Code Compliance of Pressurized Systems; Fluid/Cryogenic System Performance Analysis and Trade Studies; Hazards Analysis and Risk Assessment of Fluidic Systems; Fluids Modeling and Simulation Capabilities

Fluid↗

Cryogenic systems for spacecraft

It is noted that the use of cryogenic components on spacecraft, already quite common, will likely increase in the future. Attention is given to a number of applications including earth observation, atmospheric measurements, infrared astronomy and magnetic field measurements. These applications are discussed with regard to their cryogenic requirements. Further, four cryogenic instruments provided by the United States to be launched on spacecraft in the near future are described. Finally, other missions being planned that will use cryogenic instrumentation are also considered.

Vorreiter, J. W.↗

Design of Superconducting Gravity Gradiometer Cryogenic System for Mars Mission

Measurement of a planets gravity field provides fundamental information about the planets mass properties. The static gravity field reveals information about the internal structure of the planet, including crustal density variations that provide information on the planets geological history and evolution. The time variations of gravity result from the movement of mass inside the planet, on the surface, and in the atmosphere. NASA is interested in a Superconducting Gravity Gradiometer (SGG) with which to measure the gravity field of a planet from orbit. An SGG instrument is under development with the NASA PICASSO program, which will be able to resolve the Mars static gravity field to degree 200 in spherical harmonics, and the time-varying field on a monthly basis to degree 20 from a 255 x 320 km orbit. The SGG has a precision two orders of magnitude better than the electrostatic gravity gradiometer that was used on the ESAs GOCE mission. The SGG operates at the superconducting temperature lower than 6 K. This study developed a cryogenic thermal system to maintain the SGG at the design temperature in Mars orbit. The system includes fixed radiation shields, a low thermal conductivity support structure and a two-stage cryocooler. The fixed radiation shields use double aluminized polyimide to emit heat from the warm spacecraft into the deep space. The support structure uses carbon fiber reinforced plastic, which has low thermal conductivity at cryogenic temperature and very high stress. The low vibration cryocooler has two stages, of which the high temperature stage operates at 65 K and the low temperature stage works at 6 K, and the heat rejection radiator works at 300 K. The study also designed a second option with a 4-K adiabatic demagnetization refrigerator (ADR) and two-stage 10-K turbo-Brayton cooler.

Li, X.↗

Design of Superconducting Gravity Gradiometer Cryogenic System for Mars Mission

Measurement of a planet's gravity field provides fundamental information about the planet's mass properties. The static gravity field reveals information about the internal structure of the planet, including crustal density variations that provide information on the planet's geological history and evolution. The time variations of gravity result from the movement of mass inside the planet, on the surface, and in the atmosphere. NASA is interested in a Superconducting Gravity Gradiometer (SGG) with which to measure the gravity field of a planet from orbit. An SGG instrument is under development with the NASA PICASSO program, which will be able to resolve the Mars static gravity field to degree 200 in spherical harmonics, and the time-varying field on a monthly basis to degree 20 from a 255 x 320 km orbit. The SGG has a precision two orders of magnitude better than the electrostatic gravity gradiometer that was used on the ESA's GOCE mission. The SGG operates at the superconducting temperature lower than 6 K. This study developed a cryogenic thermal system to maintain the SGG at the design temperature in Mars orbit. The system includes fixed radiation shields, a low thermal conductivity support structure and a two-stage cryocooler. The fixed radiation shields use double aluminized polyimide to emit heat from the warm spacecraft into the deep space. The support structure uses carbon fiber reinforced plastic, which has low thermal conductivity at cryogenic temperature and very high stress. The low vibration cryocooler has two stages, of which the high temperature stage operates at 65 K and the low temperature stage works at 6 K, and the heat rejection radiator works at 300 K. The study also designed a second option with a 4-K adiabatic demagnetization refrigerator (ADR) and two-stage 10-K turbo-Brayton cooler.

Gradiometer↗

Robust Multilayer Insulation for Cryogenic Systems

New requirements for thermal insulation include robust Multilayer insulation (MU) systems that work for a range of environments from high vacuum to no vacuum. Improved MLI systems must be simple to install and maintain while meeting the life-cycle cost and thermal performance objectives. Performance of actual MLI systems has been previously shown to be much worse than ideal MLI. Spacecraft that must contain cryogens for both lunar service (high vacuum) and ground launch operations (no vacuum) are planned. Future cryogenic spacecraft for the soft vacuum environment of Mars are also envisioned. Industry products using robust MLI can benefit from improved cost-efficiency and system safety. Novel materials have been developed to operate as excellent thermal insulators at vacuum levels that are much less stringent than the absolute high vacuum requirement of current MLI systems. One such robust system, Layered Composite Insulation (LCI), has been developed by the Cryogenics Test Laboratory at NASA Kennedy Space Center. The experimental testing and development of LCI is the focus of this paper. LCI thermal performance under cryogenic conditions is shown to be six times better than MLI at soft vacuum and similar to MLI at high vacuum. The experimental apparent thermal conductivity (k-value) and heat flux data for LCI systems are compared with other MLI systems.

Fesmire, J. E.↗

STABILITY OF FILM BOILING TWO-PHASE FLOW IN CRYOGENIC SYSTEMS

The stability of film boiling two phase flow is investigated referring in particular to saturated cryogenic liquids. This type of fluid motion is unstable, such that a range of wave numbers will always be present in which disturbances are amplified. Further the mode of operation of the energy supply system may favour temperature fluctuations of large amplitude if the circuit does not provide feed-back compensation. The theoretically predicted stabilization due to capillarity is reduced considerably in liquefied gases with low surface tension, such as hydrogen. This effect causes the transition to turbulent flow to occur at low Reynolds numbers, and increases the heat transport in the turbulent regime. A comparison with experimental data, (horizontal cylinder), shows that the "critical" film Reynolds number ūδ/𝜈, at which instabilities become effective, is lowered from approximately 200, (O2), to about 30, (H2). Similar results have been found with other configurations. Therefore application of laminar film boiling solutions is restricted to small objects, entrance regions, or stagnation points. Turbulent correlations given so far are valid only for a certain group of substances with similar behavior.

LIQUID FLOW↗

Adjustable mount for electro-optic transducers in an evacuated cryogenic system

The invention is an adjustable mount for positioning an electro-optic transducer in an evacuated cryogenic environment. Electro-optic transducers are used in this manner as high sensitivity detectors of gas emission lines of spectroscopic analysis. The mount is made up of an adjusting mechanism and a transducer mount. The adjusting mechanism provided five degrees of freedom, linear adjustments and angular adjustments. The mount allows the use of an internal lens to focus energy on the transducer element thereby improving the efficiency of the detection device. Further, the transducer mount, although attached to the adjusting mechanism, is isolated thermally such that a cryogenic environment can be maintained at the transducer while the adjusting mechanism remains at room temperature. Radiation shields also are incorporated to further reduce heat flow to the transducer location.

Crossley, Edward A., Jr.↗