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All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Observations of the Helium II 304-A and Helium I 584-A atmospheric dayglow radiation.

Two photometers with bandpasses of 170 to 500 and 170 to 800 A were employed to observe dayglow emissions in the extreme ultraviolet (EUV) over an altitude range of 90 to 186 km. The emissions observed with these photometers are identified as resonantly scattered He I 584-A and He II 304-A radiations. At 186 km, 209 plus or minus 70 rayleighs of 584-A and 9.3 plus or minus 3.1 rayleighs of 304-A radiation were measured. These observations are compared with theoretical calculations of resonance scattering of solar emissions from geocoronal He and He(+). Using the Jacchia (1971) atmospheric model for He, it is found that the observed brightness of the 584-A emission requires that the solar 584-A line width be 0.014 plus or minus 0.004 A. In this model the maximum overhead brightness of 584-A dayglow would occur at 900 km, and its magnitude would be 1.9 plus or minus 0.6 kR. The authors' observation of 304-A brightness requires that the overhead column density of the He(+) ions be 4.2 x 10 to the 11th ions/sq cm column. This value is consistent with a constant-density plasmasphere model with a He(+) ion density of 320 ions/cu cm in the plasmasphere.

Kumar, S.↗
NASA NTRS1985

Prospects for determining the cosmological helium-3 to helium-4 ratio via absorption-line studies of the local interstellar medium

The prospects for determining the interstellar (He-3)/(He-4) ratio via absorption-line studies in the extreme ultraviolet are considered. A high-resolution extreme-ultraviolet spectrometer fed by a 1-meter-class telescope similar to that discussed in the Far Ultraviolet Spectroscopic Explorer Report (1983) is assumed, and it is found that detection of He-3 may be possible with less than three days of observing time. To measure the (He-3)/(He-4) ratio with sufficient precision to determine the number of light neutrino species will require over 50 days of integration time for each object studied.

Hurwitz, M.↗
DOE OSTI2021

Experimental Investigation and Monte Carlo Simulation of Quasielastic Electron Scattering From Helium-3 Clusters in Helium-4

Experiment E04-018 was conducted in Hall A of the Jefferson National Laboratory (JLab) from November 2006 through July 2007. The experiment used the two superconducting, high-resolution magnetic spectrometers of Hall A to detect scattered electrons and recoil nuclei. One goal of this experiment was to provide accurate data on the elastic charge form factor of 4He to high momentum transfers (up to Q2 = 77 fm?2). The purpose of this thesis is to analyze and simulate a very unique and unexpected class of data from this experiment. The work performed involved the analysis of electron scattering data with the 4He target of the JLab E04-018 experiment and Monte Carlo simulation studies of elastic and quasielastic electron scattering from the 4He and 3He few-body nuclear systems. The results of this experiment and the simulations provide insights into the existence of A = 3 clustering in 4He, and possibly in heavier nuclei.

Alahmade, Walaa↗
NASA NTRS2014

Liquid Oxygen Thermodynamic Vent System Testing with Helium Pressurization

This report presents the results of several thermodynamic vent system (TVS) tests with liquid oxygen plus a test with liquid nitrogen. In all tests, the liquid was heated above its normal boiling point to 111 K for oxygen and 100 K for nitrogen. The elevated temperature was representative of tank conditions for a candidate lunar lander ascent stage. An initial test series was conducted with saturated oxygen liquid and vapor at 0.6 MPa. The initial series was followed by tests where the test tank was pressurized with gaseous helium to 1.4 to 1.6 MPa. For these tests, the helium mole fraction in the ullage was quite high, about 0.57 to 0.62. TVS behavior is different when helium is present than when helium is absent. The tank pressure becomes the sum of the vapor pressure and the partial pressure of helium. Therefore, tank pressure depends not only on temperature, as is the case for a pure liquid-vapor system, but also on helium density (i.e., the mass of helium divided by the ullage volume). Thus, properly controlling TVS operation is more challenging with helium pressurization than without helium pressurization. When helium was present, the liquid temperature would rise with each successive TVS cycle if tank pressure was kept within a constant control band. Alternatively, if the liquid temperature was maintained within a constant TVS control band, the tank pressure would drop with each TVS cycle. The final test series, which was conducted with liquid nitrogen pressurized with helium, demonstrated simultaneous pressure and temperature control during TVS operation. The simultaneous control was achieved by systematic injection of additional helium during each TVS cycle. Adding helium maintained the helium partial pressure as the liquid volume decreased because of TVS operation. The TVS demonstrations with liquid oxygen pressurized with helium were conducted with three different fluid-mixer configurations-a submerged axial jet mixer, a pair of spray hoops in the tank ullage, and combined use of the axial jet and spray hoops. A submerged liquid pump and compact heat exchanger located inside the test tank were used with all the mixer configurations. The initial series without helium and the final series with liquid nitrogen both used the axial jet mixer. The axial jet configuration successfully demonstrated the ability to control tank pressure; but in the normal-gravity environment, the temperature in the upper tank region (ullage and unwetted wall) was not controlled. The spray hoops and axial jet combination also successfully demonstrated pressure control as well as temperature control of the entire tank and contents. The spray-hoops-only configuration was not expected to be a reliable means of tank mixing because there was no direct means to produce liquid circulation. However, surprisingly good results also were obtained with the sprayhoops- only configuration (i.e., performance metrics such as cycle-averaged vent flowrate were similar to those obtained with the other configurations). A simple thermodynamic model was developed that correctly predicted the TVS behavior (temperature rise or pressure drop per TVS cycle) when helium was present in the ullage. The model predictions were correlated over a range of input parameters. The correlations show that temperature rise or pressure drop per cycle was proportional to both helium mole fraction and tank heat input. The response also depended on the tank fill fraction: the temperature rise or pressure drop (per TVS cycle) increased as the ullage volume decreased.

Thermodynamic vent system↗
DOE OSTI2022

Preliminary design of a helium cryogenic system for SAND detector at LBNF-DUNE near site

The Long-Baseline Neutrino Facility (LBNF) is providing a helium cryogenic system to support the superconducting solenoid magnet of the System for on-Axis Neutrino Detection (SAND) for the Deep Underground Neutrino Experiment (DUNE) Near Site at Fermilab in Batavia, IL. The design started in 2020 and construction is set to begin in the mid 2020‘s.The helium cryogenic system primarily consists of a helium refrigerator system, distribution valve boxes, vacuum-jacketed helium and nitrogen transfer lines, warm gaseous helium transfer system, instruments and control system, and gaseous helium storage tanks. It is designed to provide supercritical helium at around 3 bara and 5 K with expansion from 3 to 1.2 bara in the SAND cryostat and 70K forced cold gas helium to cool the thermal shields of the SAND cryostat. The SAND superconductive magnet is indirectly cooled through a liquid helium thermosiphon cycle. A pair of 3 kA leads is cooled by the gas helium vaporized from the liquid helium reservoir in the cryostat turret. The helium system will share the liquid nitrogen tank and liquid nitrogen phase separator with the Near Site Liquid Argon system. The helium recycle compressor system, GHe tanks and LN2 tank will be located on the Surface. The cryogenic facilities including refrigerator cold box, valve boxes and LN2 phase separator will be located on the shaft cryo-mezzanine in the underground cavern. The shaft connecting surface and cavern is more than 60 meter deep. The helium vacuum-jacketed transfer line between the cold box and the SAND magnet is more than 50 meter long. This paper presents the preliminary design of the helium cryogenic system including the design scheme, process flow diagram, heat load estimates, layout plan and so on.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗