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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.

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At least 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Electron emissions and hot spots in dual-phase LXe TPCs

Persistent photon and single-electron emissions - in the form of “electron trains” and localized “hot spots” - have been observed in multiple dual-phase liquid xenon (LXe) time projection chambers (TPCs), often persisting long after ionizing events. Here, we show that these phenomena are naturally explained by photon-triggered single-electron emission from resistive mixed-oxide films on stainless-steel (SS304 or s.s.) wires, which behave as leaky capacitors with long RC time constants at LXe temperature. Positive ions landing on these oxides can further enhance local fields and drive Malter-like electron emission. We outline the materials physics (Cr 2 O 3 /Cr 2 O 3-x /Cr(OH) 3 mosaics), quantify expected time scales (∼1 s under illumination), and demonstrate how small damaged regions with enhanced QE can produce persistent hot spots.

Va'vra, J. [SLAC National Accelerator Laboratory (↗
NASA NTRS1978

Ion tracking in an electrostatic potential distribution

An ion tracking system utilizing a single detector was designed to resolve two dimensional potential distributions in a vacuum. The ion detector consisted of a continuous dynode electron multiplier tube mounted behind a series of aperture plates. The detector was located on a track below a wedge shaped structure used to produce the desired potential distribution. A 150 volt electron beam aimed at selected regions, ionized the residual gas in the chamber. The ions were ejected from their source points by electrostatic forces causing them to drift downward toward the detector. Measurements of particle energy, detector position, and entry angle of the incoming particle flux were used to initialize a computer trajectory-tracing program. The program assumes a known theoretically calculated potential distribution near the wedge for computation of particle trajectories, providing a basis for evaluating the data. Special attention was given to characterization of the ion detector.

Ross, D. P.↗
NASA NTRS1984

Dual ion beam deposition of carbon films with diamondlike properties

A single and dual ion beam system was used to generate amorphous carbon films with diamond like properties. A methane/argon mixture at a molar ratio of 0.28 was ionized in the low pressure discharge chamber of a 30-cm-diameter ion source. A second ion source, 8 cm in diameter was used to direct a beam of 600 eV Argon ions on the substrates (fused silica or silicon) while the deposition from the 30-cm ion source was taking place. Nuclear reaction and combustion analysis indicate H/C ratios for the films to be 1.00. This high value of H/C, it is felt, allowed the films to have good transmittance. The films were impervious to reagents which dissolve graphitic and polymeric carbon structures. Although the measured density of the films was approximately 1.8 gm/cu cm, a value lower than diamond, the films exhibited other properties that were relatively close to diamond. These films were compared with diamondlike films generated by sputtering a graphite target.

Mirtich, M. J.↗
NASA NTRS1985

Dual-ion-beam deposition of carbon films with diamond-like properties

A single and dual ion beam system was used to generate amorphous carbon films with diamond like properties. A methane/argon mixture at a molar ratio of 0.28 was ionized in the low pressure discharge chamber of a 30-cm-diameter ion source. A second ion source, 8 cm in diameter was used to direct a beam of 600 eV Argon ions on the substrates (fused silica or silicon) while the deposition from the 30-cm ion source was taking place. Nuclear reaction and combustion analysis indicate H/C ratios for the films to be 1.00. This high value of H/C, it is felt, allowed the films to have good transmittance. The films were impervious to reagents which dissolve graphitic and polymeric carbon structures. Although the measured density of the films was approximately 1.8 gm/cu cm, a value lower than diamond, the films exhibited other properties that were relatively close to diamond. These films were compared with diamond like films generated by sputtering a graphite target.

Mirtich, M. J.↗
NASA NTRS1995

Alpha-particle Gas Pressure Gauge

Described are preliminary results obtained on a novel gas pressure gauge that operates between 0.1 and 1000 mb. This gauge uses a 1- micron Ci alpha particle source to ionize the gas in a small chamber with an electric field imposed between anode and cathode electrodes that drives positive ions to the cathode where they are collected electronically. This gauge could make Martian pressure measurements.

gas pressure sensor micro-pressure gauge alpha-par↗
NASA NTRS2019

Methylation Pattern Detection in the Genome of Bacillus Pumilus Strain SAFR-032

Bacillus pumilus SAFR-032, an endospore-forming bacterial strain that was isolated from a spacecraft assembly facility (SAFR), was investigated to determine its methylation pattern (methylome) across the genome in comparison to the previously sequenced reference genome. In addition, a version of SAFR-032 that was flown as spores for 18 months on the International Space Station (ISS) was also investigated for possible genomic changes due to long-duration ISS-flight and to determine if methylation patterns may have changed. Both the genomics and methylomics were conducted using a Nanopore MinION sequencing device. In addition to the omics investigation, the two SAFR-032 strains, ISS flown and non-ISS flown, were compared phenotypically in chamber experiments testing individual environmental insults: ionizing radiation, UV exposure, and cold desiccation (i.e. freeze drying). Results from this study inform on Planetary Protection concerns and will reveal potential DNA damage associated with long-term spaceflight and how such damage may influence survivors after being transported to an extraterrestrial environment, such as Mars.

Serda, Bianca M.↗
NASA NTRSDate not supplied

Extreme Environment Hot Fire Durability of Post-Processed Additively Manufactured GRCop-Alloy Combustion Chambers in LOX/Hydrogen and LOX/Methane

Extreme environment survivability of metal additive manufactured (AM) GRCop-alloy thrust chambers has been demonstrated in different bi-propellants at near stoichiometric and even oxygen rich combustion. GRCop-alloy chambers tested at NASA Marshall Space Flight Center (MSFC) have accumulated over 26,000 seconds of hot fire duration and over 500 starts. These chambers are produced using an AM process called laser powder bed fusion (L-PBF). A major feature of this process is high wall surface roughness which can be customized in post processing to leverage various performance advantages. Post-processing can include heat treatment, final machining, polishing, and welding and is key to hardware survivability in extreme environments. Surface finish enhancement techniques were applied to the hot wall and coolant channels to reduce the overall total heat load to the chamber walls. Performance optimization of various thrust class TCA’s is a strategic technology goal of NASA MSFC. Three different chamber geometries using cryogenic methane and de-ionized water as coolants were hot fire tested to obtain their life cycle, pressure drop, and heat load performances. Several 1.2K lbf LOX/H2 chambers, 1K lbf LOX/CH4 chambers, and 7K lbf LOX/CH4 chambers were tested. All post-processed configurations performed remarkably well when subjected to extreme hot fire test conditions. Streaking and blanching due to localized oxygen rich conditions were observed on some test articles in their as-built surface finish state. However, this is actually a function of the injector mixing and only serves to further establish the durability of L-PBF GRCop-alloy thrust chambers. Several different polishing techniques were applied to the hot wall and integrated coolant channels prior to hot fire testing and their performances assessed. Overall, AM produced GRCop chambers are extremely reliable, durable, and customizable to the desired performance metrics.

grcop↗
DOE OSTI2024

Managing photon flux in a miniaturized photoionization detector

Miniaturized photoionization detectors (PIDs) are used in conjunction with gas chromatography systems to detect volatile compounds in gases by collecting the current from the photoionized gas analytes. PIDs should be inexpensive and compatible with a wide range of analyte species. One such PID is based on the formation of a He plasma in a dielectric barrier discharge (DBD), which generates vacuum UV (VUV) photons from excited states of He to photoionize gas analytes. There are several design parameters that can be leveraged to increase the ionizing photon flux to gas analytes to increase the sensitivity of the PID. To that end, the methods to maximize the photon flux from a pulsed He plasma in a DBD-PID were investigated using a two-dimensional plasma hydrodynamics model. The ionizing photon flux originated from the resonance states of helium, He(3P) and He(2 1 P), and from the dimer excimer He 2 *. While the photon flux from the resonant states was modulated over the voltage pulse, the photon flux from He 2 * persisted long after the voltage pulse passed. Several geometrical optimizations were investigated, such as using an array of pointed electrodes. However, increasing the capacitance of the dielectric enclosing the plasma chamber had the largest effect on increasing the VUV photon fluence to gas analytes.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1985

X-ray film chamber with carbon target of Tien-Shan complex array

X-ray films were exposed inside the ionization calorimeter under 74g/sq cm of carbon and 5 cm of lead. The X-ray film chamber area is 35 sq. m. Moving X-ray films were used, 50% of the events, which succeeded to determine incidence time, were identified with corresponding extensive air showers (EAS). For such events the size spectrum of associated EAS was derived. Two methods of energy measurement using X-ray films and ionization calorimeter were compared. The energy transfer from selected hadron to electromagnetic component is illustrated. It is found that in cascades with high energy release into electromagnetic components the hadron component is practically absent.

Cherdyntseva, K. V.↗
DOE OSTI2021

Effective field theory analysis of the first LUX dark matter search

The Large Underground Xenon (LUX) dark matter search was a 250-kg active mass dual-phase time projection chamber that operated by detecting light and ionization signals from particles incident on a xenon target. In December 2015, LUX reported a minimum 90% upper C.L. of 6 x 10 -46 cm 2 on the spin-independent WIMP-nucleon elastic scattering cross section based on a 1.4 x 10 4 kg ∙ day exposure in its first science run. Tension between experiments and the absence of a definitive positive detection suggest it would be prudent to search for WIMPs outside the standard spin-independent/spin-dependent paradigm. Recent theoretical work has identified a complete basis of 14 independent effective field theory (EFT) operators to describe WIMP-nucleon interactions. In addition to spin-independent and spin-dependent nuclear responses, these operators can produce novel responses such as angular-momentum-dependent and spin-orbit couplings. Here we report on a search for all 14 of these EFT couplings with data from LUX's first science run. Limits are placed on each coupling as a function of WIMP mass.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Reconstructing 3D Charge Depositions in the MicroBooNE Liquid Argon Time Projection Chamber using Convolutional Neural Networks

We have developed a convolutional neural network (CNN) that reconstructs the three dimensional location of ionization produced by charge particles traversing a wire-readout liquid argon time projection chamber (LArTPC) at MicroBooNE. This method is the first CNN application to reconstruct 3D space points directly from two dimensional images of the different wire plane views. I.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRSDate not supplied

Magnetic Measurements of Arc Instabilities in Segmented Arc Heater Column

The Aerodynamic Heating Facility (AHF) at NASA Ames Research Center (ARC) generates high enthalpy, supersonic flow environments for ground testing of NASAheat shield materials. This arc jet heater operates by passing a DC arc (<3200A,<2500V) through a gas column (~10cm diameter, 2m length) and ejecting the heatedgas through a supersonic nozzle into a test chamber. The arc plasma is a partially ionized air mixture at low temperature (< 2eV) but needs to be stable for long test times (up to 30min) at high power (< 20MW). Currently, the operational envelope of the facility is limited by arc instabilities including the kink instability. Consequently, it is of interest to characterize these instabilities to better understand facility limits and inform methods to extend stable operational ranges. Due to the high enthalpy and long timescales (i.e., minutes) diagnostics must be non-invasive. This work will cover the development of two sets of magnetic sensors: differential B-dot sensors and tri-axial magnetic hall sensors and will describe initial measurements of arc motion usingthese sensors.

Kink instability↗
NASA NTRSDate not supplied

Magnetic Measurements of Arc Instabilities in Segmented Arc Heater Column

The Aerodynamic Heating Facility (AHF) at NASA Ames Research Center (ARC) generates high enthalpy, supersonic flow environments for ground testing of NASAheat shield materials. This arc jet heater operates by passing a DC arc (<3200 A,<2500 V) through a gas column (~6 cm diameter, 2 m length) and ejecting the heated gas through a supersonic nozzle into a test chamber. The arc plasma is a partially ionized air mixture at low temperature (< 2 eV) but needs to be stable for long test times (up to 30 min) at high power (< 20 MW). Currently, the operational envelope of the facility is limited by arc instabilities including the kink instability. Consequently, it is of interest to characterize these instabilities to better understand facility limits and inform methods to extend stable operational ranges. Due to the high enthalpy and long timescales (i.e., minutes) diagnostics must be non-invasive. This work will cover the development of two sets of magnetic sensors: differential B-dot sensors and tri-axial magnetic hall sensors and will describe initial measurements of arc motion using these sensors.

Kink instability↗
DOE OSTI2025

Operation of the trigger system for the ICARUS detector at Fermilab

The ICARUS liquid argon TPC detector is taking data on the Booster (BNB) and Main Injector (NuMI) Neutrino beam lines at Fermilab with a trigger system based on the scintillation light produced by charged particles in coincidence with the proton beam extraction from the accelerators. The architecture and the deployment of the trigger system in the first two runs for physics are presented, as well as the triggered event rates. The event recognition efficiency has been evaluated as a function of the deposited energy and the position of cosmic muons stopping inside the detector.

Neutrino detectors↗
NASA NTRS1992

Detecting X-rays with an optical imaging chamber

The light emitted by electron avalanches in a parallel plate chamber can be used to image the tracks of photoelectrons liberated by the interaction of an incident X-ray with the gas filling the chamber. The different morphologies of photoelectron tracks and minimum ionizing tracks can be used for charged particle rejection. The initial direction (before scattering) of the liberated photoelectron also contains information about the polarization of the incident radiation. We have built a small test chamber with which we have imaged photoelectron tracks using an intensified CCD camera. Our results show that optical imaging could be used in a hard X-ray imaging polarimeter useful for astronomy.

Austin, Robert A.↗
NASA NTRS1992

The emulsion chamber technology experiment

Photographic emulsion has the unique property of recording tracks of ionizing particles with a spatial precision of 1 micron, while also being capable of deployment over detector areas of square meters or 10's of square meters. Detectors are passive, their cost to fly in Space is a fraction of that of instruments of similar collecting. A major problem in their continued use has been the labor intensiveness of data retrieval by traditional microscope methods. Two factors changing the acceptability of emulsion technology in space are the astronomical costs of flying large electronic instruments such as ionization calorimeters in Space, and the power and low cost of computers, a small revolution in the laboratory microscope data-taking. Our group at UAH made measurements of the high energy composition and spectra of cosmic rays. The Marshall group has also specialized in space radiation dosimetry. Ionization calorimeters, using alternating layers of lead and photographic emulsion, to measure particle energies up to 10(exp 15) eV were developed. Ten balloon flights were performed with them. No such calorimeters have ever flown in orbit. In the ECT program, a small emulsion chamber was developed and will be flown on the Shuttle mission OAST-2 to resolve the principal technological questions concerning space exposures. These include assessments of: (1) pre-flight and orbital exposure to background radiation, including both self-shielding and secondary particle generation; the practical limit to exposure time in space can then be determined; (2) dynamics of stack to optimize design for launch and weightlessness; and (3) thermal and vacuum constraints on emulsion performance. All these effects are cumulative and affect our ability to perform scientific measurements but cannot be adequately predicted by available methods.

Gregory, John C.↗