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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 109 records · Page 6

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NASA NTRS1993

TSS-1 - Orbiter current and voltage experiments

Although the deployment distance of the TSS-1 tethered satellite was only about 1 percent of nominal, experiments to study the current collection and vehicle charging effects at low voltages were performed. We present measurements of Orbiter charging resulting from electron beam emission from the Orbiter, currents in the TSS system with and without electron beam emissions, and the effects of Orbiter thrusters on charging and currents. Generally, charging induced by beam emission was limited to a few volts, though during times with low ambient plasma density the Orbiter was charged up to 80 V. Thrusters are seen to enhance Orbiter charging during beam emission, and reduce ion current collection at other times.

Thompson, D. C.↗

DOE OSTI2020

Magnetic electron collimation in three-dimensional semi-metals

While electrons moving perpendicular to a magnetic field are confined to cyclotron orbits, they can move freely parallel to the field. This simple fact leads to complex current flow in clean, low carrier density semi-metals, such as long-ranged current jets forming along the magnetic field when currents pass through point-like constrictions. Occurring accidentally at imperfect current injection contacts, the phenomenon of "current jetting" plagues the research of longitudinal magneto-resistance, which is particularly important in topological conductors. Here we demonstrate the controlled generation of tightly focused electron beams in a new class of micro-devices machined from crystals of the Dirac semi-metal Cd 3 As 2 . The current beams can be guided by tilting a magnetic field and their range tuned by the field strength. Finite element simulations quantitatively capture the voltage induced at faraway contacts when the beams are steered towards them, supporting the picture of controlled electron jets. These experiments demonstrate direct control over the highly non-local signal propagation unique to 3D semi-metals in the current jetting regime, and may lead to applications akin to electron optics in free space.

36 MATERIALS SCIENCE↗

DOE OSTI2026

Electron-irradiation induced creep in amorphous alloys

Electron-irradiation induced creep rates in amorphous alloys, a-SiO2, Fe79B16Si5, Cu60Ta40, and Cu50Ti50, were measured at room temperature using a miniaturized beam-bending apparatus within a transmission electron microscope operated at 200 keV. The creep rates of these amorphous samples increased nearly linearly with both e-beam current density and applied stress, while a reference crystalline (c-)SiO2 sample failed to creep under the same conditions. The irradiation induced creep compliance of a-SiO2 was ~ 15 times larger than that of Fe79B16Si5 and over 1,000 times larger than that of the two Cu alloys. Molecular dynamics computer simulations were employed to simulate electron irradiation induced creep using interatomic potentials representing amorphous Cu75Zr25, Ni80P20, and SiO2 as model systems. The irradiation induced creep compliances calculated for Cu75Zr25 during 200 keV electron irradiation provided good quantitative agreement with the two Cu-based alloys, but that for a-SiO2 was ~ 180 times too small. These results indicate that unlike neutron or ion-beam induced creep in a-SiO2, creep under electron irradiation is dominated by the effects of ionization owing largely to the far higher ratio of electronic stopping to nuclear stopping for electrons than for ions.

36 MATERIALS SCIENCE↗

DOE OSTI2022

Eddy current studies for the beam screen of the Electron-Ion Collider hadron storage ring superconducting magnets

A copper-clad stainless steel beam screen will be installed in each of the Relativistic Heavy Ion Collider (RHIC) superconducting (SC) magnets used for making the Electron-Ion Collider (EIC) Hadron Storage Ring (HSR). Eddy currents are induced within conductors to oppose a changing magnetic flux. Eddy currents will appear on the EIC HSR beam screens during ramp up and ramp down, after a magnet quenches and when reversing the polarity of the γ transition jump quadrupoles during γ transition crossing. This study evaluates the magnitude of the eddy currents, the temperature increase due to Joule heating and the stress at the beam screens from the eddy-current induced force.

43 PARTICLE ACCELERATORS↗

NASA NTRS1988

Spacelab 1 experiments on interactions of an energetic electron beam with neutral gas

An unusual signature of return current and spacecraft charging potential was observed during the Spacelab 1 mission launched on November 28, 1983. The phenomenon occurred during neutral gas releases from the SEPAC (Space Experiments with Particle Accelerators) magnetoplasma-dynamic arcjet (MPD) concurrent with firings of the PICPAB (Phenomena Induced by Charged Particle Beams) electron gun and was recorded by the instruments of the SEPAC diagnostic package (DGP). Data from the langmuir probe, floating probes, neutral gas pressure gauge, and the plasma wave probes are reported. As the dense neutral gas was released, the return current measured by the langmuir probe changed from positive to negative and a positive potential relative to the spacecraft was measured by the floating probe. The anomalous return current is believed to be attributable to secondary electron fluxes escaping from the spacecraft, and the unusual charging situation is attributed to the formation of a double-layer structure between a hot plasma cloud localized to the MPD and the spacecraft. The charging scenario is supported by a computer simulation.

Marshall, J. A.↗

DOE OSTI2026

Evaluation of the beam-induced depolarization of the HJET target at the EIC

The Polarized Atomic Hydrogen Gas Jet Target (HJET) has played a central role in the absolute calibration of proton beam polarization at RHIC and is foreseen as a key component of the hadron polarimetry program at the future Electron–Ion Collider (EIC). The substantially higher beam current, reduced bunch spacing, and shorter bunch length planned for EIC operation motivate a careful reassessment of possible beam-induced depolarization of the jet target. In this paper, the depolarization of ground-state hydrogen atoms caused by the time-dependent magnetic field of the circulating polarized proton beam is quantitatively evaluated. The hydrogen atom is treated as a four-level hyperfine system in a holding magnetic field, and transitions driven by harmonic components of the bunch-induced magnetic field are analyzed using time-dependent quantum-mechanical evolution along atomic trajectories. Numerical tracking of hydrogen atoms through the beam region is performed using nominal EIC beam parameters. It is shown that, for a holding field of 120 mT (as used at RHIC), the resulting depolarization of the jet target at the EIC is negligibly small, ≲ 0.01 %, and well below the level relevant for EIC polarization accuracy requirements. The stability of this result with respect to plausible variations of the EIC proton beam parameters is also evaluated. In addition, possible effects under alternative experimental conditions are also examined.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

NASA NTRS1973

A new technique for Auger analysis of surface species subject to electron-induced desorption

Pepper, S. V.↗

DOE OSTI2025

Parametric raytracing modeling for NSTX-U scenario development with high harmonic fast waves and neutral beam injection

High harmonic fast waves (HHFW) are a versatile heating and current drive tool for scenario development. Extensive modeling scans were performed to find optimal parameters for different uses of HHFW in National Spherical Tokamak Experiment (NSTX-U). Scans of plasma density, temperature, magnetic field, and antenna phasing were performed both with and without neutral beam injection. For speed of calculation, the ray-tracing code GENRAY coupled to the quasilinear Fokker–Planck code CQL3D was used. CQL3D allows for a more accurate description of the fast ion population, as well as for quasilinear effects such as HHFW-induced modifications of the distribution function. Best current drive results are obtained at elevated electron temperatures and with the lowest k φ phasing. Adding neutral beams however typically strongly reduces the HHFW current drive efficiency at the low density cases due to HHFW absorption on beam ions. Results of this parametric study will feed into scenario development and predict-first whole-shot modeling of NSTX-U discharges.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2025

Mitigating Battery Cell Failure: Role of Ag‐Nanoparticle Fillers in Solid Electrolyte Dendrite Suppression

Abstract The development of solid‐state batteries (SSBs) with lithium Li metal anodes holds significant promise for enhancing the energy density and safety of next‐generation energy storage systems. However, their commercialization is hindered by challenges related to Li dendrite formation, which can lead to short circuits and battery failure. In this study, the role of Ag nanoparticles embedded within solid electrolytes (SE) is investigated in suppressing dendrite propagation. The results demonstrate that Ag nanoparticles effectively mitigate two key failure mechanisms: (1) dendrite growth within porous networks at low current densities and (2) stress intensification‐induced SE fracture at higher current densities (12 mA cm −2 ). Ex situ characterization using focused‐ion beam – scanning electron microscopy (FIB–SEM) and energy dispersive X‐ray spectroscopy (EDS,) reveals that Ag nanoparticles migrate alongside advancing Li dendrites, promoting homogeneous dendrite growth and reducing the likelihood of localized stress concentrations. Additionally, the incorporation of Ag nanoparticles is shown to facilitate a more uniform Li distribution toward the anode side, which can potentially enable the use of higher charging rates in SSBs. This study provides a new perspective on Li dendrite suppression and presents new opportunities for enhancing the performance and safety of SSBs.

Diallo, Mouhamad Said↗

DOE OSTI2024

Luminosity and beam-induced background studies for the Cool Copper Collider

A high-energy electron-positron collider has been widely recognized by the particle physics community to be the next crucial step for detailed studies of the Higgs boson and other fundamental particles and processes. Several proposals for such colliders, either linear or circular, are currently under evaluation. Any such collider will be required to reach high lumimosities, in order to collect enough data at a reasonable time scale, while at the same time coping with high rates of background particles produced from beam-beam interactions during the collisions. In this paper, we analyze the luminosity and beam-beam interaction characteristics of the Cool Copper Collider ( C 3 ) and perform a comparison with other linear collider proposals. We conclude that C 3 can reach the same or higher collision rates as the other proposals, without having to cope with higher beam-induced background fluxes. Thus, C 3 emerges as an attractive option for a future electron-positron collider, benefiting from the collective advancements in beam delivery and final focus system technologies developed by other linear collider initiatives. Published by the American Physical Society 2024

43 PARTICLE ACCELERATORS↗

DOE OSTI2025

XeF 2 gas assisted focused electron beam induced etching of niobium thin films: towards direct write editing of niobium superconducting devices

Focused electron beam induced etching (FEBIE) of Nb films produced a maximum etching yield of 3 Nb atoms/e − while varying beam energy, beam current, dwell time, and XeF 2 precursor working pressure. An optimized etch resolution of 17 nm was achieved.

Gellerup, Spencer [Department of Material Science ↗

DOE OSTI2021

Measurement of Poly-Si Film Thickness on Textured Surfaces by X-Ray Diffraction in Poly-Si/SiOx Passivating Contacts for Monocrystalline Si Solar Cells

Polycrystalline Silicon on tunneling silicon oxide (poly-Si/SiOx) passivating contacts have shown great potential for the next-generation monocrystalline Si (c-Si) industrial photovoltaic technology. However, these cells typically suffer from strong parasitic absorption in the thick front poly-Si layer, which is designed to reduce metal-induced recombination. In previous work, we demonstrated an improved short-circuit current density, Jsc, by thinning the front poly-Si film in an SF6 plasma using the front metal grids as a self-aligned mask, but the sub - 100 nm thick poly-Si film is difficult to measure on an alkaline textured surface. Conventional optical techniques such as spectroscopic ellipsometry cannot be used due to the high scattering nature of the random pyramids. At poly-Si thicknesses below 50 nm, secondary electron microscopy (SEM) has difficulty distinguishing the poly-Si from the underlying c-Si substrate. Here, we demonstrate X-ray diffraction as an effective method to quantitatively measure the front poly-Si thickness. The thickness calculated from the diffraction peak height of the Si(111) crystallographic plane agrees well with the cross-section SEM analysis and simulations using SunSolve. We show that by thinning the front poly-Si from 200 to 60 nm, Jsc increased by 2.4 mA/cm2, while maintaining the same Voc. This led to an absolute efficiency gain of 1.73%. In addition, we also discuss possible reasons for the premature loss of passivation before the removal of all poly-Si, which prevented an even higher gain in Jsc.

light/electron beam induced current↗

NASA NTRS1973

A new technique for Auger analysis of surface species subject to electron-induced desorption.

A method is presented to observe surface species subject to electron-induced desorption by Auger electron spectroscopy. The surface to be examined is moved under the electron beam at constant velocity, establishing a time-independent condition and eliminating the time response of the electron spectrometer as a limiting factor. The dependence of the Auger signal on the sample velocity, incident electron current, beam diameter, and desorption cross section is analyzed. It is shown that it is advantageous to analyze the moving sample with a high beam current, in contrast to the usual practice of using a low beam current to minimize desorption from a stationary sample. The method is illustrated by the analysis of a friction transfer film of PTFE, in which the fluorine is removed by electron-induced desorption. The method is relevant to surface studies in the field of lubrication and catalysis.

Pepper, S. V.↗

DOE OSTI2021

Impact of Coherent Beam-Beam Interaction on the Collisionless Damping of the Transverse Coupled-Bunch Instability

In the EIC design, at high average-current operation, the transverse coupled-bunch instability (TCBI) induced by the long-range transverse resistive-wall wakefield in the electron storage ring (eSR) has a fast growth rate and requires efficient mitigation. A natural mitigation mechanism is provided by the beam-beam interaction at the interaction point (IP), which gives a strong Landau damping for the TCBI in the eSR. In this study, using a simplified simulation model, we investigate how this Landau damping from the beam-beam interaction behaves when the coherent beam-beam interaction at IP is considered. Our method and results will be presented in this paper.

Li, R.↗

DOE OSTI2020

Direct Write of 3D Nanoscale Mesh Objects with Platinum Precursor via Focused Helium Ion Beam Induced Deposition

The next generation optical, electronic, biological, and sensing devices as well as platforms will inevitably extend their architecture into the 3rd dimension to enhance functionality. In focused ion beam induced deposition (FIBID), a helium gas field ion source can be used with an organometallic precursor gas to fabricate nanoscale structures in 3D with high-precision and smaller critical dimensions than focused electron beam induced deposition (FEBID), traditional liquid metal source FIBID, or other additive manufacturing technology. In this work, we report the effect of beam current, dwell time, and pixel pitch on the resultant segment and angle growth for nanoscale 3D mesh objects. We note subtle beam heating effects, which impact the segment angle and the feature size. Additionally, we investigate the competition of material deposition and sputtering during the 3D FIBID process, with helium ion microscopy experiments and Monte Carlo simulations. Our results show complex 3D mesh structures measuring ~300 nm in the largest dimension, with individual features as small as 16 nm at full width half maximum (FWHM). These assemblies can be completed in minutes, with the underlying fabrication technology compatible with existing lithographic techniques, suggesting a higher-throughput pathway to integrating FIBID with established nanofabrication techniques.

36 MATERIALS SCIENCE↗

NASA NTRS1982

Early experiments in charged particle beams from the Space Shuttle

Characteristics of studies on board the Shuttle involving the interaction of particle beams with the atmosphere and the ionosphere, and the effects of the beams on the electrical potential of the platform, are discussed. Noting that the Shuttle allows greater weight and power demands by scientific payloads than previous satellite launches, the OSS-1 Vehicle Charging and Potential experiment and the Spacelab 1 Particle Accelerator and Phenomena Induced by Charged Particle Beams are described. Instrumentation details are provided, including charge and current probes, the Spherical Retarding Potential Analyzer, the Fast Pulse Electron Generator, and digital control and interface units. The SEPAC equipment, which comprises an electron beam accelerator, and MPD plasma jet, and diagnostic units are detailed, and operating procedures and experiment objectives are outlined.

Raitt, W. J.↗

NASA NTRS1990

Electron-impact ionization and electron attachment cross sections of radicals important in transient gaseous discharges

Electron-impact ionization and electron attachment cross sections of radicals and excited molecules were measured using an apparatus that consists of an electron beam, a molecular beam and a laser beam. The information obtained is needed for the pulse power applications in the areas of high power gaseous discharge switches, high energy lasers, particle beam experiments, and electromagnetic pulse systems. The basic data needed for the development of optically-controlled discharge switches were also investigated. Transient current pulses induced by laser irradiation of discharge media were observed and applied for the study of electron-molecule reaction kinetics in gaseous discharges.

Lee, Long C.↗

NASA NTRS1984

High time resolution measurements of rocket potential changes induced by electron beam emission

The transient charging and photon emission from the vacuum chamber testing of the Cooperative High Altitude Rocket Gun Experiment are studied. Graphs of the mother-daughter voltage versus time and high time resolution data related to the return current to the vehicle are examined. It is observed that for average sounding rocket densities of 10 to the -6th torr the slope of the voltage rise of the rocket begins to flatten 40 microsec after the onset of electron beam emission, and for higher gas pressure the rocket reaches a maximum voltage of 25 or 30 microsec after the onset of electron beam emission. The data reveal that the return current mechanism for the higher gas pressure is through the sheath.

Raitt, W. J.↗