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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 1,225 records · Page 68
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Potential for neutron and proton transmutation doping of GaN and Ga 2 O 3

As the potential applications of GaN and Ga 2 O 3 are limited by the inadequacy of conventional doping techniques, specifically when uniform selective area p-type doping is required, the potential for transmutation doping of these materials is analyzed. All transmuted element concentrations are reported as a function of time for several common proton and neutron radiation sources, showing that previously published results considered a small subset of the dopants produced. A 40 MeV proton accelerator is identified as the most effective transmutation doping source considered, with a 2.25 × 10 17 protons per cm 2 fluence yielding net concentrations of uncompensated p-type dopants of 7.7 × 10 15 and 8.1 × 1015 cm -3 for GaN and Ga 2 O 3 , respectively. Furthermore, it is shown that high energy proton accelerator spectra are capable of producing dopants required for magnetic and neutron detection applications, although not of the concentrations required for current applications using available irradiation methods.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Evaluating a Transition-jump System for the Fermilab Main Injector Using Xsuite

We describe an Xsuite simulation framework for the Fermilab Main Injector (MI) along with an evaluation of transition-crossing behaviors in the accelerator. In particular, we studied the introduction of quadrupole magnets into the lattice as part of a transition-jump system that will be implemented through the $2^{nd}$ Proton Improvement Plan (PIP-II). Simulated beam losses spurred by transition-induced instabilities were assessed under several systematic effects, including MI quad errors, magnet-to-magnet variability in the jump magnets, power-supply errors, and timing jitter.

Schreckenberger, A. P. [Fermilab] (ORCID:000000016↗
DOE OSTI2020

MQXFA Magnets (Rev.1.5)

This document specifies the functional requirements for the High Luminosity LHC (HL-LHC, or HiLumi LHC) MQXFA Magnets. Twenty (20) of these magnets shall be fabricated and delivered to CERN by the U.S. HiLumi project as part to the U.S. contributions to the LHC High Luminosity Upgrade. These magnets are the quadrupole magnetic components of the HL-LHC Q1 and Q3 inner triplet optical elements in front of the interaction points 1 (ATLAS) and 5 (CMS). Two MQXFA magnets are installed in each Q1 or Q3. Since these magnets are identical whether installed in Q1 or Q3, the functional requirements are identical for all MQXFA magnets.

43 PARTICLE ACCELERATORS↗
DOE OSTI2025

Evaluating a Transition-Jump System for the Fermilab Main Injector Using Xsuite

We describe an Xsuite simulation framework for the Fermilab Main Injector (MI) along with an evaluation of transition-crossing behaviors in the accelerator. In particular, we studied the introduction of quadrupole magnets into the lattice as part of a transition-jump system that will be implemented through the $2^{nd}$ Proton Improvement Plan (PIP-II). Simulated beam losses spurred by transition-induced instabilities were assessed under several systematic effects, including MI quad errors, magnet-to-magnet variability in the jump magnets, power-supply errors, and timing jitter.

Schreckenberger, Adam Paul [Fermilab] (ORCID:00000↗
DOE OSTI2023

Spatial Intermittency of Particle Distribution in Relativistic Plasma Turbulence

Abstract Relativistic magnetically dominated turbulence is an efficient engine for particle acceleration in a collisionless plasma. Ultrarelativistic particles accelerated by interactions with turbulent fluctuations form nonthermal power-law distribution functions in the momentum (or energy) space, f ( γ ) d γ ∝ γ − α d γ , where γ is the Lorenz factor. We argue that in addition to exhibiting non-Gaussian distributions over energies, particles energized by relativistic turbulence also become highly intermittent in space. Based on particle-in-cell numerical simulations and phenomenological modeling, we propose that the bulk plasma density has lognormal statistics, while the density of the accelerated particles, n , has a power-law distribution function, P ( n ) dn ∝ n − β dn . We argue that the scaling exponents are related as β ≈ α + 1, which is broadly consistent with numerical simulations. Non-space-filling, intermittent distributions of plasma density and energy fluctuations may have implications for plasma heating and for radiation produced by relativistic turbulence.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1974

Effect of small flares in the neutral component of secondary cosmic radiation

The results are presented of an investigation of the effect of small flares, scale divisions 1 and 1(+), in the neutron component of secondary cosmic radiation from the data of neutron supermonitors at the stations of Kiev, Bukhta Tiksi, and Deep River. It is shown that flares of scale divisions 1 and 1(+) are accompanied by an effect in the neutron component amounting to about 0.4%. A mechanism is presented for calculating the outflow of particles accelerated in small flares, owing to diffusion across the magnetic field of a trap.

Bondarenko, V. I.↗
NASA NTRS1976

Accretion onto magnetized neutron stars - Normal mode analysis of the interchange instability at the magnetopause

Results are reported for a linearized hydromagnetic stability analysis of the magnetopause of an accreting neutron star. The magnetosphere is assumed to be slowly rotating, and the plasma just outside the magnetopause is assumed to be weakly magnetized. The plasma layer is assumed to be bounded above by a shock wave and to be thin compared with the radius of the magnetosphere. Under these circumstances, the growing modes are shown to be localized in the direction parallel to the zero-order magnetic field, but the structure of the modes is still similar to the flute mode. An expression for the growth rate at each magnetic latitude is obtained in terms of the magnitude of the gravitational acceleration normal to the surface, the azimuthal mode number, the radius of the magnetosphere, the height of the shock above the magnetopause, and the effective Atwood number which embodies the stabilizing effects of favorable curvature and magnetic tension. The effective Atwood number is calculated, and the stabilizing effects of viscosity and aligned flow parallel to the magnetopause are discussed.

Arons, J.↗
NASA NTRS1978

Z-rich solar particle event characteristics 1972-1976

It is found in the reported investigation that Z-rich solar particle events usually have large and prolonged anisotropies in addition to an extremely variable charge composition that varies not only from event to event but also throughout the event. These observations suggest that one can no longer regard the event-averaged composition of solar particle events at low energies as providing an unbiased global sample of the solar atmospheric composition. The variability from event to event and among classes of events is just too great. However, the tendency for the Z-rich events to be associated with both the low-speed solar wind at or just before the onset of solar wind streams and with active regions located in the western hemisphere, indicates that charge composition studies of solar particle events can yield a better knowledge of the flare acceleration process as well as the inhomogeneous nature of magnetic field structure and particle composition in the solar atmosphere.

Zwickl, R. D.↗
NASA NTRS1979

Several recent findings concerning the dynamics of the earth's magnetotail

Several recent results concerning the nature of earth's magnetotail are briefly reviewed. These observational findings include: (1) the three-dimensional character of the plasma sheet via a comprehensive survey of proton bulk flows, (2) a region of earthward-flowing plasmas at the interfaces of the plasma sheet and magnetotail lobes during magnetic substorm recovery, and (3) the signature of electrostatic acceleration for protons within the jetting plasmas from magnetotail fireballs.

Frank, L. A.↗
NASA NTRS1985

Ultrarelativistic electrons and solar flare gamma-radiation

Ten solar flares with gamma radiation in excess of 10 MeV were observed. Almost all took place within a heliolatitude greater than 60 deg, close to the solar limb, an indication of the essential anisotropy of high-energy gamma radiation. This high-energy solar flare gamma radiation can be explained by the specific features of the bremsstrahlung of ultrarelativistic electrons trapped within the magnetic arc of the solar atmosphere, even if the acceleration of the electrons is anisotropic.

Semukhin, P. E.↗
NASA NTRS1990

Plasma flow reversals at the dayside magnetopause and the origin of asymmetric polar cap convection

Events observed in a fast plasma experiment, where the y-component of the plasma flow within the low latitude boundary layer and magnetopause current layer was oppositely directed to that in the adjacent magnetosheath, are examined. The observations are shown to be qualitatively and quantitatively consistent with previous observations of accelerated flows at the magnetopause and with models of magnetic reconnection, with reconnection occurring at low latitudes near the GSE XY plane, independently of the magnitude or the sign of the y-component ot the local magnetosheath magnetic field. Local magnetic shears at the magnetopause for these events (in 60-180 deg range) and the fact that these events occur at low latitudes do not support the antiparallel merging hypothesis. The observations of B(y)-dependent flow reversals demonstrate how the asymmetric polar cap convection and related phenomena, such as the Svalgaard-Mansurov effect, originate in magnetic reconnection at the dayside magnetopause.

Gosling, J. T.↗
NASA NTRS1991

Multi-wave band SMM-VLA observations of an M2 flare and an associated coronal mass ejection

Results are presented of observations of an M2 flare and an associated coronal mass ejection CME by instruments on the SMM as well as by the VLA and other ground-based observatories on September 30, 1988. The multiwave band data show a gradual slowly changing event which lasted several hours. The microwave burst emission was found to originate in compact moderately circularly polarized sources located near the sites of bright H-alpha and soft X-ray emission. These data are combined with estimates of an electron temperature of 1.5 x 10 to the 7th K and an emission measure of about 2.0 x 10 to the 49th/cu cm obtained from Ca XIX and Fe XXV spectra to show that the microwave emission can be attributed to thermal gyrosynchrotron radiation in regions where the magnetic field strength is 425-650 G. The CME acceleration at low altitudes is measured on the basis of ground- and space-based coronagraphs.

Willson, Robert F.↗
NASA NTRS1992

On chaotic conductivity in the magnetotail

The concept of chaotic conductivity and the acceleration of particles due to a constant dawn dusk electric field are studied in a magnetotail-like magnetic field. A test particle simulation is used including the full nonlinear dynamics. It is found that the acceleration process can be understood without invoking chaos and that the cross tail current is determined by the particle dynamics and distributions. It is concluded that in general there is no simple relationship between the electric field and the current.

Holland, Daniel L.↗
NASA NTRS1994

Magnetobraking: Use of tether electrodynamic drag for Earth return from Mars

It has often been proposed that a vehicle returning from Mars will use aerobraking in the Earth's atmosphere to dissipate hyperbolic excess velocity to capture into Earth orbit. Here a different system for dissipating excess velocity without expenditure of reaction mass, magnetobraking, is proposed. Magnetobraking uses the force on an electrodynamic tether in the Earth's magnetic field to produce thrust. An electrodynamic tether is deployed from the spacecraft as it approaches the Earth. The Earth's magnetic field produces a force on electrical current in the tether. If the tether is oriented perpendicularly to the Earth's magnetic field and to the direction of motion of the spacecraft, force produced by the Earth's magnetic field can be used to either brake or accelerate the spacecraft without expenditure of reaction mass. The peak acceleration on the Mars return is 0.007 m/sq sec, and the amount of braking possible is dependent on the density and current-carrying capacity of the tether, but is independent of length. A superconducting tether is required. The required critical current is shown to be within the range of superconducting technology now available in the laboratory.

Landis, Geoffrey A.↗
NASA NTRS1989

Overview of the Center for Advanced Space Propulsion

The mission of the Center for Advanced Space Propulsion (CASP), a Center for the Commercial Development of Space (CCDS), is to strengthen U.S. competitiveness in space technology, foster cooperative research with industry and government, assist industry in developing commercial products and services, and perform research in advanced space propulsion. Current areas of focus are (1) advanced chemical propulsion, including high area ratio nozzle performance, variable thrust engine performance, and spray combustion stability; (2) artificial intelligence propulsion applications, including health monitoring of rocket engines, fault pattern detection and diagnosis, and intelligent hypertext applications; (3) microgravity fluid management, including liquid storage and transfer, a subscale orbital fluid transfer experiment, and helical, two-phase flow; (4) electric propulsion, including magnetic annular arc thruster, ion thrustor, and electrostatic plasma accelerator; and (5) laser materials processing.

George W Garrison↗
NASA NTRS1997

What Drives the Outflows in Broad Absorption Line QSOs?

We have made progress in the areas related to the propulsion and confinement of gas responsible for broad absorption troughts in QSOs: Radiative Acceleration in BALQSOs; The "Ghost" of Lyman (alpha); and Magnetic Confinement of Absorbing Gas.

Begelman, Mitchell C.↗
NASA NTRS2005

Loss of Water from Saturn's E-Ring Through Ion Pick-Up

One of the possible loss processes for Saturn s E-ring is ionization followed by acceleration by the electric field associated with the corotating magnetized plasma. It is possible to determine if this process is occurring by detecting electromagnetic waves at the gyrofrequency of water group ions. If the energy the particle gains in this pick-up process is sufficiently great, the picked up ions will generate ion cyclotron waves. Pioneer 11 and Voyager 1 both observed intervals of such waves associated with water group ions during their passes through Saturn s E-ring. Presently the magnetometer onboard the Cassini spacecraft is also seeing water group ion cyclotron oscillations. The Cassini data allow the spatial and temporal behavior of the waves to be mapped in ways not possible during the previous flybys. Analyses of these waves allow us to study the rate of mass loading and its latitudinal and local time variation. In conjunction with previous data, we can then determine the variation as the inclination of the ring to the Sun changes, in accordance with Saturn's seasons. These waves may be the clue to how Saturn powers its magnetosphere as the newly born ions could be the driver for the radial motion of the plasma and to how the E-ring may play the equivalent role to that of Io in the jovian magnetosphere.

Leisner, J. S.↗