Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Magnetic source”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,171 records · Page 65
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

On ultrafast x-ray scattering methods for magnetism

With the introduction of x-ray free electron laser sources around the world, new scientific approaches for visualizing matter at fundamental length and time-scales have become possible. As it relates to magnetism and ‘magnetic-type’ systems, advanced methods are being developed for studying ultrafast magnetic responses on the time-scales at which they occur. We describe three capabilities which have the potential to seed new directions in this area and present original results from each: pump-probe x-ray scattering with low energy excitation, x-ray photon fluctuation spectroscopy, and ultrafast diffuse x-ray scattering. By combining these experimental techniques with advanced modeling together with machine learning, we describe how the combination of these domains allows for a new understanding in the field of magnetism. Finally, we give an outlook for future areas of investigation and the newly developed instruments which will take us there.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS2019

Results of NASA's Magnetic Gear Program to Date

In rotorcraft, one of the main sources of mechanical failure is the gearbox, because of the many wear and failure modes associated with tooth contact in traditional mechanical gear boxes. Magnetic gears transmit torque without mechanical tooth contact between gear bodies and therefore they have none of the tooth contact related failure modes associated with mechanical gearing. As a result, magnetic gears have the potential to enable more reliable rotorcraft gearboxes. However, magnetic gears have not been demonstrated to match the performance of mechanical gearboxes at a high enough technology readiness level (TRL) to be used on an aircraft to date. To that end, NASA's Revolutionary Vertical Lift Technologies project has made an investment in developing magnetic gearboxes specifically for electrified vertical lift vehicles (EVTOL). In this presentation, the results of that investment to date will be discussed.

Tallerico, Thomas↗
DOE OSTI2016

THE HIGHEST-ENERGY COSMIC RAYS CANNOT BE DOMINANTLY PROTONS FROM STEADY SOURCES

The bulk of observed ultrahigh-energy cosmic rays could be light or heavier elements and originate from an either steady or transient population of sources. This leaves us with four general categories of sources. Energetic requirements set a lower limit on single-source luminosities, while the distribution of particle arrival directions in the sky sets a lower limit on the source number density. The latter constraint depends on the angular smearing in the skymap due to the magnetic deflections of the charged particles during their propagation from the source to the Earth. We contrast these limits with the luminosity functions from surveys of existing luminous steady objects in the nearby universe and strongly constrain one of the four categories of source models, namely, steady proton sources. The possibility that cosmic rays with energy >8 × 10{sup 19} eV are dominantly pure protons coming from steady sources is excluded at 95% confidence level, under the safe assumption that protons experience less than 30° magnetic deflection on flight.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2018

Phase-control synthesis and catalytic property of magnetic Ni@NixPy core-shell microstructures

Highlights: • Ni@Ni{sub x}P{sub y} core-shell microstructures are synthesized by a low-temperature phosphidation route. • The initial Ni/NaH{sub 2}PO{sub 2} molar ratio can strongly affect the phase of the final product. • Ni@Ni{sub x}P{sub y} microstructures present good catalytic activity for the reduction of 4-nitrophenol. • The catalytic property of Ni@Ni{sub x}P{sub y} microstructures presents markedly phase-dependent features. - Abstract: Magnetic Ni@Ni{sub x}P{sub y} core-shell microstructures were successfully synthesized by a simple low-temperature phosphidation route, employing Ni nanospheres as the initial nickel source, NaH{sub 2}PO{sub 2}·H{sub 2}O as the phosphorus ion source. The phosphidation reaction was carried out in N{sub 2} atmosphere at 300 °C for 2 h. Experiments showed that the initial Ni/NaH{sub 2}PO{sub 2} molar ratio could strongly affect the phase of the final product. When the Ni/NaH{sub 2}PO{sub 2} molar ratio of 1:2.77 was used, hexagonal Ni{sub 2}P phase was obtained; while the Ni/NaH{sub 2}PO{sub 2} molar ratio was 1:5.54, hexagonal Ni{sub 5}P{sub 4} phase was produced. It was found that the magnetic properties of the products gradually decreased with the conversion from Ni nanospheres, to Ni@Ni{sub 2}P and to Ni@Ni{sub 5}P{sub 4}. Moreover, initial Ni nanospheres, Ni@Ni{sub 2}P and Ni@Ni{sub 5}P{sub 4} core-shell microstructures presented outstanding catalytic activities for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in excess NaBH{sub 4} solution. Ni@Ni{sub 5}P{sub 4} core-shell microstructures owned the best catalytic activity.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2023

Progress with applications of three-ion ICRF scenarios for fusion research: A review

The viability of magnetic confinement fusion as an energy source depends on achieving the high ion temperatures required for D-T fusion. Among the available techniques, plasma heating with waves in the ion cyclotron range of frequencies (ICRF) is a prominent method for bulk ion heating in fusion plasmas. Furthermore, a detailed understanding of the non-linear physics of alpha heating and the complex impact of MeV-range fast ions on plasma dynamics becomes progressively more important. This paper provides a comprehensive overview of recent developments with the three-ion ICRF scenarios on Alcator C-Mod, ASDEX Upgrade and JET tokamaks. The results demonstrate the flexibility of these novel scenarios for heating bulk ions in D-T ≈ 50%-50% plasmas and efficient generation of MeV-range fast ions in multi-ion species plasmas. In conclusion, several key results relevant for ITER and future fusion reactors are highlighted.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1995

An interpretation of a mysterious 3.0- to 4.6-kHz emission band observed on Voyager 2 near Neptune

A whistler mode interpretation is provided for the narrowband signal (f approx. 3 - 4.6 kHz, Delta f approx. 200 - 800 Hz) detected by the plasma wave instrument on Voyager 2 during its encounter with Neptune. Our analysis indicates that this signal may have been generated in a limited spatial region and that it propagated to other regions of the Neptunian magnetosphere in the nonducted whistler mode with wave normal vectors lying close to the whistler mode resonance cone. The observed frequency variation of the emission along the Voyager 2 trajectory is consistent with this interpretation. The source location is estimated to be near the magnetic equator at L approx. 4 and dipole longitude of 111 deg W (260 deg W longitude in Neptune coordinate system). The source frequency and bandwidth are estimated to be 3.6 kHz and 300 Hz, respectively. The waves most likely would have been generated by energetic electrons with 2- to 20-keV parallel energy via a gyroresonance mechanism. Our interpretation of the narrowband emissions places the following limits on the Neptunian thermal plasma density and temperature: (1) N(sub e, min) greater than 0.16 el/cu cm for 1.2 R(sub N) less than R less than 5 R(sub N), (2) N(sub e, max) = 597.5/cu cm at R - 1.3 R(sub N), (3) T(sub e, max) less than 500-1000 K at R approx. 5 R(sub N). It is also possible that the weak UV aurora observed near Neptune could have been caused by the precipitation of energetic particles by the narrowband emission as a result of wave particle interactions.

Sonwalkar, Vikas S.↗
DOE OSTI2013

Individual NSLS-II Multipole Magnet Alignment by Laser Trackers

The magnet alignment of the 90 th and final multipole girder assembly was completed January 17 th , 2013. Our procedure of “rough” pre-alignment by laser trackers and final alignment by vibrating wire & “Differential Variable Reluctance Transducers” (DVRT) has been quite successful, achieving magnet to magnet alignment well under the 30 micron specification. The pre-alignment accuracy is verified by the initial scan from the vibrating wire. The alignment residuals can be calculated from the offsets of a best fit line. The results are impressive, especially considering the environment of the Building 902 Annex (which has a large bay door that would open during pre-alignment, without fail), the sloppiness of the magnets’ fiducials, and especially the fact that the girders were pre-aligned to their mechanical centers, but the vibrating wire reports the magnetic centers which may be considerably different. This result hints at the potential feasibility of alignment with laser trackers for replacement magnets of NSLS-II and maybe even all magnets of future accelerators. But, it is difficult to predict the achievable accuracy until the main three error sources (a.k.a. Survey group excuses) are eliminated: measuring environment, bad magnet fiducials, and mechanical/magnetic center differences. The test performed on a large aperture quadrupole on girder assembly C19G4 was designed to answer the following questions with the aforementioned error sources either eliminated or simulated: 1) How accurately can a NSLS-II multipole be realigned after repair or other disturbance given the existing fiducials? 2) How accurately can a replacement NSLS-II multipole be installed in situ if its magnetic center is known relative to good fiducials? 3) If the current NSLS-II spares are never magnetically fiducialized, how well can they be installed using only mechanical data? 4) Could the magnets of a future accelerator (with similar alignment specifications as NSLS-II) be aligned using commercially available metrology instruments? This paper will answer these questions.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Recent Progress on the PNL Accelerator-Based Intense Fusion Neutron Source

Phoenix Nuclear Labs (PNL) has developed a full line of accelerator-based neutron generators. This paper describes the highest yield DD fusion-based system. This device utilizes a microwave ion source (MWS), 300 kV DC accelerator, magnetic solenoid focus element, differential pumping system, and gaseous deuterium target to achieve DD neutron yields of 3x10{sup 11} n/s. Lower-yield variations of the device have been built using variable voltages and a solid titanium target, and design for a DT version of the gas target system is underway that will increase neutron yield to 5x10{sup 13} n/s. PNL has delivered a number of systems to government and commercial customers and has identified a number of longer-term commercial applications for this high-yield neutron generator. These include medical isotope production, neutron radiography, active interrogation for explosives and SNM detection, and Cf-252 replacement. Most applications require the development of specialized moderator assemblies and fixtures to meet customer requirements. A photograph of the neutron generator prototype is provided in Figure 1. This state-of-the-art neutron generator technology is essential for many applications of critical global importance including neutron radiography, medical isotope production, detection of explosives and nuclear material, materials characterization, and others. The presentation will discuss these applications and recent progress made on the base accelerator technology. (authors)

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2025

Charge radii and electromagnetic moments of 214−218 Bi : Exploring the “southern” border of the 𝑍 > 82 octupole-deformation region

The changes in the mean-squared charge radii relative to 209 Bi 126 (𝛿⁢⟨𝑟 2 ⟩ 𝑁,126 ) and the magnetic dipole and electric quadrupole moments in 214−218 Bi have been measured using the in-source resonance-ionization spectroscopy technique at ISOLDE (CERN). Magnetic moments of odd-odd bismuth nuclei have been analyzed by the additivity relation. Previous tentative spin-parity and configuration assignments based on the 𝛽-decay feeding patterns have been supported. A normal odd-even staggering in charge radii of bismuth isotopes with 𝑁>126 has been observed. The new data for the 𝛿⁡⟨𝑟 2 ⟩ of bismuth isotopes allow a study of the isotonic dependencies in the charge radii, revealing jumps in 𝛿⁢⟨𝑟 2 ⟩ 132,126 and 𝛿⁢⟨𝑟 2 ⟩ 134,126 at 𝑍 = 84. This pattern could be explained by a sudden onset of octupole deformation at 𝑁 = 132 and 134 when going from polonium (𝑍 = 84) to astatine (𝑍 = 85).

fundamental symmetries↗
NASA NTRS1969

Magnetically coupled emission regulator

Magnetic coupling between input and power handling circuits isolates high voltage. A feedback regulator samples the ion source bias current and provides deviation signals to a magnetic amplifier pulse modulator. The pulse modulator controls the dc to ac power inverter which in turn, controls the emission current.

Source record↗
DOE OSTI2025

Prediction of the Wave Normal Angle of Proton‐Band EMIC Waves Near Geosynchronous Orbit

We investigate how the wave normal angle (WNA) and polarization of proton-band electromagnetic ion cyclotron (EMIC) waves change as they travel from their source to Earth. This paper marks a significant milestone as the first full-wave simulation of proton-band EMIC waves reflecting from the ionosphere. Our findings show that the WNA can change rapidly during propagation, primarily due to plasma inhomogeneities, such as variations in the Alfvén speed. The wave polarization is strongly related to the WNA, consistent with theory. Newly generated EMIC waves near the equator propagate with a WNA of 0° , then the WNA gradually shifts to 90° as they move toward Earth. In contrast, reflecting waves having 90° of WNA at Earth maintain a relatively larger WNA even near the magnetic equator. As a result, only the newly generated waves close to the source, where the magnetic latitude is less than approximately 20° , show left-handed polarization, while linear polarization remains dominant throughout the rest of the propagation.

EMIC wave↗
NASA NTRS1989

Antiproton powered propulsion with magnetically confined plasma engines

The reaction of the matter-antimatter annihilation, with its specific energy being over 250 times the specific energy released in nuclear fusion, is considered as an energy source for spacecraft propulsion. A concept of a magnetically confined pulsed plasma engine is described. In this concept, antiproton beams are injected axially into a pulsed magnetic mirror system, where they annihilate with an initially neutral hydrogen gas; the resulting charge annihilation products transfer energy to the hydrogen propellant, which is then exhausted through one end of the pulsed mirror system to provide thrust. Numerical simulations were developed to calculate the annihilation rate of antiprotons in hydrogen and to follow the resulting ion, muon, and electron/positron number density evolutions.

Lapointe, Michael R.↗
DOE OSTI2014

Beam extraction and high stability operation of high current electron cyclotron resonance proton ion source

A high current electron cyclotron resonance proton ion source is designed and developed for the low energy high intensity proton accelerator at Bhabha Atomic Research Centre. The plasma discharge in the ion source is stabilized by minimizing the reflected microwave power using four stub auto tuner and magnetic field. The optimization of extraction geometry is performed using PBGUNS code by varying the aperture, shape, accelerating gap, and the potential on the electrodes. While operating the source, it was found that the two layered microwave window (6 mm quartz plate and 2 mm boron nitride plate) was damaged (a fine hole was drilled) by the back-streaming electrons after continuous operation of the source for 3 h at beam current of 20–40 mA. The microwave window was then shifted from the line of sight of the back-streaming electrons and located after the water-cooled H-plane bend. In this configuration the stable operation of the high current ion source for several hours is achieved. The ion beam is extracted from the source by biasing plasma electrode, puller electrode, and ground electrode to +10 to +50 kV, −2 to −4 kV, and 0 kV, respectively. The total ion beam current of 30–40 mA is recorded on Faraday cup at 40 keV of beam energy at 600–1000 W of microwave power, 800–1000 G axial magnetic field and (1.2–3.9) × 10{sup −3} mbar of neutral hydrogen gas pressure in the plasma chamber. The dependence of beam current on extraction voltage, microwave power, and gas pressure is investigated in the range of operation of the ion source.

43 PARTICLE ACCELERATORS↗
NASA NTRS2000

Behavior of the Aurora During 10-12 May, 1999 When The Solar Wind Nearly Disappeared

The aurora was still active with occasional pseudobreakup events when the solar wind density diminished to unusually small densities (0.2 cc -1) during May 10-12, 1999. The aurora was observed at high magnetic latitudes indicating that the electron precipitation source moved northward as the geomagnetic activity decreased. The events we have studied indicate that the solar wind density alone is not the primary parameter that controls the auroral activity. The weak auroral activity was observed with 150 nT magnetic bays and when the interplanetary magnetic field (IMF) Bz was small and positive resulting in small _ parameter. A new auroral feature was observed on May 11, 1999, between 0900-2000 UT. The electron precipitation was energetic, uniform, and covered the region commonly identified as the polar cap. This precipitation lasted for more than 10 hours and was stable over time scales of tens of minutes. On May 12, as the solar wind began to recover, a prolonged period of dayside activity occurred and was followed by a typical aurora at 0500 UT.

Parks, G.↗
DOE OSTI2017

CLEARING MAGNET DESIGN FOR APS-U

The Advanced Photon Source is in the process of developing an upgrade (APS-U) of the storage ring. The upgrade will be converting the current double bend achromat (DBA) lattice to a multi-bend achromat (MBA) lattice. In addition, the storage ring will be operated at 6 GeV and 200 mA with regular swap-out injection to keep the stored beam current constant [1]. The swap-out injection will take place with beamline shutters open. For radiation safety to ensure that no electrons can exit the storage ring, a passive method of protecting the beamline and containing the electrons inside the storage ring is proposed. A clearing magnet will be located in all beamline front ends inside the storage ring tunnel. This article will discuss the features and design of the clearing magnet scheme for APS-U.

Abliz, M.↗
DOE OSTI2024

Field Harmonic Measurement of High-Gradient Permanent Magnet Quadrupoles for NSLS- II Upgrade

The National Synchrotron Light Source II (NSLS-II) is preparing for a major upgrade based on a new lattice concept, known as “Complex Bend,” to replace its existing double bend achromat (DBA) lattice. Here, this novel lattice will use high-gradient permanent magnet quadrupoles (PMQs) with small apertures in the range of 16–22 mm. A prototype complex bend branch with PMQs has been installed in the NSLS-II linac to evaluate the lattice's performance. An accurate and precise magnetic measurement system is required for field harmonic characterization and magnetic tuning of these PMQs. As part of this project a Rotating-Coil bench, based on a Printed Circuit Board (PCB) coil with a 12 mm diameter, has been configured to measure nine PMQs with bore diameter of 12.7 mm. This PCB coil has an active length of 270 mm, and is able to measure fields up to the 15th harmonic of the main field at a reference radius of 5 mm, while maintaining field quality levels within 10 ppm of the main field. This article presents the PCB coil setup, the harmonic measurement results and their temperature dependencies and repeatability. Simulation results on compensation of undesired multipoles using “IDBuilder”, a genetic algorithm-based optimizer code for magnetic tuning is included for field harmonic corrections.

36 MATERIALS SCIENCE↗
NASA NTRS1977

Characteristics of magnetospheric particle injection deduced from events observed on August 18, 1974

The behavior of particles injected during three well-defined substorm events that occurred on August 18, 1974, has been studied in detail. Plasma characteristics from approximately 200 eV to 80 keV detected at the ATS 6 position have been studied in detail, and we suggest that the results are consistent with the idea that there are two particle sources for electrons during substorms: one at small pitch angles, predominantly in the magnetic field direction, and the other at large pitch angles. The sources of these electrons are probably the ionosphere and the plasma sheet. For protons the results suggest a one-particle source. One possible source for the protons is the plasma sheet. The results have been interpreted in a framework of a model involving magnetospheric convection and parallel electric field.

Parks, G. K.↗
NASA NTRS2000

Transverse Magnetic Field Propellant Isolator

An alternative high voltage isolator for electric propulsion and ground-based ion source applications has been designed and tested. This design employs a transverse magnetic field that increases the breakdown voltage. The design can greatly enhance the operating range of laboratory isolators used for high voltage applications.

Foster, John E.↗