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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 649 records · Page 36
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Loss Breakdown of a Dual Conical Rotor Permanent Magnet Motor Using Grain Oriented Electrical Steel and Soft Magnetic Composites

This paper provides a loss breakdown of the NovaMAX® 215 frame, 1800 rpm motor at 5 kW. Mechanical losses, copper loss, and various types of electromagnetic losses are identified through experiment and simulation. The motor is able to achieve a very high efficiency, up to 96% at some operating points. A comparison with another highly efficient permanent magnet motor illustrates the benefits of the dual rotor axial flux topology, the use of grain oriented electrical steel, and the conical air gap and rotor flux focusing topology together with ferrite magnets. Additionally, a motor with a variable air gap was tested at different air gaps, and its losses are shown. At low speed and high torque, the losses are minimized with relatively small air gaps. However, at higher speeds and lower torques, the optimal air gaps are larger.

Gardner, Matthew C.↗
DOE OSTI2019

Magnetostructural phase transitions and large magnetic entropy changes in Ag-doped Mn 1–x Ag x CoGe intermetallic compounds

The influence of Ag-doping on the crystallographic structure, magnetic properties, and magnetocaloric effects of Mn 1–x Ag x CoGe (0.01 ≤ x ≤ 0.10) is reported. A transformation of crystal structure from orthorhombic to hexagonal was observed at room temperature. Doping Ag in Mn sites results in a first-order magnetostructural transition near room temperature. Furthermore, a Curie-temperature window of 90 K was obtained between the Curie temperatures of the austenite (Ni 2 In-type) and martensite (TiNiSi-type) phases. Large magnetic entropy change values of ~22.0 and 9.4 J/kg/K, and refrigerant capacity of 308 and 272 J/kg, were found for x = 0.06 and 0.05, respectively, for μ o ΔH = 5 T.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2020

Generation of High-Charge Magnetized Electron Beams Consistent With JLEIC Electron Cooling Requirements

The proposed Jefferson Lab Electron-Ion Collider (JLEIC), currently under design, relies on electron cooling in order to achieve the desired luminosity. This includes an electron beam with >55 Mev, 3.2 nC bunches that cools hadron beams with energies up to 100 GeV. To enhance the cooling, the electron beam must be magnetized with a specific eigen-emittance partition. This paper explores the use of the Fermilab Accelerator Science and Technology (FAST) facility to demonstrate the generation of an electron beam with parameters consistent with those required in the JLEIC high-energy cooler. We demonstrate via simulations the generation of the required electron-beam parameters and perform a preliminary experiment to validate FAST capabilities to produce such beams.

43 PARTICLE ACCELERATORS↗
DOE OSTI2022

Magnetic Reconnection in Strongly-Magnetized, Weakly-Collisional Plasmas: Onset, Turbulence, and Energy-Partition in 3D, Plasmoid-Dominated Regimes

This project is concerned with theoretical and numerical studies of magnetic reconnection. Key areas of focus are the reconnection onset (how reconnection gets started), energy partition (how the magnetic energy gets distributed during a reconnection event), and the effect of background turbulence on reconnection. We aim to shed light on these issues in kinetic plasmas (i.e., plasmas where the collisional mean free path is long compared to the length-scales of interest), with emphasis on 3D geometries.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

Magnetically Coupled Broadband Dual Magnetic Mass/Spring Vibrational Energy Harvesting Design

Self-powering sensors and networks are a reality. The ability to extract ambient energy from the surroundings to power electronic devices has a profound impact on the realization of smart adaptable sensor networks. In this study, a magnetically coupled dual spring and magnet design has been investigated to improve the efficiency and performance bandwidth of vibration energy harvesting (VEH) sensors. Using numerical models based on traditional systems of coupled ordinary differential equations (ODE), an optimized design was developed and compared to experimental measurements. Numerical and empirical results show good agreement. Results show improvement in the bandwidth over an equivalent linear system and corresponding improvement in output power conversion efficiency. The increased bandwidth allows improved conversion sensitivity and enhanced power harvesting capabilities. This operational bandwidth coincides with the expected input spectrum for in situ applications.

42 ENGINEERING↗
DOE OSTI2024

Magnetized Winds of M-type Stars and Star–Planet Magnetic Interactions: Uncertainties and Modeling Strategy

M-type stars are the most common stars in the Universe. They are ideal hosts for the search of exoplanets in the habitable zone (HZ), as their small size and low temperature make the HZ much closer-in than their solar twins. Harboring very deep convective layers, they also usually exhibit very intense magnetic fields. Understanding their environment, in particular their coronal and wind properties, is thus very important, as they might be very different from what is observed in the solar system. The mass-loss rate of M-type stars is poorly known observationally, and recent attempts to estimate it for some of them (e.g., TRAPPIST-1 and Proxima Centauri) can vary by an order of magnitude. In this work, we revisit the stellar wind properties of M dwarfs in the light of the latest estimates of $\dot{M}$ through Lyα absorption at the astropause and slingshot prominences. We outline a modeling strategy to estimate the mass-loss rate, radiative loss, and wind speed, with uncertainties, based on an Alfvén-wave-driven stellar wind model. We find that it is very likely that several TRAPPIST-1 planets lie within the Alfvén surface, which implies that these planets experience star–planet magnetic interactions (SPMIs). We also find that SPMIs between Proxima Cen b and its host star could be the reason for recently observed radio emissions.

M stars↗
DOE OSTI2019

Characterization of magnetic field lines in connection with the transport of field lines in Beltrami magnetic fields

Single and double curl Beltrami magnetic fields are studied numerically in connection with their transport properties and the results are compared and analyzed by characterizing the magnetic field lines. In the phase space of single curl Beltrami field, islands of regular field lines are embedded into the chaotic sea. Whereas the field lines for certain solutions of double curl Beltrami field are chaotic over the entire space. Due to the presence of regular islands in phase space, the chaotic trajectories show stickiness phenomena which is characterized by the distribution of a chaotic field line. The dynamical traps in chaotic orbits due to stickiness phenomena are also characterized by the distribution of finite distance Lyapunov exponents. Finally recurrence time distribution of chaotic trajectories is plotted to understand their global behaviour.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗