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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
NASA NTRS1973

Control of a 30 cm diameter mercury bombardment thruster

Increased thruster performance has made closed-loop automatic control more difficult than previously. Specifically, high perveance optics tend to make reliable recycling more difficult. Control logic functions were established for three automatic modes of operation of a 30-cm thruster using a power conditioner console with flight-like characteristics. The three modes provide (1) automatic startup to reach thermal stability, (2) steady-state closed-loop control, and (3) the reliable recycling of the high voltages following an arc breakdown to reestablish normal operation. Power supply impedance characteristics necessary for stable operation and the effect of the magnetic baffle on the reliable recycling was studied.

Terdan, F. F.↗
NASA NTRS2001

A Cryogenic Magnetostrictive Actuator using a Persistent High Temperature Superconducting Magnet, Part 1: Concept and Design: Concept and Design - Part 1

Cryogenic magnetostrictive materials, such as rare earth zinc crystals, offer high strains and high forces with minimally applied magnetic fields, making the material ideally suited for deformable optics applications. For cryogenic temperature applications, such as Next Generation Space Telescope (NGST), the use of superconducting magnets offer the possibility of a persistent mode of operation, i.e., the magnetostrictive material will maintain a strain field without power. High temperature superconductors (HTS) are attractive options if the temperature of operation is higher than 10 degrees Kelvin (K) and below 77 K. However, HTS wires have constraints that limit the minimum radius of winding, and even if good wires can be produced, the technology for joining superconducting wires does not exist. In this paper, the design and capabilities of a rare earth zinc magnetostrictive actuator using bulk HTS is described. Bulk superconductors can be fabricated in the sizes required with excellent superconducting properties. Equivalent permanent magnets, made with this inexpensive material, are persistent, do not require a persistent switch as in HTS wires, and can be made very small. These devices are charged using a technique which is similar to the one used for charging permanent magnets, e.g., by driving them into saturation. A small normal conducting coil can be used for charging or discharging. Very fast charging and discharging of HTS tubes, as short as 100 microseconds, has been demonstrated. Because of the magnetic field capability of the superconductor material, a very small amount of superconducting magnet material is needed to actuate the rare earth zinc. In this paper, several designs of actuators using YBCO and BSCCO 2212 superconducting materials are presented. Designs that include magnetic shielding to prevent interaction between adjacent actuators will also be described. Preliminary experimental results and comparison with theory for BSSCO 2212 with a magnetostrictive element will be discussed.

Horner, Garnett C.↗
NASA NTRSDate not supplied

Overview of the Lunar Transit Trajectory Performed by the Power and Propulsion Element of NASA’s Gateway

NASA has committed to returning to the moon, landing the first woman and the next man on its surface. To support a sustained lunar presence, NASA is designing an orbital platform to be assembled in an orbit near the moon called the Near Rectilinear Halo Orbit (NRHO). This platform is known as the Gateway and its purpose it to support missions primarily to the lunar south pole. As NASA continues to study ways to reduce the cost of lunar exploration, a simplification implemented in 2020combinedthe first two elements of the Gateway, the Power and Propulsion Element (PPE) and NASA’s Habitation and Logistics Outpost (HALO), onto a single commercial launch vehicle (CLV). When launched together, the PPE and HALO make up the first two elements of NASA’s Gateway and exceed the performance capacity of commercially available launch vehicles to deliver directly to the moon. The delivery of the Gateway is enabled by and takes advantage of the high efficiency of the PPEs high-power Solar Electric Propulsion (SEP) system to transfer a significant starting mass from an initial Earth orbit to final insertion into the NRHO. The PPE is a 50-kW class high power solar electric propulsion stage comprised of two different types of electric thruster strings. The SEP system is operated in two different modes, a high thrust and high Isp (specific impulse), to both maximize the final delivered mass and attempt to minimize the time spent in the Van Allen Belts early in the transit trajectory. Additionally, this SEP system brings the capability to the assembled Gateway for transfer between orbits in cislunar space. This paper captures the preliminary low thrust lunar transfer reference trajectory to be flown by the PPE it delivers itself and HALO via a spiral trajectory from launch vehicle insertion to insertion into the NRHO as well as a preliminary reference round trip transfer of the Gateway from the NRHO to a Distant Retrograde Orbit (DRO) using the PPE. Once in its final NRHO, the Gateway is being designed to enable long duration human and robotic exploration of the lunar south pole as a precursor to Mars. The Gateway’s low thrust lunar transit trajectory is envisioned to prove out the application of and flight of a high-power SEP system as a demonstration of technologies applicable to the enabling of future human space exploration.

human exploration↗
DOE OSTI2019

Reduced Common-Mode Voltage PWM Scheme for Full-SiC Three-Level Uninterruptible Power Supply With Small DC-Link Capacitors

In this article, a pulsewidth modulation (PWM) scheme for three-level full-SiC uninterruptible power supplies is developed to achieve a high power density. Two key passive components are selected for size reduction of the ac-ac stage: common-mode (CM) EMI filter, and dc-link capacitors. To reduce the CM noise, a new vector combination is proposed based on synchronous switching among three-phases. The proposed combinations align CM voltage (CMV) to be a single pulse per switching period. Owing to the simple shape, CMV cancellation between a three-level rectifier and inverter can be maximally utilized. A transition between the three combinations can control the drift of neutral point voltage. An equivalent carrier-based implementation is developed. Second, a simple algorithm to compensate neutral point voltage fluctuation is proposed both for differential mode (DM) and CM output voltage. Low-order harmonics on three-phase currents and an additional high-frequency CM noise by misaligned switching instant can be eliminated. The proposed compensation can be implemented by a simple correction on carrier slopes and injected zero-sequence voltage. The proposed PWM scheme is verified with 20-kW full-SiC UPS switching at 60 kHz with 140 μF dc-link capacitors.

42 ENGINEERING↗
DOE OSTI2025

Small-Signal Stability Constrained Optimal Power Flow of Inverter-Dominated Power Systems with Flexible Operation Mode Selection

Given the intermittence and low inertia nature of inverter-based resources (IBRs), modern power systems with high penetration of IBRs challenge the conventional optimal power flow (OPF) analysis and the system may experience unexpected failures if stability constraints are not incorporated. This study proposes a small-signal stability-constrained OPF (SSSC-OPF) with flexible operation mode selection between grid-forming (GFM) and grid-following (GFL) modes for IBRs to address these challenges. The approach aims to maintain system stability with a sufficient stability margin while minimizing operation costs. The effectiveness of the proposed method is validated through extensive case studies on the IEEE 14-bus system. The results demonstrate that the proposed method is able to support system-level power flow analysis, reduce generation costs, and ensure stability under various disturbances.

grid-following↗
NASA NTRS1999

Magnetic Flux Compression Using Detonation Plasma Armatures and Superconductor Stators: Integrated Propulsion and Power Applications

This presentation discusses the use of magnetic flux compression for space flight applications as a propulsion and other power applications. The qualities of this technology that make it suitable for spaceflight propulsion and power, are that it has high power density, it can give multimegawatt energy bursts, and terawatt power bursts, it can produce the pulse power for low impedance dense plasma devices (e.g., pulse fusion drivers), and it can produce direct thrust. The issues of a metal vs plasma armature are discussed, and the requirements for high energy output, and fast pulse rise time requires a high speed armature. The plasma armature enables repetitive firing capabilities. The issues concerning the high temperature superconductor stator are also discussed. The concept of the radial mode pulse power generator is described. The proposed research strategy combines the use of computational modeling (i.e., magnetohydrodynamic computations, and finite element modeling) and laboratory experiments to create a demonstration device.

Litchford, Ron↗
NASA NTRS1988

Generation of high-power nanosecond pulses from laser diode-pumped Nd:YAG lasers

Simulation results are used to compare the pulse energy levels and pulse energy widths that can be achieved with LD-pumped Nd:YAG lasers for both the pulse-transmission mode (PTM) and pulse-reflection mode (PRM) Q-switching methods for pulse energy levels up to hundreds of microjoules and pulse widths as short as 1 ns. It is shown that high-power pulses with pulse widths as short as 1 ns can be generated with PTM Q-switched in LD-pumped Nd:YAG lasers. With the PRM Q-switching method, pulse widths as short as 2 ns and pulse energy at the level of a few hundred microjoules can also be achieved but require pumping with 8-10-mJ AlGaAs laser diode arrays.

Chan, Kinpui↗
DOE OSTI2021

Hardware Design of Medium Voltage SiC-Based Modular Multilevel Converters for Grid-Tied Applications

This paper presents a design of a 10 kV silicon carbide (SiC) MOSFET based modular multilevel converter (MMC). The MMC functions as the interconnection between a 24 kV dc bus and a 13. SkV distribution grid. This paper focuses on the hardware design of the MMC and its submodules. The gate driver, auxiliary power supply and bus bur in submodules are major components that need to meet high dv/dt immunity and high insulation voltage requirements. The gate driver achieves over 200 kV/us common mode transient immunity (CMTI). Its associated auxiliary power supply is based on an on-board transformer with over 30 kV insulation capability and 1.4 pF barrier capacitance. The busbar achieves less than 11 kV/cm electric field in the air to avoid partial discharges. Validation tests of the MMC submodule were performed by double pulse tests at 5 kV and buck converter tests at3 kV, 52A (peak). Reliable operations were achieved in validation tests.

auxiliary power supply↗
DOE OSTI2026

Performance Assessment of a Heat Pump Integrated with Thermal Energy Storage in Cooling & Heating Modes

Thermal Energy Storage (TES) systems have demonstrated significant potential to manage the fluctuating nature of energy demand and shifting peak loads. This technology has made significant recent advances, including new research on the integration of TES with residential and commercial Heating, Ventilation, and Air-Conditioning (HVAC) systems. In this paper, we present the use of a novel laboratory assessment framework for a prototype heat pump system integrated with latent heat phase change material-based TES. The assessment framework consists of 22 total test points (11 heating, 11 cooling) using psychrometric conditions from AHRI Standard 210/240 and includes transient conditions to evaluate TES charging and discharging modes. In addition, both continuous mode and cyclic mode were evaluated for charging and discharging to explore the benefits to TES heat transfer from repeated transient operation. The ambient conditions evaluated include heating mode charging at cold-climate heat pump conditions when winter-peaking utilities may most require demand reduction (H4Full conditions, 5°F/-15°C) and cooling mode charging at high ambient temperature that may occur during times of day when excess solar power generation results in low-cost electricity (105°F/40.6°C). The work demonstrates the demand reduction capabilities of integrating TES with HVAC, including up to 44% in cooling mode and 60% in heating mode compared to conventional HVAC equipment without TES.

25 ENERGY STORAGE↗
DOE OSTI2021

Using extended MHD to explore lasers as a trigger for x-pinches

X-pinches have been shown to be a source of extremely intense x-ray emissions useful for diagnosing plasma dynamics and imaging biological objects. The most striking feature of an x-pinch is the hotspot, the point source from where all the x rays come from. Unfortunately, the exact timing and location of the hotspot are still unpredictable. Since an x-pinch hotspot forms from instabilities (like an m = 0 mode), we will computationally explore whether we can use a high-power laser to control the timing and location of these instabilities. Our goal is to reduce the temporal and spatial jitter associated with the x-ray burst. Using an extended MHD (XMHD) code, we explore the non-relativistic instability generation using a current profile of a 250 kA linear transformer driver system and laser characteristics of SLAC's Matter in Extreme Conditions laboratory. Our results include both laser-penetration results using a boundary-defined electromagnetic (EM) wave and instability results from a power-deposition method.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2024

Deposition of ultrathick heavy-metal alloys on rotating substrates by high-power impulse magnetron sputtering: Target erosion effects

Sputter deposition of ultrathick (≈20μm) Au–Ta alloy coatings on sphero-cylindrical substrates is key for the fabrication of hohlraums for magnetically assisted inertial confinement fusion. In this work, we study the deposition of AuTa 4 alloy coatings onto rotating substrates. We use high-power impulse magnetron sputtering (HiPIMS) in a constant peak target voltage mode. Results show that the target erosion state has a strong impact on the dominant crystallographic phase, microstructure, surface morphology, and electrical resistivity of AuTa 4 films. This is due to effects of changes in the confining magnetic field with target erosion on the HiPIMS discharge characteristics and the sputter source output. We quantify these effects via plasma diagnostics and discuss the optimization of HiPIMS deposition of ultrathick films for cases when target erosion effects dominate film properties.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Benefits of the Super-X divertor configuration for scenario integration on MAST Upgrade

The integration of good core and edge/pedestal confinement with strong dissipation of heat and particles in the divertors is a significant challenge for the development of fusion energy. Alternative divertor configurations offer potential advantages by broadening the operational space where a device can operate with detached divertors and acceptable power exhaust. First results from MAST Upgrade are presented from high confinement mode experiments with outer divertors in the Super-X divertor configuration, showing that the outer divertors naturally detach when the Super-X is formed with no discernible impact on the plasma core and pedestal. These initial findings confirm predicted benefits of the Super-X configuration in terms of facilitating scenario integration.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1973

Energy distribution in parallel plate plasma accelerators

A parallel plate accelerator operated in the quasi-steady regime of argon mass flow discharges permits, on account of its geometry, the appraisal of the initial ratio of energy disposition into the kinetic and thermal modes of the plasma while retaining the essential features of coaxial high power self-field MPD accelerators. The energy disposition ratio, calculated as the ratio of kinetic energy to enthalpy in the exhaust flow, shows reasonable agreement with the ratio of the induced emf in the accelerator to resistive voltage drop. Both these ratios indicate that the discharge imparts more energy to the flow by resistive heating than by direct body force acceleration. This is turn suggests that other acceleration mechanisms must be responsible for the high performance of conventional MPD arcs.

Dicapua, M. S.↗
NASA NTRS1976

Fluorescent-lamp power supply

High-efficiency, cost-effective power source employs resonant circuit to change modes when passing from starting to running condition.

Milberger, W. E.↗
NASA NTRS1977

Use of Auger spectroscopy in the evaluation of thermionic cathodes

Auger spectroscopy has been used to evaluate the properties of 'good' and 'poor' impregnated tungsten cathodes used in high-power microwave wave tubes. The results were interpreted to analyze failure modes in cathodes removed from TWT's because of poor emission characteristics. Most of the poor cathodes evaluated in this program were obtained from fabricated electron guns that had been employed and discarded from the 200-W TWT tubes developed for the Communication Technology Satellite program. The results of these measurements have shown there are at least two types of failure modes that one observes with poor cathodes. They are (1) chemical contamination of the cathode surface and (2) low partial layer barium coverage of the cathode surface.

Forman, R.↗
DOE OSTI2025

Solid State Transformer Architecture and Control Compensation for Common Mode Currents

A high-altitude electromagnetic pulse (HEMP) or similar geomagnetic disturbance (GMD) has the potential to impact the operation of large-scale electric power grids. By introducing low-frequency common-mode (CM) currents, these events can degrade the performance of critical system components, such as large power transformers by introducing CM currents which can lead to magnetic saturation of the transformer core. In this work, a solid-state transformer (SST) is developed to replace susceptible equipment and improve grid resiliency by safely absorbing these CM disturbances. This device will be referred to as a common-mode solid-state transformer (CM-SST). An SST architecture based on a four-legged AC/DC converter is developed. This architecture enables active control of CM signals without disturbing the AC voltages or the real and reactive power delivery capabilities. A system-level model of this architecture is created, and time-domain simulations are performed to evaluate the SST’s performance in response to simulated CM disturbances. A control strategy for mitigating CM current is also investigated. Hamiltonian surface shaping and power flow control (HSSPFC) is used to design a nonlinear controller for the SST’s output inverter. The objectives of the controller are to suppress CM-induced AC current offsets and regulate AC currents to desired setpoints. Nonlinear system analysis is applied to design and validate the controller. Two cases are tested: (a) the proposed four-leg inverter and (b) a standard three-leg inverter. The results show that the proposed controller rapidly mitigates CM disturbances while maintaining high-quality AC current waveforms in the four-leg configuration. Finally, the hardware performance of an SST prototype is evaluated. In particular, the ability of the SST to safely redirect and absorb CM currents is demonstrated, showing how it can protect neighboring conventional transformers in the system. The study confirms that appropriate control laws allow the SST to protect both itself and adjacent transformers during a HEMP or GMD event.

24 POWER TRANSMISSION AND DISTRIBUTION↗
NASA NTRSDate not supplied

Fluid-Thermal-Structural Interactions Induced by an Asymmetric Shock-Wave/Boundary-Layer Interaction in a Mach-6 Compression Corner

An experimental study is conducted of the fluid-thermal-structural interaction of a clamped compliant panel exposed to a three dimensional shock-wave/boundary-layer interaction (SWBLI) induced by a Mach-6 compression ramp with a spanwise nonuniform incoming boundary layer. The nonuniform boundary layer was produced by placing trips on one side of the upstream flat plate, resulting in largely turbulent flow on the tripped side and transitional flow on the untripped side. Measurements of the flowfield confirmed that the tripped boundary layer contained elevated levels of unsteadiness, and the SWBLI was observed to vary from attached to fully separated as the ramp angle was increased from 10◦ to 38◦; the separation region on the tripped side of the panel was noticeably smaller, showing the elevated turbulence levels of the tripped-side flow to remain relatively localized rather than diffusing across the whole model. Full-field, time-resolved panel deformations were measured using high-speed photogrammetry and the vibrational response at each compression angle was characterized. Although the measured modes conformed largely to those from classical clamped-plate theory, some skewing of the mode shapes was observed. IR thermography highlighted regions of the compliant region where elevated temperatures were likely to promote thermal softening effects to the transient panel response. The quasi-static deformation and stress field was used to characterize the internal stress factor of each mode and showed a meaningful relationship between transient panel response and stress contained within each mode: modes with antinodes lying in high-stress areas of the plate tended to exhibit increases in vibrational frequency and decreases in vibrational power, whereas the opposite was true for modes with antinodes in low-stress areas.

Spectral Proper Orthogonal Decomposition↗
DOE OSTI2021

High-current conduction cooled superconducting radio-frequency cryomodule

A high-current, compact, conduction cooled superconducting radio-frequency cryomodule for particle accelerators. The cryomodule will accelerate an electron beam of average current up to 1 ampere in continuous wave (CW) mode or at high duty factor. The cryomodule consists of a single-cell superconducting radio-frequency cavity made of high-purity niobium, with an inner coating of Nb3Sn and an outer coating of pure copper. Conduction cooling is achieved by using multiple closed-cycle refrigerators. Power is fed into the cavity by two coaxial couplers. Damping of the high-order modes is achieved by a warm beam-pipe ferrite damper.

Ciovati, Gianluigi↗