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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS2000

Ruthenium Oxide Electrochemical Super Capacitor Optimization for Pulse Power Applications

Electrical actuator systems are being pursued as alternatives to hydraulic systems to reduce maintenance time, weight and costs while increasing reliability. Additionally, safety and environmental hazards associated with the hydraulic fluids can be eliminated. For most actuation systems, the actuation process is typically pulsed with high peak power requirements but with relatively modest average power levels. The power-time requirements for electrical actuators are characteristic of pulsed power technologies where the source can be sized for the average power levels while providing the capability to achieve the peak requirements. Among the options for the power source are battery systems, capacitor systems or battery-capacitor hybrid systems. Battery technologies are energy dense but deficient in power density; capacitor technologies are power dense but limited by energy density. The battery-capacitor hybrid system uses the battery to supply the average power and the capacitor to meet the peak demands. It has been demonstrated in previous work that the hybrid electrical power source can potentially provide a weight savings of approximately 59% over a battery-only source. Electrochemical capacitors have many properties that make them well-suited for electrical actuator applications. They have the highest demonstrated energy density for capacitive storage (up to 100 J/g), have power densities much greater than most battery technologies (greater than 30kW/kg), are capable of greater than one million charge-discharge cycles, can be charged at extremely high rates, and have non-explosive failure modes. Thus, electrochemical capacitors exhibit a combination of desirable battery and capacitor characteristics.

Merryman, Stephen A.↗
DOE OSTI2014

High-power pulsed thulium fiber oscillator modulated by stimulated Brillouin scattering

A pulsed ∼2-μm thulium-doped fiber laser passively modulated by distributed stimulated Brillouin scattering achieves 10.2 W average power and >100 kHz repetition rate with a very simple all-fiber configuration. The maximum pulse energy and peak power surpass 100 μJ and 6 kW, respectively. Another distinct property is that the pulse width is clamped around 17 ns at all power levels. All the average-power, pulse energy, and peak power show the highest values from passively modulated fiber lasers in all wavelength regions.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Nanosecond pulsed power generator for a voltage amplitude up to 300 kV and a repetition rate up to 16 Hz for fine disintegration of quartz

A generator of high-power high-voltage nanosecond pulses is intended for electrical discharge disintegration of mineral quartz and other nonconducting minerals. It includes a 320 kV Marx pulsed voltage generator, a high-voltage glycerin-insulated coaxial peaking capacitor, and an output gas spark switch followed by a load, an electric discharge disintegration chamber. The main parameters of the generator are as follows: a voltage pulse amplitude of up to 300 kV, an output impedance of ≈10 Ω, a discharge current amplitude of up to 25 kA for a half-period of 80–90 ns, and a pulse repetition rate of up to 16 Hz.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Effect of laser cavity parameters on saturation of light – current characteristics of high-power pulsed lasers

We report an experimental study of power characteristics of semiconductor lasers based on MOVPE-grown asymmetric separate-confinement heterostructures with a broadened waveguide as functions of cavity length, stripe contact width and mirror reflectivities. It is shown that at high current pump levels, the variation of the cavity parameters of a semiconductor laser (width, length and mirror reflectivities) influences the light – current (L – I) characteristic saturation and maximum optical power by affecting such laser characteristics, as the current density and the optical output loss. A model is elaborated and an optical power of semiconductor lasers is calculated by taking into account the dependence of the internal optical loss on pump current density and concentration distribution of charge carriers and photons along the cavity axis of the cavity. It is found that only introduction of the dependence of the internal optical loss on pump current density to the calculation model provides a good agreement between experimental and calculated L – I characteristics for all scenarios of variations in the laser cavity parameters. (lasers)

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1992

Pulsed power molten salt battery

It was concluded that carbon cathodes with chlorine work well. Lithium alloy chlorine at 450 C, 1 atm given high power capability, high energy density, DC + pulsing yields 600 pulses, no initial peak, and can go to red heat without burn-up. Electrochemical performance at the cell and cell stack level out under demanding test regime. Engineering and full prototype development for advancing this technology is warranted.

Argade, Shyam D.↗
NASA NTRS1993

Low power pulsed MPD thruster system analysis and applications

Pulsed MPD thruster systems were analyzed for application to solar-electric orbit transfer vehicles at power levels ranging from 10 to 40 kW. Potential system level benefits of pulsed propulsion technology include ease of power scaling without thruster performance changes, improved transportability from low power flight experiments to operational systems, and reduced ground qualification costs. Required pulsed propulsion system components include a pulsed applied-field MPD thruster, a pulse-forming network, a charge control unit, a cathode heater supply, and high speed valves. Mass estimates were obtained for each propulsion subsystem and spacecraft component. Results indicate that for payloads of 1000 and 2000 kg, pulsed MPD thrusters can reduce launch mass by between 1000 and 2500 kg relative to hydrogen arcjets, reducing launch vehicle class and launch cost. While the achievable mass savings depends on the trip time allowed for the mission, cases are shown in which the launch vehicle required for a mission is decreased from an Atlas IIAS to an Atlas I or Delta 7920.

Myers, Roger M.↗
DOE OSTI2025

On the Inductance of a Single-Channel Spark-Gap Switch for Pulsed Power Applications

In this paper, we derive an alternative expression for calculating the inductance of a single-channel spark-gap switch. We believe this new inductance expression provides greater clarity compared to other approaches. Interestingly, both the Rosa formula and the coaxial inductance formula, which are commonly used in such calculations, emerge as special cases of our new expression. To validate the proposed formula, we conducted COMSOL simulations that show excellent agreement with our theoretical predictions.

COMSOL↗
NASA NTRS1993

Low power pulsed MPD thruster system analysis and applications

Pulsed magnetoplasmadynamic (MPD) thruster systems were analyzed for application to solar-electric orbit transfer vehicles at power levels ranging from 10 to 40 kW. Potential system level benefits of pulsed propulsion technology include ease of power scaling without thruster performance changes, improved transportability from low power flight experiments to operational systems, and reduced ground qualification costs. Required pulsed propulsion system components include a pulsed applied-field MPD thruster, a pulse-forming network, a charge control unit, a cathode heater supply, and high speed valves. Mass estimates were obtained for each propulsion subsystem and spacecraft component using off-the-shelf technology whenever possible. Results indicate that for payloads of 1000 and 2000 kg pulsed MPD thrusters can reduce launch mass by between 1000 and 2500 kg over those achievable with hydrogen arcjets, which can be used to reduce launch vehicle class and the associated launch cost. While the achievable mass savings depends on the trip time allowed for the mission, cases are shown in which the launch vehicle required for a mission is decreased from an Atlas IIAS to an Atlas I or Delta 7920.

Myers, Roger M.↗
DOE OSTI2014

A source of high-power pulses of elliptically polarized ultrawideband radiation

Here, we describe a source of high-power ultrawideband radiation with elliptical polarization. The source consisting of a monopolar pulse generator, a bipolar pulse former, and a helical antenna placed into a radioparent container may be used in tests for electromagnetic compatibility. In the source, the helical antenna with the number of turns N = 4 is excited with a high-voltage bipolar pulse. Preliminary, we examined helical antennas at a low-voltage source aiming to select an optimal N and to estimate a radiation center position and boundary of a far-field zone. Finally, characteristics of the source in the operating mode at a pulse repetition rate of 100 Hz are presented in the paper as well. Energy efficiency of the antenna is 0.75 at the axial ratio equal to 1.3. The effective potential of radiation of the source at the voltage amplitudes of the bipolar pulse generator equal to -175/+200 kV reaches 280 kV.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗