Plasma investigation in a reversed-current electron bombardment ion engine.
Plasma measurements in cesium electron bombardment ion engine indicate that reversed cathode-anode configuration improves radial ion distribution
CESIUM ENGINE↗
SEARCH · Engineering Papers
Results for “cathode and anode”
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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Large impulses of self-magnetic origin
Self magnetic impulses in gas discharge configuration as function of current and anode- cathode radii ratio
Garrison, R. L.↗
Determination of work functions near melting points of refractory metals by using a direct-current arc.
A direct-current arc in argon at atmospheric pressure was used to determine effective work functions of refractory metals, including tantalum, tungsten, molybdenum, and niobium. The procedure is experimentally advantageous, because surface cleanliness of the specimen is not critical, high vacuum is not required, and the anode-cathode spacing is not critical. The experimental procedure involves striking an arc to a metal wire cathode to form a melted ball having an emitting area defined by its diameter. The literature melting point of the metal is taken as the emitting temperature. By using these parameters and the known arc current, effective work functions were calculated from the Richardson-Dushman equation. The calculated work functions agree with recommended handbook values to within about 0.1 V and have typical repeatabilities of 0.02 V.
Gordon, W. A.↗
Design, fabrication and testing of a CFA for use in the solar power satellite
A crossed field amplifier was designed to meet the performance objectives of high signal to noise ratio, an efficiency of 85%, a CW microwave power output of 5-8 kW, and a frequency of 2450 MHz. The signal to noise ratio achieved was better than 69 db/MHz in a 2000 MHz band centered on the carrier. High circuit efficiency of 97% and a sharp knee on voltage current characteristic were achieved. The basic problem of maintaining good transfer of heat to the external radiator while providing for adequate connections to input and output was solved. Maximum efficiency achieved was 70.5% and gain and power level were below objectives. An investigation of causes of reduced performance indicated the poor field pattern in the cathode anode interaction area of the tube was a major cause.
Brown, W. C.↗
Research on the use of space resources
The second year of a multiyear research program on the processing and use of extraterrestrial resources is covered. The research tasks included: (1) silicate processing, (2) magma electrolysis, (3) vapor phase reduction, and (4) metals separation. Concomitant studies included: (1) energy systems, (2) transportation systems, (3) utilization analysis, and (4) resource exploration missions. Emphasis in fiscal year 1982 was placed on the magma electrolysis and vapor phase reduction processes (both analytical and experimental) for separation of oxygen and metals from lunar regolith. The early experimental work on magma electrolysis resulted in gram quantities of iron (mixed metals) and the identification of significant anode, cathode, and container problems. In the vapor phase reduction tasks a detailed analysis of various process concepts led to the selection of two specific processes designated as ""Vapor Separation'' and ""Selective Ionization.'' Experimental work was deferred to fiscal year 1983. In the Silicate Processing task a thermophysical model of the casting process was developed and used to study the effect of variations in material properties on the cooling behavior of lunar basalt.
Carroll, W. F.↗
Double-injection, deep-impurity switch development
The overall objective of this program is the development of device design and process techniques for the fabrication of a double-injection, deep-impurity (DI)(2) silicon switch that operates in the 1-10 kV range with conduction current of 10 and 1A, respectively. Other major specifications include a holding voltage of 0 to 5 volts at 1 A anode current, 10 microsecond switching time, and power dissipation of 50 W at 75 C. This report describes work that shows how the results obtained at the University of Cincinnati under NASA Grant NSG-3022 have been applied to larger area and higher voltage devices. The investigations include theoretical, analytical, and experimental studies of device design and processing. Methods to introduce deep levels, such as Au diffusion and electron irradiation, have been carried out to "pin down' the Fermi level and control device-switching characteristics. Different anode, cathode, and gate configurations are presented. Techniques to control the surface electric field of planar structures used for (DI)(2) switches are examined. Various sections of this report describe the device design, wafer-processing techniques, and various measurements which include ac and dc characteristics, 4-point probe, and spreading resistance.
Selim, F. A.↗
A simple demonstration of corrosion cells
The objective is to reinforce and enhance the understanding of galvanic cells, anode cathode reactions and polarization phenomena. Complete instructions are given for laboratory demonstration to be performed by students.
Guichelaar, Philip J.↗
Steady state composition with low Fe(2+) concentrations for efficient O2 production by 'magma' electrolysis of lunar soils
Parameters are estimated for a hypothetical, well stirred, continuous-feed electrolytic cell that converts 20 percent of a lunar soil feedstock to O2 gas, 26 percent to Fe-Si metal, 13 percent to spinel, and 41 percent to slag. Advantages of a molten Fe-Si cathode for trapping metal on reduction, a relatively conductive steady-state composition in equilibrium with spinel (a proposed container material), and close electrodes (less than 1 cm cathode-anode distance) are discussed. To produce 1 ton of O2, about 6 MHW of energy are required for the electrolysis and IR heating within the melt, and another about 6 MHW may be introduced as waste heat through internal resistance of the electrodes. Thus, to produce 1 ton of O2 per 24 hours, about 0.5 MW of power delivered to the cell would be required.
Haskin, Larry A.↗
A Multi-Physics Study on High-Specific Power Li-O2 Batteries for Electric Aircraft
Commercialization of lithium-air batteries faces many challenges, such as electrolyte decomposition, short cycle life, low energy and power density, etc. However, commercialization of Li-O2 batteries for aeronautics is much more challenging due to additional safety constraints on cyclability and performance (high specific power and specific energy). For this presentation, we will discuss inter-related aspects of physics-based modeling of a pack: cell and battery model calibration. In addition, we will evaluate and present optimal battery designs for high discharge current density, high discharge time, and low battery mass using simulation-based optimization.The Finite Element Model (FEM) used to simulate a Li-O2 cell is based on the work of Bevara [1]. The different aspects of the model are based on: porous electrode theory and concentrated electrolyte theory; quantum tunneling model for the resistance of conformal layer of discharge product (Li2O2) [1]; Butler-Volmer kinetics for electrochemical reaction; Fick's diffusion for oxygen transport; and an oxygen dissolution model is applied at the air/electrolyte interface [2]. The electrolyte properties such as ion conductivity, ion diffusion, oxygen diffusion, and mass density of the electrolyte were taken from Molecular Dynamics (MD) simulations [3]; while the other model parameters, which includes mass of cell components, were calibrated to match experiments at high discharge current densities. The cell mass includes the anode, cathode, separator, electrolyte, and other components (such as current collector). This calibrated model is used to perform parametric studies on cathode thickness, porosity, tortuosity, carbon particle size, electrolyte transport and material properties, partial pressure of oxygen, discharge time, and discharge current density to study optimal designs for high specific power and energy. References:1. Bevara, V. & Andrei, P. (2014), J. Electrochem. Soc. 161 (14), A2068-A2079.2.Mehta, M. & Andrei, P. (2015), J. Power Sources. 286, 299-308.3.Liyana-Arachchi, T.; Haskins, J.; Burke, C.; Diederichsen, K.; McCloskey, B.; & Lawson, J. (2018), J. Phys. Chem. B. 122 (36), 8548 - 8559.4.Choi, W.; Kikumoto, H.; Choudhary, R. & Ooka, R. (2018), Applied Energy, 209, 306-321.
Mehta, Mohit↗
Performance of an Array of 6 X 6 X 20 mm3 Virtual Frisch-Grid CdZnTe Detectors With A Waveform Sampling Readout System
Arrays of CdZnTe (CZT) bars with high spatial and energy resolution are an enabling technology for future space missions, such as the image plane detector of the Galactic Explorer with a Coded Aperture Mask Compton Telescope (GECCO). GECCO will explore the medium-energy (100 keV – 10 MeV) gamma-ray sky, which is among the least covered windows to the Universe with a massive potential for discovery. We have integrated an array of 6x6x20 mm3 virtual Frisch-grid (VFG) CZT detectors, measuring signals from the cathodes, anodes, and pads on each of the four sides of each bar. The VFG CZT detector is read out with an IDEAS GDS-100 waveform sampling readout system to optimize the signal processing and event reconstruction. We evaluated the energy and position resolution of the integrated VFG CZT array with a 137Cs source and successfully demonstrated better than 1% energy resolution and finer than 1 mm position resolution at 662 keV. Furthermore, we carried out a beam test at the High Intensity Gamma-ray Source (HIGS) at Duke University to investigate the performance of the system for higher energy gamma-rays. Together with the basic performance obtained from the 137Cs source, we present here those results from the beam test with various gamma-ray energies up to 8 MeV.
Makoto Sasaki↗
Cast thermal battery electrodes and separators using a salt binder
Cast components can improve the effectiveness of current state-of-the-art in thermal battery processing technology in terms of cost, labor, materials usage, and flexibility. Cast components can include cast cathodes, anodes, and separators.
25 ENERGY STORAGE↗
Rapid Charging Made Practical in Graphite-Based Lithium Batteries: Surface-Acoustic Wave Turbulent Electrolyte Mixing to Overcome Diffusion Limited Charging Rates
One of the key limits in rapidly recharging a lithium-ion battery is the depletion of lithium ions within the electrolyte adjacent the anode during charging and long diffusion time to overcome this depletion. It also causes dendrite formation, inefficient use of the lithium, and battery degradation over many charge-discharge cycles. Because the liquid electrolyte remains quiescent and unmixed, this depletion layer's depth rapidly grows to match the anode-cathode separation distance at even modest charge rates. The solution proposed by PI Prof. James Friend and Co-PI Prof. Ping Liu, both from the University of California, San Diego, is to mix the electrolyte and minimize the Li ion concentration gradient during charging. Even in the presence of the separator, the charging rate could then be significantly increased. They propose to accomplish this using surface acoustic wave (SAW)-driven acoustic streaming, a technique employing 10-mW fingernail-sized solid-state devices from the telecommunications industry to drive turbulent mixing to submicron length scales in a manner completely compatible with the typical 20700 and 18650 cells used in electric vehicles.
25 ENERGY STORAGE↗
The Impact of Anomalous Resistivity in Vacuum Contaminant Plasmas on the Electrothermal Instability
This manuscript presents an assessment of the electrothermal instability (ETI) in the presence of anomalous resistivity (AR) in vacuum contaminant plasmas (VCP) when applied to a magnetized liner inertial fusion (MagLIF)-like load.Pulsed-power driven dielectrically coated metallic liners, like in MagLIF, experience the current-driven electrothermal instability which occurs when a material’s resistivity changes with temperature and is subject to ohmic heating. Large scale pulsed-power facilities that use magnetically insulated transmission lines (MITL) have been shown to generate low-density plasma which enters the target chamber and coalesces around the load. The low-density high-temperature vacuum contaminant plasmas (VCP) can parasitically divert current from the load through causing a short in the anode-cathode gap inside the target chamber. Resistive magnetohydrodynamic (MHD) simulations of these VCP experience unphysical runaway ohmic heating due to under predicting the resistivity by using a purely collisional resistivity model.AR provides a physics-based way to address this runaway heating through increasing the resistivity in a proportional way with the drift speed. In this work, 1D simulations probe the effect that AR in VCP has on the magnetic diffusion rate, and 2D simulations show how this effect manifests in the nonlinear striation form of the ETI for a MagLIF-like load. Beryllium and aluminum dielectrically coated liners are used for the 1D and 2D simulations in this work. The1D simulations show that a VCP causes a delay in the current delivery to the load by upwards of 8 ns at 60 ns into atypical current pulse for an 1 × 10 7 A scale pulsed-power accelerator. The 2D simulations show the delay observed in the 1D simulations is reduced substantially (4 ns) by 2D turbulence that disrupts the VCP layer early in time. Here, the 2Dsimulated ETI growth varies across AR models, more so for the beryllium liner than the aluminum liner because the beryllium liner shows an enhanced rate of penetration for the magnetic diffusion wave in comparison to the aluminum liner. The 2D simulations show the bulk dielectric thickness varies across AR models with the Davidson AR model beingthe largest and the Buneman AR model being the smallest, and in connection with the thickness the Rayleigh-Taylor bubble-spike distances varies correspondingly.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Nanoporous separators for batteries and related manufacturing methods
Provided is a lithium battery, wherein the battery comprises an anode, a cathode, wherein the cathode comprises one or more transition metals, an electrolyte, and a porous separator interposed between the cathode and anode, wherein the separator comprises an anionic compound. Also provided are methods of manufacturing such batteries.
Carlson, Steven A.↗
Nanoporous separators for batteries and related manufacturing methods
Provided is a lithium battery, wherein the battery comprises an anode, a cathode, wherein the cathode comprises one or more transition metals, an electrolyte, and a porous separator interposed between the cathode and anode, wherein the separator comprises an anionic compound. Also provided are methods of manufacturing such batteries.
Carlson, Steven A.↗
Metal-ion deposition regulator for suppressing dendrite formation in electrochemical cells
A metal-ion deposition regulator to regulate the flux and deposition of metal ions in an electrochemical cell. The regulator containing two membranes made of a polymer and a plurality of two-dimensional porous nanosheets sandwiched between the two membranes. The regulator is capable of distributing flux of metal ions passing through the metal-ion deposition regulator and regulating the deposition of the metal ions onto the cathode or anode thereby suppressing dendrite growth in the electrochemical cell. An electrochemical cell containing an anode, a cathode, a liquid electrolyte, and a metal-ion deposition regulator. A method of making a metal-ion deposition regulator. The method includes fabricating two-dimensional porous nanosheets utilizing graphene oxide as an expendable template, and sandwiching the porous nanosheets between two membranes made of a polymer such that the nanosheets are in contact with the two membranes.
Pol, Vilas Ganpat↗
Investigation of the Effects of Cathode Flow Fraction and Position on the Performance and Operation of the High Voltage Hall Accelerator
The National Aeronautics and Space Administration (NASA) Science Mission Directorate In- Space Propulsion Technology office is sponsoring NASA Glenn Research Center (GRC) to develop a 4 kW-class Hall thruster propulsion system for implementation in NASA science missions. Tests were performed within NASA GRC Vacuum Facility 5 at background pressure levels that were six times lower than what has previously been attained in other vacuum facilities. A study was conducted to assess the impact of varying the cathode-to-anode flow fraction and cathode position on the performance and operational characteristics of the High Voltage Hall Accelerator (HiVHAc) thruster. In addition, the impact of injecting additional xenon propellant in the vicinity of the cathode was also assessed. Cathode-to-anode flow fraction sensitivity tests were performed for power levels between 1.0 and 3.9 kW. It was found that varying the cathode flow fraction from 5 to approximately 10% of the anode flow resulted in the cathode-to-ground voltage becoming more positive. For an operating condition of 3.8 kW and 500 V, varying the cathode position from a distance of closest approach to 600 mm away did not result in any substantial variation in thrust but resulted in the cathode-to-ground changing from -17 to -4 V. The change in the cathode-to-ground voltage along with visual observations indicated a change in how the cathode plume was coupling to the thruster discharge. Finally, the injection of secondary xenon flow in the vicinity of the cathode had an impact similar to increasing the cathode-to-anode flow fraction, where the cathode-to-ground voltage became more positive and discharge current and thrust increased slightly. Future tests of the HiVHAc thruster are planned with a centrally mounted cathode in order to further assess the impact of cathode position on thruster performance.
Cathode Coupling↗
Battery with aluminum-containing cathode
A battery includes an anode chamber configured to contain an anolyte and including an anode, a cathode chamber configured to contain a catholyte including a cathode, and a separator between the anode chamber and the cathode chamber. The anode includes sodium, and the cathode includes aluminum. The battery is configured to be operated above a melting point of the anolyte and the catholyte, such that the anolyte is a molten anolyte and the catholyte is a molten catholyte.
25 ENERGY STORAGE↗