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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 991 records · Page 55
All sourcesNASA NTRSDOE OSTI
NASA NTRS2016

Method and Circuit for Injecting a Precise Amount of Charge onto a Circuit Node

A method and circuit for injecting charge into a circuit node, comprising (a) resetting a capacitor's voltage through a first transistor; (b) after the resetting, pre-charging the capacitor through the first transistor; and (c) after the pre-charging, further charging the capacitor through a second transistor, wherein the second transistor is connected between the capacitor and a circuit node, and the further charging draws charge through the second transistor from the circuit node, thereby injecting charge into the circuit node.

Hancock, Bruce R.↗
NASA NTRS2016

Capacitive Trans-Impedance Amplifier Circuit with Charge Injection Compensation

A capacitive trans-impedance amplifier circuit with charge injection compensation is provided. A feedback capacitor is connected between an inverting input port and an output port of an amplifier. A MOS reset switch has source and drain terminals connected between the inverting input and output ports of the amplifier, and a gate terminal controlled by a reset signal. The reset switch is open or inactive during an integration phase, and closed or active to electrically connect the inverting input port and output port of the amplifier during a reset phase. One or more compensation capacitors are provided that are not implemented as gate oxide or MOS capacitors. Each compensation capacitor has a first port connected to a compensation signal that is a static signal or a toggling compensation signal that toggles between two compensation voltage values, and a second port connected to the inverting input port of the amplifier.

Milkov, Mihail M.↗
DOE OSTI2010

Metacapacitors for LED Lighting: Metacapacitors

ADEPT Project: The CUNY Energy Institute is developing less expensive, more efficient, smaller, and longer-lasting power converters for energy-efficient LED lights. LEDs produce light more efficiently than incandescent lights and last significantly longer than compact fluorescent bulbs, but they require more sophisticated power converter technology, which increases their cost. LEDs need more sophisticated converters because they require a different type of power (low voltage direct current, or DC) than what's generally supplied by power outlets. The CUNY Energy Institute is developing sophisticated power converters for LEDs that contain capacitors made from new, nanoscale materials. Capacitors are electrical components that are used to store energy. CUNY's unique capacitors are configured with advanced power circuits to more efficiently control and convert power to the LED lighting source. They also eliminate the need for large magnetic components, instead relying on networks of capacitors that can be easily printed on plastic substrate. CUNY's prototype LED power converter already meets DOE's 2020 projections for the energy efficiency of LED power converters.

ADEPT: Agile Delivery of Electrical Power Technolo↗
DOE OSTI2013

MEMS based pyroelectric thermal energy harvester

A pyroelectric thermal energy harvesting apparatus for generating an electric current includes a cantilevered layered pyroelectric capacitor extending between a first surface and a second surface, where the first surface includes a temperature difference from the second surface. The layered pyroelectric capacitor includes a conductive, bimetal top electrode layer, an intermediate pyroelectric dielectric layer and a conductive bottom electrode layer. In addition, a pair of proof masses is affixed at a distal end of the layered pyroelectric capacitor to face the first surface and the second surface, wherein the proof masses oscillate between the first surface and the second surface such that a pyroelectric current is generated in the pyroelectric capacitor due to temperature cycling when the proof masses alternately contact the first surface and the second surface.

42 ENGINEERING↗
DOE OSTI2017

Active energy recovery clamping circuit to improve the performance of power converters

A regenerative clamping circuit for a power converter using clamping diodes to transfer charge to a clamping capacitor and a regenerative converter to transfer charge out of the clamping capacitor back to the power supply input connection. The regenerative converter uses a switch connected to the midpoint of a series connected inductor and capacitor. The ends of the inductor and capacitor series are connected across the terminals of the power supply to be in parallel with the power supply.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2019

Bi-directional, transformerless voltage system

A multi-stage electric voltage converter is disclosed. The converter comprises a voltage source and multiple stages. Each stage of the multiple stages comprises a first and a second and a third switch, and a capacitor, wherein the capacitor is coupled to the voltage source by the first and the second switches and each stage is coupled to a different stage or to an output of the multi-stage electric voltage converter by the third switch so as to allow the capacitor to be charged by the voltage source when the first and the second switches are closed and the third switch is open, and to allow the capacitor to be connected to the output of the multi-stage electric voltage converter when the first and the second switches are open and the third switch is closed.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2022

Electrostatic energy harvester

An electrostatic energy harvester broadly comprises an electrical energy storage component, an electrical energy transfer stage, first and second variable capacitors, and a switching control module. The electrical energy transfer stage includes diode-connected transistors and dictates electrical energy transfer between the electrical energy storage component and the variable capacitors. The switching control module timely switches between the first and second variable capacitors according to a state machine. Subsequent electrical energy investments from the electrical energy storage component are less than an initial electrical energy investment due to remnant electrical energy remaining at the previously active one of the first and second variable capacitors from previous electrical energy harvesting.

Wilson, Amy Charlene↗
DOE OSTI2022

Electrostatic energy harvester

An electrostatic energy harvester broadly comprises an electrical energy storage component, an electrical energy transfer stage, first and second variable capacitors, and a switching control module. The electrical energy transfer stage includes diode-connected transistors and dictates electrical energy transfer between the electrical energy storage component and the variable capacitors. The switching control module timely switches between the first and second variable capacitors according to a state machine. Subsequent electrical energy investments from the electrical energy storage component are less than an initial electrical energy investment due to remnant electrical energy remaining at the previously active one of the first and second variable capacitors from previous electrical energy harvesting.

Wilson, Amy Charlene↗
DOE OSTI2022

Electrostatic energy harvester

An electrostatic energy harvester broadly comprises an electrical energy storage component, an electrical energy transfer stage, first and second variable capacitors, and a switching control module. The electrical energy transfer stage includes diode-connected transistors and dictates electrical energy transfer between the electrical energy storage component and the variable capacitors. The switching control module timely switches between the first and second variable capacitors according to a state machine. Subsequent electrical energy investments from the electrical energy storage component are less than an initial electrical energy investment due to remnant electrical energy remaining at the previously active one of the first and second variable capacitors from previous electrical energy harvesting.

Wilson, Amy Charlene↗
DOE OSTI2023

System and method of inverter control

A control system and method for an inverter that reduces capacitor current through a DC bus capacitor of the inverter. The control system and method may generate switching signals for a plurality of switching circuits in a manner that reduces capacitor current through the DC bus capacitor.

Xue, Lingxiao↗
DOE OSTI2015

Soliton production with nonlinear homogeneous lines

Low- and high-voltage Soliton waves were produced and used to demonstrate collision and compression using diode-based nonlinear transmission lines. Experiments demonstrate soliton addition and compression using homogeneous nonlinear lines. We built the nonlinear lines using commercially available diodes. These diodes are chosen after their capacitance versus voltage dependence is used in a model and the line design characteristics are calculated and simulated. Nonlinear ceramic capacitors are then used to demonstrate high-voltage pulse amplification and compression. The line is designed such that a simple capacitor discharge, input signal, develops soliton trains in as few as 12 stages. We also demonstrated output voltages in excess of 40 kV using Y5V-based commercial capacitors. The results show some key features that determine efficient production of trains of solitons in the kilovolt range.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2010

Low voltage operation of plasma focus

Plasma foci of compact sizes and operating with low energies (from tens of joules to few hundred joules) have found application in recent years and have attracted plasma-physics scientists and engineers for research in this direction. We are presenting a low energy and miniature plasma focus which operates from a capacitor bank of 8.4 {mu}F capacity, charged at 4.2-4.3 kV and delivering approximately 52 kA peak current at approximately 60 nH calculated circuit inductance. The total circuit inductance includes the plasma focus inductance. The reported plasma focus operates at the lowest voltage among all reported plasma foci so far. Moreover the cost of capacitor bank used for plasma focus is nearly 20 U.S. dollars making it very cheap. At low voltage operation of plasma focus, the initial breakdown mechanism becomes important for operation of plasma focus. The quartz glass tube is used as insulator and breakdown initiation is done on its surface. The total energy of the plasma focus is approximately 75 J. The plasma focus system is made compact and the switching of capacitor bank energy is done by manual operating switch. The focus is operated with hydrogen and deuterium filled at 1-2 mbar.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2014

Characterizing absolute piezoelectric microelectromechanical system displacement using an atomic force microscope

Piezoresponse Force Microscopy (PFM) is a popular tool for the study of ferroelectric and piezoelectric materials at the nanometer level. Progress in the development of piezoelectric MEMS fabrication is highlighting the need to characterize absolute displacement at the nanometer and Ångstrom scales, something Atomic Force Microscopy (AFM) might do but PFM cannot. Absolute displacement is measured by executing a polarization measurement of the ferroelectric or piezoelectric capacitor in question while monitoring the absolute vertical position of the sample surface with a stationary AFM cantilever. Two issues dominate the execution and precision of such a measurement: (1) the small amplitude of the electrical signal from the AFM at the Ångstrom level and (2) calibration of the AFM. The authors have developed a calibration routine and test technique for mitigating the two issues, making it possible to use an atomic force microscope to measure both the movement of a capacitor surface as well as the motion of a micro-machine structure actuated by that capacitor. The theory, procedures, pitfalls, and results of using an AFM for absolute piezoelectric measurement are provided.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Study of breakdown in an ablative pulsed plasma thruster

Breakdown in ablative pulsed plasma thrusters (APPTs) must be studied in order to design new types of APPTs and measure particular parameters. In this paper, we studied a parallel-plate ablative pulsed plasma thruster that used a coaxial semiconductor spark plug. By operating the APPT about 500 times with various capacitor voltages and electrode gaps, we measured and analyzed the voltage of the spark plug, the voltage between the electrodes, and the discharge current. These experiments revealed a time delay (∼1–10 μs) between spark plug ignition and capacitor discharge, which may affect the performance of high-pulsing-rate (>10 kHz) and double-discharge APPTs, and the measurements of some of the APPT parameters. The delay time decreased as the capacitor voltage increased, and it increased with an increasing electrode gap and increasing number of ignitions. We explain our results through a simple theoretical analysis.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2016

Development of a compact generator for gigawatt, nanosecond high-voltage pulses

A compact generator producing 2.2-ns 1.5 GW high-voltage pulses was developed. The generator employed a 27.6 Ω, 0.9 ns pulse-forming-line (PFL), which was charged by an iron core transformer with a turn ratio of 2:33.5 and a coefficient of 0.94. A 1.2 μF, 20 kV capacitor and a hydrogen thyratron were used in the primary circuit. When the thyratron closed at 14.5 kV, 3.4% of the energy stored in the capacitor was delivered to the PFL in 850 ns, producing a peak voltage of up to ∼500 kV. In addition, the principle of triple resonance transformation was employed by adding a 50 pF tuning capacitor and a 1.15 mH inductor between the transformer and the PFL, which led to a significant reduction of the duration and peak value of the transformer voltage without reducing that in the PFL. Meanwhile, an adjustable self-break oil switch was applied. By using transmission lines with impedance overmatched to that of the PFL, the generator delivered a 512 kV pulse across an electron beam diode, generating radiation with a dose of 20 mR/pulse at 20 cm ahead of the diode. The generator provides an excellent ultra-short radiation pulse source for the studies on radiation physics.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Charge storage and tunneling mechanism of Ni nanocrystals embedded HfO{sub x} film

A nano-floating gate memory structure based on Ni nanocrystals (NCs) embedded HfO{sub x} film is deposited by means of radio-frequency magnetron sputtering. Microstructure investigations reveal that self-organized Ni-NCs with diameters of 4-8 nm are well dispersed in amorphous HfO{sub x} matrix. Pt/Ni-NCs embedded HfO{sub x}/Si/Ag capacitor structures exhibit voltage-dependent capacitance-voltage hysteresis, and a maximum flat-band voltage shift of 1.5 V, corresponding to a charge storage density of 6.0 × 10{sup 12} electrons/cm{sup 2}, is achieved. These capacitor memory cells exhibit good endurance characteristic up to 4 × 10{sup 4} cycles and excellent retention performance of 10{sup 5} s, fulfilling the requirements of next generation non-volatile memory devices. Schottky tunneling is proven to be responsible for electrons tunneling in these capacitors.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Ferroelectric polarization retention with scaling of Hf 0.5 Zr 0.5 O 2 on silicon

In this paper, we investigate the polarization retention of Hf 0.5 Zr 0.5 O 2 (HZO)-based metal–ferroelectric–insulator–Si (MFIS) capacitors with scaling of the ferroelectric (FE) layer thickness from 5 nm to 20 nm. The capacitors have a constant interface layer capacitance of ~24 μF/cm 2 , developed due to the integration of HZO on a degenerated Si as a bottom conducting electrode. It is observed that 20 nm HZO films show a small change (~5%) in FE polarization (P FE ) between short (10 μs) and long (6 s) retention time, while 5-nm-thick films exhibit a large difference (~90%). Furthermore, the dependence of P FE retention loss on the FE thickness can be understood by the presence of a built-in electric field in the FE layer, generated due to charge continuity between the FE and the interface layers in the ground state without any external bias. A direct experimental observation also confirms that a residual voltage is developed at the node between the metal–ferroelectric–metal and metal–oxide–semiconductor capacitors connected in series, in the ground state with zero external bias. It is expected that a proper understanding of the built-in field developed in the FE layer in an MFIS stack is crucial for FE memory retention characteristics.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Influence of the voltage pulse front shortening on the pulse repetition rate in a copper vapour laser

The lasing characteristics of a copper vapour laser are investigated in the regime of a pulse train excited in the internalheating tube with the diameter of 2 cm and length of 48 cm. Two power supply schemes are compared: a conventional scheme with a storage capacitor discharged through a thyratron connected to a peaking capacitor and the scheme in which the peaking capacitor is connected to the laser active element through a kivotron – a fast switch based on the 'open discharge' with a turn-on time of less than 1 ns. It is shown that in the considered range of the pulse repetition rates f = 2 – 16 kHz in the first case we deal with a typical energy dependence on frequency having a maximum near 4 – 5 kHz. In the second case, the lasing energy is frequency-independent; hence, the average power in this range is proportional to f. The results obtained are explained by the neutralised influence of the initial electron concentration on energy characteristics of the copper vapour laser. (control of laser radiation parameters)

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗