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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 145 records · Page 8

Thermonuclear Fusion Verification of Staged Z-Pinch Fusion on a 0.5 MA LTD Pulsed Power Generator (Final Report)

LLNL fielded neutron detectors at UCSD’s CESZAR facility during the experimental campaigns investigating the staged Z-pinch concept. This concept uses high current to compress a cylindrical plasma composed a high atomic number gas, such as argon, surrounding fusion fuel. LLNL analyzed data from the diagnostics and improved the diagnostic setup specific to the experiment. This work helps to advance the mission creating a fusion energy source, which is a benefit to the economy and for energy security.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

Investigating the Performance of SF6 Replacement Gases to Enable the Next Generation of Pulsed Power

High voltage switches are essential components in pulsed power systems, where consistent and reliable performance is crucial—particularly as the field explores alternatives to SF 6 as an insulating gas. This project examines the self-break voltage distributions of various gases, with a focus on the low-voltage discharges observed in the lower tail of these distributions. Experimental results revealed that the specific housing design influenced the self-break behavior. Among the tested gases, air demonstrated a more favorable overall distribution compared to SF 6 , albeit requiring higher operating pressures. However, air also exhibited a greater likelihood of extremely low-voltage dropouts, raising concerns about its suitability as a direct replacement for SF 6 . Notably, all gases tested showed a higher-than-expected probability of low-voltage events when considering the tail of the distribution rather than the bulk behavior.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Broadband millimeter-wave GaAs transmitters and receivers using planar bow-tie antennas

We report broadband monolithic transmitters and receivers IC's for mm-wave electromagnetic measurements. The IC's use nonlinear transmission lines (NLTL) and sampling circuits as picosecond pulse generators and detectors. The pulses are radiated and received by planar monolithic bow-tie antennas, collimated with silicon substrate lenses and off-axis parabolic reflectors. Through Fourier transformation of the received pulse, 30-250 GHz free space gain-frequency measurements are demonstrated with an accuracy approximately = 0.17 dB, RMS.

Konishi, Y.↗

Ultrafast Laser Beam Switching and Pulse Train Generation by Using Coupled Vertical-Cavity, Surface-Emitting Lasers (VCSELS)

Ultrafast directional beam switching is achieved using coupled VCSELs. This approach is demonstrated to achieve beam switching frequencies of 40 GHz and more and switching directions of about eight degrees. This switching scheme is likely to be useful for ultrafast optical networks at frequencies much higher than achievable with other approaches.

Peter M Goorjian↗

Highly flexible pulse programmer for NMR applications

A pulse generator for NMR application is described. Eighteen output channels are provided to allow use in single and double resonance experiments. Complex pulse sequences may be generated by loading instructions into a 256-word by 16-bit program memory. Features of the pulse generator include programmable time delays from 0.5 micros to 1000 s, branching and looping instructions, and the ability to be loaded and operated either manually or from a PDP-11/10 computer.

Dart, J.↗

Transdermal delivery of therapeutic agent

A device for the transdermal delivery of a therapeutic agent to a biological subject that includes a first electrode comprising a first array of electrically conductive microprojections for providing electrical communication through a skin portion of the subject to a second electrode comprising a second array of electrically conductive microprojections. Additionally, a reservoir for holding the therapeutic agent surrounding the first electrode and a pulse generator for providing an exponential decay pulse between the first and second electrodes may be provided. A method includes the steps of piercing a stratum corneum layer of skin with two arrays of conductive microprojections, encapsulating the therapeutic agent into biocompatible charged carriers, surrounding the conductive microprojections with the therapeutic agent, generating an exponential decay pulse between the two arrays of conductive microprojections to create a non-uniform electrical field and electrokinetically driving the therapeutic agent through the stratum corneum layer of skin.

Kwiatkowski, Krzysztof C.↗

Ultrastable reference pulser for high-resolution spectrometers

Solid-state double-pulse generator for a high resolution semiconductor detector meets specific requirements for resolution /0.05 percent/, amplitude range /0.1-13 MeV/, and repetition rate /0.1-1000 pulses per second/. A tag pulse is generated in coincidence with each reference pulse.

Brenner, R.↗

Leading/lagging cable referencing platform for monitoring the health of underground cable networks

A system for detecting water trees in branching underground electrical cables includes a pulse generator configured to inject a pulse into a first underground cable that branches into a second underground cable and a third underground cable. The system includes a first sensor associated with the first cable, a second sensor associated with the second cable, and a third sensor associated with the third cable. The system includes a control device configured to obtain a first, second, and third signal associated with the first, second and third sensors, respectively. The control device determines a lead-lag relationship between the second and third signals and determines presence of a water tree within at least one of the second and third cable based on the lead-lag relationship. When presence of a water tree is determined, the control device generates a control action associated with repairing or replacing the second and/or third cable.

Burkes, Klaehn W.↗

Improved On-Chip Measurement of Delay in an FPGA or ASIC

An improved design has been devised for on-chip-circuitry for measuring the delay through a chain of combinational logic elements in a field-programmable gate array (FPGA) or application-specific integrated circuit (ASIC). In the improved design, the delay chain does not include input and output buffers and is not configured as an oscillator. Instead, the delay chain is made part of the signal chain of an on-chip pulse generator. The duration of the pulse is measured on-chip and taken to equal the delay.

Chen, Yuan↗