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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 469 records · Page 26
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Design and Fabrication of a Thyristor Using Ion Implantation of Anode and Cathode

A thyristor is a solid-state semiconductor switch made up of four alternating p and n type layers. When the switch is turned on by a small pulse, current can flow as long as the device stays on. When the voltage drops below the turn on level or the current reverses, the switch will turn off. Thyristors only allow current to flow in one direction. One of the benefits of a thyristor device is in its capacity to conduct large voltages with a small device and a small turn-on pulse requirement. Another distinguishing feature of thyristors compared to other semiconductor devices is that it can only be in the on or off state, there’s no in-between state for the device to exist within. These properties make thyristors very useful as switch devices, especially in applications where current flow is only needed in one direction and could potentially be damaging in the opposite direction. Currently, thyristors are most commonly used to control very high power loads and they are available commercially in many designs to control different amounts of current.

42 ENGINEERING↗
DOE OSTI2020

Flexible Magnetic Polymer Composite Substrate with Ba 1.5 Sr 1.5 Z Hexaferrite Particles of VHF/Low UHF Patch Antennas for UAVs and Medical Implant Devices

Our goal is to fabricate flexible magnetic polymer composites as antenna substrates for very high frequency (VHF)/low ultra high frequency (UHF) antennas for unmanned aerial vehicles (UAVs) and medical devices. Magnetodielectric materials, which have permeability (μ) similar to permittivity (ε), have attracted great attention, because they facilitate miniaturization of microwave devices while keeping or enhancing electromagnetic characteristics. Mechanically millled Ba 1.5 Sr 1.5 Co 2 Fe 24 O 41 (Ba 1.5 Sr 1.5 Z) hexaferrite particles were used to increase permeability in the interesting frequency band. The microwave properties of Ba 1.5 Sr 1.5 Z composites were predicted and measured. Hansen’s zero-order analysis of antenna bandwidth and electromagnetic field simulation showed that the hexaferrite-based flexible composite could enhance a bandwidth and achieve the miniaturization of antennas as well. The magnetic antenna substrates can be a good solution to integrate antennas into the UAVs whose dimensions are comparable to or larger than communication wavelength.

36 MATERIALS SCIENCE↗