Brad W. Hoff
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View article: Investigation of Viral Inactivation by High Peak Power Microwave (HPPM) Exposure in Solution
Investigation of Viral Inactivation by High Peak Power Microwave (HPPM) Exposure in Solution Open
The recent severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) pandemic had a tremendous impact on human life and global economics, motivating the invention of technology that can limit the spread of the virus from human to human …
View article: Behavioral model of a semiconductor opening switch (SOS)
Behavioral model of a semiconductor opening switch (SOS) Open
This paper presents a comprehensive experimental investigation and SPICE-based behavioral model of semiconductor opening switch devices developed using a MOSFET-driven testbed. Measurements of key device parameters, including peak diode cu…
View article: Demonstration of System Technologies Enabling Millimeter Wave Power Beaming Using Thermomechanical Power Conversion
Demonstration of System Technologies Enabling Millimeter Wave Power Beaming Using Thermomechanical Power Conversion Open
Key technologies and system components for a power beaming concept, based on a high-power mm-wave transmitter and thermomechanical conversion of the beamed energy to electrical power at the receiving station, are described. Outdoor testing…
View article: Observed reduction in fracture toughness of AlN and AlN–Mo ceramic matrix composites with carbon additive
Observed reduction in fracture toughness of AlN and AlN–Mo ceramic matrix composites with carbon additive Open
The fracture toughness of AlN ceramic matrix composites containing carbon (0.5 vol%), yttria (5.0 vol%), and Mo (0.0–4.0 vol%) was evaluated using Vickers indentation. The results of these measurements were compared to a carbon-free, comme…
View article: A reflective millimeter-wave photonic limiter
A reflective millimeter-wave photonic limiter Open
Wide-aperture free-space limiter with enhanced damage threshold provides protection from high-power millimeter-wave radiation.
View article: A Summary of the Fabrication of a Prototype Stirling Engine Heat Exchanger.
A Summary of the Fabrication of a Prototype Stirling Engine Heat Exchanger. Open
modules, including the sodium heat pipe, is briefly described. Similarities between the proposed SSE heat exchanger modules and the LeRC test modules for two test engines are presented. The benefits and weaknesses of using a sodium heat pi…
View article: A Summary of the Fabrication of a Prototype Stirling Engine Heat Exchanger.
A Summary of the Fabrication of a Prototype Stirling Engine Heat Exchanger. Open
modules, including the sodium heat pipe, is briefly described. Similarities between the proposed SSE heat exchanger modules and the LeRC test modules for two test engines are presented. The benefits and weaknesses of using a sodium heat pi…
View article: A reflective mm-wave photonic limiter
A reflective mm-wave photonic limiter Open
Millimeter wave (mm-wave) communications and radar receivers capable of processing small signals must be protected from high-power signals, which can damage sensitive receiver components. Many of these systems arguably can be protected by …
View article: Guest Editorial The Eighteenth Special Issue on High-Power Microwave and Millimeter-Wave Generation
Guest Editorial The Eighteenth Special Issue on High-Power Microwave and Millimeter-Wave Generation Open
The field of high-power microwave and millimeter-wave generation continues to be an active area of research and technological development to meet the demand of high peak, average, and prime power needs of government and industrial applicat…
View article: Characterization of AlN-based ceramic composites for use as millimeter-wave susceptor materials at high temperature: Dielectric properties of AlN:Mo with 0.25 vol% to 4.0 vol% Mo from 25 to 550 °C
Characterization of AlN-based ceramic composites for use as millimeter-wave susceptor materials at high temperature: Dielectric properties of AlN:Mo with 0.25 vol% to 4.0 vol% Mo from 25 to 550 °C Open
View article: $W$ -Band Complex Permittivity Measurements at High Temperature Using Free-Space Methods
$W$ -Band Complex Permittivity Measurements at High Temperature Using Free-Space Methods Open
Free-space measurement techniques can be contactless and are able to accommodate large, flat sheets of dielectric material, making them useful for characterization of hightemperature, millimeter-wave, window and radome candidate materials.…
View article: Characterization of AlN-based Ceramic Composites for Use as Millimeter Wave Susceptor Materials at High Temperature: High Temperature Thermal Properties of AlN:Mo with 0.25% to 4.0% Mo by Volume
Characterization of AlN-based Ceramic Composites for Use as Millimeter Wave Susceptor Materials at High Temperature: High Temperature Thermal Properties of AlN:Mo with 0.25% to 4.0% Mo by Volume Open
In order to begin to evaluate and model the suitability of high temperature ceramic composites, such as AlN:Mo, as susceptor materials for power beaming applications, the electromagnetic, thermal, and mechanical properties of the material …
View article: Dielectric strength heterogeneity associated with printing orientation in additively manufactured polymer materials
Dielectric strength heterogeneity associated with printing orientation in additively manufactured polymer materials Open
Anisotropy in dielectric properties can have deleterious effects in structures intended for use in high-field environments. We show that dielectric anisotropy is introduced into parts fabricated using additive manufacturing techniques base…
View article: High current nonlinear transmission line based electron beam driver
High current nonlinear transmission line based electron beam driver Open
A gigawatt-class nonlinear transmission line based electron beam driver is experimentally demonstrated. Four experimental series, each with a different Marx bank charge voltage (15, 20, 25, and 30 kV), were completed. Within each experimen…
View article: Harmonic generation under small signal conditions in a traveling wave tube
Harmonic generation under small signal conditions in a traveling wave tube Open
In a klystron, charge overtaking of electrons leads to an infinity of AC current. The harmonic content therein can be calculated exactly, with or without space charge effects. This paper extends the klystron theory to a traveling wave tube…