A5082195646- Gyrotron and Vacuum Electronics Research
- Particle accelerators and beam dynamics
- Microwave Engineering and Waveguides
- Plasma Diagnostics and Applications
- Pulsed Power Technology Applications
- Stellar, planetary, and galactic studies
- Particle Accelerators and Free-Electron Lasers
- Astrophysics and Star Formation Studies
- Terahertz technology and applications
- Astronomy and Astrophysical Research
- Plasma Applications and Diagnostics
- Astro and Planetary Science
- Millimeter-Wave Propagation and Modeling
- Superconducting Materials and Applications
- Aerosol Filtration and Electrostatic Precipitation
- Semiconductor Quantum Structures and Devices
- Botany and Plant Ecology Studies
- Lipid Membrane Structure and Behavior
- Electromagnetic Fields and Biological Effects
- Microwave and Dielectric Measurement Techniques
- linguistics and terminology studies
- Nuclear Physics and Applications
- Supramolecular Self-Assembly in Materials
- Microwave Dielectric Ceramics Synthesis
- GaN-based semiconductor devices and materials
United States Air Force Research Laboratory
2021-2024
Kirtland Air Force Base
2021-2023
U.S. Air Force Research Laboratory Directed Energy Directorate
2023
Biomedical Research Institute of New Mexico
2021
Pennsylvania State University
2021
Plasma Technology (United States)
2014-2020
Massachusetts Institute of Technology
2013-2020
Fusion Academy
2014-2020
Fusion (United States)
2014-2020
Southeastern Universities Research Association
2015-2016
We report the experimental demonstration of a mm-wave electron accelerating structure powered by high-power rf source. demonstrate reliable coupling an unprecedented power—up to 575 kW into accelerator using quasi-optical setup. This standing wave consists single-cell copper cavity and Gaussian TM01 mode converter. The is 110 GHz, 10-ns long pulses. These pulses are chopped from 3 ms gyrotron oscillator laser-driven silicon switch. show high gradient up 230 MV/m that corresponds peak surface...
Electron density and neutral gas have been measured in a non-equilibrium air breakdown plasma using optical emission spectroscopy two-dimensional laser interferometry, respectively. A was created with focused high frequency microwave beam air. Experiments were run 110 GHz 124.5 microwaves at powers up to 1.2 MW. Microwave pulses 3 μs long 2.2 GHz. over pressure range of 25 700 Torr as the input power varied. found be close critical density, where collisional is equal frequency, studied vary...
A laser-driven semiconductor switch (LDSS) employing silicon (Si) and gallium arsenide (GaAs) wafers has been used to produce nanosecond-scale pulses from a 3 μs, 110 GHz gyrotron at the megawatt power level. Photoconductivity was induced in using 532 nm laser, which produced 6 ns, 230 mJ pulses. Irradiation of single Si wafer by laser RF with 9 ns width >70% reflectance. Under same conditions, GaAs yielded 24 >78% For both materials, higher value reflectance observed increasing beam...
Terahertz accelerators can achieve potential gradients beyond 200 MV/m. Gyrotrons are the only power sources capable of producing megawatt-level, microsecond-long pulses in this frequency range, yet nanosecond-long required for breakdown-free operation. The authors explore possibility using a single GaAs wafer to enable production pulse widths, with rise and fall times that closely track illuminating laser's length. They demonstrate quantify reflective properties laser-induced...
ABSTRACT We explore the photometrically variable central stars of planetary nebulae HaTr 4 and Hf 2-2. Both have been classified as close binary star systems previously based on their light curves alone. Here, we present additional arguments data confirming identification both binaries with an irradiated cool companion to hot star. include updated curves, orbital periods, preliminary modeling for systems. also identify first time eclipsing binary. Neither system has well studied in past, but...
A growing number of close binary stars are being discovered among central planetary nebulae. Recent and ongoing surveys finding new systems contributing to our knowledge the evolution systems. The push find more was largely based on early discoveries which suggested that 10 15% all binaries. One goal this series papers is confirmation classification these as binaries determination system parameters. Here we provide time-resolved multi-wavelength photometry star Abell 65 well further analysis...
We report experimental measurements of the threshold for multipactor discharges on dielectric surfaces at 110 GHz. Multipactor was studied in two geometries: electric field polarized parallel to or perpendicular sample surface. Measured thresholds ranged from 15 $34\text{ }\text{ }\mathrm{MV}/\mathrm{m}$, more than 10 times higher those found conventional microwave frequencies. were compared with prior data lower frequencies, showing agreement theoretical predictions that increase linearly...
Directed assembly of nanostructures within temporary and recyclable self-assembled scaffolds is emerging as an attractive method for the synthesis nanomaterials with programmed properties. Understanding interactions building blocks amphiphilic critical rational design new nanodevices. Here we examine loading hydrophobic monomers into bilayers different curvatures. Time-resolved was studied by high performance liquid chromatography dynamic light scattering. Despite differences in initial...
We report experimental results on a two frequency gyrotron, operating in the TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">22,6</sub> mode at 110 GHz and xmlns:xlink="http://www.w3.org/1999/xlink">24,7</sub> 124.5 GHz. The gyrotron uses same electron gun as previous single 110-GHz with new cavity internal converter designed for optimized performance frequencies. For 98 kV, 42-A beam 3-μs pulses, an output power of 1.25 MW was obtained (30%...
The reflectance (R) and transmittance (T) of Si GaAs wafers irradiated by a 6 ns pulsed, 532 nm laser have been studied for s- p-polarized 250 GHz radiation as function fluence time. measurements were carried out using precision timing the R T signals, allowing an accurate determination absorptance (A) where A=1-R-T. Both had maximum above 90% ≥8 mJ/cm2. also showed peak ~50% lasting ~2 during risetime pulse. Experimental results compared with stratified medium theory Vogel model carrier...
A set of three apparatus enabling RF exposure aerosolized pathogens at four chosen frequencies (2.8 GHz, 4.0 5.6 and 7.5 GHz) has been designed, simulated, fabricated, tested. Each was intended to operate high power without leakage into the local environment be compact enough fit within biocontainment enclosures required for elevated biosafety levels. Predictions range electric field exposure, represented by complex vector magnitude, that an aerosol stream would expected encounter while...
We present single-cell accelerating structures designed for high-gradient testing at 110 GHz. The purpose of this work is to study the basic physics ultrahigh vacuum RF breakdown in accelerators. are π-mode standing-wave cavities fed with a TM01 circular waveguide. fabricated using precision milling out two metal blocks, and blocks joined diffusion bonding brazing. impact fabrication joining techniques on cell geometry performance will be discussed. First prototypes had measured Q0 2800,...
Gyrotrons produce power in high-order, transverse electric modes that are typically converted to a Gaussian beam inside the tube. In fusion plasma heating applications, is transmitted through diamond window an external mirror optical unit where it coupled into HE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> mode corrugated waveguide. Anew coupler described couples cavity RF directly waveguide gyrotron. A highpower gyrotron with...
Abstract An apparatus for measuring the W-band (75–110 GHz) complex permittivity of dielectrics at 1000 °C was developed. This allows measurements approximately twice temperature previously published high free-space measurement systems while maintaining similar precision. Challenges were addressed related to measurements, including uniformity, accuracy and preventing changes mm-wave systems. The details extraction from measured S-parameters are discussed. Sources error mathematical models...
A reduced parameter model of fast laser-driven semiconductor switches THz and mm-waves has been developed. The predicts peak reflectivity minimum transmissivity switches, showing good agreement with experimental data, while requiring fewer inputs than published models. This simplification facilitated a systematic survey laser parameters required for efficient switching. Laser energy density requirements are presented as function wavelength, pulse width, switched frequency, reflection angle,...