A5043314223- Laser Design and Applications
- Gyrotron and Vacuum Electronics Research
- Laser-Plasma Interactions and Diagnostics
- Pulsed Power Technology Applications
- Plasma Diagnostics and Applications
- High voltage insulation and dielectric phenomena
- Particle accelerators and beam dynamics
- Solid State Laser Technologies
- Laser-induced spectroscopy and plasma
- Particle Accelerators and Free-Electron Lasers
- Plasma Applications and Diagnostics
- Geophysics and Sensor Technology
- Electromagnetic Launch and Propulsion Technology
- Electrostatic Discharge in Electronics
- Laser-Matter Interactions and Applications
- Advanced Sensor Technologies Research
- Magnetic confinement fusion research
- Spectroscopy and Laser Applications
- Lightning and Electromagnetic Phenomena
- Photocathodes and Microchannel Plates
- Power Transformer Diagnostics and Insulation
- Aerosol Filtration and Electrostatic Precipitation
- Optical Systems and Laser Technology
- Semiconductor materials and devices
- Civil and Structural Engineering Research
United States Naval Research Laboratory
2013-2025
Indianapolis Zoo
2023-2024
Phuket Rajabhat University
2024
Massachusetts Academy of Math and Science
2022-2023
Denver School of Nursing
2020-2022
Knoxville College
2021-2022
Institute of Electrical and Electronics Engineers
2016-2022
TED Conferences (United States)
2022
The University of Sydney
2022
University of British Columbia
2022
Laser fusion researchers have realized since the 1970s that deep UV light from excimer lasers would be an advantage as a driver for robust high-performance capsule implosions inertial confinement (ICF). Most of this research has centered on krypton-fluoride (KrF) laser. In article we review advantages KrF laser direct-drive ICF, history high-energy development, and present state art describe development path to performance needed its energy application. We include descriptions architecture...
A coordinated, focused effort is underway to develop Laser Inertial Fusion Energy. The key components are developed in concert with one another and the science engineering issues addressed concurrently. Recent advances include: target designs have been evaluated that show it could be possible achieve high gains (>100) needed for a practical fusion system.These feature low-density CH foam wicked solid DT over-coated thin high-Z layer. These results verified three independent one-dimensional...
Single microwave pulses centered at 9.68 GHz with 100-MHz (full width half maximum) bandwidth are used to evanescently tunnel through a one-dimensional photonic crystal. In direct time-domain measurement, it is observed that the peak of tunneling wave packets arrives (440+/-20) ps earlier than companion free space (air) packets. Despite this superluminal behavior, Einstein causality not violated since earliest parts signal, also known as Sommerfeld forerunner, remain exactly luminal. The...
We are carrying out a multidisciplinary multi-institutional program to develop the scientific and technical basis for inertial fusion energy (IFE) based on laser drivers direct-drive targets. The key components developed as an integrated system, linking science, technology, final application of 1000-MWe pure-fusion power plant. science technologies here flexible enough be applied other size systems. justification this work is family target designs (simulations) that show direct drive has...
Frank Hegeler, Jerome Castellon, Nancy Frost, George Laity, Pietro Romano, and Feipeng Wang
A unique all solid-state pulsed power system has been tested at the Naval Research Laboratory that produced 200 kV, 4.5 kA, and 300 ns pulses, continuously for more than 11,500,000 shots into a resistive load repetition rate of 10 pps. The Marx an efficiency 80% based on calorimetric measurements. This pulser is used to evaluate components advance solid state designs next generation drive electron beam pumped KrF laser inertial fusion energy. pulser, designed constructed by PLEX LLC,...
An ultraviolet (UV) absorption technique is used to investigate the spatial and temporal distributions of ozone after a positive streamer discharge in air at atmospheric pressure. The apparatus consists 45-cm long wire-to-plate configuration with an electrode gap distance 2.5 cm. Results show average density about 5/spl times/10/sup 15/ cm/sup -3/ area 2 mm/sup 2/ just below application voltage pulse amplitude 65 kV duration 80 ns. Toward cathode, decreases rapidly. diffusion coefficient...
This paper presents measurements of the enhanced current density along edges a large area electron beam as well successful techniques that eliminated this edge effect/beam halo. The is measured with Faraday cup array at anode, and spatial, time-integrated obtained radiachromic film. Particle-in-cell simulations support experimental results. Experiments show recessing cathode reduces electric field eliminates effect. However, recess structure itself emits under long-term repetitive operation....
Extensive research has been performed to elucidate the transport of electron beam energy from a vacuum diode, through foil support structure (hibachi), and into Electra laser cell. Measurements simulations deposition in cell are reported for various krypton/argon mixtures, gas pressures, thickness material hibachi foil. Two several cathode configurations investigated efficiencies up 75% have achieved with 500 kV, 180 ns full width at half maximum diode pulse. The experimental data compared...
High-energy electron beam pumped krypton fluoride (KrF) gas lasers are an attractive choice for inertial fusion energy (IFE). Their short wavelength and demonstrated high uniformity optimizes the laser-target physics, their pulsed power technology scales to a large system. This paper presents principals of this type laser progress toward developing technologies that can meet IFE requirements repetition rate (5 Hz), efficiency (>6%), durability (>3/spl times/10/sup 8/ shots). The Electra at...
In this paper, we describe the development of electron beam pumped KrF lasers for inertial fusion energy. are an attractive driver fusion, on account their demonstrated very high quality, which is essential reducing imprint in direct drive targets; short wavelength (248 nm), mitigates growth plasma instabilities; and modular architecture, reduces costs. paper present a basic overview laser technology as well current research three key areas: stability transport; kinetics propagation; pulsed...
Laser interferometry is used for the first time to measure plasma electron density along slow wave structure (SWS) wall during microwave generation in a vacuum, long pulse, high power backward-wave oscillator (BWO). The University of New Mexico pulse oscillator, which displays characteristic shortening phenomenon, investigated these studies. Although observed across wide class devices, its origin not definitively understood. Many hypotheses suggest that unintentional introduction into...
The primary physical mechanism responsible for charge-carrier amplification, in a developing surface discharge, has eluded conclusive identification decades. This paper describes the results of experiments to directly detect charge-carriers, above dielectric surface, within discharge. Free electrons are detected by measuring deflection laser beam, focused 20 /spl mu/m 1/e diameter, with an angular sensitivity 0.18 mVspl mu/rad and risetime 6 ns. estimated detection threshold discharge is...
Inserting a thick slab of porous dielectric (e.g., ceramic honeycomb) in front the emitting surface large-area planar diode improves electron beam emission uniformity, decreases current rise and fall times, maintains more constant impedance. Particle-in-cell simulations first few nanoseconds operation show that initially numerous secondary electrons ions load honeycomb. The were confined within pores, redistributing electric field by reducing it pores increasing on cathode (by factor 2–3)....
The Electra pulsed power system at the Naval Research Laboratory is capable of supplying 16 kJ to a low impedance load within 140 ns, and it allows continuous operation up 5 pulses per second for several hours. Four laser triggered SF6 gas switches transfer stored pulse forming line energy load. Each switch has hold-off voltage more than 1 MV transfers charge 10 mC shot. This paper describes redesign with hemispherical electrodes flat electrode configuration, which led an improvement in...
A UV absorption technique is used to investigate the ozone generation after a positive or negative streamer discharge in air at atmospheric pressure. The apparatus consists of 45 cm long wire-to-plate configuration with an electrode gap distance 2.5 cm. After either discharges, highest density occurs area just below wire electrode. Towards ground plate, decreases rapidly. Positive discharges produce about twice as much same pulse duration.
Krypton fluoride (KrF) lasers produce highly uniform beams at 248 nm, allow the capability of 'zooming' spot size to follow an imploding pellet, naturally assume a modular architecture and have been developed into pulsed-power-based industrial technology that readily scales fusion power plant sized system. There are two main challenges for application: develop system with overall efficiency greater than 6% (based on target gains 100) achieve durability 3 × 108 shots (two years 5 Hz). These...
With high-speed electrical and optical diagnostics, an attempt is made to elucidate the physical mechanisms leading surface flashover. The experimental device uses a cable discharge study self-breakdown along of insulator in vacuum. Preflashover current, breakdown voltage, luminosity, soft X-ray emission are measured temporal correlation with resolution 1 ns. results show linearly increasing current subampere range, corresponding before exponential increase both signals takes over. linear...
In a series of experiments on the Naval Research Laboratory's Electra generator, we have measured dependence laser output in principal (1.733μm) transition Ar–Xe upon both initial gas temperature and Xe concentration. The data show that is less sensitive to when contains more Xe. destruction rate molecular ion ArXe+ increases rapidly with temperature, but Xe2+ does not. Interpreted kinetics model, these indicate contribute pumping ArXe laser.
The Ar–Xe infrared laser has been investigated in several series of experiments carried out on the Naval Research Laboratory’s Electra generator. Our primary goals were to optimize efficiency (within Electra’s capabilities) and gain understanding main physical processes underlying laser’s output as a function controllable parameters such Xe fraction, power deposition, gas pressure. We find that intrinsic maximizes at ∼3% total pressure 2.5 atm, fraction 1%, electron beam deposition density...
Inserting a slab of honeycomb ceramic in front the emitting surface large-area cathode improves electron beam emission uniformity, decreases current rise and fall times, maintains more constant diode impedance. Moreover, changing material from velvet to carbon fiber achieved robust that starts emit at higher electric field without degradation uniformity. In addition, an 80% reduction postshot pressure was also observed when gamma alumina deposited on ceramic. A possible explanation is...
We first reported the operation of a relativistic backward-wave oscillator (BWO) in so-called cross-excitation regime 1998. This instability, whose general properties were predicted earlier through numerical studies, resulted from use particularly shallow rippled-wall waveguide [slow wave structure (SWS)] that was installed an experiment to diagnose pulse shortening long-pulse electron beam-driven high-power microwave (HPM) source. SWS necessary accommodate laser interferometry measurements...
Electra is a repetitively pulsed, double-sided, electron-beam pumped krypton fluoride laser. has recently operated as an oscillator with output pulse of 510 J, 100 ns duration for single shots. At 1 Hz repetition rate ten-shot burst, the laser averaged 500 J per shot. The dependence energy on partial pressures Kr, Ar, and F2 were examined. Over 10 to 30 psi total pressure range, decreases decreasing argon concentration. Specifically, drops slightly concentration reduces from 60% 40%, then...