A5075942577- Particle accelerators and beam dynamics
- Particle Accelerators and Free-Electron Lasers
- Gyrotron and Vacuum Electronics Research
- Magnetic confinement fusion research
- High-pressure geophysics and materials
- Laser-Plasma Interactions and Diagnostics
- Superconducting Materials and Applications
- Nuclear Physics and Applications
- Astro and Planetary Science
- Pulsed Power Technology Applications
- Space Technology and Applications
- Muon and positron interactions and applications
- X-ray Spectroscopy and Fluorescence Analysis
- Plasma Diagnostics and Applications
- Electrostatic Discharge in Electronics
- Particle Detector Development and Performance
- Advanced X-ray Imaging Techniques
- Fusion materials and technologies
- Photonic and Optical Devices
- Particle physics theoretical and experimental studies
- Electromagnetic Launch and Propulsion Technology
- Nuclear Materials and Properties
- Atomic and Molecular Physics
- Rare-earth and actinide compounds
- Advanced Fiber Laser Technologies
Los Alamos National Laboratory
2008-2024
Fermi National Accelerator Laboratory
2018
Lawrence Livermore National Laboratory
2012-2014
University of Washington
2010
University of New Mexico
1994-2005
Los Alamos National Security (United States)
2002
High-pressure x-ray emission measurements are used to provide crucial evidence in the longstanding debate over nature of isostructural ($\ensuremath{\alpha}$, $\ensuremath{\gamma}$) volume collapse elemental cerium. Extended local atomic model calculations show that satellite $L\ensuremath{\gamma}$ line offers direct access total angular momentum observable $⟨{J}^{2}⟩$. This experiences a 30% steplike decrease across collapse, validating Kondo conjunction with previous measurements. Direct...
We present an x-ray scattering study of the temperature-induced phase separation and Si nanocrystal formation in bulk amorphous SiOx with x≈1. X-ray Raman at LII,III-edge reveals a significant contribution suboxides native SiO. The suboxide decreases increasing annealing temperature between 800–1200 °C pointing toward SiO into SiO2 domains. In combination diffraction small angle microstructure is found to be dominated by internal interfaces state. For higher temperatures above 900 growth...
Bragg mirrors can be used to direct a free-electron laser's x-ray beam onto sample, but the are extensively cratered by intense beam. To create mirrored surface that is reproducible from one laser shot next, authors in this work lithograph micropillars single crystal of silicon, and demonstrate strategy whereby each reflects light pillar surface, fresh micropillar would then indexed into position for next shot.
The LANL PHELIX pulsed-power driven liner implosion apparatus is fielded to measure the growth of Richtmyer-Meshkov instabilities (RMIs) in a cylindrical geometry under conditions liquid (Cren-1), mixed-state (Cren-2), and solid (Cren-3) release. 2D Lagrangian hydrocode simulations this imploding are compared against 800-MeV proton radiography data RMI growth. release (>35 GPa) was achieved with velocity 3 km s−1, demonstrates linear, continuous spike that agrees model. mixed (20 - 35 1.4...
Spallation Neutron Source (SNS) accelerator includes a nominally 1000 MeV, 2 mA average current linac consisting of radio frequency quadrupole (RFQ), drift tube (DTL), coupled cavity (CCL), medium and high beta superconducting (SC) linac, two buncher cavities for beam transport to the ring. Los Alamos is responsible RF systems all sections linac. The SNS pulsed proton system must support 1 msec pulse at up 60 Hz repetition rate. RFQ DTL utilize seven, 2.5 MW klystrons operate 402.5 MHz. CCL,...
Tokamak disruption simulation experiments have been conducted at the University of New Mexico using PLADIS I plasma gun system. Earlier work had characterized plasma-surface interaction in terms parameters such as incident energy from bucket calorimeter measurements and rough beam area flat damage targets. A variety new diagnostics used to further investigate characteristics vapor shield a simulated tokamak disruption. These included laser interferometry, two-color pyrometry, emission...
The Spallation Neutron Source being built at the Oak Ridge National Lab in Tennessee requires a 1 GeV proton linac. Los Alamos has responsibility for RF systems entire linac 3 distinct types of systems: 2.5-MW peak, 402.5 MHz, RFQ and DTL (7 total); 5-MW 805 MHz CCL two energy corrector cavities (6 550-kW superconducting sections (81 total). design SNS Linac system was presented 2001 Particle Accelerator Conference Chicago. Vendors have been selected klystrons (3 different vendors),...
The high voltage DC power supplies are predicted to be the most expensive component of accelerator at Accelerator Production Tritium (APT) plant. Two different types candidate HV being tested on Low Energy Demonstration (LEDA) Los Alamos National Laboratory. first type uses SCRs in a twelve pulse topology with spark gap crowbar. second IGBTs Solid State Modulator without While both topologies have been proven existing applications, systems contain new features improve performance and...
The RF transmitters for the 1-GeV Spallation Neutron Source (SNS) linear accelerator are powered by 15 converter-modulator stations. Each provides pulses up to 11 MW peak power with a 1.1 average multiple-klystron load. A low-voltage switching network, comprised of three sets four IGBTs in an 'H-bridge' configuration, is used generate 20 kHz drive waveform components step-up transformer primaries. This setup brings total number 3300-volt semiconductor operating within at 180. When biased...
The Los Alamos Neutron Science Center (LANSCE) is in the planning phase of a refurbishment project that will sustain reliable facility operations well into next decade. LANSCE accelerator was constructed late 1960s and early 1970s national user provides pulsed protons spallation neutrons for defense civilian research applications. focus on systems are approaching "end life" where modern upgrades hold promise significant operating cost savings. current baseline consist replacing all 201 MHz...
Successful operation of the Accelerator Production Tritium (APT) plant will require that accelerator downtime be kept to an absolute minimum. Over 230 separate 1 MW RF systems are expected used in APT plant, making efficiency and reliability these two most critical factors operation. The Low Energy Demonstration (LEDA) being constructed at Los Alamos National Laboratory serve as prototype for APT. design LEDA has been driven by need high extremely system reliability. We present details...
The availability goals and installation schedule for the Spallation Neutron Source (SNS) have driven of SNS linac's high-power RF systems. This paper discusses how systems' been addressed in transmitter design procurement. Design features that allow component failures to be quickly diagnosed repaired are also presented. Special attention has given interlocks, PLC fault logging real-time interfaces accelerator's Experimental Physics Industrial Control System (EPICS) archive system. cost...
The klystron microwave amplifier tubes used in the low energy demonstration accelerator (LEDA) and to be production of tritium (APT) plant have a strict upper limit on amount which can safely dissipated within klystron's vacuum envelope during high voltage arc. One way prevent damage from occurring tube is through use crowbar circuit diverts stored power supply filter capacitors must extremely reliable. To test circuit, wire that designed fuse when it absorbs predetermined switched between...
The effects of shock from alternating current (ac) power frequencies (50 and 60 Hz) direct. (dc) has been studied for a century thresholds safety are now clearly defined in worker standards (i.e., NFPA 70E). However, other waveforms not stated U.S. electrical standards. This includes sub-radio frequency (RF) (1 Hz to 3 kHz) than 50/60 Hz, RF (3 kHz 100 MHz) mixed waveforms, such as modulated dc. Of particular interest 400 dc with significant ac ripple, RF. These found many commercial,...
The Spallation Neutron Source (SNS) linac will provide a 1 GeV proton beam for injection into the accumulator ring. In normal conducting (NC) section of this linac, Radio Frequency Quadupole (RFQ) and six drift tube (DTL) tanks are powered by seven 2.5 MW, 402.5 MHz klystrons four coupled cavity (CCL) cavities 5.0 805 klystrons. Eighty-one 550 kW, each drive single in superconducting (SC) linac. high power radio frequency (HPRF) equipment was specified procured LANL tested before delivery to...
Shock compression of granular ceria (CeO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> ) was studied in converging cylindrical geometry using LANL proton radiography, and driven by the Precision High Energy-Density Liner Implosion Experiment (PHELIX) magnetic implosion system. PHELIX delivered nearly 4 MA to a 1.25-mm thick liner-impactor magnetically accelerate it ~0.8-1.0 mm μs <sup xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup>...