A5011265007- Laser-Plasma Interactions and Diagnostics
- Laser-induced spectroscopy and plasma
- Laser Material Processing Techniques
- Laser-Matter Interactions and Applications
- Particle Accelerators and Free-Electron Lasers
- Laser Design and Applications
- Particle accelerators and beam dynamics
- Atomic and Molecular Physics
- Magnetic confinement fusion research
- Gyrotron and Vacuum Electronics Research
- Solid State Laser Technologies
- Terahertz technology and applications
- High-pressure geophysics and materials
- Parkinson's Disease Mechanisms and Treatments
- Adaptive optics and wavefront sensing
- Magnetic and transport properties of perovskites and related materials
- Optical measurement and interference techniques
- Diamond and Carbon-based Materials Research
- Pulsed Power Technology Applications
- Mechanical and Optical Resonators
- Combustion and Detonation Processes
- Crystallography and Radiation Phenomena
- Electrohydrodynamics and Fluid Dynamics
- Characterization and Applications of Magnetic Nanoparticles
- Advanced Chemical Physics Studies
Northrop Grumman (United States)
2023
Naval Research Laboratory Plasma Physics Division
2020-2021
United States Naval Research Laboratory
2020-2021
Alion Science and Technology (United States)
2021
National Academies of Sciences, Engineering, and Medicine
2020
University of California, Los Angeles
2011-2017
Iscte – Instituto Universitário de Lisboa
2016
Tsinghua University
2016
Instituto Superior Técnico
2016
University of South Florida
2012
Laser wakefield acceleration of electrons holds great promise for producing ultracompact stages GeV scale, high-quality electron beams applications such as x-ray free lasers and high-energy colliders. Ultrahigh intensity laser pulses can be self-guided by relativistic plasma waves (the wake) over tens vacuum diffraction lengths, to give >1 energy in centimeter-scale low density plasmas using ionization-induced injection inject charge into the wake even at densities. By restricting a distinct...
<h3>Objective:</h3> To evaluate the efficacy and tolerability of lubiprostone (Amitiza) for constipation in Parkinson disease (PD) a double-blind, randomized, controlled study. <h3>Methods:</h3> Patients with PD clinically meaningful (constipation rating scale score > 10 [range: 0−28]) were recruited from 2 academic movement disorder centers to participate After enrollment, patients initially followed weeks then randomly assigned 1:1 lubiprostone, dose was titrated up 48 μg/day. They...
A new generation of laser wakefield accelerators, supported by the extreme accelerating fields generated in interaction PW-Class lasers and underdense targets, promises production high quality electron beams short distances for multiple applications.Achieving this goal will rely heavily on numerical modeling further understanding underlying physics identification optimal regimes, but large scale these scenarios is computationally heavy requires efficient use state-of-the-art Petascale...
We discovered period doubling and chaos in a simulated MEMS cantilever system with electrostatic sensing actuation, intended for based mass storage chip, without servo control. used graphical interface Poincare map method that allowed us to simulate multiple initial conditions simultaneously. investigated both the static dynamic instabilities of subjected weak strong disturbances. observed bistability Hopf bifurcation closed loop controlled gain phase margin when was Furthermore, we have...
Advanced Parkinson's disease (PD) is associated with various motor and non-motor symptoms which adversely impact health-related quality of life (HRQoL). Subthalamic nucleus (STN) deep brain stimulation (DBS) has been reported to improve some dimensions HRQoL in appropriately selected candidates. Prior studies following DBS have used instruments comprising a predetermined list questions assess issues that are generally relevant PD, but may not be equal or consistent importance all...
Ultrarelativistic-energy electron ring structures have been observed from laser-wakefield acceleration experiments in the blowout regime. These rings had 170-280 MeV energies with 5%-25% energy spread and ∼10 pC of charge were over a range plasma densities compositions. Three-dimensional particle-in-cell simulations show that laser intensity enhancement wake leads to sheath splitting formation hollow toroidal pocket density around behind first period. If propagates distance greater than...
A numerical model for laser-matter interactions in the warm dense matter regime is presented with broad applications, e.g., ablation, thermionic emission, and radiation. unique approach adopted, which a complete set of collisional transport data calculated using quantum incorporated into classical two-temperature electron lattice-ion temperatures. The was produced by average atom that combines speed, conceptual simplicity, straightforward development. Such are suitable use regime, where most...
We have used Poincare mapping to find and characterize nonlinear dynamics chaos in a periodically forced, electrostatically actuated MEMS cantilever intended for probe-based data storage chip. The results show significant chaotic regions the excitation parameter space that would not be found with standard Simulink-type simulations both open closed loop control of cantilever. For one case stable operation range is reduced by 25% because response. also region bi-stability at low gain.
The generation of low-frequency radiation from a short pulse (∼100 fs) laser with mJ energy incident on metal surface is investigated. electrons within the absorb pulse, increasing in temperature to few electron volts and resulting some at high-energy tail distribution overcome work function barrier. Emission these contributes current which sources secondary emission. Richardson–Dushman emission picture breaks down due Coulombic effects modified model presented. Previous precedence exists...
Abstract Collisional and transport parameters for Cu are computed using the average atom model. Transition metals such as copper difficult to model within framework of due presence a narrow band 3 d electrons that mix hybridize with broad 4 s nearly-free electrons. With electron temperature increasing, play key role in thermodynamics properties (Lin et al 2008 Phys. Rev. B 77 075133), well stability lattice (Loboda 2011 High Energy Density 7 361). In this work, was used track energy its...
Using the code OSIRIS we examine wakes and particle trapping for non-evolving drivers. We how threshold depends on wake amplitude phase velocity as well pseudo-potential. concentrate beam drivers vary driver strength (normalized current), shape, spot size velocity. compare of to that beam. find one nears onset can evolve even if does not evolve.
The generation of low-frequency radiation from sub-picosecond laser pulses incident on metal targets is investigated. field drives time-varying currents in a thin sub-surface layer the metal, which emits broadband that peaks at terahertz frequencies. We present one-dimensional electrostatic model for copper appropriate interaction normal incidence combined with an infinitely disk. latter uses as input single parameter, temporal dependence integrated current density axis, derived model....
A high-power klystrode RF system for the RFQ1 facility at Chalk River Laboratories has been manufactured by Continental Electronics corporation, Dallas using amplifier tubes developed Varian, San Carlos. The consists of two units, each capable 250 kW in pulsed or CW mode. units can be operated independently to drive separate accelerator structures, together a master/slave combination one structure. This is first power accelerator, and significant step development, increasing average per tube...
The existing “quotidian equation of state (QEOS)” model [More et al., Phys. Fluids 31, 3059 (1988)] has been revised, and an alternative set formulas is provided for the Helmholtz free energy, internal heat capacity, pressure. A novel scheme constructing ion equation-of-state proposed based on additive solid fluid components that act throughout temperature range, in contrast to QEOS matches thermodynamic parameters at selected interfaces. These are continuous along with their first second...
The emission of multi-MeV ($γ$-ray) photons from the interaction a high-powered laser pulse with dense plasma target is studied using particle-in-cell simulations. A new set diagnostic techniques presented and applied to analyze intense field ultra-relativistic electrons. Such methods elucidate dominant processes responsible for efficient laser-to-$γ$ energy conversion, which include nonlinear Compton scattering magneto-bremsstrahlung radiation, provide clear picture on microscopic level. We...
Thermionic emission of electrons is a process fundamental to our understanding laser–matter interactions in the ultra-short pulse regime. Charge collected from an process, as well secondary radiation generated by their collective motion, provides avenues for diagnosing and verifying existing laser–solid interaction models. Laser fluences (∼104 J/m2) are particular interest they heat surface temperatures on order few electron volts (eV), placing it warm dense matter regime where much...
High-current, cw linear accelerators have been proposed as spallation neutron source drivers for applications to tritium production, transmutation of nuclear waste, and safe power generation. Key features these are high current (100 mA) low emittance-growth beam propagation, or duty-factor operation, efficiency, minimal maintenance downtime. A 267.1 MHz, RFQ klystrode based RF system were obtained from CRL installed at LANL support next generation accelerator studies. The reconditioning the...
Recently it was proposed in [A. F. Lifschitz, et. al., J. Comp. Phys. 228, 1803 (2009)] that laser wakefield acceleration could be modeled efficiently using a particle-in-cell code cylindrical coordinates if the fields and currents were expanded into Fourier modes azimuthal angle, ɸ. We have implemented this algorithm OSIRIS, including new rigorous charge conserving deposition routine applicable for Davidson, 281, 1063 (2014)]. This can interpreted as PIC description r – z gridless ɸ which...
A detailed study of the scaling laws for LWFA in self-guided, nonlinear blowout regime is presented. The enabled through recent implementation quasi-3D algorithm into OSIRIS, which permits particle-in-cell simulations at lower densities and higher laser energy. We find that continue to work well when we fix normalized amplitude, pulse-length, spot size, while reducing plasma density. examine parameters self-injected electron energies are between 1 10 GeV. Over a wide parameter space,...
There are significant gaps in the memory hierarchy of small and large computer systems. Gaps entry price, latency, power, volume can be filled with a non-volatile probe-based MEMS-actuated storage chip. The Carnegie Mellon vision for this system uses magnetic medium positioned xy plane by electrostatic comb motors, writes magnetically using an array probe tips, each z axis servo. This paper reviews published work several authors on aspects system.
The scaling laws for laser wakefield acceleration in the nonlinear, self-guided regime [Lu et al. Phys. Rev. Spec. Top. Accel. Beams 10, 061301 (2007)] are examined detail using quasi-3D version of particle-in-cell code OSIRIS. We find that continue to work well as plasma density is reduced while normalized amplitude kept fixed. For fixed energy, energy gain an isolated bunch electrons can be improved with some loss charge by shortening pulse length until self-guiding no longer occurs, and...