A5031673992- Particle Accelerators and Free-Electron Lasers
- Particle accelerators and beam dynamics
- Laser-Plasma Interactions and Diagnostics
- Advanced X-ray Imaging Techniques
- Laser-induced spectroscopy and plasma
- Gyrotron and Vacuum Electronics Research
- Laser-Matter Interactions and Applications
- Crystallography and Radiation Phenomena
- Laser Design and Applications
- Adrenal and Paraganglionic Tumors
- Superconducting Materials and Applications
- Spectroscopy Techniques in Biomedical and Chemical Research
- Atomic and Subatomic Physics Research
- Magnetic confinement fusion research
- Advancements in Photolithography Techniques
- Electromagnetic Simulation and Numerical Methods
- High-pressure geophysics and materials
- Dust and Plasma Wave Phenomena
- Advanced Radiotherapy Techniques
- Advanced Fiber Laser Technologies
- Advanced Optical Sensing Technologies
- Advanced Data Storage Technologies
- Thermal Radiation and Cooling Technologies
- Ocular and Laser Science Research
- Superconducting and THz Device Technology
Argonne National Laboratory
2012-2024
Brookhaven National Laboratory
2021-2023
Illinois Institute of Technology
2020
Lawrence Berkeley National Laboratory
2004-2009
University of California, Berkeley
2002-2009
University of California, Los Angeles
2009
Hebrew University of Jerusalem
2008
Princeton Plasma Physics Laboratory
2008
The spatiotemporal response of crystals in x-ray Bragg diffraction resulting from excitation by an ultra-short, laterally confined pulse is studied theoretically. theory presents extension the analysis symmetric reflection geometry [1] to generic case, which includes both (Bragg) and transmission (Laue) asymmetric scattering geometries. presented as a product crystal-intrinsic plane wave function envelope defined crystal-independent transverse profile incident beam geometry. diffracted...
Simulations of the x-ray free-electron laser (FEL) oscillator are presented that include frequency-dependent Bragg crystal reflectivity and transverse diffraction focusing using two-dimensional FEL code GINGER. A review physics reflectors is made, followed by a discussion its numerical implementation in The simulation results for two-crystal cavity realistic parameters indicate $\ensuremath{\sim}{10}^{9}$ photons nearly Fourier-limited, ps pulse. Compressing electron beam to 100 fs...
A plasma-based resonant backward Raman amplifier/compressor for high power amplification of short laser pulses might, under ideal conditions, convert as much 90% the pump energy to seed pulse. While theoretical highest possible efficiency this scheme has not yet been achieved, larger efficiencies than ever before obtained experimentally (6.4%) are now being reported, and these accompanied by strong pulse compression. Based on recent extensive experiments, it is deduce that realized amplifier...
Free-electron lasers (FELs) can now generate temporally short, high power x-ray pulses of unprecedented brightness, even though their longitudinal coherence is relatively poor. The be potentially improved by employing narrow bandwidth crystal optics, in which case one must also understand how the affects field profile time and space. We frame dynamical theory diffraction as a set coupled waves order to derive analytic expressions for spatiotemporal response Bragg scattering from short...
Measurements of the multishot-averaged, soft x-ray, self-seeding spectrum at LCLS free-electron laser often have a pedestal-like distribution around seeded wavelength, which limits spectral purity and can negatively affect some user applications not employing post-undulator monochromator. In this paper, we study origins such pedestals, focusing on longitudinal phase space modulations produced by microbunching instability upstream (FEL) undulator. We show from theory numerical simulation that...
We augment the usual three-wave cold-fluid equations governing Raman backscatter (RBS) with a new kinetic thermal correction, proportional to an average of particle energy weighted by ponderomotive phase. From closed-form analysis within homogeneous model and ponderomotively averaged simulations in more realistic pulsed case, magnitude these contributions is shown be measure dynamical detuning between pump laser, seed Langmuir wave. Saturation RBS analyzed, role trapped particles...
A modified version of the plasma beat-wave accelerator scheme is proposed, based on autoresonant phase locking Langmuir wave to slowly chirped beat frequency driving lasers by passage through resonance. Peak electric fields above standard detuning limits seem readily attainable, and excitation robust large variations in density or chirp rate. This might be implemented existing pulse amplification ${\mathrm{C}\mathrm{O}}_{2}$ laser systems.
Experiments are described in which a 1mJ, 1ps, 1200nm seed laser beam is amplified by the interaction with an intersecting 350J, 1ns, 1054nm pump low density (1×1019∕cm3) plasma. The transmission of observed to be enhanced ≳25× when plasma near resonant for stimulated Raman scattering, compared measured transmissions at wavelengths just below value. amplification increase rapidly increases both intensity and density.
Generation of short-wavelength radiation by a free-electron laser using up-frequency conversion an electron bunch density modulation is currently area active research. We propose new scheme for producing the longitudinal similar to recently proposed echo-enabled harmonic generation but based on emittance exchange beam line and multislit mask. Beam analysis start-to-end simulation are presented.
We report observations of an intense sub-THz radiation extracted from a ∼3 MeV electron beam with flat transverse profile propagating between two parallel oversized copper gratings side openings. Low-loss outcoupling is accomplished using horn antenna and miniature permanent magnet separating beams. A tabletop experiment utilizes radio frequency thermionic gun delivering thousand momentum-chirped microbunches per macropulse alpha-magnet movable scraper producing sub-mm microbunches. The...
Undulator radiation is partially coherent in the transverse plane, with degree of coherence depending on ratio electron beam phase space area (emittance) to characteristic wavelength $\ensuremath{\lambda}$. On other hand, numerical codes used predict x-ray line performance can typically only propagate fields from source image plane. We investigate methods for representing undulator using a suitably chosen set that be standard wave propagation codes, and discuss such ``coherent mode...
The longitudinal dynamics of a resonantly driven Langmuir wave are analyzed in the limit that growth electrostatic is slow compared to bounce frequency. Using simple physical arguments, nonlinear distribution function shown be nearly gaussian canonical particle action, with slowly evolving mean and fixed variance. Self-consistency potential provide basic properties including frequency shift agrees well driven, simulations. This extends earlier work on waves by Morales O'Neil [G. J. T. M....
New solutions to the coupled three-wave equations in a nonuniform plasma medium are presented that include both space and time dependence of waves. By including dominant nonlinear frequency shift material wave, it is shown if driving waves sufficiently strong (in relation gradient), nonlinearly phase-locked solution develops characteristic autoresonance. In this case, (electrostatic) wave into front starting at linear resonance point moving with group velocity manner such intensity increases...
Impedance modeling for accelerator applications has improved over the years, largely as a result of advances in simulation capabilities. While this been successful reproducing certain measurements, it is still significant challenge to predict collective effects real machines. In paper, we review our approach impedance and subsequent simulations effects. We discuss choice electrodynamics codes required computer power resources, geometric, resistive wall impedances, their comparison with...
An approach for studying atom-radiation interaction has been developed, associating quantum operators with stochastic variables governed by discrete Heisenberg equations. This framework models general multilevel atomic systems using the paraxial approximation in both single- and multipass configurations. Simulation results x-ray laser oscillators parameters of interest are presented. The model is efficient to solve, as required computational resources scale linearly number emitters, it may...
A model of kinetic effects in Langmuir wave dynamics is presented using a nonlinear distribution function that includes particle separatrix crossing and self-consistent electrostatic evolution. This based on the adiabatic motion electrons to describe Bernstein–Greene–Kruskal-like waves over wide range temperatures (0.1⩽kλD⩽0.4). The asymptotic yields frequency shift agrees well with Vlasov simulations, can furthermore be used determine energy required develop phase-mixed, state. From this...
Modern electron storage rings produce bright x rays via spontaneous synchrotron emission, which is useful for a variety of scientific applications. The x-ray free-electron laser oscillator (XFELO) has the potential to amplify this output, both in terms peak power and photon coherence. However, even current fourth generation (4GSRs) lack requisite beam brightness drive XFELO due its energy spread. transverse gradient undulator (TGU) can overcome issue, thus providing practical means couple...
A numerical code based on an eikonal formalism has been developed to simulate laser-plasma interactions, specifically Raman backscatter (RBS). In this code, the dominant laser modes are described by their wave envelopes, avoiding need resolve frequency; appropriately time-averaged equations describe particle motion. The is fully kinetic, and thus includes critical physics such as trapping Landau damping which beyond scope of commonly used fluid three-wave equations. forces particles...
Free-electron lasers for hard X-rays can be constructed in the oscillator configuration by employing diamond crystals as X-ray mirrors. An FEL (XFELO) will produce highly stable beams of ultra-high spectral purity and high average brightness, offering scientific opportunities areas not covered high-gain devices. XFELO combined with a amplifier, possibly harmonic generation, would constitute an ultimate machine.
We analyze single bunch transverse instabilities due to wakefields using a Fokker-Planck model. first expand on the work of T. Suzuki, Part. Accel. 12, 237 (1982) derive theoretical model including chromaticity, both dipolar and quadrupolar wakefields, effects damping diffusion synchrotron radiation. reduce problem linear matrix equation, whose eigenvalues eigenvectors determine collective stability beam. then show that various predictions theory agree quite well with results from particle...