A5089032950- Particle Accelerators and Free-Electron Lasers
- Particle accelerators and beam dynamics
- Advanced X-ray Imaging Techniques
- Laser-Plasma Interactions and Diagnostics
- Gyrotron and Vacuum Electronics Research
- Advanced Electron Microscopy Techniques and Applications
- Electron and X-Ray Spectroscopy Techniques
- Laser Design and Applications
- Photocathodes and Microchannel Plates
- Laser-Matter Interactions and Applications
- Terahertz technology and applications
- Integrated Circuits and Semiconductor Failure Analysis
- Photonic and Optical Devices
- Pulsed Power Technology Applications
- Particle Detector Development and Performance
- Advanced Fiber Laser Technologies
- Crystallography and Radiation Phenomena
- Advanced Surface Polishing Techniques
- Laser-induced spectroscopy and plasma
- Laser Material Processing Techniques
- Superconducting Materials and Applications
- Advancements in Photolithography Techniques
- Plasma Diagnostics and Applications
- Spectroscopy and Laser Applications
- Orbital Angular Momentum in Optics
University of California, Los Angeles
2016-2025
Argonne National Laboratory
2022
Lawrence Berkeley National Laboratory
2022
UCLA Health
1999-2020
Tel Aviv University
2019
Particle Beam Lasers (United States)
2018
SLAC National Accelerator Laboratory
2010-2018
Arizona State University
2018
Cornell University
2018
University of Colorado Boulder
2017
Since the discovery of electron-wave duality, electron scattering instrumentation has developed into a powerful array techniques for revealing atomic structure matter. Beyond detecting local lattice variations in equilibrium structures, recent research efforts have been directed towards long sought-after dream visualizing dynamic evolution matter real-time. The behavior at ultrafast timescales carries critical information on phase transition and chemical reaction dynamics, coupling...
Ultralow emittance (≤20 nm, normalized) electron beams with 105 electrons per bunch are obtained by tightly focusing an ultrafast (∼100 fs) laser pulse on the cathode of a 1.6 cell radio frequency photoinjector. Taking advantage small initial longitudinal emittance, downstream velocity bunching cavity is used to compress beam <10 fs rms length. The measurement performed using thick high-voltage deflecting which shown be well suited measure ultrashort durations beams, provided that reaches...
Electron beams can generate radiation spanning a wide range of the electromagnetic spectrum. Creating temporal structure in beam density results intense emission proportional to square particle number as compared linear dependence on from randomly distributed electron beam. In this article various coherent processes are discussed including spontaneous emission, superradiance, and stimulated superradiance.
In this Letter we report a demonstration of electron ghost imaging. A digital micromirror device directly modulates the photocathode drive laser to control transverse distribution relativistic beam incident on sample. Correlating structured illumination pattern total sample transmission then retrieves target image, avoiding need for pixelated detector. our example, use compressed sensing framework improve reconstruction quality and reduce number shots compared raster scanning small across...
We experimentally investigate surface-plasmon assisted photoemission to enhance the efficiency of metallic photocathodes for high-brightness electron sources. A nanohole array-based copper surface was designed exhibit a plasmonic response at 800 nm, fabricated using focused ion beam milling technique, optically characterized and tested as photocathode in high power radio frequency photoinjector. Because larger absorption localization optical field intensity, charge yield observed under...
A radical change to the electron source could improve by orders of magnitude combined spatiotemporal resolution ultrafast microscopy. The authors design and evaluate an instrument featuring a high-brightness MeV beam from rf photoinjector. Being able take snapshots at 1000 times formerly highest rate would enable researchers study nanoscale dynamical processes in real time.
For 40 years, uniformly filled ellipsoidal beam distributions have been studied theoretically, as they hold the promise of generating self-fields linear in coordinate offset all three directions. Recently, a scheme for producing such distributions, based on strong longitudinal expansion an initially very short under its own space-charge forces, has proposed. In this Letter we present experimental demonstration scheme, obtained by illuminating cathode rf photogun with ultrashort laser pulse...
We report the experimental demonstration of time-resolved relativistic electron diffraction. Single shot diffraction patterns from a single crystal gold sample were recorded using ultrashort 3.5 MeV bunches radio frequency photoinjector. By scanning pump pulse time-delay, we studied Bragg peaks amplitude change due to laser-induced melting sample. The observed time scale matches one predicted simple two temperature model heating thin foil. Time-resolved megaelectronvolt beams with 107...
THz radiation promises breakthrough advances in compact advanced accelerators due to the high frequency and GV/m fields achievable, orders of magnitude larger than conventional radiofrequency (RF) based accelerators. Compared laser-driven schemes, large phase acceptances THz-driven are advantageous for operation with sizable charge. Despite burgeoning research, sources, particularly laser-based ones, cannot yet compete efficiency RF amplifiers average current Nevertheless, THz-based space...
Abstract Advances in ultrafast laser technology and nanofabrication have enabled a new class of particle accelerator based upon miniaturized laser-driven photonic structures. However, developing useful on this approach requires control the dynamics at field intensities approaching damage limit. We measure acceleration fused silica dielectric driven by fields up to 9 GV m −1 observe record 1.8 accelerating mode. At these is beyond its linear response self-phase modulation changes phase...
We present the experimental demonstration of a new scheme for generation ultrashort pulse trains based on free-electron-laser (FEL) emission from multipeaked electron energy distribution. Two beamlets with difference larger than FEL parameter ρ have been generated by illuminating cathode two ps-spaced laser pulses, followed rotation longitudinal phase space velocity bunching in linac. The resulting self-amplified spontaneous radiation, measured through frequency-resolved optical gating...
In the field of beam physics, two frontier topics have taken center stage due to their potential enable new approaches discovery in a wide swath science. These areas are: advanced, high gradient acceleration techniques, and x-ray free electron lasers (XFELs). Further, there is intense interest marriage these fields, with goal producing very compact XFEL. this context, recent advances radio-frequency cryogenic copper structure research opened door use surface electric fields between 250 500...
Using an 800 nm, 45 fs pulse-front-tilted laser we demonstrate a record 315 keV energy gain in dual grating dielectric accelerator (DLA) and average accelerating gradients of 560 MV/m over 0.5 mm. These results open new regime DLA characterized by significant evolution the beam distribution longitudinal phase space, corresponding to >1/4 synchrotron oscillation. By tilting wavefront control resonant velocity observe net gain, indicating that tapered optical could be used achieve very high gain.
Single shot diffraction patterns using a 250-fs-long electron beam have been obtained at the UCLA Pegasus laboratory. High quality images with spatial resolution sufficient to distinguish closely spaced peaks in Debye–Scherrer ring pattern recorded by scattering 1.6 pC 3.5 MeV generated rf photoinjector off 100-nm-thick Au foil. Dark current and high emittance particles are removed from before sending it onto target 1 mm diameter collimating hole. These results open door study of...
In this Letter we report on the use of ultrashort infrared laser pulses to generate a copious amount electrons by copper cathode in an rf photoinjector. The charge yield verifies generalized Fowler-Dubridge theory for multiphoton photoemission. emission is verified be prompt using two pulse autocorrelation technique. thermal emittance associated with excess kinetic energy from process comparable one measured frequency tripled uv pulses. high field gun, up 50 pC can extracted 80 fs long,...
This paper discusses the extension to different electron beam aspect ratio of Child-Langmuir law for maximum achievable current density in guns. Using a simple model, we derive quantitative formulas good agreement with simulation codes. The new scaling laws peak temporally long and transversely narrow initial distributions can be used estimate brightness suggest paths injector optimization.
Recent studies of the performance radio-frequency (rf) copper cavities operated at cryogenic temperatures have shown a dramatic increase in maximum achievable surface electric field. We propose to exploit this development enable new generation photoinjectors that may attain, through enhancement launch field photocathode, significant five-dimensional electron beam brightness. present detailed dynamics associated with such system, by examining an S-band photoinjector $250\text{ }\text{...
Dielectric laser accelerators (DLAs) are fundamentally based on the interaction of photons with free electrons, where energy and momentum conservation satisfied by mediation a nanostructure. In this scheme, photonic nanostructure induces near-fields which transfer from photon to electron, similar inverse-Smith–Purcell effect described in metallic gratings. This, turn, may provide ground-breaking applications, as it is technology promising miniaturize particle down chip scale. This...
The generation of electron bunches on the attosecond timescale is important for a multitude accelerator-based applications. Here, we report tomographic measurement (pre)linearized longitudinal phase space low charge 3 MeV bunch generated with 1.6 cell Pegasus photoinjector bunches. nonlinear correlations in induced by at photocathode, radiofrequency field curvature gun, and vacuum dispersion are compensated using compact X-band linearizer. Then, initial picosecond precisely reconstructed...
With the recent development of Diversity Electro-Optic Sampling (DEOS), significant progress has been made in range applicability single shot EOS measurements, allowing broadband THz waveforms to be captured a over large temporal windows. In addition decrease acquisition time compared standard multishot data acquisition, this technique allows measurements on systems far from equilibrium with shot-to-shot noise or irreversible poorly repeatable dynamics. Although DEOS demonstrated and...
With the recent development of Diversity Electro-Optic Sampling (DEOS), significant progress has been made in range applicability single shot EOS measurements, allowing broadband THz waveforms to be captured a over large temporal windows. In addition decrease acquisition time compared standard multishot data acquisition, this technique allows measurements on systems far from equilibrium with shot-to-shot noise or irreversible poorly repeatable dynamics. Although DEOS demonstrated and...