A5052767061- Laser-Plasma Interactions and Diagnostics
- Laser-Matter Interactions and Applications
- Laser Design and Applications
- Laser-induced spectroscopy and plasma
- Advanced Fiber Laser Technologies
- Nuclear Physics and Applications
- Particle Accelerators and Free-Electron Lasers
- Radiation Detection and Scintillator Technologies
- Solid State Laser Technologies
- Laser Material Processing Techniques
- Advanced X-ray Imaging Techniques
- Spectroscopy and Laser Applications
- High-pressure geophysics and materials
- Particle Detector Development and Performance
- Particle accelerators and beam dynamics
- Transition Metal Oxide Nanomaterials
- Gyrotron and Vacuum Electronics Research
- Photonic Crystal and Fiber Optics
- Ion-surface interactions and analysis
- Medical Imaging Techniques and Applications
- Atomic and Molecular Physics
- Terahertz technology and applications
- Advanced Optical Sensing Technologies
- Force Microscopy Techniques and Applications
- Physics of Superconductivity and Magnetism
Lawrence Livermore National Laboratory
2010-2024
The University of Texas at Austin
1991-2023
Massachusetts Institute of Technology
2023
Rutherford Appleton Laboratory
2023
University of California, Los Angeles
2023
Florida Agricultural and Mechanical University
2023
General Atomics (United States)
2023
SLAC National Accelerator Laboratory
2019
Friedrich Schiller University Jena
2019
Czech Technical University in Prague
2019
Femtosecond x-ray and visible pulses were used to probe structural electronic dynamics during an optically driven, solid-solid phase transition in ${\mathrm{VO}}_{2}$. For high interband excitation $(\ensuremath{\sim}5\ifmmode\times\else\texttimes\fi{}{10}^{21}{\mathrm{cm}}^{\ensuremath{-}3})$, a subpicosecond transformation into the high- $T$, rutile of material is observed, simultaneous with insulator-to-metal transition. The fast time scale observed suggests that, this regime, may not be...
In the 2015 review paper ‘Petawatt Class Lasers Worldwide’ a comprehensive overview of current status high-power facilities ${>}200~\text{TW}$ was presented. This largely based on facility specifications, with some description their uses, for instance in fundamental ultra-high-intensity interactions, secondary source generation, and inertial confinement fusion (ICF). With 2018 Nobel Prize Physics being awarded to Professors Donna Strickland Gerard Mourou development technique chirped...
We analyze the scalability of diffraction-limited fiber lasers considering thermal, non-linear, damage and pump coupling limits as well mode field diameter (MFD) restrictions. derive new general relationships based upon practical considerations. Our analysis shows that if fiber's MFD could be increased arbitrarily, 36 kW power obtained with quality from a laser or amplifier. This limit is determined by thermal non-linear combine to prevent further scaling, irrespective increases in size....
Using ultrafast, time-resolved, 1.54 angstrom x-ray diffraction, thermal and ultrafast nonthermal melting of germanium, involving passage through nonequilibrium extreme states matter, was observed. Such optical-pump, diffraction probe measurements provide a way to study many other transient processes in physics, chemistry, biology, including direct observation the atomic motion by which solid-state chemical biochemical reactions take place.
The new plasma diagnostic technique of spectral blueshifting femtosecond pulses is used for the first time to analyze quantitatively ionization noble gases under influence intense, illumination. two processes strong-field tunneling and electron impact are found play competing roles on these scales.
A laser wakefield acceleration study has been performed in the matched, self-guided, blowout regime producing 720 +/- 50 MeV quasimonoenergetic electrons with a divergence Deltatheta_{FWHM} of 2.85 0.15 mrad using 10 J, 60 fs 0.8 microm laser. While maintaining nearly constant plasma density (3 x 10{18} cm{-3}), energy gain increased from 75 to when length was 3 8 mm. Absolute charge measurements indicate that self-injection occurs power P exceeds times critical P{cr} for relativistic...
Plasma density oscillations (Langmuir waves) in the wake of an intense ( ${I}_{\mathrm{peak}}\ensuremath{\sim}3\ifmmode\times\else\texttimes\fi{}{10}^{17}\mathrm{W}/{\mathrm{cm}}^{2}$) laser pulse (100 fs) are measured with ultrafast time resolution using a longitudinal interferometric technique. Phase shifts consistent large amplitude $\ensuremath{\delta}{n}_{e}/{n}_{e}\ensuremath{\sim}1$) waves at electron plasma frequency were observed fully tunnel-ionized He plasma, corresponding to...
Damping of impulsively generated coherent acoustic oscillations in a femtosecond laser-heated thin germanium film is measured as function fluence by means ultrafast x-ray diffraction. By simultaneously measuring picosecond strain dynamics the and unexcited silicon substrate, we separate anharmonic damping from transmission through buried interface. The rate its dependence on calculated temperature thermal bath consistent with estimated four-body, elastic dephasing times $({T}_{2})$ for 7-GHz...
A high peak brilliance, laser-based Compton-scattering $\ensuremath{\gamma}$-ray source, capable of producing quasimonoenergetic photons with energies ranging from 0.1 to 0.9 MeV has been recently developed and used perform nuclear resonance fluorescence (NRF) experiments. Techniques for characterization beam parameters are presented. The key source the size ($0.01\text{ }\text{ }{\mathrm{mm}}^{2}$), horizontal vertical divergence ($6\ifmmode\times\else\texttimes\fi{}10\text{...
The Mercury laser system is a diode-pumped solid-state that has demonstrated over 60 J at repetition rate of 10 Hz (600 W) near-infrared light (1047 nm). Using yttrium calcium oxyborate frequency converter, we have 31.7 J/pulse second harmonic generation. converted will pump high-average-power Ti:sapphire chirped pulse amplifier produce compressed peak power > 1 PW and irradiance 1023W/cm2.
Compound parabolic concentrator (CPC) targets are utilized at the National Ignition Facility Advanced Radiographic Capability (NIF-ARC) laser to enhance acceleration of electrons and production high energy photons, for durations 10 ps energies up 2.4 kJ. A large enhancement mean electron (>2 ×) photon brightness (>10×) is found with CPC compared flat targets. Using multiple diagnostic techniques different spatial locations scaling by gold activation data, spectra characterized...
We demonstrate a novel, Michelson-based, ultrafast multiplexer with throughput approaching 100% for polarization-multiplexed train and 50% linearly polarized train, which is compatible high-energy pulse shaped-pulse generation. The interpulse spacings in the resultant 2n-pulse can be adjusted continuously from multinanoseconds through zero. Using this interferometer, we also generation of 16-pulse terahertz pulses.
A developed formalism<sup>1</sup> for analyzing the power scaling of diffraction limited fiber lasers and amplifiers is applied to a wider range materials. Limits considered include thermal rupture, lensing, melting core, stimulated Raman scattering, Brillouin optical damage, bend induced limits on core diameter coupling pump diode light into fiber. For conventional based upon silica, single aperture, limit was found be 36.6kW. This hard upper that results from an interaction scattering with...
A monoenergetic gamma-ray (MEGa-ray) source based on Compton scattering, targeting nuclear physics applications such as resonance fluorescence, has been constructed and commissioned at Lawrence Livermore National Laboratory. In this paper, the overall architecture of system, well some design decisions (such laser pulse lengths interaction geometry) made in development source, are discussed. The performances two systems (one for electron production, one scattering), photoinjector, linear...
A design study has been carried out for a second-generation experiment on laser guiding and wakefield excitation in channel. From simple scaling laws the amplitude, dephasing length, relativistic group velocity factor /spl gamma//sub g/, energy gain with without guiding, we find that parameter regime compact single stage GeV accelerator favors systems producing short pulses (10 fs/spl les//spl tau//spl les/100 fs), each containing an order of 100 mJ to few J's. Taking length as maximum...
What we believe to be the first demonstration of isotope-specific detection a low-Z and low density object shielded by high-Z high-density material using monoenergetic gamma rays is reported. The LiH Pb Al accomplished nuclear resonance fluorescence line L7i at 478 keV. Resonant photons are produced via laser-based Compton scattering. techniques general, confidence level obtained shown superior that yielded conventional x-ray gamma-ray in these situations.
The design of narrow-band Compton scattering sources for specific applications using nuclear resonance fluorescence (NRF) is presented. NRF lines are extremely narrow ($\ensuremath{\Delta}E/E\ensuremath{\sim}{10}^{\ensuremath{-}6}$) and require spectrally to be excited selectively efficiently. This paper focuses on the theory spectral broadening mechanisms involved during laser photons from relativistic electron beams. It shown that in addition beam emittance, energy spread, parameters,...
The generation of frequency upshifted, pressure-tunable third-harmonic pulses during ultrafast ionization subatmospheric noble gases at peak intensity 1016 W/cm2 is reported. Pressure tuning the power spectrum centroid over range 10−5 ≲ Δω/ω 10−1, corresponding to a pressure 0.1 p 700 Torr, demonstrated. We also demonstrate that blue-shifted portions both 3ω and ω are preferentially self-guided in limited (10 500 Torr), which key separating component harmonic from nontunable generated by...
Electromagnetic plasma computer simulations are used to analyze the frequency shifts caused by ionization of atmospheric-density noble gases during interaction with intense femtosecond laser pulses; results presented and compared experimental data. The trace temporal evolution growth ionizing pulse calculate resulting self-induced blue shift spectrum. Variations intensity, gas pressure, species calculated. relative contributions strong-field electron-impact on discussed. provide qualitative...
The pulse-width dependence of thermal melting and ablation thresholds in germanium gallium arsenide is correlated to direct, ultrafast x-ray measurements laser-heated depths. heating dynamics, determined by the interplay nonlinear optical absorption, delayed Auger heating, high-density carrier diffusion, explain scaling laws different semiconductors.
Time-resolved spectral blue shifts of 100-fs laser pulses caused by ionization atmospheric density N/sub 2/ and noble gases subjected to high (10/sup 14/ W/cm/sup 10/sup 16/ 2/) light intensities are examined. Included data for two experiments: self-shifting the ionizing varying peak intensities, pressures (1-5 atm), gas species; time-resolved a weak copropagating probe pulse same range conditions. The self-shift reveal universal, reproducible pattern in shape blueshifted spectra: as...
Novel architectures of Petawatt-class, high peak power laser systems that allow operating at repetition rates are opening a new arena commercial applications secondary sources and discovery science. The natural path to higher average is the reduction total heat load induced generated in gain medium eliminating other inefficiencies with goal turn more energy into photons while maintaining good beam quality. However, architecture must be tailored specific application parameters such as...
This document provides detailed information on the status of Advanced and Novel Accelerators techniques describes steps that need to be envisaged for their implementation in future accelerators, particular high energy physics applications. It complements overview prepared update European Strategy particle physics, a description field. The scientific priorities community are described each technique acceleration able achieve accelerating gradient GeV~range or above. ALEGRO working group...