A5052891225- Laser-Plasma Interactions and Diagnostics
- Laser-induced spectroscopy and plasma
- Laser-Matter Interactions and Applications
- Atomic and Molecular Physics
- High-pressure geophysics and materials
- Plasma Diagnostics and Applications
- Laser Design and Applications
- Magnetic confinement fusion research
- Particle accelerators and beam dynamics
- Dust and Plasma Wave Phenomena
- Nuclear Physics and Applications
- Ionosphere and magnetosphere dynamics
- Advanced X-ray Imaging Techniques
- Particle Accelerators and Free-Electron Lasers
- Laser Material Processing Techniques
- Solar and Space Plasma Dynamics
- Ultrasound and Hyperthermia Applications
- Ion-surface interactions and analysis
- Gamma-ray bursts and supernovae
- Geophysics and Sensor Technology
- Space Satellite Systems and Control
- Astro and Planetary Science
- Electrohydrodynamics and Fluid Dynamics
- Radiation Therapy and Dosimetry
- Ocular and Laser Science Research
University of California, San Diego
2017-2025
Université de Bordeaux
2022
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2022
Centre Lasers Intenses et Applications
2022
Centre National de la Recherche Scientifique
2022
P.N. Lebedev Physical Institute of the Russian Academy of Sciences
2022
The University of Texas at Austin
2010-2020
Peking University
2016-2020
University of Michigan
2016-2020
Lawrence Berkeley National Laboratory
2020
We use numerical simulations to demonstrate that a source of collimated multi-MeV photons with high conversion efficiency can be achieved using an all-optical single beam setup at intensity 5×10^{22} W/cm^{2} is already within reach existing laser facilities. In the studied setup, unprecedented quasistatic magnetic field (0.4 MT) driven in significantly overdense plasma, coupling three key aspects laser-plasma interactions intensities: relativistic transparency, direct acceleration, and...
The direct laser acceleration (DLA) of electrons in underdense plasmas can provide hundreds nC accelerated to near-GeV energies using currently available lasers. Here we demonstrate the key role electron transverse displacement and use it analytically predict expected maximum energies. energy scaling is shown be agreement with full-scale quasi-3D particle-in-cell simulations a pulse propagating through preformed guiding channel directly used for optimizing DLA near-future facilities....
We report on a novel compact laser-driven neutron source with an unprecedented short pulse duration ($<50\text{ }\text{ }\mathrm{ps}$) and high peak flux ($>{10}^{18}\text{ }\mathrm{n}/{\mathrm{cm}}^{2}/\mathrm{s}$), order of magnitude higher than any existing source. In our experiments, high-energy electron jets are generated from thin ($<3\text{ }\ensuremath{\mu}\mathrm{m}$) plastic targets irradiated by petawatt laser. These intense beams employed to generate neutrons metal converter. Our...
It is shown that electrons with momenta exceeding the `free electron' limit of $m_eca_0^2/2$ can be produced when a laser pulse and longitudinal electric field interact an electron via non-wakefield mechanism. The mechanism consists two stages: reduction dephasing rate $\gamma-p_x/m_ec$ by accelerating region acceleration Lorentz force. This can, in principle, produce have longtudinal significant multiple $m_eca_0^2/2$. 2D PIC simulations relatively simple laser-plasma interaction indicate...
We examine a regime in which linearly polarized laser pulse with relativistic intensity irradiates sub-critical plasma for much longer than the characteristic electron response time. A steady-state channel is formed this case quasi-static transverse and longitudinal electric fields. These relatively weak fields significantly alter dynamics. The field reduces dephasing between wave, leading to an enhancement of energy gain from pulse. ultimately limited by superluminosity wave fronts induced...
Since the invention of chirped pulse amplification, which was recognized by a Nobel Prize in physics 2018, there has been continuing increase available laser intensity. Combined with advances our understanding kinetics relativistic plasma, studies laser–plasma interactions are entering new regime where plasmas is strongly affected strong-field quantum electrodynamics (QED) processes, including hard photon emission and electron–positron (e−–e+) pair production. This coupling processes...
Intense lasers enable generating high-energy particle beams in university-scale laboratories. With the direct laser acceleration (DLA) method, leading part of pulse ionizes target material and forms a positively charged ion plasma channel into which electrons are injected accelerated. The high energy conversion efficiency DLA makes it ideal for large numbers photonuclear reactions. In this work, we reveal that, efficient to prevail, sufficiently atomic number is required maintain injection...
Some plasma propulsion concepts rely on a strong magnetic field to guide the flow through thruster nozzle. The question then arises of how magnetically confined can detach from spacecraft. This work presents magnetohydrodynamic (MHD) detachment scenario in which stretches lines infinity. Detachment takes place after energy density expanding drops below kinetic plasma. As flows along lines, originally sub-Alfvénic becomes super-Alfvénic; this transition is similar what occurs solar wind. In...
The ongoing development of the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) involves basic physics analysis its three major components: helicon plasma source, ion cyclotron-resonance heating module, and magnetic nozzle. This paper presents an overview recent theoretical efforts associated with project. It includes (1) a first-principle model for (2) nonlinear theory deposition rf-power at cyclotron frequency into flow, (3) discussion detachment mechanism relevant to VASIMR.
A new mechanism is reported that increases electron energy gain from a laser beam of ultrarelativistic intensity in underdense plasma. The increase occurs when the produces an ion channel confines accelerated electrons. frequency oscillations across strongly modulated by beam, which causes parametric amplification and enhances gain. This has threshold determined product density.
Powerful laser-plasma processes are explored to generate discharge currents of a few $100\,$kA in coil targets, yielding magnetostatic fields (B-fields) excess $0.5\,$kT. The quasi-static provided from hot electron ejection the laser-irradiated surface. According our model, describing qualitatively evolution current, major control parameter is laser irradiance $I_{\mathrm{las}}\lambda_{\mathrm{las}}^2$. space-time B-fields experimentally characterized by high-frequency bandwidth B-dot probes...
Using three-dimensional kinetic simulations, we examine the emission of collimated $\ensuremath{\gamma}$-ray beams from structured laser-irradiated targets with a prefilled cylindrical channel and its scaling laser power (in multi-PW range). The is increased by increasing energy size focal spot while keeping peak intensity fixed at $5\ifmmode\times\else\texttimes\fi{}{10}^{22}\phantom{\rule{0.2em}{0ex}}\mathrm{W}/{\mathrm{cm}}^{2}$. radius proportionally to accommodate change in size....
Using two-dimensional particle-in-cell simulations, we examine how an externally applied strong magnetic field impacts proton acceleration in laser-irradiated solid-density targets. We find that a kT-level external can sufficiently inhibit transverse transport of hot electrons flat target. While the electron heating by laser remains mostly unaffected, reduced during leads to enhancement maximum energies and overall number energetic protons. The resulting beam is much better collimated...
We present an in-depth experimental-computational study of the parameters necessary to optimize a tunable, quasi-monoenergetic, efficient, low-background Compton backscattering (CBS) x-ray source that is based on self-aligned combination laser-plasma accelerator (LPA) and plasma mirror (PM). The main findings are (1) LPA driven in blowout regime by 30 TW, fs laser pulses produce not only high-quality, quasi-monoenergetic electron beam, but also relativistically intense (a0 ∼ 1) spent drive...
A long laser beam propagating through an underdense plasma produces a positively charged ion channel by expelling electrons in the transverse direction. We consider dynamics of test electron resulting two-dimensional under action field and electric channel. considerable enhancement axial momentum can be achieved this case via amplification betatron oscillations. It is shown that oscillations parametrically amplified when frequency, which increases with wave amplitude, becomes comparable to...
We analytically investigate the acceleration of electrons undergoing betatron oscillations in an ion channel, driven by a laser beam propagating with superluminal (or luminal) phase velocity. The universal scalings for maximum attainable electron energy are found arbitrary and plasma parameters deriving set dimensionless equations paraxial ultra-relativistic motion. One our analytic predictions is emergence forbidden zones electrons' space. For individual electron, these give rise to...
The interaction of a multipicosecond, kilojoule laser pulse with surface solid target has been shown to produce electrons energies far beyond the free-electron ponderomotive limit ${m}_{e}{c}^{2}{a}_{0}^{2}/2$. Particle-in-cell simulations indicate that an increase in duration from 1 10 ps leads formation low-density shelf (about 10% critical density). extends over $100\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$ toward vacuum side, nonstationary potential barrier forming area. Electrons...
The ability of an intense laser pulse to propagate in a classically over-critical plasma through the phenomenon relativistic transparency is shown facilitate generation strong magnetic fields. Particle-in-cell simulations demonstrate that these fields significantly enhance radiation rates laser-irradiated electrons, and furthermore they collimate emission so directed dense beam multi-MeV gamma-rays achievable. This capability can be exploited for electron-positron pair production via linear...
Superponderomotive-energy electrons are observed experimentally from the interaction of an intense laser pulse with a relativistically transparent target. For target, kinetic modeling shows that generation energetic is dominated by energy transfer within main, classically overdense, plasma volume. The produces narrowing, funnel-like channel inside volume generates field structure responsible for electron heating. combines slowly evolving azimuthal magnetic field, generated strong...
A high-intensity laser beam propagating through a dense plasma drives strong current that robustly sustains quasistatic azimuthal magnetic field. The field efficiently accelerates electrons in such confines the transverse motion and deflects forward direction. Its advantage is threshold rather than resonant behavior, accelerating to high energies for sufficiently laser-driven currents. We study electron dynamics via test-electron model, specifically deriving corresponding critical density....
Abstract Creation of electrons and positrons from light alone is a basic prediction quantum electrodynamics, but yet to be observed. Our simulations show that the required conditions are achievable using high-intensity two-beam laser facility an advanced target design. Dual irradiation structured produces high-density γ rays then create > 10 8 at intensities 2 × 22 Wcm −2 . The unique feature this setup pair creation primarily driven by linear Breit-Wheeler process ( → e + − ), which...
Abstract Experimental measurements using the OMEGA EP laser facility demonstrated direct acceleration (DLA) of electron beams to (505 ± 75) MeV with (140 30) nC charge from a low-density plasma target 400 J, picosecond duration pulse. Similar trends energy density are also observed in self-consistent two-dimensional particle-in-cell simulations. The intensity pulse is sufficiently large that electrons rapidly expelled along propagation axis form channel. dominant mechanism confirmed be DLA...
Direct Laser Acceleration (DLA) of electrons during a high-energy, picosecond laser interaction with an underdense plasma has been demonstrated to be substantially enhanced by controlling the focusing geometry. Experiments using OMEGA EP facility measured accelerated maximum energies exceeding 120 times ponderomotive energy under certain focusing, pulse energy, and density conditions. Two-dimensional particle-in-cell simulations show that conditions alter field evolution, channel fields...
With the advent of high repetition rate laser facilities, novel diagnostic tools compatible with these advanced specifications are required. This paper presents design an active gamma-ray spectrometer intended for experiments, particular emphasis on functionality within a PW level laser-plasma interaction chamber’s extreme conditions. The uses stacked scintillators to accommodate broad range energies, demonstrating its adaptability various experimental setups. In addition, it has been...
Abstract We investigate the mechanisms responsible for single-lobed versus double-lobed angular distributions of emitted γ-rays in laser-irradiated plasmas, focusing on how direct laser acceleration (DLA) shapes emission profile. Using test-particle calculations, we show that efficiency DLA plays a central role. In inefficient regime, electrons rapidly gain and lose energy within single cycle, resulting profile heavily influenced by fields. contrast, efficient steadily accumulate over...