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Laser wakefield accelerator driven by the super-Gaussian laser beam in the focus
摘要： Recent rapid progress in the development of laser wakefield accelerators has shown that these devices could become a compact and affordable alternative to conventional electron accelerators. The latter, fitted with radiofrequency cavities, attain the values of electric field gradients lower than 100 MV/m due to the cavity-wall breakdown [1]. In contrast, laser wakefield accelerators reach about thousand-fold higher gradients [2]. Therefore, much lower acceleration lengths are required for obtaining hundreds-MeV or even GeV class electron bunches.
关键词： particle-in-cell method,super-Gaussian beam,electron injection,laser-wakefield acceleration,laser-plasma accelerators
更新于2025-09-16 10:30:52
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Ultrahigh brightness attosecond electron beams from intense X-ray laser driven plasma photocathode
摘要： The emerging intense attosecond X-ray lasers can extend the Laser Wakefield Acceleration mechanism to higher plasma densities in which the acceleration gradients are greatly enhanced. Here we present simulation results of high quality electron acceleration driven by intense attosecond X-ray laser pulses in liquid methane. Ultrahigh brightness electron beams can be generated with 5-dimensional beam brightness over 1020 A · m?2 · rad?2. The pulse duration of the electron bunch can be shorter than 20 as. Such unique electron sources can benefit research areas requiring crucial spatial and temporal resolutions.
关键词： attosecond X-ray lasers,ultrahigh brightness electron beams,liquid methane,Laser Wakefield Acceleration,5-dimensional beam brightness
更新于2025-09-16 10:30:52
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On the use of the envelope model for down-ramp injection in laser-plasma accelerators
摘要： The path towards high 6D-brightness electron beams coming from plasma accelerators relies on numerical simulations to investigate and explain novel physics and parameter regimes. Particle-in-cell codes are a reliable tool for this purpose, but full-scale simulations can be computationally challenging, specifically when performing large parameter scans. Approximate models and solvers are an alternative to quickly assess new regimes, but one needs to understand the validity of these models for each specific problem. In this work, we investigate the usefulness of a ponderomotive guiding center solver to model density down-ramp injection in laser wakefield accelerators. We also report results for density down-ramp injection in the context of EuPRAXIA, where we find that this method can produce 250 MeV, 30 pC beams that fulfill all the requirements for the injector stage, with <1 % energy spread and <100 nm emittance.
关键词： particle-in-cell,ponderomotive guiding center,simulations,density down-ramp injection,EuPRAXIA,laser wakefield acceleration,kinetic
更新于2025-09-12 10:27:22
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Demonstration of Femtosecond Broadband X-rays from Laser Wakefield Acceleration as a Source for Pump-Probe X-ray Absorption Studies
摘要： We present X-ray absorption measurements near the K-edge of laser heated aluminum in a pump-probe configuration using X-rays generated in a laser wakefield accelerator. A 30 fs duration laser pulse from the Hercules laser system was split into two beam lines, with one used to heat a 4 μm thickness Al foil and the second to drive a laser wakefield accelerator. The laser-heated plasma was probed at various pump-probe delays using the femtosecond duration X-rays generated by betatron oscillations of the electrons in the wakefield. We observe an apparent blue-shift of the K-edge occurring on a sub-picosecond timescale in the transmission spectra.
关键词： Broadband X-rays,X-ray Absorption Studies,Femtosecond,Laser Wakefield Acceleration,Pump-Probe
更新于2025-09-12 10:27:22
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Circumventing the Dephasing and Depletion Limits of Laser-Wakefield Acceleration
摘要： Compact electron accelerators are paramount to next-generation synchrotron light sources and free-electron lasers, as well as for advanced accelerators at the TeV energy frontier. Recent progress in laser-plasma driven accelerators (LPA) has extended their electron energies to the multi-GeV range and improved beam stability for insertion devices. However, the subluminal group velocity of plasma waves limits the final electron energy that can be achieved in a single LPA accelerator stage, also known as the dephasing limit. Here, we present the first laser-plasma driven electron accelerator concept providing constant acceleration without electrons outrunning the wakefield. The laser driver is provided by an overlap region of two obliquely incident, ultrashort laser pulses with tilted pulse fronts in the line foci of two cylindrical mirrors, aligned to coincide with the trajectory of the accelerated electrons. Such a geometry of laterally coupling the laser into a plasma allows for the overlap region to move with the vacuum speed of light, while the laser fields in the plasma are continuously being replenished by the successive parts of the laser pulses. Our scheme is robust against parasitic self-injection and self-phase modulation as well as drive-laser depletion and defocusing along the accelerated electron beam. It works for a broad range of plasma densities in gas targets. This method opens the way for scaling up electron energies beyond 10 GeV, possibly towards TeV-scale electron beams, without the need for multiple laser-accelerator stages.
关键词： Laser-wakefield acceleration,photonics,optics,electron accelerators,plasma physics
更新于2025-09-11 14:15:04
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A spectrometer for ultrashort gamma-ray pulses with photon energies greater than 10 MeV
摘要： We present a design for a pixelated scintillator based gamma-ray spectrometer for non-linear inverse Compton scattering experiments. By colliding a laser wakefield accelerated electron beam with a tightly focused, intense laser pulse, gamma-ray photons up to 100 MeV energies and with few femtosecond duration may be produced. To measure the energy spectrum and angular distribution, a 33 × 47 array of cesium-iodide crystals was oriented such that the 47 crystal length axis was parallel to the gamma-ray beam and the 33 crystal length axis was oriented in the vertical direction. Using an iterative deconvolution method similar to the YOGI code, modeling of the scintillator response using GEANT4 and fitting to a quantum Monte Carlo calculated photon spectrum, we are able to extract the gamma ray spectra generated by the inverse Compton interaction.
关键词： CsI scintillator,inverse Compton scattering,laser wakefield acceleration,gamma-ray spectrometer,GEANT4 simulations
更新于2025-09-09 09:28:46