20 research outputs found
Extremely powerful and frequency-tunable terahertz pulses from a table-top laser-plasma wiggler
The production of broadband, terawatt terahertz (THz) pulses has been demonstrated by irradiating relativistic lasers on solid targets. However, the generation of extremely powerful, narrow-band, and frequency-Tunable THz pulses remains a challenge. Here, we present a novel approach for such THz pulses, in which a plasma wiggler is elaborated by a tabletop laser and a near-critical density plasma. In such a wiggler, the laser-Accelerated electrons emit THz radiations with a period closely related to the plasma thickness. Theoretical model and numerical simulations predict a THz pulse with a laser-THz energy conversion over 2.0%, an ultra-strong field exceeding 80 GV/m, a divergence angle approximately 20?, and a center-frequency tunable from 4.4 to 1.5 THz, can be generated from a laser of 430 mJ. Furthermore, we demonstrate that this method can work across a wide range of laser and plasma parameters, offering potential for future applications with extremely powerful THz pulse. © 2023 Authors. All rights reserved.11Nsciescopu
Synchronous post-acceleration of laser-driven protons in helical coil targets by controlling the current dispersion
Post-acceleration of protons in helical coil targets driven by intense, ultrashort laser pulses can enhance ion energy by utilizing the transient current from the targets’ self-discharge. The acceleration length of protons can exceed a few millimeters, and the acceleration gradient is of the order of GeV/m. How to ensure the synchronization between the accelerating electric field and the protons is a crucial problem for efficient post-acceleration. In this paper, we study how the electric field mismatch induced by current dispersion affects the synchronous acceleration of protons. We propose a scheme using a two-stage helical coil to control the current dispersion. With optimized parameters, the energy gain of protons is increased by four times. Proton energy is expected to reach 45 MeV using a hundreds-of-terawatts laser, or more than 100 MeV using a petawatt laser, by controlling the current dispersion
Um programa de ginástica para coronariopatas Coletânea de ExercÃcios Sugeridos
The acceleration of super-heavy ions (SHIs) from plasmas driven by ultrashort
(tens of femtoseconds) laser pulses is a challenging topic waiting for
breakthrough. The detecting and controlling of the ionization process, and the
adoption of the optimal acceleration scheme are crucial for the generation of
highly energetic SHIs. Here, we report the experimental results on the
generation of deeply ionized super-heavy ions (Au) with unprecedented energy of
1.2 GeV utilizing ultrashort laser pulses (22 fs) at the intensity of 10^22
W/cm2. A novel self-calibrated diagnostic method was developed to acquire the
absolute energy spectra and charge state distributions of Au ions abundant at
the charge state of 51+ and reaching up to 61+. The measured charge state
distributions supported by 2D particle-in-cell simulations serves as an
additional tool to inspect the ionization dynamics associated with SHI
acceleration, revealing that the laser intensity is the crucial parameter for
the acceleration of Au ions over the pulse duration. The use of double-layer
targets results in a prolongation of the acceleration time without sacrificing
the strength of acceleration field, which is highly favorable for the
generation of high-energy super heavy ions
Production of multi-oriented polarization for relativistic electron beams via a mutable filter for nonlinear Compton scattering
We propose a feasible scenario to directly polarize a relativistic electron
beam and obtain overall polarization in various directions through a filter
mechanism for single-shot collision between an ultrarelativistic unpolarized
electron beam and an ultraintense circularly polarized laser pulse. The
electrons are scattered to a large angular range of several degrees and the
polarization states of the electrons are connected with their spatial position
after the collision. Therefore, we can employ a filter to filter out a part of
the scattered electrons based on their position and obtain high-degree overall
polarization for the filtered beam. Through spin-considered Monte-Carlo
simulations, polarization with a degree up to 62% in arbitrary transverse
directions and longitudinal polarization up to 10% are obtained for the
filtered beams at currently achievable laser intensity. We theoretically
analyze the distribution formation of the scattered electrons and investigate
the influence of different initial parameters through simulations to
demonstrate the robustness of our scheme. This scenario provides a simple and
flexible way to produce relativistic polarized electron beams for various
polarization directions.Comment: 9 pages, 5 figure
High-flux and bright betatron X-ray source generated from femtosecond laser pulse interaction with sub-critical density plasma
Recent progress on betatron X-ray source enables the exploration of new physics in fundamental science; however, the application range is still limited by the source flux and brightness. In this Letter, we show the generation of more than 1 × 1012 photons (energy > 1 keV) with a peak brightness of 7.8 × 1022 photons/(s mm2 mrad2) at 0.1% bandwidth (BW) at 10 keV, driven by a femtosecond laser pulse of ≈5.5 J and a sub-critical density plasma (SCDP). The source flux is more than two orders of magnitude higher than that from typical laser wakefield electron acceleration. This method to produce high-flux and bright X-ray source would open a wide range of applications. © 2023 Optica Publishing Group.11Nsciescopu
Brilliant GeV electron beam with narrow energy spread generated by a laser plasma accelerator
The production of GeV electron beam with narrow energy spread and high brightness is investigated using particle-in-cell simulations. A controlled electron injection scheme and a method for phase-space manipulation in a laser plasma accelerator are found to be essential. The injection is triggered by the evolution of two copropagating laser pulses near a sharp vacuum-plasma transition. The collection volume is well confined and the injected bunch is isolated in phase space. By tuning the parameters of the laser pulses, the parameters of the injected electron bunch, such as the bunch length, energy spread, emittance and charge, can be adjusted. Manipulating the phase-space rotation with the rephasing technique, the injected electron bunch can be accelerated to GeV level while keeping relative energy spread below 0.5% and transverse emittance below 1.0  μm. The results present a very promising way to drive coherent x-ray sources