Stable radiation field positron acceleration in a micro-tube

Nowadays, there is a desperate need for an ultra-acceleration-gradient method for antimatter particles, which holds great significance in exploring the origin of matter, CP violation, astrophysics, and medical physics. Compared to traditional accelerators with low gradients and a limited acceleration region for positrons in laser-driven charge separation fields, we propose an innovative high-gradient positron acceleration mechanism with implementation advantages. Injecting a relativistic electron beam into a dense plasma micro-tube generates a stable and periodic high-intensity mid-infrared radiation (mid-IR) field, reaching tens of GV/m. This field, propagating synchronously with the electron beam, achieves a 1 GeV energy gain for the positron bunch within 140 picoseconds with a minimal energy spread-approximately 1.56% during a stable phase. By utilizing continuous mid-IR, the efficiency of energy transfer from the electron beam to either a single positron bunch or three positron bunches simultaneously could reach up to 20% and 40%, respectively. This acceleration scheme can achieve cascaded acceleration for a single positron bunch and series acceleration for multiple positron bunches in a continuous, stable, and efficient manner.Comment: 22 pages, 5 figure

Quasi-monoenergetic carbon ions generation from a double-layer target driven by extreme laser pulses

High quality energetic carbon ions produced via laser-plasma have many applications in tumor therapy, fast ignition and warm dense matter generation. However, the beam achieved in current experiments is still limited by either a large energy spread or a low peak energy. In this paper, a hybrid scheme for the generation of quasi-monoenergetic carbon ions is proposed by an ultra-intense laser pulse irradiating a double-layer target. Multi-dimensional particle-in-cell (PIC) simulations show that the carbon ions are first accelerated via laser piston mechanism in the former carbon layer and then further accelerated by Coulomb repulsion force in the attached neon target. Since electrons are bunched synchronously in longitudinal and transverse direction by radiation reaction during the whole acceleration process, a quasi-monoenergetic carbon ion beam is eventually produced. In the following stage, the neon target provides the Coulomb field required for the continuous acceleration of the carbon ions which helps to prevent the carbon ion layer from diffusion. It is demonstrated that quasi-monoenergetic carbon ions with peak energy of 465 MeV u ^−1 , energy spread of ∼13%, a divergence of ∼15 ^∘ , and laser-to-ion energy conversion of 20% can be achieved by using a laser pulse with intensity of 1.23 × 10 ^23 W cm ^−2 . An analytical model is also proposed to interpret the carbon ion acceleration, which is fairly consistent with the PIC simulations

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

Twisted radiation from nonlinear Thomson scattering with arbitrary incident angle

Thomson/Compton scattering is well-known as a scattering process between electromagnetic radiation and charged particles, which is found in laboratories and nature. Here, we investigate the radiative properties of nonlinear Thomson scattering with arbitrary incident angle. Based on classical electrodynamics, the analytical universal expressions of the electric field and energy spectrum of the radiation emitted by a relativistic electron scattering of circularly polarized laser field are derived. It is shown that the spatial distributions of the radiation energy of high-order harmonics have annular shapes and the symmetry of the annular shapes is strongly affected by the incident angle, which may relate with the angular momentum of twisted high-order harmonics. These results would help the understanding of the properties of twisted γ/X-ray and high energy electron-laser scattering experiments in laboratory

Correlation between high temperature performance of gussasphalt mixture for steel bridge decks and rheology of asphalt mastic

Rutting is a prevalent issue in the Gussasphalt (GA) mixture layer of steel bridge deck pavements. This study aims to investigate the correlation between the rheology of GA mastic and the high-temperature performance of the GA mixture. To achieve this objective, GA mastic underwent temperature and frequency sweep tests, along with multiple stress creep and recovery tests employing a dynamic shear rheometer. Additionally, indentation tests, uniaxial penetration tests, and Lueer fluidity tests were conducted on the GA mixture. The Grey Relational Analysis method was employed to evaluate the relationship between asphalt mastic rheology and the high-temperature deformation resistance of the GA mixture. The findings reveal that the addition of mineral filler enhances the deformation resistance of both GA mastic and the mixture. The percent difference in non-recoverable creep compliance (Jnr-diff) was minimized when the weight ratio of filler to asphalt binder (F/B) was 2.5. Furthermore, increasing the F/B ratio from 2.0 to 3.5 resulted in a more than twofold increase in the GA mixture’s shear strength. Asphalt type emerged as a significant factor affecting the indentation parameter of the GA mixture, with an F-value reaching 8.82 based on ANOVA analysis. The rheological properties of GA mastic exhibited a significant correlation with the high-temperature performance of the mixture. The highest Grey Relational Grade of 0.87 was observed between the non-recoverable creep compliance at a 3.2 kPa stress level (Jnr3.2) and indentation. In future research, greater emphasis can be placed on exploring the micromechanical properties of the GA mastic-aggregate interface

Betatron radiation polarization control by using an off-axis ionization injection in a laser wakefield acceleration

Tunable X-ray sources from a laser-driven wakefield have wide applications. However, due to the difficulty of electron dynamics control, currently the tunability of laser wakefield-based X-ray sources is still difficult. By using three-dimensional particle-in-cell simulations, we propose a scheme to realize controllable electron dynamics and X-ray radiation. In the scheme, a long wavelength drive pulse excites a plasma wake and an off-axis laser pulse with a short wavelength co-propagates with the drive pulse and ionizes the K-shell electrons of the background high-Z gas. The electrons can be injected in the wakefield with controllable transverse positions and residual momenta. These injected electrons experience controllable oscillations in the wake, leading to tunable radiations both in intensity and polarization

Efficient bright γ-ray vortex emission from a laser-illuminated light-fan-in-channel target

X/ γ -ray have many potential applications in laboratory astrophysics and particle physics. Although several methods have been proposed for generating electron, positron and X/ γ -photon beams with angular momentum (AM), the generation of an ultra-intense brilliant γ -ray is still challenging. Here, we present an all-optical scheme to generate a high energy γ -photon beam with large beam angular momentum (BAM), small divergence, and high brilliance. In the first stage, a circularly-polarized laser pulse with intensity of W/cm irradiates a micro-channel target, drags out electrons from the channel wall and accelerates them to high energies via the longitudinal electric fields. During the process, the laser transfers its spin angular momentum (SAM) to the electrons' orbital angular momentum (OAM). In the second stage, the drive pulse is reflected by the attached fan-foil and a vortex laser pulse is thus formed. In the third stage, the energetic electrons collide head-on with the reflected vortex pulse and transfer their AM to the -photons via nonlinear Compton scattering. Three-dimensional particle-in-cell simulations show that the peak brilliance of the γ -ray beam is ~ 10 22 photons/s/mm2/mrad2 /0.1% BW at 1 MeV with a peak instantaneous power of 25 TW and averaged BAM of 10δћ /photon. The angular momentum conversion efficiency from laser to the γ -photons is unprecedentedly 0.6