The European Physical Journal D最新文献

This study focuses on optimizing beam driving modes to enhance laser-target coupling efficiency and improve particle quality in laser-driven ion acceleration. The aim is to increase proton and ion beam energy. Two-dimensional particle-in-cell simulations are conducted to investigate the proton beam generated by a Petawatt laser-driven multilayer target. The results indicate that optimal space overlap between the laser and targets improves energy coupling efficiency. Numerical simulation results indicate that the overlap of two laser pulses in front of the target, specifically at the same focal point, results in the generation of higher-energy ion beams. This result is primarily attributed to the enhanced longitudinal electric field under such conditions, which leads to increased energies of protons and ions. By adjusting the longitudinal size of the CH layer, a high-quality proton beam with a maximum cut-off energy of approximately 290 MeV and a small energy spread of 5.2(%) and 14.7(%) is achieved

Atmospheric pressure plasma jets (APPJs) are versatile devices with numerous applications. This work focuses on APPJs generated at the tip of long, flexible tubes using the jet transfer technique. The plasma source consists of a primary discharge and a secondary discharge forming the plasma jet. Discharge power measurements were carried out in a way that it was possible to separate the contribution of the primary discharge from the total power dissipated by the plasma source. Both power and effective current were analyzed under different operating conditions. The results show that the variation in the primary discharge power is much lower than the power dissipated by the plasma jet. Additionally, the electrical characteristics of the plasma device were analyzed. Notable differences were observed between the negative and positive phases of the discharge, with a more resistive load in the negative one, which suggests that the electrical equivalent circuit model changes according to the voltage polarity.

The primary discharge spectra are not affected by differences in electrical characteristics of the discharges with the plasma jet on and off

Electron motion in an atom driven by an intense linearly polarized laser field can exhibit a laser-dressed stable state, referred to as the Kramers–Henneberger (KH) state or KH atom. Up to now, the existence conditions of this state rely on the presence of a double well in the KH potential, obtained by averaging the motion over one period of the laser. However, the approximation involved in the averaging is largely invalid in the region of the double well structure; therefore, this raises the question of its relevance for identifying signatures of these exotic states. Here, we present a method to establish conditions for the existence of the KH atom based on a nonperturbative approach. We show that the KH atom is structured by an asymmetric periodic orbit with the same period as the laser field in a wide range of laser parameters. Its imprint is clearly visible on the wavefunction in quantum simulations. We identify the range of parameters for which this KH state is effective, corresponding to an elliptic periodic orbit.

Korteweg–de Vries (KdV) equation with the influence of Landau damping of electrons is developed to explore the weakly nonlinear and weakly dispersive ion-acoustic waves in a non-collisional unmagnetized plasma system whose constituents are adiabatic warm ions, negative-charged immobile dust grains and combined Kappa–Cairns distributed electrons. It is found that the nonlinear coefficient of the KdV equation vanishes along different parametric curves in the parametric space. In this situation, a modified KdV equation with the Landau damping effect is obtained to demonstrate the nonlinear propagation of the ion-acoustic waves. By employing multiple time scale method, the solitary wave solutions of these equations are derived. The solitary wave’s amplitudes have been noticed to decay gradually over time.

In a two-photon Jaynes–Cummings model which consists of an atom interacting with a cavity mode with a two-photon interaction, we find the photon blockade effect can be largely improved by inducing a interference pathway. The interference pathway can be either a two-photon transition or an atom transition. The purity of the single photon can be improved by (10 sim 100) times, and we find the high purity of single photon is induced by combination of conventional and unconventional photon blockade. The method provides a way to improve the purity of single photon.

In a system consisting of a cavity coupled to a two-level atom via a two-photon interaction, the two photon state can be reduced by destructive interference between different transition pathways.