In this paper, we report on the acceleration of protons and oxygen ions from tens of micrometer large water droplets by a high-intensity laser in the range of 1020 W/cm2. Proton energies of up to 6 MeV were obtained from a hybrid acceleration regime between classical Coulomb explosion and shocks. Besides the known thermal energy spectrum, a collective acceleration of oxygen ions of different charge states is observed. 3D PIC simulations and analytical models are employed to support the experiential findings and reveal the potential for further applications and studies.

In this paper, we have investigated the relativistic electron acceleration by plasma wave in an axially magnetized plasma by considering the self-magnetic field effects. We show that the optimum value of an external axial magnetic field could increase the electron energy gain more than 40% than that obtained in the absence of the magnetic field. Moreover, results demonstrate that the self-magnetic field produced by the electric current of the energetic electrons plays a significant role in the plasma wakefield acceleration of electron. In this regard, it will be shown that taking into account the self-magnetic field can increase the electron energy gain up to 36% for the case with self-magnetic field amplitude Ωs = 0.3 and even up to higher energies for the systems containing stronger self-magnetic field. The effects of plasma wave amplitude and phase, the ion channel field magnitude, and the electron initial kinetic energy on the acceleration of relativistic electron have also been investigated. A scaling law for the optimization of the electron energy is eventually proposed.

In this study, an atmospheric pressure dielectric barrier discharge-based argon plasma jet has been modeled using COMSOL Multiphysics, which is based on the finite element method. The fluid dynamics and plasma modules of COMSOL Multiphysics code have been used for the modeling of the plasma jet. The plasma parameters, such as electron density, electron temperature, and electrical potential, have been examined by varying the electrical parameters, that is, supply voltage and supply frequency for both cases of static and with the flow of argon gas. The argon gas flow rate was fixed at 1 l/min. Ring electrode arrangement is subjected to a range of supply frequencies (10–25 kHz) and supply voltages (3.5–6 kV). The experimental results of the ring electrode configuration have been compared with the simulation analysis results. These results help in establishing an optimized operating range of the dielectric barrier discharge-based cold plasma jet in the glow discharge regime without arcing phenomenon. For the applied voltage and supply frequency parameters examined in this work, the discharge was found to be consistently homogeneous and displayed the characteristics of atmospheric pressure glow discharge.

The ablation and acceleration of diamond-like high-density carbon foils irradiated by thermal X-ray radiations are investigated with radiation hydrodynamics simulations. The time-dependent front of the ablation wave is given numerically for radiation temperatures in the range of 100–300 eV. The mass ablation rates and ablation pressures can be derived or implied from the coordinates of ablation fronts, which agree well with reported experiment results of high-density carbon with radiation temperatures Trad in the range of 160–260 eV. It is also found that the $T_{{\rm rad}}^3$ scaling law for ablation rates does not apply to Trad above 260 eV. The trajectories of targets and hydrodynamic efficiencies for different target thicknesses can be derived from the coordinates of ablation fronts using a rocket model and the results agree well with simulations. The peak hydrodynamic efficiencies of the acceleration process are investigated for different foil thicknesses and radiation temperatures. Higher radiation temperatures and target thicknesses result in higher hydrodynamic efficiencies. The simulation results are useful for the design of fusion capsules.

In the paper, relativistic self-focusing in the interaction of laser beam and plasma with periodical density ripple has been studied by the applied WKB approximation and higher-order paraxial theory. The result shows that under the influence of relativistic nonlinear effect, the dielectric function shows the fierce oscillational variation with similar periodicity, which then leads to the intense relativistic beam self-focusing along the propagation distance, such self-focusing also presents similar periodic variation. Besides, in the plasma with periodical density ripple, the initial density and the density ripple amplitude have obvious influence on self-focusing. When the two factors increase, then there will be more strength self-focusing. Choosing the appropriate initial density and the periodic density parameter is benefit to the formation of the more stable self-focusing.

The relativistic mirror (RM) is an interesting subject which introduced in the nonlinear regime of the laser–plasma interaction. Reflection of counter-propagating probe pulse from relativistic flying mirror has some excellent features, such as frequency up-shifting and compressing by a factor of 4γ2. In the high-intensity laser–plasma interaction, sometimes a sequence of RMs creates. For example, electron density cusps generate in the nonlinear laser wakefield generation or flying electron sheaths create in the blown-out regime of the laser foil interaction. Under these circumstances, the second counter-propagated seed (probe) pulse can be reflected back and forth between two or more successive RMs. This structure may be used as a relativistic cavity (RECA). Amplification and threshold conditions for the gain medium and pumping rate in the RECA are obtained, and it is shown that amplification can be started from background simultaneous emission (without seed pulse). A new feature of RECA is it's bidirectional (two frequencies) characteristic. Thereupon, the gain process can be implemented on the two different transitions in this bidirectional gain structure. In the RECA, driver pulse may be assembled as a pumping operation, and background plasma medium with high degree ionized substances is a good candidate for gain medium in the UV or X-ray regions. In this paper, we propose a new all-optical cavity for the generation of the ultrashort laser pulse in the UV or X-ray regions.

We present an accurate approach of the basic ultra-relativistic effects which occur at the interactions between laser beams and electrons and correspond to laser beam intensities greater than 1020 W/cm2. These effects are the generation of extremely bright pulses and the existence of a very large frequency spectrum of the radiation generated by this interaction, containing relative intense harmonics of orders higher than 800. Our results are in good agreement with the experimental results published in the literature.

In the present work, Titanium dioxide (TiO2) micro–nanostructured thin films are deposited by a cold atmospheric plasma jet on carbon fiber substrates. The surface morphology, grain size, and structure phase of TiO2 thin films are investigated by scanning electron microscopic (SEM), X-ray diffraction (XRD), and Raman spectrum. As the discharge voltage increased from 5 to 15 kV, the size of these TiO2 particles decreased from 2 to 3 μm to less than 1 μm. The XRD and Raman spectroscopic results show TiO2 on the carbon fiber surface prepared by atmospheric plasma jet is at the mixture phase of anatase and rutile. We also investigated the adhesion and proliferation assays of MC3T3-E1 preosteoblasts on the samples. The surface with smaller TiO2 particles deposited on carbon fiber is more appropriate for attachment of preosteoblasts. Furthermore, the highest proliferation of MC3T3-E1 was found on a sample with smaller TiO2 particles after incubation. Our data suggest that the increased roughness fosters cell attachment and proliferation on the surface of TiO2/carbon fibers.

The ab initio molecular dynamics (MD) simulations using an atom-centered density matrix propagation method are carried out in the first time to investigate the dissociative electron attachment (DEA) processes of adenine and its tautomer in the gas phase. Since the incoming electron are captured on the lowest π∗ anti-bond orbital, which is led to the different N–H bond, the C–H bond and the C–N bond are broken. The dominant anion observed in DEA dissociation process is the closed-shell dehydrogenated anion (Ade − H)−. The additional anions (Ade − NH2)− and (Ade − 2H)− are also obtained in ADMP simulation. The results are well consistent with the previous DEA experimental results. Thus, the ADMP method is used to gain a more intuitive and better understanding of the necessary dissociation process in the DEA experiment.

Földes and Pokol in their letter “Inertial fusion without compression does not work either with or without nanoplasmonics” criticized our works. Here, we refute their argumentation. Our proposed improvement is the combination of two basic research discoveries: (i) the possibility of detonations on space-time hypersurfaces with time-like normal (i.e., simultaneous detonation in a whole volume) and (ii) to increase the ignition volume to the whole target, by regulating the laser light absorption using nanoantennas. These principles can be realized in an in-line, one-dimensional configuration, in the simplest way with two opposing laser beams as in particle colliders.

In this paper, the generation of relativistic electron mirrors (REMs) and the reflection of an ultra-short laser off this mirrors are discussed, applying two-dimensional particle-in-cell (2D-PIC) simulations. REMs with ultra-high acceleration and expanding velocity can be produced from a solid nanofoil illuminated normally by an ultra-intense femtosecond laser pulse with a sharp rising edge. Chirped attosecond pulse can be produced through the reflection of a counter-propagating probe laser off the accelerating REM. In the electron moving frame, the plasma frequency of the REM keeps decreasing due to its rapidly expanding. The laser frequency, on the contrary, keeps increasing due to the acceleration of REM and the relativistic Doppler shift from the lab frame to the electron moving frame. Within an ultra-short time interval, the two frequencies will be equal in the electron moving frame, which leads the resonance between laser and REM. The reflected radiation near this interval and the corresponding spectra will be amplified due to the resonance. Through adjusting the arriving time of the probe laser, certain part of the reflected field could be selectively amplified or depressed, leading to the selectively adjusting of the corresponding spectra.