In indirect-drive inertial confinement fusion (ICF), plasma mixing between high-Z hohlraum plasmas and low-Z filling plasmas significantly affects local plasma conditions, thereby influencing the evaluation of laser p...
详细信息
In indirect-drive inertial confinement fusion (ICF), plasma mixing between high-Z hohlraum plasmas and low-Z filling plasmas significantly affects local plasma conditions, thereby influencing the evaluation of laser plasma instabilities (LPI). This study investigates the diffusion-driven mixing between hohlraum-ablated Au plasmas and filling C5H12 plasmas using one-dimensional particle-in-cell simulations. We find that ion–ion collisions slow the diffusion of ions, rendering Au ions sub-diffusive, while C and H ions remain super-diffusive. Due to their lower collisionality, H ions diffuse faster into Au regions than C ions, leading to a distinct separation between C and H ions at the interface. Compared with collisionless scenarios, the electrostatic shock wave persists at the plasma interface even in the presence of collisions, though collisions notably reduce its electric field amplitude and propagation velocity. Systematic analyses show that laser irradiation and plasma flow have minimal influence on ion mixing speed compared to diffusion-driven mechanisms, whereas inhomogeneous density profiles substantially restrict ion diffusion from low density to high density regions. By incorporating realistic hohlraum plasma conditions from radiation hydrodynamic models into our simulations, we demonstrate the persistent dominance of diffusion-driven ion mixing. Further theoretical calculations indicate that the penetration of H and C into Au plasmas suppresses stimulated Brillouin scattering within the mixing layer. This highlights the importance of incorporating ion mixing processes into LPI modeling for more accurate predictions in ICF experiments.
The current and the voltage of an X-pinch were measured. The inductance of the X-pinch was assumed to be a constant and estimated by the calculation of the magnetic field based on the well-known Biot–Savart’s Law. T...
详细信息
The current and the voltage of an X-pinch were measured. The inductance of the X-pinch was assumed to be a constant and estimated by the calculation of the magnetic field based on the well-known Biot–Savart’s Law. The voltage of the inductance was calculated with L · di/dt and subtracted from the measured voltage of the X-pinch. Then, the resistance of the X-pinch was determined and the following results were obtained. At the start of the current flow the resistance of the exploding wires is several tens of Ohms, one order of magnitude, higher than the metallic resistance of the wires at room temperature, and then it falls quickly to about 1 , which reflects the physical processes occurring in the electrically exploding wires, i.e., a current transition from the highly resistive wire core to the highly conductive plasma. It was shown that the inductive contribution to the voltage of the X-pinch is less than the resistive contribution. For the wires we used, the wires’ material and diameter have no strong influence on the resistance of the X-pinch, which may be explained by the fact that the current flows through the plasma rather than through the metallic wire itself. As a result, the current is almost equally divided between two parallel X-pinches even though the diameter and material of the wires used for these two X-pinches are significantly different.
The reproducing kernel particle method （RKPM） has been efficiently applied to problems with large deformations, high gradients and high modal density. In this paper, it is extended to solve a nonlocal problem modele...
详细信息
The reproducing kernel particle method （RKPM） has been efficiently applied to problems with large deformations, high gradients and high modal density. In this paper, it is extended to solve a nonlocal problem modeled by a fractional advectiondiffusion equation （FADE）, which exhibits a boundary layer with low regularity. We formulate this method on a moving least-square approach. Via the enrichment of fractional-order power functions to the traditional integer-order basis for RKPM, leading terms of the solution to the FADE can be exactly reproduced, which guarantees a good approximation to the boundary layer. Numerical tests are performed to verify the proposed approach.
Building on recent advances of the embedded cluster approach combined with multiconfigurational theory, this work investigates the electronic states in thorium-doped CaF2 crystals. Th:CaF2 is established as a promisin...
详细信息
Building on recent advances of the embedded cluster approach combined with multiconfigurational theory, this work investigates the electronic states in thorium-doped CaF2 crystals. Th:CaF2 is established as a promising material for solid-state nuclear clocks, which utilize the laser-accessible isomeric state in thorium-229. By comparing simulated absorption spectra of a library of defect configurations with experimental data, we demonstrate the impact of fluorine vacancies and calcium vacancies on the Th:CaF2 electronic structure. Our results indicate that fluorine-deficient sites can introduce local electronic states within the band gap, resonant with the isomer energy, potentially contributing to nonradiative decay or quenching of the Th-229 isomer. We also explore the potential of electron-nuclear-bridge mechanisms to enhance nuclear excitation or deexcitation, offering a pathway for more efficient control over the nuclear clock. This study provides key insights for optimizing the crystal environment for nuclear metrology applications and opens new avenues for further experimental and theoretical exploration of thorium-doped ionic crystals.
in indirect-drive experiment, the blank effect caused by X-rays from Hohlraum will show the dark area in time scale of optical streak camera （OSC）. This blank effect, which was a serious problem in indirect-drive sh...
详细信息
in indirect-drive experiment, the blank effect caused by X-rays from Hohlraum will show the dark area in time scale of optical streak camera （OSC）. This blank effect, which was a serious problem in indirect-drive shock wave experiments, has been explained by the semiconductor model. The X-rays cause the band to band transition and the probe laser is absorbed by the intraband transition, which leads to a dark region in time scale of the OSC image. In the experiment, the reflectivity of shock wave front was measured to be about 50% at shock wave velocity 32 km/s and was compared to the theoretical calculations with the Drude free electron model. From the experimental data, it is found that the blank effect can be avoided at radiation temperature of 170 eV if the Al layer is thicker than 60μm.
The alternating segment Crank-Nicolson method has been developed for a 1-dimensional diffusion equation, as well as the alternating band and block Crank-Nicolson methods for 2-dimensional problems. Here the alternatin...
The alternating segment Crank-Nicolson method has been developed for a 1-dimensional diffusion equation, as well as the alternating band and block Crank-Nicolson methods for 2-dimensional problems. Here the alternating block technique is further extended to a 3-space dimension diffusion equation, and the new method called alternating block Crank-Nicolson ABkC-N method, which is suitable to MIMD computers, is set up.
The interplay between topology and dissipation can give rise to a wealth of new phenomena and pave the way for novel topological lasers, sensors, and other quantum devices. Along these lines, we propose here an optome...
详细信息
The interplay between topology and dissipation can give rise to a wealth of new phenomena and pave the way for novel topological lasers, sensors, and other quantum devices. Along these lines, we propose here an optomechanical setup in which the concomitant presence of a spatially modulated external drive and dissipation gives rise to a topologically nontrivial state for mechanical and optical excitations. We are able to show that the one-dimensional system considered here exhibits topologically protected end states for which mechanical and optical degrees of freedom are entangled. We show such entanglement to be robust with respect to the presence of nonzero-temperature baths and we propose a protocol for experimental observation of the entanglement.
In this paper,for a bounded C2 domain,we prove the existence and uniqueness of positive classical solutions to the Dirichlet problem for the steady relativistic heat equation with a class of restricted positive C2 bou...
详细信息
In this paper,for a bounded C2 domain,we prove the existence and uniqueness of positive classical solutions to the Dirichlet problem for the steady relativistic heat equation with a class of restricted positive C2 boundary *** have a non-existence result,which is the justification for taking into account the restricted boundary *** is a smooth positive boundary datum that precludes the existence of the positive classical solution.
The linear optical properties of potassium dihydrogen phosphate（KDP） with oxygen vacancy are investigated with first-principles density functional theory calculations. We use Heyd–Scuseria–Ernzerhof（HSE06） funct...
详细信息
The linear optical properties of potassium dihydrogen phosphate（KDP） with oxygen vacancy are investigated with first-principles density functional theory calculations. We use Heyd–Scuseria–Ernzerhof（HSE06） functional to calculate the linear optical properties because of its accuracy in the band gap calculation. Compared with the perfect KDP, we found that due to the defect states located at the band gap, the defective KDP with oxygen vacancy has new optical adsorption within the energy region from 4.8 eV to 7.0 eV（the corresponding wavelength region is from 258 nm to 177 nm）. As a result, the oxygen vacancy can decrease the damage threshold of KDP crystal. It may give a direction to the KDP production for laser system.
This paper investigates the interaction of a small number of modes in the two-fluid Kelvin-Helmholtz instability at the nonlinear regime by using a two-dimensional hydrodynamic code. This interaction is found to be re...
详细信息
This paper investigates the interaction of a small number of modes in the two-fluid Kelvin-Helmholtz instability at the nonlinear regime by using a two-dimensional hydrodynamic code. This interaction is found to be relatively long range in wave-number space and also it acts in both directions, i.e. short wavelengths affect long wavelengths and vice versa. There is no simple equivalent transformation from a band of similar modes to one mode representing their effective amplitude. Three distinct stages of interaction have been identified.
暂无评论