Studies Of The Quantum And Nonlinear Effects In Dense Plasmas

High energy density physics has received a lot of attention due to its important value in astrophysics,inertial confinement nuclear fusion and other fields.In this paper,we take plasma physics as the starting point to study quantum effects in high-energy-density matter.When the plasma density is high enough and the temperature is not particularly high,the collective effect of electrons in the plasma has a spacetime scale comparable to that of the thermal de Broglie waves of electrons,and the classical plasma theory is no longer applicable.We call this type of plasma a quantum plasma.Most of the widely studied models of high-energy-density matter are based on wave functions,such as density functional theory(DFT)or time-dependent density functional theory(TDDFT).These methods tend to deal with physics at the microscopic scale only,while a kinetic method focus on physics at the macroscopic or mesoscopic scale.The linear approximation of collisionless quantum kinetics is equivalent to the well-known random phase approximation(RPA),while the full quantum kinetic equation describes the nonlinear coupling of the quantum and plasma waves.In this paper,quantum effects and nonlinear effects are discussed in terms of the eigenmodes of quantum plasma and the response to single-particle perturbations.First,the linear analytical behavior of the quantum kinetic equations is analyzed from the perspective of plasma physics,and the exact numerical solution of the quantum dielectric function in the full complex space is obtained,which leads to the solution of the complete electrostatic eigenmodes.In order to further investigate the nonlinear process of quantum kinetics,a C++parallel program is developed to solve the Wigner-Poisson system.The program uses a hybrid splitting scheme to eliminate the numerical noise that occurs in long-time nonlinear simulations by conventional FFT method,and achieves credible long-time nonlinear quantum kinetics simulation.Based on this program,the quantum Landau damping,quantum BGK equilibrium,and two-stream abnormal oscillations,which are unique to quantum plasmas,are analyzed in this paper.The eigen-modes of a plasma are the intrinsic in plasmas,which also determine the response of the plasma system to the external perturbation.From the viewpoint of a single particle incident on the plasma system,we analyze the wake-field generated by a single particle in a quantum plasma and the effect of quantum recoil effect and quantum degenerate effect on the wake-field.When a single particle moves in the plasma,the energy is transferred to the plasma eigen-modes through electromagnetic or electrostatic coupling,resulting in the stopping power of the plasma on the particles.In view of the limitations of the RPA method,the effect of quantum effects on the stopping power in the quantum plasma is investigated by using the collisional integration method,and the exact quantum transport cross section is obtained by combining the direct solution of the phase shift equation and the WKB approximation.Finally,due to the relatively high mass of the nucleus,the nuclear stopping power is not affected by quantum effects,but the nonlinear and simplification effects of dense electrons are found to enhance the nuclear stopping power.