Simulation Of The Interaction Between Intense Proton Beam And A Solid Target By Quantum Hydrodynamic Model

Since intense ion beams were available to generate high energy density matter, the research of high energy density physics has received much attention for inertial confinement fusion, astro-physics, and heavy ion fusion. In the field of high energy density physics, there has been steady interest in interaction between charged particles and solid density plasmas. Energy distribution of inertial confinement fusion target can be determined through the interaction process between the ion beam and the target, which has shown many innovative results and will become an indis-pensable part of inertial confinement fusion research. In recent years, the high-energy intense ion beam is proven to be an efficient tool to produce warm dense matter for the investigations of high energy density matter. For these applications, the ion beam should be simultaneously compressed in both transverse and longitudinal directions to small spot size and short pulse, re-spectively. However, The recent laser-matter interaction technology can produce a high energy (several hundreds eV to MeV) intense proton beam. These proton beam can be a promising driving source of warm dense matter. The intense, highly directional proton beams could be generated during the interaction of an ultra-intense laser pulse with a solid target in a picosec-ond time scale, and the energy deposition process of these protons is also completed within a femtosecond or picosecond time scale in which hydrodynamic expansion of the target is negligi-ble, therefore, isochoric heating of the target can be achieved. It has been revealed in subsequent experiments that an intense, collimated, laser-generated proton beam can volumetrically heat solid density material to warm dense states on a picosecond time scale, which offers new possi-bilities in high energy density physics through creating unique states of matter. In this work, a self-consistent quantum hydrodynamic simulation method is adopted to investigate the interac-tion of high-energy single proton and intense proton beams (or clusters) in a solid target, taking into account the influences of quantum effects, strong coupling effects between the injection proton and target electrons, and internal interaction and exchange-correlation effects between target electrons.In this work, we first briefly review the research background and recent advances in the ion beam driven high energy density physics, and then give the research purpose of current work in Chapter1. Chapter2describes the simulation model of this work-quantum hydrodynamic model. The rest of this work is presented as follows: In Chapter3, quantum electron statistic pressure, collision frequency of electrons, density distributions, stopping power and wake potential, induced by a charged particle moving through a three-dimensional nonidcal finite temperature electron gas, are simulated within the frame-work of linearized quantum hydrodynamic formalism. Quantum effects modifies the interaction process of test charges and back ground electrons. The values of the stopping power and wake potential are greatly increased and depend strongly on the temperature for the nonideal electron gas in comparison with those for a ideal electron gas, that is, the effect of internal interaction is worth while to be taken into account. When the temperature increases, the peak position of the stopping power shifts greatly to higher particle velocities and the wake potential becomes symmetrical with respect to the position of the incident particle.In Chapter4, nonlinear quantum hydrodynamic formalism is used to study the interaction of a proton with a one-dimensional quantum electron gas, where electron density, wake potential and stopping power have been numerically calculated by solving the nonlinear quantum hydro-dynamic equations with FCT numerical method. The nonlinear effects on the density, wake potential and stopping power are clearly observed and presented. In the moving coordinate, comparisons are made between the nonlinear and linear wake potentials, in which the maximum values are larger and more oscillations appear behind the projectile in a nonlinear case in con-trast to that in a linear case. The nonlinear wake potentials show a clear dependence on time, that is, the FCT algorithm solves the nonlinear quantum hydrodynamic equations by time inte-gration starting from the initial time. It is shown that the nonlinear elfects can enhance the wake potential and stopping power for particle velocities greater than a few Bohr velocity. For a fixed proton velocity, election temperature increase induces attenuating wake field, due to increasing thermal electron velocity. For a fixed electron temperature, proton velocity increase induces a enhancing wake field, that is thermal electron velocity is neglected in comparison with high proton velocity. However, when projectile velocity increase enough, there is no time to respond to background electrons, then the wake field disappears.In Chapter5, we adopt two dimensional quantum hydrodynamic model to study the iso-choric heating of a solid target under an proton cluster interaction in cylindrical coordinate, in which a Gaussian cluster is used. The target is heated to warm dense matter on a picosecond time scale. The density and temperature of the target are calculated by a full self-consistent treatment of the quantum hydrodynamic formalisms and the Poisson equation. The technique described in chapter5, provides a method for creating uniformly heated warm dense matter states.In Chapter6, we adopt two dimensional quantum hydrodynamic model to study the isochoric heating of a solid target under an intense continuous proton beam interaction in cylindrical coordinate. The proton beam with particle energy Eb(1.5-10MeV), intensity N(1×108-7.9×108) and focal radius rb(19-28μm), with a fixed pulse time10ps, is con-sidered. The results show that:most of the proton beam energy is deposited in a narrow region (a few mu m) near the surface of the beam-target interaction. Cold target electrons are heated by the high intensity proton beam and take collective excitations, then reach the temperature of5eV within a few picoseconds time. Thus warm dense matter is created in the heated target region on a picosecond time scale. As beam-target isochoric heating is considered, the target ion contribution is very small, almost equivalent to a fixed background ionic lattice.