Simulation Of The Charged Particles Propagating In Plasmas

The interactions of charged particles with plasmas have been an interesting topic during the past decades due to the fact that these studies play important roles in fundamental researches and practical applications. In fundamental researches, these studies help us to fully understand the plasma properties, including the atomic processes in plasmas and the plasma polarition. In practical applications, these studies can be used for plasma diagnostics, the neutral beam injection(NBI) in the magnetically confined fusion plasmas, the plasma lens, the heavy-ion-driven high-energy density matter(HEDM) and inertial confinement fusion(ICF), and the design of the future ion accelerators based on the plasma technology. In this work, the propagation of charged particles in plasmas, including the collision dynamics of charged particles moving through plasmas, the excitation of plasma wake field, the subsequent slowing-down process, and the focusing effects of ion beams, is investigated.In Chapter 1, we first briefly review the research background and recent advances in the interactions of charged particles with plasmas, and then give the research purpose of current work.In Chapter 2, the classical trajectory Monte Carlo simulation code in plasmas(CTMCIP) is adopted to investigate the heavy-particle collision dynamics in dense quantum plasmas, including the charge exchange collisions and ionization collisions. For charge exchange collisions, it is found that the dense quantum plasma screening effects reduce charge exchange cross sections slightly in weak screening conditions. However, cross sections are reduced substantially in stong screening conditions. For ionization collisions, the quantum plasma screening effects lead to a significant increase of ionization cross sections. In addition, the charge exchange and ionization collisions in dense quantum plasmas are compared with those in ideal classical plasmas. It is found that the collision dynamics in dense quantum plasmas significantly differ from that in ideal classical plasmas due to the oscillatory screening effects of dense quantum plasmas.In Chapter 3, the particle-in-cell method is adopted to investigate the plasmas electromagnetic effects on the ion beams. The wake fied and stopping power of the ion beams propagationg in plasmas are first studied. It is found that the beam’s collective effects play important roles in determining the wake field and stopping power. In addition, the collective effects are related to the beam velocity, density and the external magnetic field. The collective effects are the strongest in the case of the intermediate beam velocities and densities, and decrease with the increase of the external magnetic field magnitude. Then, the focusing effects of ion beams in plasmas are studied. It is found that the beam, with the long length and the small density gradient profile, is focused to high density. The beam, with long length and the large density gradient profile, is modulated into many high density and periodic short beam pulses.These studies help us to fully understand the interactions of charged particles with plasmas. In addition, in the view of practical applications, these studies could be extended to applications in explanations of some astrophysical phenomenon, investigations of the inertial confinement fusion and researches of plasma lens.