Stimulated Raman scattering(SRS)in a low-density plasma slab is investigated byparticle-in-cell(PIC)simulations.The backward stimulated Raman scattering(B-SRS)dominatesinitially and erodes the head of the pump wave,while the forward stimulated Raman scattering(F-SRS)subsequently develops and is located at the rear part of the slab.Two-stage electronacceleration may be more efficient due to the coexistence of these two instabilities.The B-SRSplasma wave with low phase velocities can accelerate the background electrons which may befurther boosted to higher energies by the F-SRS plasma wave with high phase velocities.Thesimulations show that the peaks of the main components in both the frequency and wave numberspectra occur at the positions estimated from the phase-matching conditions.
A PIC (particle-in-cell)-MC (Monte Carlo) code to model electron beam transport into dense matter is developed. The background target is treated as a cold, stationary fluid and the fast electrons as particles with the relativistic motions. The process is described by a particle-in-cell method with consideration of the influence of both the self-generated electric and magnetic fields as well as collisions between the fast electrons and the target. The collisional part of the code is solved by the Monte Carlo-type method. Furthermore by assuming that the background current balances with the fast electron current, the electric field is given by the Ohm's law and the magnetic field is calculated from the Faraday's law. Both are solved in a two-dimensional cylindrical geometry. The algorithms implemented in the code are demonstrated and the numerical experiments are performed for monoenergy homogeneous fast electron beam transport in an aluminum target when the fields, collision and angular scattering are switched on and off independently.
We have developed a three dimensional (3D) PIC (particle-in-cell)-MC (MonteCarlo) code in order to simulate an electron beam transported into the dense matter based onour previous two dimensional code.The relativistic motion of fast electrons is treated by theparticle-in-cell method under the influence of both a self-generated transverse magnetic field andan axial electric field,as well as collisions.The electric field generated by return current is ex-pressed by Ohm's law and the magnetic field is calculated from Faraday's law.The slowing downof monoenergy electrons in DT plasma is calculated and discussed.
