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.
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.
In the framework of the relativistic mean field theory, the isovector scalar interaction is considered by exchanging δ meson to study the influence of δ meson on the cooling properties of neutron star matter. The calculation results show that with the inclusion of δ meson, the neutrino emissivity of the direct Urca processes increases, and thus enhances the cooling of neutron star matter. When strong proton superfluidity is considered, the theoretical cooling curves agree with the observed thermal radiation for isolated neutron stars.
