Introducing a magnetic field on a LPI-generated hot electron population

The growth of laser-plasma instabilities can be modified by the application of an external magnetic field. It has been inferred that the gyrating electrons transport energy away from the instabilities when they travel parallel to the growing field, weakening the electron plasma waves (EPWs) through Landau damping, reducing the instabilities’ growth. Moreover, the applied Lorentz force can confine the gyrating high energy (“hot”) electrons in a limited region of space, dictated by the magnetic field’s strength.

This can have several applications, such as a reduction in hot electron preheat in the case a magnetic field is applied to a laser-driven spherical implosion and to inertial confinement fusion (ICF), but also to the study of magnetized plasma jets in MagLIF experiments.

We performed 2D simulations, using the hybrid code Laser Plasma Simulation Environment (LPSE), of Stimulated Raman Scattering (SRS), Two-Plasmon Decay (TPD), Langmuir Decay Instability (LDI) and Langmuir Wave collapse (LW collapse). We performed a scan of plasma parameters at different magnetic field strength up to a 45 T field. We report an increased confinement close to quarter critical density of electron plasma waves (EPWs) from SRS, TPD and LDI activity in the nominal magnetized case (30 T) compared to the unmagnetized one, due to an increased resonance probability of the electrons with the EPWs, increasing Landau damping. The study of HE generation through the velocity distribution function (VDF), the particle trajectories and hot electron (HE) energy flux at the simulation boundaries shows an increase in electron Larmor radius and hot electron average temperatures. Moreover, we observe an increase in hot electron confinement for stronger B fields. Finally, we analyzed the parameter scan of HE conversion fraction as a function of the B field, the electron temperature and density scale length.