Abstract
We identify a mechanism for magnetic field generation in the interaction of intense electromagnetic waves and underdense plasmas. We show that Raman scattered plasma waves trap and heat the electrons preferentially in their propagation direction, resulting in a temperature anisotropy. In the trail of the laser pulse, we observe magnetic field growth which matches the Weibel mechanism due to the temperature anisotropy. We discuss the role of the initial electron temperature in our results. The predictions are confirmed with multi-dimensional particle-in-cell simulations. We show how this configuration is an experimental platform to study the long-time evolution of the Weibel instability.
Highlights
Understanding the interaction between electromagnetic waves and plasmas is of fundamental importance with implications in inertial confinement fusion, plasma-based accelerators, and laboratory astrophysics
We identify a mechanism for magnetic field generation in the interaction of intense electromagnetic waves and underdense plasmas
We have presented a mechanism for magnetic field generation in intense laser-plasma interactions
Summary
Understanding the interaction between electromagnetic waves and plasmas is of fundamental importance with implications in inertial confinement fusion, plasma-based accelerators, and laboratory astrophysics. In the context of intense electromagnetic wave interaction with underdense plasmas, effects such as stimulated Raman scattering (SRS) are important, and can determine the magnetic field generation process, as electrons can heat and drive strong currents in the plasma [17,18,19]. Reference [19] shows evidence of magnetic field growth due to the current of trapped electrons on the scattered plasma waves and hints of subsequent Weibel instability Despite these early efforts, the connection between SRS and the Weibel has not been explored, nor its interplay, long-time evolution, and dependence on the physical configuration. We show this setup is ideal for studying the long-time evolution of the Weibel instability, addressing the fundamental question of how magnetic fields evolve from small to long scales This has important implications on the structure of collisionless shocks in astrophysical objects [38,39]. The numerical parameters for these simulations are explained in the
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