Magnetic field phenomenology: from the Universe to laboratory experiments

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Magnetic fields are an ubiquitous feature of astrophysical and laboratory plasmas, as revealed by diffuse radio-synchrotron emission and Faraday rotation observations. The energy density of these fields is typically comparable to the energy density of the fluid motions of the plasma in which they are embedded, making magnetic fields essential players in the dynamics of the luminous matter. How such fields are created and amplified remains a mystery. It is believed that turbulent dynamo action can efficiently amplify magnetic fields and this is supported by novel laboratory experiments that we have performed in the past few years. Thus the magnetic fields observed in astronomical bodies today could plausibly have arisen from tiny initial seeds. Still, the origin of such seeds remains unclear - and a variety of plasma processes have been proposed, Moreover, such amplification process cannot occur in cosmic voids, where the plasma density is too small for dynamo to become operative.These considerations are part of a more fundamental question of how the energy injected at large scales into a compressible plasma is partitioned, in a turbulent cascade, between small-scale motions, magnetic and compressive fluctuations, and dissipated via cosmic rays. Indeed, the presence of energetic particles in the Universe is a well established fact. The exact mechanism that leads to such high energy particles remains controversial. Although many different processes may result in cosmic ray acceleration, the current understanding is that turbulence and magnetic fields play an essential role in energizing both the electrons and ions present in the interstellar medium.We plan to tackle this problem using a multi-strategy approach that focuses on:1. Developing novel theoretical models for magnetic field generation in the Universe that applies plasma-physics processes (such as returns currents, baroclinic effects and/or turbulent dynamo) and go beyond them (for example, using non-standard model physics). We will investigate processes that occurs in the early Universe as well those that occurs in supernova remnants.2. Embed these models into simulation codes - particularly particle-in cell (OSIRIS and/or EPOCH) and predict measurable quantities that can be tested against observations and laboratory experiment. Examples are the spectrum of the magnetic field, or secondary processes such as photon (x-ray) production.3. Understand the interplay between magnetic field generation, amplification and particle acceleration - for example second order Fermi acceleration - and develop phenomenological models that can be validated with experiments on high-power laser facilities.This project fits "Plasmas and lasers"