Title           Laboratory betatron cooling as a source of ring-beam distributions analogous to astrophysical synchrotron cooling
Speaker     Pablo Bilbao, from IST in Lisbon, Portugal

Abstract

Investigations of astrophysical and laboratory plasmas in extreme environments prompt the integration of strong field effects into classical plasma physics. This reveals a new phenomenon: radiation reaction cooling leading to kinetically unstable plasmas under strong electromagnetic fields. This is a consequence of the fact that the radiation reaction force cools the momentum distribution nonlinearly, altering the shape of plasma momentum distributions and causing anisotropies and energy population inversion. Our theoretical results demonstrate that astrophysical plasmas undergoing synchrotron cooling develop ring momentum distributions and can lead to the generation of coherent radiation. The magnetic fields needed for ring formation are beyond the current capabilities of laboratory settings. Nonetheless, betatron cooling resulting from the focusing electric field in the bubble/blowout of a beam/laser driven wakefield, is analogous to astrophysical synchrotron cooling. We explore this potential avenue for studying radiatively cooled kinetic plasmas in a realisable beam plasma experimental platform.

Simulation results using the Particle-in-cell code OSIRIS confirm our analytical results.

Material:

P. J. Bilbao and L. O. Silva, Radiation Reaction Cooling as a Source of Anisotropic Momentum Distributions with Inverted Populations, Phys. Rev. Lett. 130, 165101 (2023).

P. J. Bilbao et al. Ring momentum distributions as a general feature of Vlasov dynamics in the synchrotron dominated regimehttps://arxiv.org/abs/2404.11586