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LULI2000 - A laser experiment to understand solar radio emissions (C. Briand)

Solar flares generate intense electromagnetic radiation in the radio domain (1-100 MHz), part of which corresponds to emission at the electron plasma frequency ωp or its second harmonic 2ωp. These waves are the signature of electron beams propagating in the interplanetary medium. Detected by space and ground-based radio telescopes, these electromagnetic waves can be used to remotely infer the characteristics of the electron beams. If the main steps of the process from electron beam to Electron Plasma Waves (EPW) and mode conversion to electromagnetic radiations are known, several questions are still unresolved, in particular: (i) the efficiency of the conversion, (ii) the study of the directionality of the process. We propose to tackle these questions with a laboratory laser-plasma experiment. Indeed, if the parameters of the interplanetary plasma and laser-generated plasmas are very different in absolute values, they happen to be very similar in relative numbers (such as kλDe and Te/Ti), which makes these laser experiments suitable for astrophysical purposes. The experiment is designed for the LULI 2000 facility operated at 2ω0 in the nanosecond regime. The main diagnostics of the experiment will be backscattering measurements performed through the focusing length and measurements of the emitted radiation near 2ωp.

LULI2000 - S36-38 / 2018