Laserlab-Europe Talk "Investigations of Laser-Plasma Interaction and hot electron generation in Direct-Drive Inertial Confinement Fusion: approaching to the Shock Ignition irradiation regime"

  • What Laserlab-Event
  • When Jun 22, 2022 from 04:00 PM to 05:00 PM (Europe/Berlin / UTC200)
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Investigations of Laser-Plasma Interaction and hot electron generation in Direct-Drive Inertial Confinement Fusion: approaching to the Shock Ignition irradiation regime

Speaker: Gabriele Cristoforetti (INO-CNR)

Wednesday, 22 June 2022, 4 pm CET

One of the main concerns of Shock Ignition (SI) scheme to Inertial Confinement Fusion is the growth of parametric instabilities in the plasma corona, such as Stimulated Brillouin Scattering (SBS), Stimulated Raman Scattering (SRS) and Two Plasmon Decay (TPD). Their extent can be tremendous during the interaction of the high intensity laser peak (I~1016 W cm-2) with the precompressed corona and they are expected to scatter a significant amount of laser energy and to generate large fluxes of suprathermal electrons (HE), with a considerable impact on both the shock pressure and the preheat of the fuel capsule. The non-linear character of these instabilities becomes progressively more important with the increase of laser intensity, which makes the extrapolation of analytical models quite inaccurate; a more detailed understanding of these processes therefore calls for experiments dedicated at investigating Laser Plasma Interaction (LPI) in conditions as close as possible to those envisaged in SI.

In this presentation, we report results obtained in experiments at Gekko XII, PALS and VULCAN laser facilities, focussed at investigating LPI and at identifying the mechanisms originating suprathermal hot electrons. In all of them, Stimulated Raman Scattering and Two Plasmon Decay were accurately and time-resolved characterized by means of spectroscopic and calorimetric tools, while a full set of diagnostics – including Ka imaging and spectroscopy, Bremsstrahlung cannons and Magnetic Electron Spectrometers - were used for achieving an energy-resolved characterization of hot electrons. The regime of interaction in these experiments is significantly different, with laser intensity ranging from Il2 ~2·1014 Wmm2/cm2 to ~2·1016 Wmm2/cm2, plasma density scalelength rising from 50 to 400 mm, laser wavelength going from the UV to the IR range, laser irradiation in single- and multi-beam configuration, allowing a good understanding of the role played by the different experimental parameters.

After critically discussing the experimental results, we will show here the future directions of our research in this field and the aims of the forthcoming experiments.

 

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