Experimental observation of the effect of an external magnetic field on Backward Stimulated Raman Scattering (SRS)

ORAL

Abstract

SRS plays a detrimental role in inertial confinement fusion (ICF) due to pump depletion and preheat of the fuel by suprathermal electrons generated by electron plasma waves (EPW). However, recent numerical work [1] has shown that SRS in the kinetic regime (kλD ~ 0.3 where k is the EPW wavenumber and λD is the Debye length and at a density) can be mitigated by a moderate external magnetic field. With the availability of the MIFEDS coil to pre-magnetize the plasma at OMEGA-EP, investigation of the effect of magnetic field on SRS is now possible. We present recent results of a new platform designed to investigate the mitigation of SRS by an external magnetic field at OMEGA-EP. The Sub-Aperture Backward Scatter (SABS) diagnostic was fielded to time resolve reflected light from backward-SRS (BSRS). Interestingly, we observed a mitigation of the BSRS by an external B-field in the kinetic regime (kλD ~ 0.3) and at a density ne ~ 10% ncr (ncr is the critical density). At lower density (ne < 8% ncr), the magnetic field induces an enhancement of the SRS.



Reference:

[1] B. J. Winjum, et al. Phys. Rev. E 98, 043208 (2018)

*This material is based upon work supported by the Department of Energy, National Nuclear Security Administration under Award Number(s) DE-NA0003842. The experiment was conducted at the Omega Laser Facility at the University of Rochester’s Laboratory for Laser Energetics with the beam time through the National Laser Users’ Facility (NLUF) program.

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Presenters

  • Simon Bolaños

    • University of California, San Diego

Authors

  • Simon Bolaños

    • University of California, San Diego

  • Mario Manuel

    • General Atomics - San Diego

  • Mathieu Bailly-Grandvaux

    • University of California, San Diego

  • Farhat Beg

    • University of California, San Diego
    • University of California San Diego
    • Center for Energy Research UC San Diego, San Diego, CA 92093

  • Alemayehu Bogale

    • University of California, San Diego

  • Roman Lee

    • University of California, Los Angeles

  • Frank S Tsung

    • University of California, Los Angeles

  • Warren Mori

    • University of California, Los Angeles
    • University of California Los Angeles

  • Benjamin J Winjum

    • University of California, Los Angeles

  • Chris A Walsh

    • Lawrence Livermore National Laboratory
    • Lawrence Livermore Natl Lab