LLE Review 164

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Highlights

This volume of LLE Review 164 covering the period from July–September 2020. Articles appearing in this volume are the principal summarized results for long-form research articles. Readers seeking a more detailed account of research activities are invited to seek out the primary materials appearing in print, detailed in the publications and presentations section at the end of this volume.

Highlights of research presented in this volume include:

• E. M. Campbell et al. summarize the present status and future plans for laser direct drive (p. 169).
• A. R. Christopherson et al. make the first direct measurements of the energy deposited by hot electrons into the DT fuel and its spatial distribution within the fuel. They also present a new technique to quantify the hot-electron preheat energy depos­ited into the dense DT fuel for all laser-fusion schemes (p. 172).
• W. Farmer et al. perform experiments using OMEGA’s state-of-the-art 4ω Thomson-scattering diagnostic to isolate the ef­fect of heat transport using a directly driven, solid beryllium sphere. By comparing LASNEX simulations that included the Thomson probe beam, they found that the heat transport is being modeled correctly and that there are deficiencies in model­ing other processes (p. 174).
• F. García-Rubio et al. investigate the effects of self-generated magnetic fields on the ablative Rayleigh–Taylor instability in the linear regimes. They find that the self-generated magnetic field significantly modifies the Rayleigh–Taylor dispersion relation even at small Mach numbers (p. 177).
• F. García-Rubio et al. study the Rayleigh–Taylor and Darrieus–Landau instabilities in an inertial confinement fusion context within the framework of the small critical-to-shell density ratio and weak acceleration regimes. This novel study includes non-isobaric effects and self-generated magnetic fields (p. 180).
• J. R. Davies et al. found that there are multiple magnetic-field advection terms that arise from the resistivity and electrother­mal tensors in a magnetized plasma. Because these advection terms depend on significantly modified transport coefficients, the authors re-examined the well-established fits and summarize their findings (p. 183).
• H. Wen et al. study the convective gain and the kinetic inflation threshold for stimulated Raman scattering (SRS) driven by a broadband laser in an inhomogeneous plasma. They derive a formula that can predict when the convective SRS gain is enhanced and when the inflationary SRS threshold reaches a minimum (p. 186).
• A. L. Milder et al. present the first measurements of complete electron distributions without any assumptions on their shape or the underlying physics that produced them (p. 189).
• T. T. Simpson et al. introduce the “self-flying focus” (a nonlinear technique for spatiotemporal control), which produced an arbitrary trajectory intensity peak that can be sustained for distances comparable to the focal length and apply it to the generation of long plasma channels (p. 192).
• J. P. Palastro et al. report on the discovery of a novel regime of plasma wave excitation and wakefield acceleration that removes the wave-breaking limit, allowing for arbitrarily high electric fields. Laser-wakefield accelerators operating in this regime provide energy tunability independent of the plasma density and can accommodate large laser amplitudes (p. 195).
• S. Zhang et al. completed a comprehensive study of the equation of state of boron carbide (p. 198).
• V. Yu. Glebov et al. developed a neutron time-of-flight (nTOF) detector that can operate without a scintillator. The lack of a scintillator reduces the instrument response and makes it the fastest nTOF in use on OMEGA (p. 201).
• Z. L. Mohamed et al. extend the energy range of neutron detectors by interpolating the instrument response function (IRF) for neutrons of arbitrary energies, constructing an energy-dependent IRF, and then using a forward fit to apply that IRF (p. 205).
• C. Dorrer developed a framework to support optical parametric amplifier simulations using normalized equations and used that framework to study optical parametric amplification (OPA) operation with spectrally incoherent signals. Simulations are in agreement with the experimental demonstration of OPA with spectrally incoherent signals (p. 208).
• J. Lamaignère et al. compared laser-induced–damage thresholds of optical coatings at five well-equipped damage-testing facilities and find that the damage-testing results differ significantly between facilities (p. 211).
• M. S. Wei and S. F. B. Morse present summary information of the 12th Omega Laser Facility Users Group Workshop. Also presented are user Findings and Recommendations to the Omega Laser Facility (p. 214).
• J. Puth et al. summarize operations of the Omega Laser Facility during the fourth quarter of FY20 (p. 216).