The Effects of Beam Geometry and Polarization on Two-Plasmon Decay Driven by Multiple Laser Beams

It is now well established that in direct-drive geometries, two-plasmon decay (TPD) is a collective process, in which a given set of decay waves is driven by several laser beams.\footnote{ C. Stoeckl\textit{ et al.}, Phys. Rev. Lett. \textbf{90}, 235002 (2003).}$^{\mathrm{,}}$\footnote{ D. T. Michel\textit{ et al.}, Phys. Rev. Lett. \textbf{109}, 155007 (2012).} The single-beam decay is maximized on a hyperbola in $k$ space, so that maximum convective gain for the multibeam process occurs near the intersection of the hyperbolas corresponding to the beams involved. These hyperbolas intersect at the origin in $k$ space, so TPD is most strongly driven in this region and can be absolute there. This small-$k$ absolute instability is expected to dominate the linear phase of TPD growth, which is found to be consistent with Zakharov simulations.\footnote{ J. Zhang\textit{ et al.}, ``Two-plasmon decay driven by multiple finite bandwidth laser beams,'' this conference.} This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.