137638473
Preheat Studies on Laser Ablatively-Accelerated Foils.
Abstract : The achievement of laser fusion requires the inward acceleration of pellet shells to very high velocity without excessive preheat of the pellet fuel. In a study of ablatively accelerated thin planar Al foils, we have determined the complete time history of the rear surface temperatures, and evaluated the energy transport mechanisms that contribute to the heating. Extrapolation to larger, reactor-sized pellets indicates that preheat is minimal at low laser irradiances. (Author)
117848574
Ablated plasma flow from planar targets
The experimentally observed flow of plasma ablated by a laser from a planar target resembles the nozzle flow of fluid from a circular orifice. This has implications for experimental simulations of spherical laser fusion pellets using planar targets and affects far field ion measurements in planar geometry experiments.
116987073
Experimental tests of induced spatial incoherence using short laser wavelength
14414169
Non-topological non-commutativity in string theory
Quantization of coordinates leads to the non-commutative product of deformation quantization, but is also at the roots of string theory, for which space-time coordinates become the dynamical fields of a two-dimensional conformal quantum field theory. Appositely, open string diagrams provided the inspiration for Kontsevich's solution of the long-standing problem of quantization of Poisson geometry by virtue of his formality theorem. In the context of D-brane physics non-commutativity is not limited, however, to the topolocial sector. We show that non-commutative effective actions still make sense when associativity is lost and establish a generalized Connes-Flato-Sternheimer condition through second order in a derivative expansion. The measure in general curved backgrounds is naturally provided by the Born–Infeld action and reduces to the symplectic measure in the topological limit, but remains non-singular even for degenerate Poisson structures. Analogous superspace deformations by RR–fields are also discussed.
118748347
Quantum A-infinity Structures for Open-Closed Topological Strings
We study factorizations of topological string amplitudes on higher genus Riemann surfaces with multiple boundary components and find quantum A-infinity relations, which are the higher genus analog of the (classical) A-infinity relations on the disk. For topological strings with $\hat c=3$ the quantum A-infinity relations are trivially satisfied on a single D-brane, whereas in a multiple D-brane configuration they may be used to compute open higher genus amplitudes recursively from disk amplitudes. This can be helpful in open Gromov--Witten theory in order to determine open string higher genus instanton corrections. Finally, we find that the quantum A-infinity structure cannot quite be recast into a quantum master equation on the open string moduli space.
16254267
Localization and traces in open-closed topological Landau-Ginzburg models
We reconsider the issue of localization in open-closed B-twisted Lan- dau-Ginzburg models with arbitrary Calabi-Yau target. Through careful analsysis of zero-mode reduction, we show that the closed model allows for a one-parameter fam- ily of localization pictures, which generalize the standard residue representation. The parameter λ which indexes these pictures measures the area of worldsheets with S 2 topology, with the residue representation obtained in the limit of small area. In the boundary sector, we find a double family of such pictures, depending on parameters λ andwhich measure the area and boundary length of worldsheets with disk topology. We show that setting � = 0 and varying λ interpolates between the localization picture of the B-model with a noncompact target space and a certain residue representation proposed recently. This gives a complete derivation of the boundary residue formula, starting from the explicit construction of the boundary coupling. We also show that the various localization pictures are related by a semigroup of homotopy equivalences.