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Full-Text Articles in Physics

Gravity-Driven Thin Liquid Films With Insoluble Surfactant: Smooth Traveling Waves, Rachel Levy, Michael Shearer, Thomas P. Witelski Dec 2007

Gravity-Driven Thin Liquid Films With Insoluble Surfactant: Smooth Traveling Waves, Rachel Levy, Michael Shearer, Thomas P. Witelski

All HMC Faculty Publications and Research

The flow of a thin layer of fluid down an inclined plane is modified by the presence of insoluble surfactant. For any finite surfactant mass, traveling waves are constructed for a system of lubrication equations describing the evolution of the free-surface fluid height and the surfactant concentration. The one-parameter family of solutions is investigated using perturbation theory with three small parameters: the coefficient of surface tension, the surfactant diffusivity, and the coefficient of the gravity-driven diffusive spreading of the fluid. When all three parameters are zero, the nonlinear PDE system is hyperbolic/degenerateparabolic, and admits traveling wave solutions in which ...


Hot Electron And X-Ray Production From Intense Laser Irradiation Of Wavelength-Scale Polystyrene Spheres, H. A. Sumeruk, S. Kneip, D. R. Symes, I. V. Churina, A. V. Belolipetski, G. Dyer, J. Landry, G. Bansal, A. C. Bernstein, Thomas D. Donnelly, A. Karmakar, A. Pukhov, T. Ditmire Jun 2007

Hot Electron And X-Ray Production From Intense Laser Irradiation Of Wavelength-Scale Polystyrene Spheres, H. A. Sumeruk, S. Kneip, D. R. Symes, I. V. Churina, A. V. Belolipetski, G. Dyer, J. Landry, G. Bansal, A. C. Bernstein, Thomas D. Donnelly, A. Karmakar, A. Pukhov, T. Ditmire

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Hot electron and x-ray production from solid targets coated with polystyrene-spheres which are irradiated with high-contrast, 100 fs, 400 nm light pulses at intensity up to 2×1017 W/cm2 have been studied. The peak hard x-ray signal from uncoated fused silica targets is an order of magnitude smaller than the signal from targets coated with submicron sized spheres. The temperature of the x-rays in the case of sphere-coated targets is twice as hot as that of uncoated glass. A sphere-size scan of the x-ray yield and observation of a peak in both the x-ray production and temperature ...


Domain Relaxation In Langmuir Films, James C. Alexander, Andrew J. Bernoff, Elizabeth K. Mann, J. Adin Mann Jr., Jacob R. Wintersmith '06, Lu Zou Jan 2007

Domain Relaxation In Langmuir Films, James C. Alexander, Andrew J. Bernoff, Elizabeth K. Mann, J. Adin Mann Jr., Jacob R. Wintersmith '06, Lu Zou

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We report on theoretical studies of molecularly thin Langmuir films on the surface of a quiescent subfluid and qualitatively compare the results to both new and previous experiments. The film covers the entire fluid surface, but domains of different phases are observed. In the absence of external forcing, the compact domains tend to relax to circles, driven by a line tension at the phase boundaries. When stretched (by a transient applied stagnation-point flow or by stirring), a compact domain elongates, creating a bola consisting of two roughly circular reservoirs connected by a thin tether. This shape will then relax slowly ...


Motion-Sensitive 3-D Optical Coherence Microscope Operating At 1300 Nm For The Visualization Of Early Frog Development, Barbara M. Hoeling, Stephanie S. Feldman, Daniel T. Strenge, Aaron Bernard, Emily R. Hogan, Daniel C. Petersen, Scott E. Fraser, Yun Kee, J. Michael Tyszka, Richard C. Haskell Jan 2007

Motion-Sensitive 3-D Optical Coherence Microscope Operating At 1300 Nm For The Visualization Of Early Frog Development, Barbara M. Hoeling, Stephanie S. Feldman, Daniel T. Strenge, Aaron Bernard, Emily R. Hogan, Daniel C. Petersen, Scott E. Fraser, Yun Kee, J. Michael Tyszka, Richard C. Haskell

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We present 3-dimensional volume-rendered in vivo images of developing embryos of the African clawed frog Xenopus laevis taken with our new en-face-scanning, focus-tracking OCM system at 1300 nm wavelength. Compared to our older instrument which operates at 850 nm, we measure a decrease in the attenuation coefficient by 33%, leading to a substantial improvement in depth penetration. Both instruments have motion-sensitivity capability. By evaluating the fast Fourier transform of the fringe signal, we can produce simultaneously images displaying the fringe amplitude of the backscattered light and images showing the random Brownian motion of the scatterers. We present time-lapse movies of ...


Control Of Strong-Laser-Field Coupling To Electrons In Solid Targets With Wavelength-Scale Spheres, H. A. Sumeruk, S. Kneip, D. R. Symes, I. V. Churina, A. V. Belolipetski, Thomas D. Donnelly, T. Ditmire Jan 2007

Control Of Strong-Laser-Field Coupling To Electrons In Solid Targets With Wavelength-Scale Spheres, H. A. Sumeruk, S. Kneip, D. R. Symes, I. V. Churina, A. V. Belolipetski, Thomas D. Donnelly, T. Ditmire

All HMC Faculty Publications and Research

Irradiation of a planar solid by an intense laser pulse leads to fast electron acceleration and hard x-ray production. We have investigated whether this high field production of fast electrons can be controlled by introducing dielectric spheres of well-defined size on the target surface. We find that the presence of spheres with a diameter slightly larger than half the laser wavelength leads to Mie enhancements of the laser field which, accompanied by multipass stochastic heating of the electrons, leads to significantly enhanced hard x-ray yield and temperature.