Laser diffraction effects on the Rayleigh-Taylor instability of a radiation pressure accelerated thin foil

Eliasson, B. (2015) Laser diffraction effects on the Rayleigh-Taylor instability of a radiation pressure accelerated thin foil. In: 42nd EPS Conference on Plasma Physics, 2015-06-22 - 2015-06-26, Centro Cultural de Belém.

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Abstract

We derive a theoretical model for the Rayleigh-Taylor (RT)-like instability for a thin foil accelerated by an intense laser, taking into account finite wavelength effects in the laser wave field. The latter leads to the diffraction of the electromagnetic wave off the periodic structures arising from the instability of the foil, which significantly modifies the growth rate of the RT-like instability when the perturbations on the foil have wavenumbers comparable to or larger than the laser wavenumber. In particular, the growth rate has a local maximum at a perturbation wavenumber approximately equal to the laser wavenumber. This is due to resonant excitations of surface waves parallel to the foil [2]. The standard RT instability, arising from a pressure difference between the two sides of a foil, is approximately recovered for perturbation wavenumbers smaller than the laser wavenumber. Differences in the results for circular and linear polarization of the laser light are pointed out. The model has significance to radiation pressure acceleration of thin foils, where RT-like instabilities are significant obstacles.