Ponderomotive Acceleration of Hot Electrons in Tenuous Plasmas
Authors: V.I. Geyko and G.M. Fraiman, I.Y. Dodin and N.J. Fisch
Abstract:
The oscillation-center Hamiltonian is derived for a relativistic electron injected with an arbitrary momentum in a linearly polarized laser pulse propagating in tenuous plasma, assuming that the pulse length is smaller than the plasma wavelength. For hot electrons generated at collisions with ions under intense laser drive, multiple regimes of ponderomotive acceleration are identified and the laser dispersion is shown to affect the process at plasma densities down to 1017 cm−3.
Assuming a/ϒg << 1, which prevents net acceleration of the cold plasma, it is also shown that the normalized energy ϒ of hot electrons accelerated from the initial energy ϒo < , ⌈ does not exceed ⌈ ~ aϒg,
where a is the normalized laser field, and ϒg is the group velocity Lorentz factor. Yet ϒ ~ ⌈ is attained within a wide range of initial conditions; hence a cutoff in the hot electron distribution is predicted.
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Submitted to: Physical Review Letters (February 2009)
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