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Harmonics emission during forced oscillation of an atomic electron under strong laser field action
Author(s): R. V. Karapetyan; V. B. Fedorov
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Paper Abstract

In the frame of classical mechanics the analytical expression has been obtained for the radiation emission spectrum, consisting of a large number of the odd harmonics. It has been shown that the high frequency boundary of the spectrum is determined by the ratio of the electron oscillation velocity to the atom size. The oscillations of the electron in a laser field take steady-state form for a time about of optical cycle. The field amplitude should be sufficient for electron tunneling through the variable in the time potential barrier created by Coulomb attractive force of a nucleus and by an alternate extracting electrical field radiation E(t). The quantum tunneling process will be exponential depending on the absolute value of E(t) and will be quasistatic under certain conditions. This statement corresponds to experimental fact of the sharp occurrence and the fast increase of high harmonics radiation intensity in the range of laser radiation intensity 1014 less than I less than 1016 W/cm2, corresponding to subatomic values of field Eo less than Ea. The electrons appear outside of the barrier at the peaks of the sinusoidal field. Consequently they have zero drift velocity and hereinafter make the forced oscillations near their 'parent' atoms. At the large laser field strength Eo greater than or equal to Ea the electrons can tunnel during a considerable part of every optical period, when field time derivative differs from a zero, and therefore they will have drift velocity Vd less than eEom(omega) . In this case the electron drift displacement for a time of laser pulse (tau) very much greater than 1/(omega) can exceed the oscillation amplitude and interatomic distance. This can result in turn in appearance of the fully ionized plasma. But in the present paper only the case Eo less than Ea is considered.

Paper Details

Date Published: 6 May 1996
PDF: 5 pages
Proc. SPIE 2796, ICONO '95: Fundamentals of Laser-Matter Interaction, (6 May 1996); doi: 10.1117/12.239741
Show Author Affiliations
R. V. Karapetyan, General Physics Institute (Russia)
V. B. Fedorov, General Physics Institute (Russia)

Published in SPIE Proceedings Vol. 2796:
ICONO '95: Fundamentals of Laser-Matter Interaction
Konstantin N. Drabovich; Nikolai I. Koroteev, Editor(s)

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