WorldCat Identities

Frantz, Lee M.

Works: 2 works in 4 publications in 1 language and 4 library holdings
Publication Timeline
Most widely held works by Lee M Frantz
High intensity laser propagation in the atmosphere( Book )

3 editions published between 1966 and 1967 in English and held by 3 WorldCat member libraries worldwide

Two nonlinear propagation effects which limit the transmission of intense laser radiation through the atmosphere are discussed, namely, self-defocusing due to atmospheric heating, and the stimulated Raman effect. The self-defocusing studies are restricted, in this report, to the heating mechanisms, and in particular to the theory of the very far wings of atmospheric absorption lines, beyond the domain of conventional pressure broadening theories. Specifically, in order to understand the apparent dominance of H2O absorptivity in the atmosphere at the 10 microns window, the very far wing collision broadening of the rotational spectrum of polar molecules is investigated. First, the classical Debye theory of dielectric absorptivity is extended to account for higher frequencies and finite collisional time duration. It is then demonstrated that this theory is inadequate to explain the dominant role of H2O - H2O collisions observed in recent experiments at 10 microns with H2O - N2 mixtures, and it is found necessary to introduce a new mechanism: a hindered rotation, or librational motion, arising from the angular dependence of the strong dipole-dipole interaction. Preliminary calculations indicate that this mechanism is promising. With regard to the Raman effect, a previously developed theory of stimulated Raman propagation is applied to describe a Raman amplifier and also to explain recent observations of very short intense pulses of Raman backscattered light. (Author)

1 edition published in 1965 in English and held by 1 WorldCat member library worldwide

A formal expression was derived for the field theoretic transition amplitude in a Brillouin-Wigner perturbation expansion. The principal innovation is the use of wave packets to introduce the boundary conditions, thereby avoiding the need for invoking the adiabatic hypothesis. The field of incident particles, but not the scatter, is second quantized. No restrictions are placed on the number of incident quanta. The resulting expression is thus appropriate, for example, to the nonrelativistic description of the scattering of a photon beam of arbitrary intensity by an atom. A set of formally exact scattering eigenvectors is produced. A time-dependent solution to the Schroedinger equation is then formed from a weighted superposition of them. An asymptotic expansion of the wave function in reciprocal powers of the time was developed and shown to have the form, in the remote past and future, of a free wave packet of quanta spatially isolated from the scatterer. The transition amplitude was identified by a comparison of the initial and final-state wave packets, and found to be a super-position of elements of the usual Brillouin-Wigner T-matrix, each weighted by the corresponding weight factor in the initial-state wave packet. (Author)
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