Bremsstrahlung and harmonic generation in laser-assisted electron-nucleus collision

Abstract

The spectrum of radiation emitted by an electron colliding with a nucleus in the presence of a monochromatic laser field is calculated. The Coulomb potential is treated at all orders and the radiation is seen as spontaneous transition between two free states. The kinetic energy of the electron is T 9 100--3000 eV and the laser intensity I 9 101~ W/cm2; in this condition we see strong enhancement in the bremsstrahlung cross-section when the emitted frequency is an integral multiple of the laser frequency.PACS 32.80 -Photon interactions with atoms. PACS 41.70 -Particles in electromagnetic fields (including synchrotron radiation).

Two-photon bremsstrahlung processes in atoms: Polarization effects and analytic results for the Coulomb potential

“…This question was investigated in [37] in the Born approximation. A more detailed inclusion of the effects of an atomic (Coulomb) potential was carried out in [38,39]. It is also appropriate to mention publications [40,41], in which "combined" Compton-type bremsstrahlung processes (absorption of a laser photon by an electron followed by spontaneous BrS in the field of the nucleus) were considered.…”

“…In spite of the cumbersome form typical of analytic calculations with Coulomb functions of the continuum, formulas (38)- (40) and (43) cannot apparently be sim- -----------------------------------------------------------------------------…”

“…This can easily be done for the integrated terms through the known asymptotic expansion of function 2 F 1 in inverse powers of argument [56]. The separation of singularities from J m'm in expressions (38)- (40) requires more complex transformations. It should be noted above all (see Eq.…”

“…(43)) that integrals J 00 and J 11 are finite for E' = E, while J 01 and J 10 diverge as ln(E' -E). The presence of the logarithmic singularity alone allows us to set E' = E in the coefficients of the integrated terms in expressions (38)…”

“…In the low-frequency region ω Ӷ p 2 (although the frequency in this case may be significant as compared to the binding energy, ω ~ 1), the partial Born series can be reduced to low-frequency series in which we must assume that a 0 (see Subsection 5.1). For an arbitrary ω, partial Coulomb MEs are also simplified significantly in the Born region: first, the terms containing integrals in relations (38)- (40) are small for a, a' Ӷ 1 since these terms contain an extra factor Z/p; second, the parameters of functions 2 F 1 become integral so that these function can be reduced to elementary functions. For example, the expression for in the Born limit assumes the form…”