Interaction of Intense Optical Radiation With Free Electrons (Nonrelativistic Case)

Enhanced inverse bremsstrahlung heating rates in a strong laser field

“…Several classical models of the effective collision frequency have been derived from explicit treatment of the dynamics of electron-ion scattering assuming instantaneous and elastic interactions [3,6,10]. We will identify them as the impact approximation [3,6], or the ballistic model [10].…”

“…Advances in laser technology, particularly those related to the generation of ultra-short laser pulses and progress in inertial confinement fusion studies have challenged our understanding of scattering processes over a wide range of conditions and plasma parameters. Nonetheless, heating rate calculations [1,2,3,4,5,6,7,8,9,10] in strong laser fields have involved simplifications that are equivalent to a Born approximation for electron trajectories in the Coulomb fields. This approximation, although well-accepted in the physics community, should be revisited in view of recently discovered nonlinear processes such as harmonic generation and above threshold ionization [11,12,13] that have been explained as being due to strong modifications of electron orbits in the laser field during electronion scattering events.…”

“…the Born approximation is used for the electron orbits in a Coulomb field and the cross-section is assumed to have a weak dependence on the laser field phase. The first approximation, with notable exception of the low frequency approximation [4], has been employed in most quantum mechanical calculations [3] where it applies to fast electrons with the velocity v 0 satisfying the condition Ze 2 /hv 0 ≪ 1 [16], where Ze is the ion charge. The Born approximation is equivalent to small angle scattering and small momentum exchange in classical kinetic theory studies [1,2,9].…”

“…For the purpose of making comparisons, seminal works by Dawson and Oberman [1] and Silin [2] and numerous subsequent publications on high field effects [3,4,5,6,7,8,9,10] are classified into several broad categories: classical-mechanical analysis of binary electron-ion collisions in the dielectric approximation [1,7,8,9]; kinetic theory which uses the Landau-type collision integral in the oscillating electron field [2]; ballistic model (or the model of instantaneous electron-ion collision) [3,6,10]; "first principle" quantum-mechanical calculations [3,4]; and, more recently, the quantum kinetic theory in the dielectric approximation [5]. All theories consider the two body scattering problem as a starting point and their predictions lead to remarkably similar expressions which may differ only by a logarithmic factor.…”

Narrowband inverse Compton scattering x-ray sources at high laser intensities

“…The inverse Compton scattering of a laser pulse on a bunch of high-energy electrons generates bright and short pulses of x-rays or gamma-rays due to the Doppler up-shift of the laser light [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Many applications of these inverse Compton x-ray sources require a high spectral brightness, i.e.…”