Showing papers on "Ponderomotive energy published in 2007"

Electron surface acceleration on a solid capillary target inner wall irradiated with ultraintense laser pulses

Abstract: When ultraintense laser pulses irradiate solid targets with a large incident angle, quasistatic magnetic and electric fields are induced, which confine electrons along the target surface in an electrostatic and vector potential well. In this case, electrons are resonantly accelerated along the surface by laser electric field inside the potential well. By this surface acceleration process, high energy electrons are effectively generated whose temperature well exceeds the ponderomotive energy. The optimum conditions for realizing surface acceleration and its energy scalings are given. Capillary type targets are shown to have an advantage in utilizing the surface acceleration process by increasing the interaction length.

Effects of the electron's anomaly in relativistic laser-assisted Mott scattering

Abstract: We investigate the influence of the electron's anomalous magnetic moment on the process of relativistic Mott scattering in a powerful electromagnetic plane wave for which the ponderomotive energy is of the order of the magnitude of the electron's rest mass. For this purpose, we use the Coulomb - Dirac - Volkov and the Dirac - Volkov functions with the electron's anomaly to describe the initial and final states respectively. First- order Born differential cross-sections of induced and inverse bremsstrahlung are obtained for linearly polarized laser light. Numerical calculations are carried out for various parameters values (i.e. scattering angle, the nucleus charge, photon energy, electrical field) and are compared with results obtained by Li et al 2004 ( J. Phys. B: At. Mol. Opt. Phys. 37 653). It is found that for parameters used in the present work, incorporating the anomaly of the electron in the initial and final states yields cross-sections which are strongly modified whatever the scattering geometry as compared to the outcome of the previous treatment.

Control of electron transfer and high harmonic generation in the linear triatomic system at large internuclear distances with short intense laser fields

Abstract: We numerically investigate high order harmonic generation (HHG) in the one electron linear H+– molecular system at large internuclear distances R = α and πα/2, where α is the ponderomotive radius, using ultra-short (two-cycles) intense (I > 1014 W cm −2) 800 nm laser pulses linearly polarized along the internuclear axis. We obtain the HHG spectra by solving exactly, in the Born–Oppenheimer approximation, the 3D time-dependent Schrodinger equation (TDSE). At large internuclear distances R, HHG spectra are obtained with an energy cut-off larger than the atomic maximum of I p + 3.17U p, where U p is the ponderomotive energy and I p is the ionization potential. The extended cut-off is shown to be related to the nature of electron transfer, whose direction is shown to depend critically on the absolute carrier envelope phase (CEP) of the ultrashort pulse. Constructive and destructive interferences in the HHG spectrum of coherent superpositions of electronic states in the H+– system are interpreted in terms of m...

Ponderomotive tunnelling in electron-laser interactions

Abstract: We have investigated the electron tunnelling of the ponderomotive potential by using the nonperturbative quantum electrodynamic and a modified Gaussian quantized field Volkov solution. We have shown that the electron can tunnel a ponderomotive potential, which is too wide to tunnel as a static barrier, by absorbing laser photons. The effect is quantized in nature: the tunnelled electron is discrete in both the energy spectra and diffraction patterns as a result of the multiphoton processes. A resonant tunnelling occurs when the ponderomotive energy equals the multiple integer of the laser photon energy.

Infrared Optical Parametric Chirped Pulse Amplifier for High Harmonic Generation

Abstract: Rapid advances in high-field physics achieved in recent years, most notably generation of isolated soft X-ray attosecond pulses, owe their success to the development of driver lasers with specific pulse properties. The latter include ultrahigh peak intensity, quasi-monocycle duration, and reliable control over the carrier-envelope phase (CEP) [1],[2]. Although the driver lasers currently employed in this research field operate nearly exclusively in the wavelength region of the Ti:sapphire gain (i.e. around 0.8 µm), a switching over to a longer, infrared (IR) wavelength would offer significant advantages. Because of the λ 2 scaling of the ponderomotive energy, the intensity of IR pulses needed to attain emission at a given X-ray photon energy could be substantially lowered in comparison with the 0.8-µm case [3]–[5]. This is expected to be extraordinarily helpful for up-scaling the X-ray frequency, decreasing the duration of X-ray attosecond pulses by at least a factor of λ 3/2, and suppressing undesired target preionization before the interaction with the strongest half-cycle of the laser pulse. From the standpoint of laser technology, the longer duration of the IR optical period reduces the number of cycles for a given pulse envelope and, therefore, relaxes the demand to the amplifier gain bandwidth, which in the case of 5-fs 0.8-µm pulses typically reaches the extreme > 100 THz.