Abstract
In order to study the particle dynamics in strongly nonuniform and/or localized laser fields, we extend the theory of the ponderomotive force by taking into account the laser field structure up to the higher order with respect to � , the ratio between the particle excursion length and the scale length of the laser field amplitude variation. This extension is realized by keeping the rigorous phase space Lagrangian structure utilizing the noncanonical Lie perturbation up to higher orders. As a result, the equations of motion in a oscillation center coordinate is derived up to the third order of � , which include the second and third spatial derivatives of the laser field amplitude. This denotes that the ponderomotive force depends not only on the local field gradient, but also on the curvature and its derivative. The additional higher-order force originates from the nonlocal particle motion around the oscillation center, which could have an influence especially in the case of tight focusing in the level of laser wavelength.
Highlights
The intensity of ultra-short high power lasers has reached the range of 1018−22 W/cm2, where electrons irradiated by such lasers exhibit highly relativistic characteristics
In order to study the particle dynamics in strongly nonuniform and/or localized laser fields, we extend the theory of the ponderomotive force by taking into account the laser field structure up to the higher order with respect to, the ratio between the particle excursion length and the scale length of the laser field amplitude variation
Based on the noncanonical Lie perturbation theory, we investigated the higher order terms to the ponderomotive force in high intensity laser fields
Summary
The intensity of ultra-short high power lasers has reached the range of 1018−22 W/cm, where electrons irradiated by such lasers exhibit highly relativistic characteristics. Higher intensities of 1023−26 W/cm are expected by further reducing the pulse length and the spot size to the level of laser wavelength, which will open up an entirely new scientific regime [1] In such spatially localized laser fields, the ponderomotive force (light pressure) becomes of critical importance in determining the laser-plasma interaction [2]. The ponderomotive force has been derived by applying the averaging method to the equation of motion and is explained as the force proportional to the field gradient, which results from the first order perturbation to the uniform field [3, 4] In this method, terms related to the higher-order derivatives in the perturbation expansion have been neglected. By introducing a noncanonical coordinate, we derive the oscillation-center equations of motion describing the ponderomotive force that includes the nonlocal effect up to the higher order corresponding to the third derivative of the field amplitude
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
