Acceleration of ultra-thin electron layer. Analytical treatment compared with 1D-PIC simulation

In this paper, we apply an analytical model [V.V. Kulagin et al., Phys. Plasmas 14,113101 (2007)] to describe the acceleration of an ultra-thin electron layer by a schematic single-cycle laser pulse and compare with one-dimensional particle-in-cell (1D-PIC) simulations. This is in the context of creating a relativistic mirror for coherent backscattering and supplements two related papers in this EPJD volume. The model is shown to reproduce the 1D-PIC results almost quantitatively for the short time of a few laser periods sufficient for the backscattering of ultra-short probe pulses.Comment: 4 pages, 4 figures, submitted to the special issue "Fundamental Physics with Ultra-High Fields" in The European Physical Journal

Inelastische Prozesse in ultra-kurzer Laser-Materie-Wechselwirkung

Within the framework of this thesis particle-in-cell (PIC) simulations of relativistic laser matter interaction have been developed including inelastic processes such as field and electron collisional ionization, binary collisions and bremsstrahlung. The code LPIC is a 1D3V PIC code with one spatial and three velocity dimensions. The implementation for field ionization is based on the ADK tunneling formula by Ammosov, Delone and Krainov or alternatively on the ''barrier suppression ionization'' model. Energy conservation throughout this process is realized by a fictitious ionization current withdrawing the ionization energy from the field. The electron collisional ionization is also energy conserving The binary Coulomb collisions are treated in a way that is equivalent to the Fokker-Planck operator in Landau form. With this code the ionization dynamics of a 1 #mu#m thick helium gas layer at slightly overcritical density (2n"c) using a six cycles long laser pulse with an intensity of 9 x 10"1"6 W/cm"2 is studied focusing on the time-dependence and clear identification of the different ionization mechanisms. Of particular importance is a new field ionization mechanism via quasi-static space charge separation fields generated by fast electrons leading especially at the rear surface of the target to directed electric fields of the same order of magnitude as the laser field amplitude. The feedback of the ionization on the reflected and transmitted pulse and the importance of collisional ionization are discussed. The fields at the rear side are characterized in space and time and compared to the ones at the front surface and systematic variations of the laser intensity and target density are investigated. With regard to an experimental realization a solid target is studied also. A 395 nm thick boron foil is irradiated with 10"1"8 W/cm"2 under 31 . The rearside electric field is quasi-static, parallel to the target normal and shows over a period of several laser cycles field strengths of the same order of magnitude as the laser amplitude (10"1"2 V/m). This field might be used to build a high Z ion source for heavy ion accelerators. (orig.)Available from TIB Hannover: RN 5339(248) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

LPIC++. A parallel one-dimensional relativistic electromagnetic particle-in-cell code for simulating laser-plasma-interaction

The code LPIC++ presented here, is based on a one-dimensional, electromagnetic, relativistic PIC code that has originally been developed by one of the authors during a PhD thesis at the Max-Planck-Institut fuer Quantenoptik for kinetic simulations of high harmonic generation from overdense plasma surfaces. The code uses essentially the algorithm of Birdsall and Langdon and Villasenor and Bunemann. It is written in C++ in order to be easily extendable and has been parallelized to be able to grow in power linearly with the size of accessable hardware, e.g. massively parallel machines like Cray T3E. The parallel LPIC++ version uses PVM for communication between processors. PVM is public domain software, can be downloaded from the world wide web. A particular strength of LPIC++ lies in its clear program and data structure, which uses chained lists for the organization of grid cells and enables dynamic adjustment of spatial domain sizes in a very convenient way, and therefore easy balancing of processor loads. Also particles belonging to one cell are linked in a chained list and are immediately accessable from this cell. In addition to this convenient type of data organization in a PIC code, the code shows excellent performance in both its single processor and parallel version. (orig.)Available from TIB Hannover: RN 5339(225) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman