Propagation of electromagnetic (EM) wave through a meta-material having anisotropic permittivity and permeability tensors is simulated through Finite Difference Time Domain (FDTD) simulations using a technique of transformation optics. Details of the algorithm used in the simulation are given here. Using the simulation code developed, a two-dimensional dual-purpose polarization-sensitive meta-material is designed and demonstrated. Such a material can perform two independent tasks simultaneously for Transverse Electric (TE) and Transverse Magnetic (TM) polarization. All-dielectric design for TM polarization is also proposed and demonstrated to reduce the constrains on physical realization of such materials.
The dynamics of ionization-induced electron injection in the high density (~ 1:2 × 10<sup>19</sup>cm<sup>-3</sup>) regime of Laser Wakefield Acceleration (LWFA) was investigated by analyzing betatron X-ray emission inside dielectric capillary tubes. A comparative study of the electron and betatron X-ray properties was performed for both self-injection and ionization-induced injection. Direct experimental evidence of early onset of ionization-induced injection into the plasma wave was obtained by mapping the X-ray emission zone inside the plasma. Particle-In-Cell (PIC) simulations showed that the early onset of ionization-induced injection, due to its lower trapping threshold, suppresses self-injection of electrons. An increase of X-ray fluence by at least a factor of two was observed in the case of ionization-induced injection due to an increased trapped charge compared to self-injection mechanism.
Numerical modeling of laser wakefield electron accelerator inside a long (~ 1 m) dielectric capillary tube is presented. Simulations were performed in a quasi-linear regime of laser wakefield acceleration using a quasi-static particle code, WAKE [ P. Mora and T.M.Antonsen, Jr., Phys. Plasmas 4, 217(1997)]. The code was modified to simulate the acceleration of an externally injected electron bunch and guiding of the laser inside a dielectric capillary tube. Results of simulations demonstrating the acceleration of the injected electron bunch to multi-GeV (~ 5 GeV) energies are discussed.