Narrow Results

A fourth-order in time and space, finite-difference time-domain (FDTD) algorithm is applied to study the electromagnetic propagation in homogeneous, collision and warm plasma. The approach can significantly minimize the dispersion errors while still maintaining minimal memory requirement. For the problem of three-dimensional propagation, the scheme requires only three additional memory cells per Yee cell over and above that of the generic FDTD scheme. To investigate the validation of the fourth-order FDTD algorithm, the reflection coefficient of a slab of non-magnetized collision plasma is calculated. Comparisons between the accurate data and the results of second-order or fourth-order FDTD methods are discussed.

A fourth-order in time and space, finite-difference time-domain (FDTD) algorithm is applied to study the electromagnetic propagation in homogeneous, collision and warm plasma. The approach can significantly minimize the dispersion errors while still maintaining minimal memory requirement. For the problem of three-dimensional propagation, the scheme requires only three additional memory cells per Yee cell over and above that of the generic FDTD scheme. To investigate the validation of the fourth-order FDTD algorithm, the reflection coefficient of a slab of non-magnetized collision plasma is calculated. Comparisons between the accurate data and the results of second-order or fourth-order FDTD methods are discussed.

The radio technique of cosmogenic neutrino detection, which relies on the Cherenkov signals coherently emitted from the particle showers in dense medium, has now become a mature field. We present an alternative approach to calculate such Cherenkov pulse by a numerical code based on the finite difference time-domain (FDTD) method that does not rely on the far-field approximation. We show that for a shower elongated by the LPM (Landau-Pomeranchuk-Migdal) effect and thus with a multi-peak structure, the generated Cherenkov signal will always be a bipolar and asymmetric waveform in the near-field regime regardless of the specific variations of the multi-peak structure, which makes it a generic and distinctive feature. This should provide an important characteristic signature for the identification of ultra-high energy cosmogenic neutrinos.