Approximate method for calculating the radiation from a moving charge in the presence of a complex object

摘要

An approximate method for calculating the radiation from a moving charge in the presence of a dielectricnobject is developed. The method is composed of two steps. The first step is calculation of the field in the mediumnwithout considering the external boundaries of the object, and the second step is an approximate (ray-optical)ncalculation of the wave propagation outside the object. As a test problem, we consider the case of a chargencrossing a dielectric plate. Computations of the field are performed using exact and approximate methods. Itnis shown that the results agree well. Additionally, we apply the method under consideration to the case of ancone-shaped object with a vacuum channel. The radiation energy spectral density as a function of the locationnof the observation point and the problem’s parameters is given. In particular, the convergent radiation effect isndescribed.