Modelling and numerical simulation of microwave pulse propagation in an air-breakdown environment

Abstract

The dependences of the propagation characteristics of an intense microwave pulse on the intensity, frequency, width and shape of the pulse in an air- breakdown environment are examined. Numerical simulations lead to a useful empirical relation P³W = α = const, where P and W are the incident power and width of the pulse and α depends on the percentage of the pulse energy transferred from the source point to a given position. The results also show that, using a single unfocused microwave pulse transmitted upwards from the ground, the maximum electron density produced at, for example, 50 km altitude is limited by the tail erosion effect to below 10⁶ cm^-3. Repetitive-pulse and focused-beam approaches are then examined. Both approaches can increase the maximum electron density by no more than an order of magnitude. Hence a scheme using two obliquely propagating pulses intersecting at the desired height (e.g. 50 km) is considered. It is shown that the generated electron density at the lowest intersecting position can be enhanced by more than two orders of magnitude.