Modeling High-Power Microwave Beam Channeling and Self-Focusing by Neutral Gas Ionization

An experiment was performed in our laboratory where a short (~0.7 ns) high-power (~500 MW) microwave (9.6 GHz) beam focused into a He or air -filled Pyrex tube, produced a hollow plasma channel. The latter is followed downstream from the focal area by a long trace of plasma around the axis, in the region where the beam should have expanded. The presence of high-energy (~ 15 ke V) electrons and nanosecond plasma density build-up (> 1 0
¹²
cm-3) were also observed.