
288 Compact Plasma and Focused Ion Beams
Summary
In summary, when high-power, short-pulse microwaves impinge on a gas-
eous medium, EPWs are created that last for a few microseconds. TFA of
the EPWs indicate simultaneous existence of two frequency bands centered
around 3.8 and 13.0 MHz (with a frequency spread of 4 MHz), corresponding
to two populations of electrons in the plasma wave. The temporal behavior of
the electron current in the EPW is explained on the basis of a model obtained
by considering the force on the electrons, the space charge eld arising from
charge separation between electrons and ions, electron–neutral collisions,
and d