It was observed experimentally that high power laser light (I approx. 10**1**6W/cm**2) as produced by the CO//2-laser Gemini and Helios systems generates very high harmonics with nearly constant efficiency over several high harmonics with a cutoff given by the local plasma frequency at the upper density shelf. We study the response of a strongly inhomogeneous plasma to the high power laser light. We derive the equation of electron motion in lagrangean variables and find the conditions on the density scale length and power intensities for wavebreaking (typically, one waveperiod for density profile L//n approx. 0. 1 lambda and I approx. 10**1**6W/cm**2 near the critical layer). We show that the source of a given high harmonic frequency is localized around the density region corresponding to a local plasma wave at that frequency.
|Title of host publication||Laser Interaction and Related Plasma Phenomena|
|Editors||Heinreich Hora, George H Miley|
|Number of pages||15|
|Publication status||Published - 1984|