ABSTRACT
Indeed, why plasma harmonics? Why we need plasma harmonics
while we have a well-elaborated technique of frequency conversion
of laser radiation through high-order harmonic generation (HHG) in
gaseous media? One can remind that there is also another technique
of HHG, surface harmonic generation. Both of them have a relatively
long history of development, improvement, and application for
various needs, and it seemed that those two methods fully satisfied
scientific community from the point of view of creation of the
sources of coherent extreme ultraviolet (XUV) radiation.
