Observation of 101<sup>st</sup>harmonic generated from laser-produced Mn plasma
Abstract
The results of variation of the high-order harmonic distribution generating from the manganese plasma plume are presented. Harmonic plateau was extended from the 31st order, at the intensities below the barrier suppression intensity for singly charged Mn ions, to the 101st one (λ = 7.9 nm), at higher intensities, highest ever observed in plasma HHG studies. The second plateau appearance for the harmonics exceeding 31st order was observed in this case, while the low-order harmonic plateau was decreased or completely disappeared, with only plasma lines dominating for the wavelength region above 27.6 nm. Origin of the harmonics appearing at the second plateau was attributed to the interaction of intense laser field with doubly charged manganese ions.