Rising the signal-to-noise ratio in X-ray spectra of femtosecond laser-produced plasmas using the 'mean-median' algorithm

As femtosecond laser pulses increase in intensity and decrease in duration, interaction between the focused laser radiation and a substance is followed by a sharp increase in the intensity of fast-electron, ion, and electromagnetic noise generation. In turn, the noise signals of X-ray detectors grow in amplitude and the signal-to-noise ratio in recording X-ray spectra of multiply charged ions approaches unity. A significant excess of the noise level over the useful signal is observed in plasmas generated by laser pulses with a power density of >= 10(17) W/cm(2). The most powerful effect of the above factors is exerted on X-ray spectra recorded by such electromagnetic equipment as CCD-based detectors, photoelectron amplifiers, etc. A new '' mean-median '' algorithm is described, with which it is possible to considerably increase the signal-to-noise ratio of CCD detectors used to measure X-ray spectra of femtosecond laser-produced plasma.