Soft X-ray Lasers Via Electron-Collisional Pumping
One possible technique for obtaining gain in the soft x-ray region of the spectrum is to use electron-collisional pumping of an appropriate ion species. This can be done in a manner analogous to known ion lasers which operate in the visible portion of the spectrum. The differences being: 1) more highly ionized ions are used to obtain shorter wavelength transitions, 2) the pumping electrons are at a higher temperature to populate the more energetic transitions, and 3) the lifetimes are shorter which implies higher pump intensity per unit area (P/a ∝ ν4). In the case of shorter wavelength transitions one can project known laser transitions isoelectronically to higher Z ions and hence shorter wavelengths or investigate unique ionic electron configurations that are not observed in neutral or weakly ionized species. This technique works well for electronic configurations with relatively few electrons. With many-electron systems, level crossings and other anomalous effects with increasing Z limit the range over which a group of levels which are a viable laser scheme can be isoelectronically projected to higher Z.
KeywordsLaser Transition Lower Laser Level Laser Level Picosecond Laser Picosecond Laser Pulse
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