Abstract
For pt.I see ibid., vol.8, no.18, p.3044 (1975). The total intensity of an optically thick line can be greater from a differentially expanding plasma than from a non-expanding plasma of similar geometry, and can approach the optically thin value at sufficiently high streaming velocities. A population inversion, localized to one region of a differentially expanding plasma, can give rise to nett amplified spontaneous emission even though it would not do so in the absence of expansion. This enhances the prospects of a laser-produced plasma as a source of amplified spontaneous emission. Within the one line profile from a differentially expanding plasma, maximum amplified spontaneous emission and peak gain to an external signal need not occur at the line centre and need not occur at the same wavelength as one another.