MICROSPHERE-BASED SHORT-WAVELENGTH RECOMBINATION X-RAY LASER
Valeo,E.J., Cowley,S.C.: 1993, Phys.Rev.E., 47, 1321.
We describe a scheme for obtaining very short wavelengths (10 A) in
recombination lasers. The rapid cooling rates necessary to achieve population
inversion during recombination are attained by adiabatic expansion of
submicrometer spheres. The spheres are heated impulsively by a powerful
picosecond laser. First, they ionize, then as they expand, they cool and
recombine. We have calculated the optimum sphere size and initial
temperature for maximum gain in the n=3 to 2 transition of hydrogenlike ions
of elements with atomic numbers, Z, between 10 and 30. gain of about 250 per cm
is calculated in aluminum at 38.8 A. Gain rapidly decreases with Z so that
gain in titanium at 13.6 A is about 10 per cm. We have calculated the required
pump-laser intensity and found it to be attainable with current lasers. The
propagation of the pump through the 'gas' of spheres is considered and the
problems arising from pump scattering by the spheres are discussed.
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