The Maxwell-Bloch code COLAX has been upgraded to use detailed hydrodynamical and collisional-radiative simulations of a soft x-ray laser plasma with traveling-wave pumping. The seeding of short pulses of high-order harmonics of the pump laser into the x-ray laser medium has been simulated. The amplification is shown to be a dynamic, two-stage process: the atomic dipoles of the lasing ions are first coherently excited by the short pulse, and subsequently generate a radiation wake which is amplified along its path through the plasma, with consequences on the experimentally recorded spectra.
Multichannel quantum defect theory is applied in the treatment of the dissociative recombination and vibrational excitation processes for the BeD + ion in the 24 vibrational levels of its ground electronic state). Three electronic symmetries of BeD ** states ( P 2 , S +
2, and D 2 ) are considered in the calculation of cross sections and the corresponding rate coefficients. The incident electron energy range is 10 −5 -2.7 eV and the electron temperature range is 100-5000K. The vibrational dependence of these collisional processes is highlighted. The resulting data are useful in magnetic confinement fusion edge plasma modeling and spectroscopy, in devices with beryllium based main chamber materials, such as ITER and JET, and operating with the deuteriumtritium fuel mix. An extensive rate coefficients database is presented in graphical form and also by analytic fit functions whose parameters are tabulated in the supplementary material.
The 19.6 nm laser line due to a 3p -3s, J=0-1 transition in Ne-like Ge ions was found to be polarized parallel to the target plane with a degree of polarization of -53 % by Kawachi et al. (1995). The intepret it a s a consequence of a an unbalanced population of the 3s magnetic sublevels. Kieffer et al. 6993) have shown that, during plasma heating, some electrons could be accelerated preferentially in the same direction as the pump laser. In the present work, we shall show that such anisotropic electrons can give a small difference in populations of the 3s sublevels. The 3s level spontaneous emission to the ground level is linearly polarized and can be reabsorbed by the Ne-like ion ground state which amplifies the population of the 3s levels, as well as it increases the different sublevel populations. The 3p-3s X-ray laser amplification depending on the 3s level population becomes polarized but with an opposite sign to the absorbed radiation from the ground level.
This paper is devoted to the effect of frequency
redistribution on x-ray laser beams.
The redistribution function,
calculated by extending the frequency fluctuation model to two-photon
processes, shows coherent scattering and a redistributed contribution.
The spectral emissivity,
corrected in order to account for this effect, is
calculated for lasers using neon-like germanium
and hydrogen-like carbon as amplifiers.
The radiative transfer equation is solved, and the intensity
of the x-ray laser output is given for two
3p-3s lines in a neon-like amplifier.
We also study the variation in the emissivity of the
C5+ Balmer-α lasing line. The
physical conditions of the calculation are derived from modelling of
experiments conducted at the Rutherford Appleton Laboratory.
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