Feasibility of achieving gain in transition to the ground state of C VI at 34 nm

Abstract

We present numerical studies of recombination gain in the transition to the ground state of H-like C (2 → 1 transition at = 3.4 nm). It is shown that high gain (up to about 180 cm −1) can be achieved using currently available, relatively compact, laser technology. The model includes the ionization of the plasma by an ultraintense, ultrashort laser pulse, followed by plasma expansion, cooling, and recombination. Transient population inversion is generated during the recombination process. We investigate the behavior of the gain with respect to different plasma parameters and pump pulse parameters and explain how the different properties of the plasma and the pump pulse affect the gain.

Demonstration of detuning and wavebreaking effects on Raman amplification efficiency in plasma

“…Powerful short laser pulses have wide applications in physics, including wake field accelerators [1], fast ignition scheme of fusion [2], compact x-ray lasers [3], and compact terahertz sources [4]. Currently, short powerful laser pulses are generated using the chirped pulse amplification (CPA) technique.…”

X-Ray laser: past, present, and future

“…Indication about non-Maxwellian electron distribution during fast OFI and importance of adding low ionization atoms (e.g. Hydrogen) to lasing medium for decreasing OFI effect on plasma temperature rise [93,94] led to better "prescriptions" [88,95] for design recombination SXLs.…”

“…Furthermore, by investigating the effects of different laser and plasma parameters on the gain generation at various wavelengths the optimal conditions required to achieve high gain in C VI ions in 2-1 transition at 3.4 nm were predicted [88].…”

“…In addition, the ultrashort pumping pulses are necessary because of the very short radiative life time, τ , of the first excited levels of ions and the decrease of this time with Z as Z −4 (Z is atomic number of ions). In fact, this time has to be much shorter than radia- [88] tive live time of the first excited level because at high electron density, which is required for high gain, collisional life time is much shorter than radiative time. Short pumping time is required because high gain in 2-1 transition exists before Maxwellization of electron energy distribution takes place.…”

“…Using an elaborate numerical model the gain was calculated for the recombination scheme for the 2-1 transition of C VI ions at 3.4 nm [88]. The recombination gain relies on having fully stripped carbon ions (C 6+ nucleus) in relatively cold plasma.…”