Table-top two-color soft X-ray laser by means of Ni-like plasmas

Abstract

Laser-produced Ni-like plasmas are known as active media for extreme ultraviolet lasing, with the flexibility to two-color lasing. Two-color laser generation is very complex at accelerator facilities. In this work, plasma lasing at the 3d 9 4d 1 (J ¼ 0) ! 3d 9 4p 1 (J ¼ 1) (collisional-pumping process) and the 3d 9 4f 1 (J ¼ 1) ! 3d 9 4d 1 (J ¼ 1) (photo-pumping process) transitions is studied experimentally and computationally. Several key characteristics of collisional-and photo-pumping laser, such as divergence, pointing stability, and intensity have been investigated. The measurements showed different pulse characteristics for the two lasing processes affected by plasma inhomogeneity in temperature and density. Analytical expressions of these characteristics for both collisional-and photopumping are derived. It is found that the plasma that maximizes the photo-pumping lasing is 20% hotter and 70% denser than the plasma that optimizes the collisional-pumping lasing. The gain of collisional pumping is %4 times higher than the gain for the photo-pumping. The gain lifetime is a factor of %5.2 larger for the monopole-pumping. Similarly, the gain thickness is a factor of %1.8 larger. It is also found that the gain build-up time for collisional-and photo-pumping is 0.7 ps and 0.9 ps, respectively, whereas the build-up length-scale is 11.5 lm and 6.3 lm, respectively. Published by AIP Publishing. [http://dx.

Soft X-ray laser ablation for nano-scale chemical mapping microanalysis

“…In particular, the two-color scheme used to prepare and probe the spectra of radical anions is very interesting. It should be mentioned that Masoudnia et al 105 have shown two-color so X-ray lasing on a tabletop laser setup.…”

Table-top two-color soft x-ray laser from Ni-like Mo plasma

“…0.12 nm (10'332 eV). Masoudnia et al 3 have summarized the three beamline architectures that are functional to generate two-color pulses, i.e. (i) double split undulator mode, (ii) gain-modulated undulator mode, and (iii) double-bunch undulator mode.…”

“…Different authors agree that the thick plasma requires radiative pumping at ca. 350eV (3.53nm) 3,7 . Such soft X-ray pump may be calculated as the peak radiation for a black-body emitter at a temperature of 70eV, using Wien's law.…”

“…2). Nilsen 7 calculated strict spatio-temporal windows for the accomplishment of the self-photopumping, while Masoudnia et al 17 provided less strict ranges. It should be said that the laser input conditions are not exactly the same for the two references, and in this respect the two works provide comparable orders of magnitude for the temporal and spatial windows.…”

“…Two major limitations to propagating the gain through the plasma are possibly refraction and transit-time 7 . Nilsen however excluded that refractive effects are important as the gradients are claimed to be small 5 , while a few other workers do indicate that this effect must be considered carefully 17 . Nilsen computed the gain for a number of Ni-like Mo lines (Tab.…”