Modeling and demonstration of a saturated Ni-like Mo X-ray laser

Citation
J. Nilsen et al., Modeling and demonstration of a saturated Ni-like Mo X-ray laser, J PHYS IV, 11(PR2), 2001, pp. 67-73
Citations number
7
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physics
Journal title
JOURNAL DE PHYSIQUE IV
ISSN journal
1155-4339 → ACNP
Volume
11
Issue
PR2
Year of publication
2001
Pages
67 - 73
Database
ISI
SICI code
1155-4339(200107)11:PR2<67:MADOAS>2.0.ZU;2-L
Abstract
The technique of using a nsec pulse to preform and ionize the plasma follow ed by a psec pulse to heat the plasma has enabled us to achieve saturated l aser output for low-Z neon-like and nickel-like ions driven by small lasers with less than ten joules of energy. In this work we present and model rec ent experiments done using the COMET laser at Lawrence Livermore National L aboratory to illuminate slab targets of Mo up to I cm long with a one joule , 600 ps prepulse followed 700 psec later by a five joule, one psec drive p ulse. The experiments demonstrate saturated output on the Ni-like Mo 3d(9) 4d S-1(0) --> 3d(9) 4p P-1(1) laser line at 18.9 nm. The small signal gain and gain length product are estimated by measuring the laser output versus target length. Experiments are done using multilayer mirrors to obtain two- dimensional images of the output aperture of the laser and to measure the t otal laser energy as a function of various parameters such as the delay bet ween the short and long pulses and the energy of the two pulses. To model t he experiments the LASNEX code is used to calculate the hydrodynamic evolut ion of the plasma and provide the temperatures and densities to the XRASER code, which then does the kinetics calculations to determine the gain. The temporal and spatial evolution of the plasma is studied both with and witho ut radiation transport included for the 4f and 4p --> 3d Ni-like Mo resonan ce lines, High gains are predicted for both the 3d(9) 4d S-1(0) --> 3d(9) 4 p P-1(1) laser line at 18.9nm and the 3d(9) 4f P-1(1) --> 3d(9) 4d P-1(1) p hotopumped line which is observed to laser at 22.6 nm.