| |
 |
UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-27 9:46 |
 |
|
|
|
Conference: Bucharest University Faculty of Physics 2017 Meeting
Section: Theoretical Physics and Applied Mathematics
Title:
Maxwell-Bloch modelling of inner-shell x-ray lasing in neon gas
Authors:
Cristian IORGA(1,2), Viorica STANCALIE(1)
*
Affiliation:
1) National Institute for Laser Plasma and Radiation Physics, Atomistilor 409, P. O. Box MG-36, Magurele-Ilfov 077125, Romania
2) Faculty of Physics, University of Bucharest, Atomistilor 405, CP-MG 11, Magurele-Bucharest 077125, Romania
E-mail
criiorga@gmail.com
Keywords:
x-ray laser, Maxwell-Bloch formalism, inner-shell photo-ionization.
Abstract:
The advent of high brilliance x-ray free electron lasers (XFELs) has enabled x-ray laser pumping by means of inner-shell photo-ionization processes in neon gas [1] and in solid copper [2]. In the present work we use the Generalized Maxwell-Bloch formalism [3] to theoretically optimize the laser gain in neon gas on the Ne II 1s-2p (1.46 nm) transition taking into account the fine-splitting of the lower lasing level. All related atomic data calculations have been performed within the relativistic model-potential approximation [4]. The propagation of the XFEL pulse (hv=960eV) in neon gas is performed via numerical simulation. Population inversion is created for the 1s-2p transition through the inner-shell photo-ionization process the cross section of which was calculated as 0.28 Mb. The x-ray pulses are initiated by the stochastic term included in the Maxwell-Bloch equations which corresponds to spontaneous emission. The x-ray lasers, theevolution of which has been monitored along the plasma column, are characterized in time and space (number of photons, frequency and temporal profiles). In order to theoretically optimize the gain, the temporal duration (FWHM) of the pumping pulse is varied (1fs-1000fs) along with the focusing radius (2000nm-120nm) into the neon gas medium. The present simulation predicts the optimum conversion of 15% of the XFEL radiation into x-ray pulses at well defined wavelength.
References:
1. N. Rohringer et al., Nature 481, 488-491, 2012;
2. H. Yoneda et al., Nature 524, 446-449, 2015;
3. C. Weninger and N. Rohringer, Phys. Rev. A 90, 063828, 2014;
4. M. F. Gu, Can. J. Phys. 86(5), 675-689, 2008
Acknowledgement:
This work has been financed by the National Authority for
Research and Innovation in the frame of Nucleus programmecontract
4N/2016
|
|
|
|