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Title: Progress in understanding the short-pulse-driven collisional x-ray lasers

Abstract

Recently, the technique of using a nsec pulse to preform and ionize the plasma followed by a psec pulse to heat the plasma has enabled low-Z neon-like and nickel-like ions to lase driven by small lasers with only ten joules of energy. In this work we model recent experiments done using the COMET laser at LLNL to illuminate I cm long slab targets of Ti with a 4.8 J, 800 ps prepulse followed 1.6 nsec later by a 6 J, 1 psec drive pulse. The LASNEX code is used to calculate the hydrodynamic evolution of the plasma and provide the temperatures and densities fo 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 without radiation transport included for the 3d and 3s (arrow) 2p Ne-like Ti resonance lines. Large regions with gains greater than 80 cmminus1 are predicted for the 3p 1S0 (arrow), 3s 1P,1Ne-like Ti laser line at 326 Å. Given the large gain and low gradients in these plasmas, we do propagation calculations including refraction to understand which regions have the right combination of high gain and low gradients to contributemore » to the X-ray laser output. Calculations are also presented using different delays between the long and short pulse and different widths for the short pulse to provide better insight for optimizing the laser output. In addition to the standard 326 Å laser line, high gain is also predicted and observed for the 3d 1P1 (arrow) 3p 1P1, laser line at 301 Å in Ne-like Ti. We present calculations with and without radiation rransport included on the strong 3d 1P1 (arrow) 2p 1S0, resonance line to better understand this self photopumping effect. We also look at the analog transition in Ni-like ions to understand if self photopumping may also play a role in Ni-like ions. High gain is predicted on the 3d9 4f 1P1 (arrow) 3d9 4d 1P1 Ni-like transition and this line has recently been observed at 226 Å in Ni-like Mo.« less

Authors:
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE Office of Defense Programs (DP)
OSTI Identifier:
2488
Report Number(s):
UCRL-JC-130948
R&D Project: DP0102052; ON: DE00002488
DOE Contract Number:  
W-7405-Eng-48
Resource Type:
Conference
Resource Relation:
Conference: 6th International Conference on X-Ray Lasers, Kyoto, Japan, August 30-September 4, 1998
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING NOT INCLUDED IN OTHER CATEGORIES; X-Ray Lasers; Plasma; Computerized Simulation

Citation Formats

Nilsen, J. Progress in understanding the short-pulse-driven collisional x-ray lasers. United States: N. p., 1998. Web.
Nilsen, J. Progress in understanding the short-pulse-driven collisional x-ray lasers. United States.
Nilsen, J. 1998. "Progress in understanding the short-pulse-driven collisional x-ray lasers". United States. https://www.osti.gov/servlets/purl/2488.
@article{osti_2488,
title = {Progress in understanding the short-pulse-driven collisional x-ray lasers},
author = {Nilsen, J},
abstractNote = {Recently, the technique of using a nsec pulse to preform and ionize the plasma followed by a psec pulse to heat the plasma has enabled low-Z neon-like and nickel-like ions to lase driven by small lasers with only ten joules of energy. In this work we model recent experiments done using the COMET laser at LLNL to illuminate I cm long slab targets of Ti with a 4.8 J, 800 ps prepulse followed 1.6 nsec later by a 6 J, 1 psec drive pulse. The LASNEX code is used to calculate the hydrodynamic evolution of the plasma and provide the temperatures and densities fo 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 without radiation transport included for the 3d and 3s (arrow) 2p Ne-like Ti resonance lines. Large regions with gains greater than 80 cmminus1 are predicted for the 3p 1S0 (arrow), 3s 1P,1Ne-like Ti laser line at 326 Å. Given the large gain and low gradients in these plasmas, we do propagation calculations including refraction to understand which regions have the right combination of high gain and low gradients to contribute to the X-ray laser output. Calculations are also presented using different delays between the long and short pulse and different widths for the short pulse to provide better insight for optimizing the laser output. In addition to the standard 326 Å laser line, high gain is also predicted and observed for the 3d 1P1 (arrow) 3p 1P1, laser line at 301 Å in Ne-like Ti. We present calculations with and without radiation rransport included on the strong 3d 1P1 (arrow) 2p 1S0, resonance line to better understand this self photopumping effect. We also look at the analog transition in Ni-like ions to understand if self photopumping may also play a role in Ni-like ions. High gain is predicted on the 3d9 4f 1P1 (arrow) 3d9 4d 1P1 Ni-like transition and this line has recently been observed at 226 Å in Ni-like Mo.},
doi = {},
url = {https://www.osti.gov/biblio/2488}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Sep 21 00:00:00 EDT 1998},
month = {Mon Sep 21 00:00:00 EDT 1998}
}

Conference:
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