Modeling short-pulse-driven collisional x-ray lasers and other new schemes
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 laser 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 1 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 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 without radiation transport included for the 3d and 3s {_} 2p Ne-like Ti resonance lines. Large regions with gains greater than 80 cm{sup {minus}1} are predicted for the 3p {sup 1}S{sub 0} {_} 3s {sup 1}P{sub 1} Ne-like Ti laser line at 326 {angstrom}. Given the large gain and large 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 {angstrom} laser line, high gain is also predicted and observed for the 3d {sup 1}P{sub 1} {_} 3p {sup 1}P{sub 1} laser line at 301 {angstrom} in Ne-like Ti. We present calculations with and without radiation transport included on the strong 3d {sup 1}P{sub 1} {_} 2p {sup 1}S{sub 0} 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 3d{sup 9} 4f {sup 1}P{sub 1} {_} 3d{sup 9} 4d {sup 1}P{sub 1} Ni-like transition and this line has recently been observed at 226 {angstrom} in Ni-like Mo. Gain of 13 cm{sup {minus}1} has been measured for this line.
- Research Organization:
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE Office of Defense Programs (DP) (US)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 9356
- Report Number(s):
- UCRL-JC-132649; DP0102011; DP0102011; TRN: AH200122%%217
- Resource Relation:
- Conference: 1999 International Symposium on Optical Science, Engineering, and Instrumentation, Denver, CO (US), 07/18/1999--07/23/1999; Other Information: PBD: 1 Jul 1999
- Country of Publication:
- United States
- Language:
- English
Similar Records
Modleing of psec laser driven Ne-like and Ni-like x-ray lasers
Modeling and Demonstration of a Saturated Ni-Like Mo X-Ray Laser