&lt;title&gt;High-energy high-average power pulsed hf/df chemical laser&lt;/title&gt;

Brunet, H.; Mabru, Michel; Voignier, F.

doi:10.1117/12.204942

Cited by 7 publications

(10 citation statements)

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“…HF lasers energized by electrical discharges have been the subject of many studies [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. The best laser performances, namely the maximum output energy and electrical efficiency, have been achieved using pre-ionized pulsed discharges between flat electrodes and reactive gas mixtures which contain H 2 and F 2 molecules [6,7].…”

Section: Introductionmentioning

confidence: 99%

“…The best laser performances, namely the maximum output energy and electrical efficiency, have been achieved using pre-ionized pulsed discharges between flat electrodes and reactive gas mixtures which contain H 2 and F 2 molecules [6,7]. However, these mixtures are very difficult to handle owing to the great risk of explosion, so that research has also been devoted to the non-chain HF laser [1][2][3][4][5][8][9][10][11][12][13][14][15]. For such a laser, the ro-vibrational levels of the HF molecule are produced by reaction between a hydrogenated compound RH and F-atom obtained from the dissociation, during the discharge, of a chemically inert fluorinated molecule.…”

Section: Introductionmentioning

confidence: 99%

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The influence of and molecules on discharge equilibrium and F-atom production in a phototriggered HF laser using

Richeboeuf¹,

Pasquiers²,

Legentil³

et al. 1998

J. Phys. D: Appl. Phys.

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The discharge equilibrium and the F-atom production kinetics in a phototriggered HF laser using gas mixtures containing Ne and with hydrogen or ethane have been investigated. Coupled experimental and theoretical studies have been carried out, through a 0D discharge modelling and measurements of the current, of the voltage and of the extracted laser energy, together with emission spectroscopy on F 3p excited states. A quantitative comparison of the total F-atom density produced in mixtures of with or is performed and the results are compared with the discharge pumped HF laser performance achieved with these molecules. An overall validation of the model has been obtained, both for the energy transfer to the active media and for the kinetics of F and its excited states. It is shown that the transmitted energy and electrical charge, as well as the discharge electric field, weakly depend on the type and on the concentration of the RH molecule, or , in the gas mixtures. Moreover, the F-atom production depends very slightly on the nature of RH. Therefore the fact that the laser performance achieved with hydrogen is lower than the performance achieved with ethane is not due to differences in the energy transfer and in the F-atom production kinetics in mixtures of with or .

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The influence of and molecules on discharge equilibrium and F-atom production in a phototriggered HF laser using

Richeboeuf¹,

Pasquiers²,

Legentil³

et al. 1998

J. Phys. D: Appl. Phys.

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“…In the excimer laser 10 , experimental results clearly show a non-uniform energy deposition along the electrodes due to electric post-discharge overdensities which strongly affect the output energy laser beam. However, in the HF/DF chemical laser, such inhomogeneities have never been reported so far and only the inactive volume between the electrode edge and the optical window, Figure 1, can produce strong disturbances travelling between optics 2,15 . As a consequence, a 2cm side effect of the electrodes has been implemented at the initial time of the modelization.…”

Section: Comparisons Of 2d-3d Numerical Resultsmentioning

confidence: 93%

“…On one hand, from the analysis of experimental results obtained in multidischarge operating mode with both chemical 2,15 and excimer 8-10 lasers, one can mainly notice the asymptotic rise of the pressure in the cavity, which finally reaches a maximum level. This maximum level seems to be characteristic of the laser device employed.…”

Section: Limitations Of the 2d Approachmentioning

confidence: 99%

“…Consequently, due to the strong energy deposition during the laser pumping process, efficient removal of waste heat and effective damping of shock and acoustic waves must be achieved during the interpulse time. However, at a high repetition rate, experimental results 15 show a decrease of the output energy laser beam coupled with a pressure increase in the cavity. The short characteristic time of the laser production effect 16 by comparison with those of the flow (t laser << t flow ) indicates that the output energy decrease is induced by the flow perturbations and mainly, by the residual pressure perturbations, remaining in the laser cavity after the strong electric discharge.…”

Section: Introductionmentioning

confidence: 99%

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Numerical study of 2D and 3D flowfields in a high‐power pulsed chemical laser

Vuillon

Zeitoun²

1997

International Journal of Numerical Methods for Heat &Amp; Fluid Flow

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High‐power chemical lasers operating in high repetitive rate show a decrease of the output energy laser beam. In such lasers, the characteristic time which depends on the laser output is short in comparison with those related to the flow. Consequently, shock waves, acoustic waves and thermal perturbations, induced by the strong electric energy deposition and remaining in the laser cavity between two pulses, may explain the decrease of output energy of the laser beam. For a better understanding of the flowfields, a numerical approach is carried out using flux corrected transport algorithms (FCT methods) associated with a Riemann solver on the computational domain boundaries. Under two‐dimensional assumptions, the inviscid flow in the convergent‐divergent laser cavity is computed to describe the creation and propagation of the wave system and the hot gas column in both single and multidischarge operating modes. Distortions of the contact surfaces are put into evidence through the study of flowfield instabilities. Finally, the limitations of the two‐dimensional modelization become apparent. The numerical resolution is extended to a 3D case in order to take into account the optical direction. This allows to study the influence of shock waves travelling between optics and being generated by a side effect developing at the electrodes. These waves have an effect of long duration on the flowfield and lead to a high residual perturbation level.

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