Abstract
The plasma plume of a hydrogen plasma jet used for diamond synthesis is analyzed by a Pitot tube and by mass spectrometry. In the investigated pressure range of 2–10 mbar, supersonic gas velocities with Mach numbers of up to 2 were observed, which decreased with increasing pressure and increasing distance from the nozzle. The injection of the carbon-containing species either at the exit of the jet nozzle or simply into the background gas of the reaction chamber confirmed the importance of recirculation of background gas into the plasma plume. In the case of background injection the rise of the total carbon content in the plume with increasing distance from the nozzle is much slower than in the case of nozzle injection. The results of a numerical model of the hydrocarbon gas-phase reactions in the jet are presented. The model considers the entrainment of background gas into the plasma plume. Two domains along the jet axis can be distinguished. The first one in the vicinity of the nozzle is dominated by methyl radicals, the second one by atomic carbon. Increase of the hydrogen dissociation level results in the broadening of the atomic carbon domain and the rise of C2 far from the nozzle. Background injection of CH4 leads to lower total carbon content in the plume but has little effect on the species distribution along the jet axis.
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K. Kurihara, K. Sasaki, M. Kawarada, and N. Koshino,Appl. Phys. Lett. 52, 437 (1988).
N. Ohtake and M. Yoshikawa,J. Electrochem. Soc. 137, 717 (1990).
D. G. Goodwin,J. Appl. Phys. 74, 6888 (1993).
D. G. Goodwin,J. Appl. Phys. 74, 6895 (1993).
M. H. Loh and M. A. Cappelli,Surf. Coat. Technol. 54/55, 408 (1992).
M. H. Loh and M. A. Cappelli,Diamond Relat. Mater. 2, 454 (1993).
M. A. Cappelli and M. H. Loh,Diamond Relat. Mater. 3, 417 (1994).
S. J. Harris and L. R. Martin,J. Mater. Res. 5, 2313 (1990).
S. J. Harris,Appl. Phys. Lett. 56, 2298 (1990).
M. Frenklach and K. E. Spear,J. Mater. Res. 3, 133 (1988).
M. Frenklach,J. Chem. Phys. 97, 5794 (1992).
M. E. Coltrin and D. S. Dandy,J. Appl. Phys. 74, 5803 (1993).
J. R. Fincke, W. D. Swank, S. C. Snyder, and D. C. Haggard,Rev. Sci. Instrum. 64, 3585 (1993).
J. G. Liebeskind, R. K. Hanson, and M. A. Cappelli, AIAA 93-2530, 29th Joint Propulsion Conference, Monterey, California, June 1993.
C. G. Schwärzler, O. Schnabl, J. Laimer, and H. Störi,Plasma Chem. Plasma Process. 16, 173 (1996).
G. N. Abramovich,The Theory of Turbulent Jets, MIT Press, Cambridge, Massachusetts (1963).
R. J. Kee, F. M. Rupley, and J. A. Miller, Sandia Report No. SAND 89-8009, Sandia National Laboratories, Livermore, California (1989).
R. F. G. Meulenbroeks, A. J. van Beek, A. J. G. van Helvoort, M. C. M. van de Sanden, and D. C. Schram,Phys. Rev. E 49, 4397 (1994).
A. E. Lutz, R. J. Kee, and J. A. Miller, Sandia Rep. 87-8248 UC-401, Sandia National Laboratories, Livermore, California (1993).
R. F. G. Meulenbroeks, D. C. Schram, M. C. M. van de Sanden, and J. A. M. van der Mullen,Phys. Rev. Lett. 76, 1840 (1996).
P. Glarborg, R. J. Kee, J. F. Grcar, and J. A. Miller, Sandia Rep. 86-8209 UC-4, Sandia National Laboratories, Livermore, California (1993).
A. H. Shapiro,The Dynamics and Thermodynamics of Compressible Fluid Flow, Wiley, New York (1953), Vol. 1.
D. K. Otorbaev, A. J. M. Buuron, N. T. Guerassimov, M. C. M. van de Sanden, and D. C. Schram,J. Appl. Phys. 76, 4499 (1994).
D. M. Gruen, C. D. Zuiker, A. R. Krauss, and X. Pan,J. Vac. Sci. Technol. A 13, 1628 (1995).
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Pauser, H., Schwärzler, C.G., Laimer, J. et al. Reactions of hydrocarbons in a supersonic vacuum plasma jet. Plasma Chem Plasma Process 17, 107–121 (1997). https://doi.org/10.1007/BF02766810
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DOI: https://doi.org/10.1007/BF02766810