Abstract

A single pulse from a TEA CO2 laser is used to heat 1:7:14 mixtures of SF6:CH4:O2 to temperatures near 1000 K. A short- or long-duration pulse (one-half the energy deposited in 0.25 or 0.82 μsec, respectively) from a second TEA CO2 laser is used to ignite the mixture. At comparable values of absorbed energy from the second laser, ignition-delay times for the long-duration secondary pulse are approximately twice those for the short-duration pulse. Ignition of the hot mixture requires about 10% less absorbed energy with the short-duration pulse than with the long-duration pulse. These results indicate the short-duration pulse is more effective in producing a high population density of reactive species that initiate the reactions necessary for ignition.

© 1981 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. R. A. Hill, G. A. Laguna, Opt. Commun. 32435 (1980).
    [CrossRef]
  2. Supplied by the Harshaw Chemical Co.
  3. JANAF Thermochemical Tables, NSRDS-NBS 37, (1971).
  4. J. F. Swegle, “TOODY IV, A Computer Program for Two-Dimensional Wave Propagation,” SAND78-0552, Sandia National Laboratories, Albuquerque, N. Mex. (1978).

1980 (1)

R. A. Hill, G. A. Laguna, Opt. Commun. 32435 (1980).
[CrossRef]

1971 (1)

JANAF Thermochemical Tables, NSRDS-NBS 37, (1971).

Hill, R. A.

R. A. Hill, G. A. Laguna, Opt. Commun. 32435 (1980).
[CrossRef]

Laguna, G. A.

R. A. Hill, G. A. Laguna, Opt. Commun. 32435 (1980).
[CrossRef]

Swegle, J. F.

J. F. Swegle, “TOODY IV, A Computer Program for Two-Dimensional Wave Propagation,” SAND78-0552, Sandia National Laboratories, Albuquerque, N. Mex. (1978).

NSRDS-NBS 37 (1)

JANAF Thermochemical Tables, NSRDS-NBS 37, (1971).

Opt. Commun. (1)

R. A. Hill, G. A. Laguna, Opt. Commun. 32435 (1980).
[CrossRef]

Other (2)

Supplied by the Harshaw Chemical Co.

J. F. Swegle, “TOODY IV, A Computer Program for Two-Dimensional Wave Propagation,” SAND78-0552, Sandia National Laboratories, Albuquerque, N. Mex. (1978).

Cited By

OSA participates in CrossRef's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (4)

Fig. 1
Fig. 1

Schematic of the optical cell and beam splitter arrangement: P, primary laser beam; S, secondary laser beam; W, window; B, beam splitter; and R, retroreflecting mirror. Ei, Em, and Ef are the energies recorded by the initial, middle, and final pyroelectric detectors, respectively.

Fig. 2
Fig. 2

Absorbed energy density as a function of incident fluence of the secondary laser beam for (a) T0 = 960 K, representing an absorbed energy of 0.139 J/cm3 from the primary beam, and (b) T0 = 1010 K, representing an absorbed energy of 0.149 J/cm3 from the primary beam. Triangles (circles) correspond to short- (long-) pulse data. Starred symbols represent shots that resulted in ignition. Error bars represent the probable error for ±1.5% deviations in the average values of the calorimeter readings.

Fig. 3
Fig. 3

Ignition-delay times as a function of incident fluence of the secondary laser beam for (a) T0 = 960 K and (b) T0 = 1010 K. Triangles (circles) correspond to short- (long-) pulse data. Arrows indicate the highest values of incident fluence for which ignition did not occur.

Fig. 4
Fig. 4

Ignition-delay time as a function of the effective temperature and total absorbed energy density of the gas mixture. S and L correspond to short- and long-duration pulse data, respectively, as derived from the empirical curves shown in Figs. 2 and 3. Error bars reflect the uncertainties represented by the error bars shown in Fig. 2.

Equations (1)

Equations on this page are rendered with MathJax. Learn more.

Δ E = T i T f C υ ( T ) dT ,

Metrics