The Effects of Pressure on the Laser Initiation of TiHx/KC104 and Other Pyrotechnics
The ignition thresholds of TiHx/KC104, Mg/Teflon, and an A1-torch mix are measured as a function of gas pressure for ignition by 514.5 nm pulses from an argon ion laser. The TiHx/KC104 system in argon gas has three distinct pressure regimes. The thresholds are very high below about 0.3 MPa, decrease rapidly between 0.3 and 1.5 MPa, and decrease gradually and become constant between 1.5 and 7 MPa. Mg/Teflon and the A1-torch mix also have decreasing thresholds with increasing gas pressures and decreasing pellet densities. Ignition pulse lengths between 0.25 and 20 milliseconds at a spot diameter of 65 microns in the TiHx/KC104 system indicate that the thresholds are predominantly power, not energy, thresholds for pulses longer than one millisecond. The increase in threshold power below one millisecond is consistent with a calculated time to reach thermal equilibrium of 0.96 milliseconds. The effect of beam diameters between 40 and 175 microns on the TiHx/KC104 thresholds is consistent with ignitions occurring at approximately the same temperature at the center of the beam. TiHx/KC104 and Zr/KC104/Viton/Graphite pyrotechnics are also ignitied in sealed devices through sapphire windows. Ignition thresholds are comparable to those on open surfaces in pressures of 0.1 to 0.5 MPa which suggests that samples first decompose and ignite under a pocket of pressure. Ignition failures in TiHx/KC104 and in low density Zr/KC104/Viton/Graphite samples are attributed to increased porosity and/or gaps near the windows which allow reaction products to escape from the ignition zone.
- Research Organization:
- Mound Plant, Miamisburg, OH
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC04-76DP00053
- OSTI ID:
- 968982
- Report Number(s):
- MLM-3533(OP)
- Country of Publication:
- United States
- Language:
- English
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