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Microwave heating of energetic materials

a technology of energetic materials and microwave ignition, which is applied in the field of microwave ignition of explosive charges, can solve the problems of too long ignition time for a practical use of microwave ignition

Inactive Publication Date: 2006-01-19
LOS ALAMOS NATIONAL SECURITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Benefits of technology

[0015] In accordance with the purposes of the present invention, as embodied and broadly described herein, the present invention includes a method for igniting high explosive. The method includes preparing a mixture of high explosive having a first dielectric loss and a material having a second dielectric loss that is higher than the f...

Problems solved by technology

These ignition times are too long for a practical use using microwave ignition.

Method used

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  • Microwave heating of energetic materials
  • Microwave heating of energetic materials
  • Microwave heating of energetic materials

Examples

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example 1

[0039] Ignition of a mixture of HMX with carbon nanotubes. A mixture of HMX (0.5 g) and carbon nanotubes (1 percent by mass) was prepared and ignited by microwave radiation. FIG. 2 shows a graph of absorbed power as a function of time (solid line, power in units of Watts, time in units of milliseconds) of the mixture. FIG. 2 also shows the photodiode signal (i.e. the light output) as a function of time (dashed line) from the mixture, along with the absorbed power. As FIG. 2 shows, the microwave power was turned on at a time of minus 10 milliseconds, and ignition occurred about 10 milliseconds later.

[0040]FIG. 3 shows a graph of the absorbed microwave power as a function of time (solid line) and a graph of the absorbed energy as a function of time (the dashed line) of the mixture. The absorbed energy is the integral of the absorbed power). The total absorbed energy was 7.5 Joules (J) at an average rate of 750 Watts for a duration of 10 milliseconds. For comparison, raising the same ...

example 2

[0041] Evidence for variable energy release rate. The size of container fragments generated during an explosive event provides a measure of the energy release rate (see, for example, P. R. Lee, “Hazard Assessment of Explosives and Propellants” in Explosive Effects and Applications, J. A. Zukas and W. P. Walters, Springer-Verlag (New York, 1998) p. 327, incorporated by reference). For this example, two experiments were performed to examine the fragment size of the pyrex sample container and the quartz containment cylinder. In both experiments, the nominal conditions were the same: incident power, sample size and sample loading were nominally identical. Absorbed power data was not recorded but inconsistencies between the two experiments resulted in a difference in impedance matching such that the absorbed power was different, which is indicated by the difference in sizes of the fragments in FIG. 4 and FIG. 5. FIG. 5 (experiment 1) shows larger fragments than those of FIG. 4 (experimen...

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Abstract

Mixtures of high explosives with materials that readily absorb microwaves ignite more readily when exposed to microwave energy than the corresponding neat explosives. A charge of HMX (0.5 gram) mixed with carbon nanotubes (1 percent by mass) ignited with 7.5 joules at an average rate of 750 W for 10 milliseconds. To raise a charge of the same mass of neat HMX to an autoignition temperature of 200 degrees Celsius would require much more energy (about 110 joules) for a longer duration (about 150 milliseconds).

Description

STATEMENT REGARDING FEDERAL RIGHTS [0001] This invention was made with government support under Contract No. W-7405-ENG-36 awarded by the U.S. Department of Energy. The government has certain rights in the invention.FIELD OF THE INVENTION [0002] The present invention relates generally to devices employing energetic materials (i.e. explosives) and more particularly to microwave heating of a charge of explosive. BACKGROUND OF THE INVENTION [0003] Microwave radiation is electromagnetic radiation with a frequency in the range from about 1,000 MHz to about 30,000 MHz. Microwave techniques have been employed for a wide variety of applications that include radio astronomy, long distance communication, navigation, microwave ovens, and the study of physical and chemical properties of matter. [0004] Recently, the ignition of several important high explosives by microwave irradiation has been reported (see Kazuo Hasue, Masami Tanabe, Nobutune Watanabe, Shoji Nakahara, and Fumiaki Okada, “Initi...

Claims

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Application Information

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IPC IPC(8): C06C9/00
CPCB82Y30/00C06C7/00C06B23/001
Inventor PERRY, WILLIAM L.SON, STEVEN F.ASAY, BLAINE W.
Owner LOS ALAMOS NATIONAL SECURITY
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