Studies into Laser Ignition of Unconfined Propellants

Abstract

Prior to laser ignition tests, spectral absorption properties of three different solid motor propellants were analysed. The extruded double base (EDB) propellant exhibited >95 % absorption over the 250–550 nm wavelength band whereas, the cast double base (CDB) showed similar absorption over a wider band extending between 375–800 nm. The composite sample (CP) showed a uniform spectral absorption at about 90 % over 250–800 nm band. Ignition tests using an average of 500 nm output from an Ar‐ion laser showed that the double base propellants undergo deflagration prior to ignition due to the presence of carbon black material. Within the laser power density range of 24–125 Wċcm−2, the threshold laser energy densities for deflagration and ignition in the double base propellant were found to␣be between 2–2.5 Jċcm−2, and 40–215 Jċcm−2, respectively. No deflagration was observed for the composite propellant, and the threshold ignition energy was found to be within the range, 11–18 Jċcm−2 for the same range of laser power densities. From the ignition map for this propellant, the threshold energy for ignition at this wavelength was found to be approximately 18 Jċcm−2 and was practically independent of laser power density. In the near infrared wavelength (780 nm) the EDB propellant was not readily ignitable due to its comparatively much higher reflectance at this wavelength. The ignition threshold values were found to be between 19–23 Jċcm−2 for a similar power density level. The results indicate that the ignitability of propellants is enhanced through the promotion of deflagration.

Metal-based reactive nanomaterials

“…Lasers are now commonly used for laboratory studies of material ignition, e.g., Refs. [183][184][185][186][187][188]. Often, however, a number of issues make the interpretation of laser ignition experiments difficult.…”

Laser‐induced Deflagration for the Characterization of Energetic Materials

“…Deflagrating explosives burn faster and more violently than non-explosive combustible materials, which require an external supply of oxygen to sustain the burning [15]. Laser-induced deflagrations have been investigated using laser pulses hundreds of microseconds or longer on HMX [16][17][18], TATB [16,17], RDX [18][19][20], and rocket propellants [21]. McGrane and Moore also investigated the effect of CW laser wavelength on the reaction of various explosives [22].…”

Laser ignition of elastomer-modified cast double-base (EMCDB) propellant using a diode laser

“…It has become an important and interesting topic not only to researchers, but for manufacturers of explosive ignitors, due to the modern advancements in the development of lasers which are more compact, more cost effective, and more efficient in comparison to those lasers used during the first laser ignition attempts in the 1960's [1]. Despite the extensive research which has been carried out into the laser ignition of energetic materials [2][3][4][5][6][7][8][9][10][11][12][13][14][15] including propellants [13][14][15], few laser-based ignitors have been developed for real world use to date and the details of these systems are not currently available in the open literature.…”