Laser-supported Absorption Wave Research Articles

Experimental studies of laser-supported absorption waves with 5-ms pulses of 10.6-μ radiation

The response of materials to ≈5-ms pulses of 10.6-μ laser radiation at peak power densities of 1 to 2 MW/cm2 has been observed with simultaneous determination of (i) both front and back surface temperature rises, (ii) pressure delivered to the specimen as a function of time, (iii) total impulse delivered to the specimen, and (iv) absorption wave effects via high-speed framing camera coverage. The materials studied are 2024 aluminum alloy, 304 stainless steel, graphite, a Fiberglas-epoxy composite, alumina, MgO, and Pyroceram. It was found that Fiberglas-epoxy and graphite exhibit continuous coupling of the laser energy during the entire pulse, whereas the metals showed strong initial coupling which gradually diminished to near zero and then recoupled at the end of the pulse. The ceramics exhibited repetitive decoupling and recoupling during the entire pulse. The photographic evidence indicates the formation of laser-supported plasmatrons in the case of the metals and laser-supported combustion waves with the ceramic materials.