CO2 Pulsed Laser Damage Mechanisms and Assessment of Plasma Effects (Unfocused Beam).
Abstract
A theoretical study and experimental investigation of the plasma surface interactions and laser damage mechanisms associated with the irradiation of flat, cylindrical AISI SS 304 stainless steel targets was conducted. Two experiments were accomplished, one at normal atmospheric pressure and one in a high vacuum environment, using a Carbon Dioxide transversely excited atmospheric pressure (TEA), high energy, pulsed laser with an unfocused beam to ascertain the power density threshold requirements for plasma generation. Irradiated target specimens were thoroughly examined for evidence of surface damage with a scanning electron microscope capable of clearly displaying damage features of micron size dimensions. Experimental results confirmed that surface damage was confined solely to unipolar arcing for targets irradiated with power densities near the plasma formation thresholds. These thresholds were determined to be 0.88 Megawatts per square centimeter + or - 12% at atmospheric pressure and 0.43 Megawatts per square centimeter + or - 12% in the high vacuum. A Sequential Unipolar Arcing Model, which incorporated the elaborate details of the refined Schwirzke Model, was developed to thoroughly describe the complex series of interrelated events that constitute the unipolar arcing damage mechanism. The qualitative predictions of the theoretical model were confirmed by experimental results. (Theses)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1986
- Accession Number
- ADA176926
Entities
People
- John S. Olson
Organizations
- Naval Postgraduate School