Pulsed CO<inf>2</inf>lasers for the surface heating and melting of metals

Abstract

We explore the possibilities of using pulsed electron-beamexcited C 0 2 lasers for the generation of metal surfaces with improved properties through surface alloying or microsecond melting and thermalconductance quenching (self quenching). Air plasma ignition yields enhanced thermal coupling to highly reflective metals, but is shown nevertheless to prohibit the melting of metals with lasers of reasonable size. Suppression of the air plasma by evacuation leads not only to unimpaired metal heating but to a new and little-understood mode of enhanced thermal coupling, with highly favorable characteristics. The surface melting of even refractory metals with single microsecondduration pulses should be possible with pulsed COa lasers of modest size.

Detection of Long-Lived Electrons Around $ \hbox{CO}_{2}$-Laser-Produced Plasma in Atmospheric Gases Using Symmetric Double-Probe System

“…It exhibits good properties with respect to electric conductivity and chemical activity because of its high electron temperature and high plasma density during the initial stage of generation. The PLPP can be widely applied for laser-induced electrical discharge (LIED) [1]- [10], laser-triggered gap switch [11]- [13], and laser material depositions [14], [15] in gas or liquid phases.…”