Measurement of atomic carbon densities by the laster-induced fluorescence method with an Ar2∗ laser

Abstract

A high power argon excimer laser (Ar2∗ laser; 5 MW/cm2 nm at λ = 126 nm, Δλ ~ 1.7 nm) has been developed to measure the density and transport of carbon atoms in edge plasmas by the laser-induced fluorescence method (LIFM). The first measurement of carbon atoms has been performed by the observations of 1.16 μm fluorescence light due to the 3d 3Po → 3p 3S transition during the laser pumping through the 2p 3P → 3d 3Po transition. The density of carbon atoms released from a thin carbon film (90 nm) with the laser blow-off technique was determined to be 6 × 109 cm−3 at a distance of 30 mm from the target, indicating that almost all carbon atoms are in states other than the ground state (~ 10−4). The thermal velocity was measured, by the time-of-flight technique, to be 8 × 105 cm/s which was almost the same as the average velocity of sputtered carbon atoms.