Laser-based diagnostics for condensation in laser-ablated copper plasmas

Conference · Tue Jan 01 04:00:00 EST 1991

DOI:https://doi.org/10.2514/6.1991-1460· OSTI ID:6046267

Sappey, A D; Gamble, T K

We are investigating the thermodynamic conditions under which condensation occurs in laser-ablated copper plasma plumes. The plasma is created by XeCl excimer laser ablation (308 nm, 350 mJ/pulse) at power densities from 500--1000 MW/cm{sup 2}. The atomic vapor expands rapidly into backing pressures of helium ranging from 0--50 torr. The backing gas serves to slow the vapor before it rarefies and provides a third body to stabilize collision complexes between vapor atoms to produce small cluster species. The formation of these small clusters is indicative of the onset of condensation, a process which, under the proper conditions, eventually forms macroscopic particulate in the plume. We use laser-induced fluorescence (LIF) to probe both atomic copper and the copper dimer molecule, Cu{sub 2}. Velocities of atomic Cu have been obtained by a time-of-flight method under varying conditions of backing gas pressure. At low pressure (10 mtorr), the atomic Cu velocity peaks at approximately 2 {times} 10{sup 6} cm/s. Excitation scans of the Cu{sub 2} A {minus} X (0,0) and (1,1) bands yield both a rotational temperature and a vibrational temperature. Direct laser beam absorption is used to determine the number density of atomic copper. Rayleigh scattering from particulate is easily observable under conditions favorable to particulate production. The Cu{sub 2} LIF and Rayleigh-scattered signals disappear instantaneously in the absence of the ablation laser pulse indicating that the particulate is formed during a single laser shot. 10 refs., 9 figs.

• Research Organization: Los Alamos National Lab., NM (USA)
• Sponsoring Organization: DOE; USDOE, Washington, DC (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 6046267
• Report Number(s): LA-UR-91-1158; CONF-910651--7; ON: TI91011394
• Country of Publication: United States
• Language: English

Related Subjects

640302 -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
640410* -- Fluid Physics-- General Fluid Dynamics
74 ATOMIC AND MOLECULAR PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABLATION
COHERENT SCATTERING
COPPER
ELEMENTS
EXCIMER LASERS
FLUORESCENCE
GAS LASERS
LASER-PRODUCED PLASMA
LASERS
LUMINESCENCE
METALS
PLASMA
PLASMA DIAGNOSTICS
RAYLEIGH SCATTERING
SCATTERING
TEMPERATURE MEASUREMENT
TIME-OF-FLIGHT METHOD
TRANSITION ELEMENTS