Laser-based diagnostics for condensation in laser-ablated copper plasmas
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 Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE; 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
- Resource Relation:
- Conference: 10. AIAA computational fluid dynamics conference in conjunction with the 22nd AIAA fluid dynamics, plasma dynamics and lasers conference and the 26th AIIA thermophysics conference, Honolulu, HI (USA), 24-26 Jun 1991
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
74 ATOMIC AND MOLECULAR PHYSICS
COPPER
LASER-PRODUCED PLASMA
PLASMA DIAGNOSTICS
ABLATION
EXCIMER LASERS
FLUORESCENCE
RAYLEIGH SCATTERING
TEMPERATURE MEASUREMENT
TIME-OF-FLIGHT METHOD
COHERENT SCATTERING
ELEMENTS
GAS LASERS
LASERS
LUMINESCENCE
METALS
PLASMA
SCATTERING
TRANSITION ELEMENTS
640410* - Fluid Physics- General Fluid Dynamics
640302 - Atomic
Molecular & Chemical Physics- Atomic & Molecular Properties & Theory