Physics and diagnostics of laser ablation plume propagation for high- Tc superconductor film growth
The formation, composition and propagatin of laser-produced plasmas used for pulsed laser deposition (PLD) of Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7-x} have been studied under film growth conditions. Four complementary spatially- and temporally-resolved in situ diagnostic techniques are applied to characterize the expansion of the laser plume into both vacuum and ambient gases: optical emission and absorption spectroscopy, fast ion probe measurements, and fast photography with a gated, image-intensified CCD array (ICCD) camera system. Transient optical absorption spectroscopy reveals large densities of ground state atoms, ions, and molecules in the plume as well as a slower component to the plume transport than is indicated by the plasma fluorescence and ion current. Ablation into background gases results in scattering attenuation of the laser plume. The exponential attenuation of the positive ion flux transmitted through 50--300 m Torr background oxygen is measured and used to define an overall ion-oxygen reaction cross section of {sigma}{sub {eta}-O{sub 2}} = 2.3 {times} 10{sup {minus}16} cm{sup 2} under the described film growth conditions. The slowing of the laser plasma and formation of shock structures due to collisions with the ambient gas are described using ion probe measurements and ICCD photographic comparisons of expansion into vacuum and background oxygen. At the pressures used for PLD, distance-time (R-t) plots derived from the photographs and ion probe waveforms indicate that the higher pressure plume initially expands through the ambient gas in accordance with a drag model experiencing little slowing until a visible shock structure forms. Following a transition period, in which the plume appears to have two components, a single component shock structure propagates in better agreement with a shock, or blast wave model.
- Research Organization:
- Oak Ridge National Lab., TN (United States)
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 5634093
- Report Number(s):
- CONF-920439-3; ON: DE92009386
- Resource Relation:
- Conference: International conference on metallurgical coatings and thin films, San Diego, CA (United States), 6-10 Apr 1992
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BARIUM OXIDES
LASER-PRODUCED PLASMA
COPPER OXIDES
YTTRIUM OXIDES
ABLATION
ABSORPTION SPECTROSCOPY
EMISSION SPECTROSCOPY
HIGH-TC SUPERCONDUCTORS
ION PROBES
PLUMES
SUPERCONDUCTING FILMS
ULTRAHIGH-SPEED PHOTOGRAPHY
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
FILMS
OXIDES
OXYGEN COMPOUNDS
PHOTOGRAPHY
PLASMA
PROBES
SPECTROSCOPY
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
360201* - Ceramics
Cermets
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665300 - Interactions Between Beams & Condensed Matter- (1992-)
700320 - Plasma Diagnostic Techniques & Instrumentation- (1992-)