Laser-Based Diagnostics for Plasma

Technical Report · Thu Oct 24 04:00:00 EDT 2002

OSTI ID:804438

Zare, Richard N ^[1]

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1. Stanford University, Stanford, CA

OAK 270 - The basic objective of this research was to develop nonintrusive, laser-based optical diagnostic tools for the investigation of trace amounts of molecular species in hostile environments such as plasmas, flashes, flames, and other forms of combustion that are important to energy science and technology. Initially we studied the use of degenerate four-wave mising as a means to reach our objetive. Later on we employed cavity ring-down spectroscopy (CRDS) in our investigation of the transient species, radicals, and ions present in harsh luminous environments, particularyly in the synthesis of diamond thin films based on chemical vapor deposition. In order to understand the gas phase processes in a hot-filament reactor as it relates to CVD, we used CRDS to measure the concentration and temperature profiles of the relevant growth species (precursors). Using CRDS we were able to determine the important hydrogen dissociation ratio as the decisive parameter for the gas phase chemistry in the CVD diamond growth. We were also able to demonstrate through our research work that CDRS is versatile enough to serve as a complete diagnostic for materials process control. Thus, CRDS can be used not only as in situ diagnostic for investigating the chemistry of diamond film deposition, but it can also be used as a gas purity diagnostic for any chemical vapor deposition system.

• Research Organization: Stanford University
• Sponsoring Organization: USDOE Office of Energy Research (ER)
• DOE Contract Number: FG03-92ER14304
• OSTI ID: 804438
• Country of Publication: United States
• Language: English

Related Subjects

cavity ring-down spectroscopy
degenerate four-wave mixing