Mass-Spectrometric Studies of Graphite Vaporization at High Temperatures
Abstract
The status and preliminary performance of a high capacity, three- stage, high pressure sampling system--Nuclide HT-12-90 mass spectrometer detector and data acquisition system (including time-of-flight velocity analysis of beam neutrals) is presented. A troublesome feature of the present ion source is that some modulation of background peaks occur in the presence of modulated beams. A series of attempts to heat graphite in vacuum to temperatures greater than 3000K are described. Best results are obtained with slotted pyrolytic graphite cells but arcing still limits heating to 3000 to 3100K. Carbon species through C7 have been observed from a pyrolytic graphite Knudsen cell. The C1 to C5 data agree well with literature values, at the two temperatures of 2800K and 2630K. A correlation of dimer formation versus expansion conditions for a number of gases, studied to date, indicates that nucleation cannot be ruled out in high-pressure Knudsen cells or laser heatings.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1971
- Accession Number
- AD0881236
Entities
People
- Frank T. Greene
- Stephen L. Bennett
- Thomas A. Milne