| 摘要 |
<p>1,099,782. Thermionic ion sources. COMMISSARIAT A L'ENERGIE ATOMIQUE. March 22, 1965 [March 27, 1964], No. 12035/65. Heading H1D. A thermionic ion source for use in a mass spectrometer comprises a heating filament coated with a porous layer of an activating substance, which increases the work function of the filament surface, and an outer layer containing a mixture of the activating substance with the sample to be analysed. In particular, a Pt, Re or W filament may be coated with a refractory substance having poor thermal and electrical conductivity, which may, for example, be one or more of MgSiO 3 , ThSiO 4 , SiO 2 and ZrO 2 in the form of a hydrated gel. A heating current is passed through the filament to evaporate the water from the hydrated gel and leave a porous layer of the activating substance on the filament surface, which is then charged with the outer layer and subjected to a further calcination. The thickness of the filament coating may be 0À2 to 1 mm., e.g. 0À5 mm. The product to be analysed may be galena, zircon or other ore containing traces of Pb. The source may also be used in the isotopic analysis of other elements, e.g. U or Th.</p> |
