Method and apparatus for the automatic measurement of start time of evaporation of barium getter devices
US5139452A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 11, 1991 |
| Grant date | Aug 18, 1992 |
| Priority date | — |
| Expiry date | Apr 11, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J9/39
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A method is described for the automatic determination of the time when barium starts to evaporate, or "start time", of barium evaporable getters. A temperature difference measurement is made of the temperature of the glass wall outside the getter location by means of a sensor preferably comprising an infrared pyrometer calibrated on a wave length of about 10 .mu.m suitable for measuring temperatures of 0.degree.-500.degree. C. Under these conditions the temperature curve measured, through an integral function, follows the behavior of the temperature of the getter which reveals a typical behavior at the moment in which barium starts to evaporate. Once .DELTA.T has been calculated from the analysis of a series of experimental test results on the integral curve, that value corresponds to the start time. The measurement of temperature is transformed into a suitably amplified voltage this giving a value of V corresponding to the start time. This can then be used to automatically regulate the R.F. generator power level to obtain a constant start time or to regulate the total time of evaporation of the getter so as to obtain a constant barium yield.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.