| 摘要 |
<p>Apparatus for measuring and/or determining the presence or absence of vacuum pressure within sealed vessels comprising an electrode (4), at earth potential, and an electrode (3), driven by a high frequency, high voltage generator (5). A vessel (1), under test, is placed between the two electrodes. Radiation from a radio-isotope source (7), is directed through the vessel (1). The intensity of radiation is sufficient to ensure virtually instantaneous ionization of the low pressure gas within the vessel (1), if an adequate vacuum is present within. An analogue signal indicative of electrode current is provided by generator (5), and fed to a comparator (6). If the current exceeds a preset threshold level, an output signal is produced, thus indicating the presence of a satisfactory vacuum.</p> |
