Pressure Measurements Below 10-10 Torr with Bayard-Alpert and Magnetron Gauges
Below 1 x 10-10 Torr, pressure measurement by means of Bayard- Alpert type ion gages is complicated by the existence of a current associated with soft x rays.'' The precise measurement of a true ion current requires precise determination of the so-called x-ray limit of each gage. The present work describes the use of a BayardAlpert gage containing a modulating electrode (after the design of Redhead) to measure pressures below 10-10 Torr. Magnetron-type gages, which do not have x-ray limitations, were then compared directly with the Bayard-Alpert gages. In addition, gage comparisons were carried out in a dynamic system involving pressure ratios across a capillary. Both series of experiments showed that the output current of the magnetron gage was a power function (exponent 1.8) below approximately 2 x 10-10 Torr (N2). In the latter work it was possible to make measurements to below 1 x 10 Torr N2 equivalent.
- Research Organization:
- National Research Corp., Cambridge, Mass.
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-17-037415
- OSTI ID:
- 4636383
- Journal Information:
- Review of Scientific Instruments, Vol. 34, Issue 9; Other Information: Orig. Receipt Date: 31-DEC-63; ISSN 0034-6748
- Publisher:
- American Institute of Physics (AIP)
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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