A SMALL, SENSITIVE, BAKEABLE MASS SPECTROMETER

Technical Report · Thu Sep 01 04:00:00 EDT 1960

OSTI ID:4081874

Davis, W D; Vanderslice, T A

A small, portable, magnetic, deflection type mass spectrometer with a secondary emission multiplier was built for studying residual gases at ultrahigh vacua and making transient pressure studies. Because of its small size it has the advantage that it can be sealed directly to the tube or system being investigated, and is easily transportable. The spectrometer may be baked out at 450 deg C. The design consists of a 90 deg sector, 5-cm radius of curvature magnetic analyzer which will resolve adjacent mass peaks to about mass 140. A Nier-type ion source is used and the ion detector is a 10-stage DuMont, No. 6467 electron multiplier with a gain of 10/sup 7/. Partial pressures of 10/sup -13/ mm Hg were measured under normal operating conditions. By cooling the multiplier in liquid nitrogen, pressures of the order of 10/sup -15/ mm Hg are measurable. Using the multiplier, the signal level is raised to a point at which a low output load resistance may be used to get a short response time. This makes it possible to scan a large mass range and display the spectrum on an oscilloscope. Different ion species may thus be observed almost simultaneously during the course of transient phenomena. Sweep rates as high as 1.5 mu sec per mass unit were used sucessfully. (auth)

• Research Organization: General Electric Co. Research Lab., Schenectady, N.Y.
• NSA Number: NSA-15-011142
• OSTI ID: 4081874
• Report Number(s): 60-RL-2501 G
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

COOLING
DETECTION
EFFICIENCY
ELECTRON TUBES
EMISSION
ENGINEERING AND EQUIPMENT
GASES
ION SOURCES
IONS
LIQUIDS
MASS SPECTROMETERS
MEASURED VALUES
NITROGEN
OSCILLOGRAPHS
OSCILLOSCOPES
PHOTOMULTIPLIERS
PLANNING
PRESSURE
SPECTRA
VACUUM