A SMALL, SENSITIVE, BAKEABLE MASS SPECTROMETER

Technical Report · Sat Apr 01 04:00:00 EST 1961

OSTI ID:4751373

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 ultra-high 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 tranportable. The spectrometer may be baked out at temperatures of 450 deg C. The design consists of a 90 degree sector, 5 cm radius of curvature, magnetic analyzer which will resolve adjacent mass peaks up to about mass 140. A Nier-type ion source is used and the ion detector is a 10- stage electron multiplier with a gain of 10/sup 7/. Partial pressures of 10/sup - 13/ mm Hg were measured under normal operating conditions, and by cooling the multiplier in liquid nitrogen, pressures of the order of 10/sup -15/ mm Hg are measurable. By use of 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 microseconds per mass unit were used successfully. (auth)

• Research Organization: General Electric Co. Research Lab., Schenectady, N.Y.
• NSA Number: NSA-17-006379
• OSTI ID: 4751373
• Report Number(s): 61-RL-2501G(Rev.)
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

COOLING
ELECTRON BEAMS
GASES
INSTRUMENTS AND INSTRUMENTATION
ION SOURCES
MAGNETIC FIELDS
MASS
MASS SPECTROMETERS
MEASURED VALUES
MULTIPLICATION FACTORS
OSCILLOGRAPHS
PRESSURE
SEALS
SENSITIVITY
TEMPERATURE
TRANSIENTS
VACUUM