Modulated voltage metastable ionization detector

Patent · Tue Aug 27 04:00:00 EDT 1985

OSTI ID:6030469

Carle, G C; Humphry, D E; Kojiro, D R

Metastable ionization detectors used for chromatographic analysis usually employa fixed high voltage for the ionization potential. For this reason, the operating range is limited to about three orders of magnitude. By use of the technique disclosed in the instant invention, operating ranges of about nine orders of magnitude are obtained. The output current from a metastable ionization detector (MID) is applied to a modulation voltage circuit. An adjustment is made to balance out the background current, and an output current, above background, is applied to an input of a strip chart recorder. For low level concentrations, i.e., low detected output current, the ionization potential will be at a maximum and the metastable ionization detector will operate at its most sensitive level. When the detected current from the metastable ionization detector increases above a predetermined threshold level, a voltage control circuit is activated which turns on a high voltage transistor which acts to reduce the ionization potential. The ionization potential applied to the metastable ionization detector is then varied so as to maintain the detected signal level constant. The variation in ionization potential is now related to the concentration fo the constituent and a representative amplitude is applied to another input of said strip chart recorder.

• Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space Administration
• Patent Number(s): US 4538066
• OSTI ID: 6030469
• Country of Publication: United States
• Language: English

Related Subjects

440300* -- Miscellaneous Instruments-- (-1989)
47 OTHER INSTRUMENTATION
CHROMATOGRAPHY
DESIGN
ELECTRIC MEASURING INSTRUMENTS
ELECTRICAL EQUIPMENT
ELECTROMETERS
ENERGY LEVELS
EQUIPMENT
EXCITED STATES
FLUIDS
GAS ANALYSIS
GAS CHROMATOGRAPHY
GASES
INERT ATMOSPHERE
IONIZATION
IONIZATION POTENTIAL
IONIZED GASES
MEASURING INSTRUMENTS
MEASURING METHODS
METASTABLE STATES
SEPARATION PROCESSES
VOLTAGE REGULATORS