Calibration and characterization of Bayard--Alpert gauges operating in high magnetic fields

Journal Article · Thu May 01 04:00:00 EDT 1986 · J. Vac. Sci. Technol., A; (United States)

DOI:https://doi.org/10.1116/1.573967· OSTI ID:5725947

Pickles, W L; Hunt, A L

Standard Bayard--Alpert gauges have been successfully operated for several months in 0.3--0.7 T magnetic fields at eleven locations near the plasma edge of the Tandem Mirror Experiment-Upgrade (TMX-U). After individual calibration in the local TMX-U magnetic field, the gauges clearly measure gas density. One of these eleven gauges has been studied extensively and has maintained calibration within 12% during this period of operation. All gauge filaments are tungsten and are heated with direct current. The gauge housing allows operation in the low density plasma outside the limiter radius by thermalizing the neutral gas that enters the gauge and by preventing plasma from entering the gauge. Changing the orientation of the gauge with respect to the magnetic field changes the gauge calibration, or effective sensitivity, by as much as a factor of 100. Only some orientations of the filament collector plane with respect to the magnetic field direction allow calibrated operation as a pressure gauge. This range of angles is approximately from 20/sup 0/ to 50/sup 0/. Each of the eleven gauges was oriented to produce a usable sensitivity, then calibrated for the magnetic field effects at that position. After initial operation in the magnetic field, a small recalibration of less than 10% for permanent filament distortion was necessary for the unshielded gauge. For D/sub 2/, CH/sub 4/, X/sub e/ and Kr gas, the measured recalibration factor to the gauge sensitivity in the same high magnetic field varied only 16% rms about the average of 9.7 for the unshielded gauge. Repeated measurement of the magnetic recalibration for each of the species over a 1 month period showed less than 12% variation.

• Research Organization: Lawrence Livermore National Laboratory, Livermore, California 94550
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5725947
• Journal Information: J. Vac. Sci. Technol., A; (United States), Journal Name: J. Vac. Sci. Technol., A; (United States) Vol. 4:3; ISSN JVTAD
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700102 -- Fusion Energy-- Plasma Research-- Diagnostics
700209* -- Fusion Power Plant Technology-- Component Development & Materials Testing
ALKANES
BAYARD-ALPERT GAGES
CALIBRATION
DEUTERIUM
ELEMENTS
FLUIDS
GASES
HYDROCARBONS
HYDROGEN ISOTOPES
IONIZATION GAGES
ISOTOPES
KRYPTON
LIGHT NUCLEI
MAGNETIC FIELDS
MAGNETIC MIRRORS
MEASURING INSTRUMENTS
METHANE
NONMETALS
NUCLEI
ODD-ODD NUCLEI
OPEN PLASMA DEVICES
OPERATION
ORGANIC COMPOUNDS
PLASMA DIAGNOSTICS
PRESSURE GAGES
RARE GASES
SENSITIVITY
STABLE ISOTOPES
TANDEM MIRRORS
THERMONUCLEAR DEVICES
TMX DEVICES
VACUUM GAGES
XENON