Measurement of barium emitted from thermionic electrodes in steady-state Hg-rare gas discharges

Conference · Thu Jul 01 04:00:00 EDT 1999

OSTI ID:20067650

Garner, R C

Using atomic absorption the authors measure the densities of neutral and ionic barium in the vicinity of the barium oxide coated electrodes in low pressure Hg-rare gas discharges. The technique is sensitive to the small amount of barium that evaporates from the electrode during a steady state discharge. It uses a current modulated barium hollow cathode lamp light source and a phase sensitive detector. Several researchers previously have detected barium using spectroscopic techniques. Two researchers have used simple atomic absorption as described here. One researcher has employed frequency modulated laser atomic absorption. A variety of laser induced fluorescence experiments also have been performed. In the present work the authors concentrate on comparing barium densities with electrode temperature. Spatially resolved electrode temperature is measured with a thermal emission based diagnostic developed previously. Comparisons are made with respect to variations of key discharge parameters, such as current and rare gas pressure. As such, they investigate in detail the connection between the electrode temperature and the presence of free barium in the discharge.

• Research Organization: Osram Sylvania, Beverly, MA (US)
• OSTI ID: 20067650
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
ABSORPTION SPECTROSCOPY
BARIUM
ELECTRIC DISCHARGES
ELECTRODES
LIGHT BULBS
MERCURY
PLASMA DENSITY
TEMPERATURE MEASUREMENT