Abstract
In the previous report, mass spectroscopic measurement showed that helium was concentrated at the arc axis of argon-helium gas tungsten arcs. In this report, a method was proposed to measure the position-dependent composition of the demixed arc plasma by using a monochromator.
The composition and temperature of argon-hydrogen, argon-helium and argon-nitrogen gas tungsten arcs could be deduced from the intensity ratio of the ArI and ArIl lines in the LTE plasma.
When helium or hydrogen gas was added to an argon arc, the additional gas was found to significantly concentrate at the arc plasma axis. The demixing ratio of the helium in the arc core was the same as that measured previously using mass spectroscope. When nitrogen was added to the argon plasma, a slight concentration of nitrogen at the arc core was also observed.
Furthermore, the results obtained suggest that the arc plasma temperature at the arc core decreased upon introduction of hydrogen gas.
