RE: Thoriated Tungsten Electrodes

[Brent Rogers <brogers@mps.ohio-state.edu>]

In lighting, they dope the tungsten with thorium because it lowers the work 
function, meaning that the binding energy of the outer shell electron(s) is 
lower (photoelectric effect), than with pure tungsten.  It's just a guess, 
but the same physical properties may be useful in welding, as well.

Brent Rogers
mailto: brogers@ohstpy.mps.ohio-state.edu

Hello Radsurfers!

I would like to know why Thorium (Th-232) is used in
tungsten electrodes during arc welding ?

Have other elements (actinides?) been used to
replace thorium in electrodes?

A short abstract on this subject was written by
Crim et al  in the June 1993 Health Physics Journal
(Vol 64, S85).

The author lists the advantages of Th as:
easier arc starting, reduced weld contamination,  and
greater stability.

Any other information on this topic would be of interest
to me,    Thank you,

			Jason Flora
			Cinc   OH
(Comments are those of the author and not my
employers)