3 - 5
Transpector MPS Operating Manual
3.3.1 Transpector MPS Filament
Dual Yttria-coated Iridium is the only available filament for Transpector MPS.
Yttria-coated iridium filaments have a coating of yttrium oxide over an iridium core.
Yttria is a rare-earth element that, in its oxide form, is fully oxidized. This means
that the surface of the yttria-coated iridium filament is inert with respect to oxygen
damage. For applications which will include exposure to oxygen, choosing the
yttria-coated iridium filament is appropriate.
Yttria-coated iridium filaments do not withstand exposure to halogens. Upon
exposure to halogens, the yttria coating will form yttria-oxyhalides which will chip
off of the filament and cause direct exposure of the iridium core, shortening the
lifetime of the filament.