)Tungstenfilamentsoperateataveryhightemperature,resultinginahighgaugefactor.Thisfilamentisverysusceptibletofailurebyoxidationduetopoorvacuumorsuddenpressurization,butisrelativelyinsensitivetocontaminationasfoundinimplanterorsputteringsystems.(2)Gaugefactor(S)isdefinedas:S=actualpressure/indicatedpressure(3)Iridiumfilamentscannotbeoperatedatthesametemperatureastungstenfilamentsbecauseofiridium’slowermeltingtemperature.Athoriaoryttriacoatingisrequiredtoimproveelectronemissionattheloweroperatingtemperature.Theiridium/thoriaandiridium/yttriafilamentsareveryresistanttooxidationduetopoorvacuumorsuddenpressurization,butareverysusceptibletocontaminationbyvacuumoil,andsputteringorimplantationcontamination.BayardAlpertIonizationGaugeOperatingConditi***GlassEnvelopeOperatingBiasesCollector:0VDCtoGroundGrid:+150to+180VDCtoGroundFilament:+30VDCtoGroundGridDegas:6.3to7.5VAC@10AOperatingRatingFilament:4to6amp@3to5voltsOperatingFactorsTungstenFilament(1):GaugeFactor(2)14PressureRange1x10-3to2x10-10Iridium(ThO2Coating)(3)GaugeFactor(2)10PressureRange1x10-3to2x10-10)