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Hi Pete We run at 200 uA trap like all Ar people I guess and the filaments run at between 2.35 and 2.45 A. We use the standard MAP coiled filament which is on 24 hours a day (I know some people turn them of and claim it extends the lifetime). I guess we have had between 2-6 years per filament with the low end of that spectrum probably due to a badly fitted filament. Simon. > -----Original Message----- > From: Pete Burnard [SMTP:[log in to unmask]] > Sent: 15 July 2001 22:09 > To: [log in to unmask] > Subject: filament lifetimes > > Hi all, > We are trying to find a better compromise for the filament > lifetime/sensitivity on the MAP215 at Caltech. To get high He sensitivity, > the filament has been run with the trap current regulated at 500 microA > for > the last 5 years (2.5 - 2.6 A on the filament); however, this has > necessitated changing the filament every 12 months or so. This is fine for > running just He, but is not an effiecient way to run for Ne as it can take > 3 months to get CO2 down to operating levels. > > I would be interested to hear the experience of the Noble gas network re: > filament operating conditions and the lifetime of the filament. If > listmembers could email me (NOT the list) to save repetitious emails > flinging around, I promise I will summarize the info and re-post it to the > list. Please send me details of how long your last filament lasted, the > approximate filament current, the regulating trap current, and whether it > was a homemade filament or supplied by VG/Micromass/MAP. And any other > information you might have that could relate to the filament lifetime > (e.g. > construction, wire type etc) will also be good. I'm primarily interested > in > Nier-type sources, but will collate the info from Baur-Signeur sources for > the benefit of the list. > > Pete > > __________________________________________________________________________ > ____ > Dr Pete Burnard > Division of Geological and Planetary Sciences, > California Institute of Technology MS100-23 > Pasadena CA91125 > USA > > Tel: 626 396 3872 Fax: 626 683 0621 Website: > http://www.gps.caltech.edu/~peteb