[3dem] Ambient humidity and glow discharger efficiency?

[Talya Levitz]

Hi all,

We are troubleshooting an issue where our glow discharger(s) seem to be of
variable efficiency (sometimes making carbon grids appropriately
hydrophilic, sometimes less so, occasionally not at all). My current theory
is that the ambient humidity of the room is affecting the efficiency of the
glow discharge. Has anyone encountered this or looked into it more
thoroughly, and if so, what was your fix (account for humidity in timing /
current? move the glow discharger into a more humidity-controlled room?
desiccate the air going back into the chamber... somehow?). Other variables
that have been ruled out are a faulty glow discharger, location of grid in
the metal block, and whether it is the first glow of the day / session.

We regularly have >50% humidity in the room during the summer, even with
the dehumidifier running at full speed, because of air flow etc. variables
in the room that we cannot change. We have two glow dischargers, a Pelco
Easiglo and a Quorum/EMS GloQube, and have seen this with both dischargers,
although we use the GloQube more so we have seen it more with that. At one
point I tried to blow all the carbon off a grid with a very prolonged (5
min @ 20 mA) glow discharge on the GloQube, and all the carbon was still
entirely intact, which made me a bit nervous.

Relatedly, how often and how do you all clean your metal blocks that grids
glow discharge on? We were thinking of using acetone and/or alcohol, but
would appreciate recommendations!

Talya Levitz, PhD
Scientist I
talya_levitz at dfci.harvard.edu
Pronouns: they/she
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