Wow, you are really in a mess, Phil,
remember a little about it since we had BD-problems in a package years ago. Then we found that breakdown is dependent on a)the relative breakdown voltage b)temperature c) gas type d) electrode material (the metals between which you expect breakdown) e) dV/dt i.e. voltage increase, relative gas pressure, possibly more factors, I'm not an expert. But I have the figures for the gases:

Oxygene Rel Breakdown : o.86
Nitrogene    "        : 1.00
Dry air      "        : 0.95
Humid air    "        : diagram
Hydrogene    "        : 0.50

To get true Vbd you multiply above values with Nitrogene breakdown at room temperature and certain gas pressure, I think it's approx. 3 kV/mm. Don't forget the gas pressure, which is highly determinating.


Breakdown for Vacuum and Copper electrodes : 37  kV/mm
            "            Aluminium   "     : 41  kV/mm
            "            Steel       "     : 125 kV/mm


As you can see, breakdown is complicated and dependent on a number of factors. I must confess that we gave up because we couldn't make a good model. We changed our design instead.

Good Luck

Ingemar Hernefjord
Ericsson Microwave Systems

----------------------------sep-----------------------

Subject: [TN] Electrical Breakdown, O2 vs. N2?


Would anyone expect there to be a difference in the
conductivity of N2 vs. O2, air, or vacuum as effects
the electrical breakdown voltage?  We seem to be
getting failures in a backfilled "dry" Nitrogen
environment that we don't see with a lid just taped on
in air.

Thanks, Phil Hersey

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