Van de Graaf is leaking charge

[Patric]

Dear all,
my Van de Graaf had been working flawlessly. I was able to pull 40cm coronal discharges from it.
Here is a long exposure:



The column is made from 160mm diameter PVC pipe.



After half a year of non operation I brought it back to life and I now have some severe problems. When it starts up it nicely charges the top load as usual, but after about 30 secs there is charge leaking from the column. In the dark you can clearly see several jets coming out of the side of the column. The origins of the jets seem to be arranged along a line parallel to the column. I cannot take pictures but here is a sketch:



I already checked in the outside and inside of the column for any contamination or damages. Nothing, all looks smooth. Really scratching my head about this.
The column is a sandwich from PVC and foam. Looks like this:



If anyone has got some ideas, let me know!

Cheers Patric

[ElectroXa]

Was the Van de graaf stored in a moist place?
Because the foam can retain moisture, so it becomes conductive and thus cause current leaks.

[Patric]

Was the Van de graaf stored in a moist place?
Because the foam can retain moisture, so it becomes conductive and thus cause current leaks.

No not really, always sat in the workshop which is not humid. (ok, the laundry room is next door...  )
I will take it apart and try to dry it, maybe run the hair dryer for some time.

My next VDG is planned to feature a transparent acrylic column. Those shouldnt be prone to take on moisture.

[nik282000]

I have had good luck using only a hair dryer to get my leaky VDG running.
After A year or two in the basement it tends to work very poorly if I don't blow it down, both inside and out with a hair dryer for about 10 minutes. It seems to remove any accumulated surface moisture and lets it run even on humid days.

Hope that helps.