Scanning Electron Microscope - High Voltage Power
Supply
I didn't think to get a picture of the SEM's
high voltage power supply in its original condition, with the lid duct-taped
on and sitting in a tub full of dirty oil. Use your imagination.
Upon opening the case, my first thought was, oh great...rust.
Closer inspection of the flaky brown stuff showed that it was rather elastic,
suggesting that it was the remains of the missing gasket. Here
is a picture of the case, with less than pristine oil and the sophisticated
oil recovery (disposable plastic cup) and filtration (funnel and coffee
filters from Wal-Mart, used 1-gallon milk jugs) systems.
About half a gallon of oil was recovered from
the tub, filtered and tested for breakdown strength, using the polycarbonate
and tungsten cell shown below. The oil from the tub was found to have a
breakdown strength of 320 Volts/mil, using a 125 mil gap between 1/8",
spherically tipped, tungsten electrodes (compared to 300 Volts/mil for
the unfiltered oil in the case).
The following pics show the electronics depending from the lid of the
case, from all four sides.
The gasket remains were removed from the case and electronics assembly
with paper towels and cotton swabs, the remainder of the oil filtered,
combined with the oil recovered from the tub and the tank flange lined
with expanded polytetrafluoroethylene rope gasketing.
The five gallons of filtered oil back in the tank.
The electronics lowered into place and the lid bolted down.
Should be good for another 27 years. Let's get it mounted.
