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Bombing again.
>> mentioned a two-inch gap. That seems really big. I would have thought 1/2
an inch or so, but I've never tried it. <<
15K jumps 1.25" in atmospheric pressure. So you can figure it from there.
Most insulators are designed with a length double the anticipated arc jump.
>> Most people I've seen with slide chokes end up just using blocks of wood
to hold the thing open at various settings. I think that's bad practice,
since you really need to change several times during bombing - using an
ammeter. <<
That is the method I use and never have to change settings during bombing. I
have wood marked for the type of electrode shell I use and if the unit is
extremely long I will move up one size block. Everything times out perfectly.
The electrode on the manifold would be bad practice for me. I have considered
it but it would be too easy for the resistance to the electrode to be less
than through the tube. That is why I like the spark gap method best. With an
adjusting screw you could get it to jump just before it took the wrong path.
My manifold design isolates the filling side and gauges from the rest of the
system so it is protected by a stopcock anyway.
I have a question for Ted. How do you clean your metal manifold? I find that
I have to clean my pyrex one about every 5-6 months. I just unscrew it and
wash it out with water. I made it with maintenance in mind. Any particles of
matter that cling to the side walls of the manifold slows pumping considerably
and it also traps molecules that then have to be re-outgassed after exposure
to air.
E-mail from: Tom Biebel, 03-Sep-1995