Glass Jar Vacuum Chamber
Table of Contents

Description

A vacuum chamber made from a glass jar.

The HV wires are for using the vacuum chamber as a glow discharge tube,
they can be omitted if this will not be the purpose of the vacuum chamber.
Ensure that the lid is screwed on tightly before evacuating.

As is shown in the diagram, the construction is simple:
A glass jar with a metal lid,
the paint is removed from both sides of the lid, at the center where the hole will be made,
A hole is made in the metal lid,
and a piece of copper tubing is soldered therein,
the copper tubing then connects to a vacuum pump.

I connected the HV wires on mine to a flyback transformer, but seperated the wires inside such that an arc would not form.
I then began to evacuate the jar, and after a short period, an arc formed between the wires, which became more like a spherical glow as the air pressure inside decreased.
I was using a freezer compressor, which attains an estimated 90% vacuum.

At this pressure (90% vacuum, or 27.16 in Hg) the force exerted on the glass jar is about 2.5KG/CM^2,
so about 424KG is exerted over the total surface area of the glass jar, excluding the lid (524KG including the lid).
In my case, the glass jar and the lid withstood this force,
however,
this force is many times higher than the maximum force a glass jar of this form is designed to withstand,
so it is quite possible that a glass jar might in a different circumstance not withstand this force,
resulting in a violent and loud implosion, complete with flying pieces of glass and metal.
Thus it is advisable to take precautions, the most effective of which would be to place the jar underwater, in a solid (and water tight) container,
this will absorb much of the force if it implodes, saving you from untimely (or otherwise) death or serious injury.
Another thing I would suggest would be to use a glass jar which is thick, and perhaps which has some flat edges.

Diagram

Vacuum%20chamber.png
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