Odd electron tube - how do I wire up this physics experiment correctly?

Factual Questions
1

The school where I work has a lot of different old equipment that no-one currently knows how to use. One such apparatus is this electron tube with helmholtz coils:

Front

Back

Close-up front

Close-up back

Sp+ and Sp- are easy, those are the connectors for the coil.

2V and K- are connected to each other and to one of the two connectors on the bottom of the tube.

Uh is connected to one of the 2Ohm connectors, while the other 2Ohm connector is connected to the second connector on the bottom of the tube.

A+ is connected through a 22kOhm resistor to the wire that can be connected to the top of the tube.

As can be seen in the close up, the electrode at the bottom consists of a metal ribbon with a single twist, connecting the two inputs to the tube. There’s also a disc connected only on one side, with a hole aligned with the twist in the ribbon.

Rather than experimenting, and possibly frying something irreplacable (under the current budget regime) I’m hoping someone here has some advice and/or knowledge to share.

2

Here are nearly identical devices.
http://www.tel-atomic.com/tubes/_e/m_fine_beam.html

This company should be able to advise you on how to set up the experiment.

3

If we restrict ourselves to electron tubes, they’re not nearly identical but fundamentally different. But you’re right, they probably have the expertise to tell me how to wire it properly. I figure they’ll be more interested in selling me new equipment though, and I was hoping someone on the straight dope would have an idea so I wouldn’t have to ask every manufacturer out there.