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DIY Electron Accelerator: A Cathode Ray Tube in a Wine Bottle

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Step 8: Assemble the Vacuum System

To connect the vacuum pump to your cathode ray tube, you will need your brass pump to hose converter, about 2 feet of 1/4" rubber tubing, a pair of screw clamps, and some Teflon tape.

First, apply a few layers of Teflon tape over the middle of the steel brake line and over the middle of the threads on screw connector of your vacuum pump.

Second, install the pump to hose converter such that the Teflon tape is inside the interlocking threads of the screw connector and converter. Basically, this means you need to keep screwing the converter onto the pump until little or no Teflon tape is visible.

Third, apply a layer or two of Teflon tape over the hose end of the pump to hose converter and slide the hose over it until it is all the way on. Then, use a screw clamp to secure the hose.

Fourth, use a screw clamp to secure the other end of the hose over the Teflon tape on the steel brake line sticking out of the cathode ray tube.

*phew*

The mechanical portion of the exercise is now complete.

/* If you're never worked with Teflon tape before, you should be warned that it's not actually tape; there's nothing sticky about it. The way you secure it is by wrapping it tightly around your work piece and then letting the vacuum pump do the rest. When you turn the pump on, the difference in pressure will cause it to assume whatever form you've forced it into and it will block air from leaking into the system (which is something that it's very good at). The first time I assembled my system, I decided not to put any tape over the vacuum pump's screw connector and I only used the screw clamp to hold the rubber tube in place. Big mistake! I wasn't able to reach anywhere near cathode ray tube operation pressure until I added that tape.

It is possible to assemble the system without a pump to hose converter if your pump's inlet is small enough for the rubber tube to fit over it. Instead of screwing on a converter, just force the hose over the Teflon tape and clamp it down: */
 
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