Build a x-ray tube using a test tube

Introduction

My exeperiments have often needed some kind of vacuum tube of my own project, and so I started to build them using laboratory glass equipment like test tubes, flasks and burrets. The only problem is that this tubes need a vacuum pump to work.

Needed Stuff

• 1 Pirex test tube 1.5 cm internal diameter
• 1 Glass little tube 7 cm long, 0.5 cm external diameter
• 2 Copper tubes 1 cm long, 1.4 cm external diameter
• 1 Copper foil piece 2 cm long, 1 cm width, 0.1 mm thick
• 3 pieces of steel wire 10 cm long, 1 mm thick
• 1 piece of hair-drier heating wire 2-3 cm long
• A bit of plaster
• Teflon tape (PTFE)

Construction

The first thing to do is to cut the bottom of the test tube with a silicon-carbide cutter ( I used a Dremel tool ) to obtain a pirex tube.

Bend one steel wire as shown in the picture.

Solder the copper plate at the top of the steel wire.

Wind a 7-8 mm long, 5 mm diameter coil with the heating wire and bend the two other steel wires as shown in the picture. To fix the heating wire, make two hooks at the top of the steel wires, insert the two heater terminals, and so press the hooks with pliers.

Fill a copper tube with plaster, insert the little glass tube, and the first steel wire.

Fill the other copper tube with plaster and insert the heater terminals.

Roll the copper tubes in the PTFE tape to reach the diameter of 1.55-1.6 mm and so insert them into the pirex tube openings.

Now fix them with epoxy glue and your x-ray tube is completed. With a vacuum pump connected to the little glass tube bring the internal pressure of the lamp to about 10^-4 mm of Hg ( 10^-7 bar or 2x10^-6 psi ), then with a torch-cutter close the little tube, and disconnect the pump: now your x-ray lamp is operational!

How does x-ray tube work?

  Connect a 80-100 KV power supply to the tube (heater at the negative, the plate to the positive) and supply the heater with 12 V 1-2 A.

Safety Hints

•  Cover the entire tube with a 1 mm thick lead foil with a window under the plate

• When use this tube enclose it in a "bricks box" for more safety