Geissler tube

The Geissler tube or Geißlersche tube is a cold cathode gas discharge tube for examination and demonstration of gas discharges. It was invented by physicist Heinrich Geissler, who was also a glass blower.

Design and function

Geissler the tube consists of two electrodes ( generally made of aluminum ), a cathode and an anode. These are usually formed equal. The two electrode penetrations into the interior of the tube are made in old tubes made ​​of thin platinum wire, as this has a very similar thermal expansion coefficient as glass. The electrodes are in a with gases (eg, neon, air, argon, hydrogen), vapors (water, alcohol ) or aerosols filled, sealed partially evacuated glass tube, which can have various forms. Thus, there are also helical tubes with fluorescent liquid jacket or those from uranium glass. Different gases produce different colors and spectral lines of excited to luminescence fillings.

The operating voltage of the tube is about 0.5 to 20 kV, it depends on the internal pressure, the electrode spacing and the gas filling. Depending on the operating voltage and internal pressure during operation of X-rays arise. Series of such tubes with different internal pressure used in physics education to demonstrate the processes in a gas discharge. Decreases with increasing pressure as the cross section of the discharge channel until this is at normal pressure for spark discharge.

Geissler tubes are usually supplied with a spark coil.