Gas Discharge Tube
A discharge tube is a device that allows an electric current to flow through a gas or vapor under reduced pressure conditions.
Structure and Components
• It typically consists of a sealed glass or other insulating tube. Inside the tube, there are electrodes at each end. One is the anode (positive electrode) and the other is the cathode (negative electrode).
Working Principle
• When a high enough voltage is applied across the electrodes, electrons are emitted from the cathode. These electrons accelerate towards the anode due to the electric field.
• As they move through the gas or vapor in the tube, they collide with the gas molecules. These collisions can cause ionization of the gas molecules, creating more free electrons and positive ions.
• The movement of these charged particles (electrons and ions) constitutes an electric current through the gas in the tube.
Applications
• In lighting. For example, fluorescent lamps are a type of discharge tube. The electric discharge through the gas in the tube excites the phosphor coating on the inside of the tube, which then emits visible light.
• In some types of electrical switches and surge protectors. Discharge tubes can be used to conduct excess electrical energy during a voltage spike, protecting other electrical components from damage.
• In scientific research, such as in studying plasma physics and gas discharges to understand the behavior of charged particles in gases under different conditions.
