Electric current flows not only in metals but in fluids and gases.However, the mechanism of the electric current in these other cases.In gases, it all starts with the electric discharge.It is by its nature may be of several types, one of them - the so-called glow discharge.
To understand what it is, you can read the description of an experiment conducted by scientists to demonstrate this phenomenon.For its use of a glass tube of a certain length, which are at the ends of the two electrodes.Connect to the DC power source.There are two possible options for further experimentation - or begin to gradually raise the voltage to a value of several thousand volts, or begin to pump the air out of the tube to reduce the pressure inside to a few millimeters.Hg.column.
under reduced pressure to a certain value in the tube flares glowing cord from electrode to electrode.It came a glow discharge.His appearance contributes to low blood pressure, and it is supported by the secondary electron emission from the cathode.The fact that under normal conditions of gas does not conduct electric current, but under special conditions, such as described, between the electrodes of the electric current.In this case, the positive ions bombard the cathode and knock out electrons.
current flow due to the formation of free charge carriers, but the mechanism of their appearance is different.Now it is known for the following types of discharges in gases - the spark, corona, arc and glow.The reasons due to which current begins to flow, is also different.When we are out of the glass tube is evacuated, then in the end, we obtain a glow discharge, and when we increase the voltage across the terminals of the electrodes - spark.
order not to return more to the classification, we note that there are independent and self-sustaining discharge.Types of independent discharges are already listed and non-automatic arise in any additional external effects.
All kinds of interesting bits and have extremely interesting properties, but still focus on one of them.Let's see what a glow discharge.If you examine its outward manifestation, you can set two areas - non-luminous and glowing.Unlighted called the cathode dark space and luminous - positive column, and it takes almost the entire volume of the tube.
Light color depends on the gas, among which there is a discharge.These luminous tubes are used as lamps, so-called fluorescent lamps.And the lights of advertising also performed with the use of such tubes.And the process of decorating and lighting design is virtually impossible without such products.
But it's not all possible applications of glow discharge.There are industries such as laser technology and plasma chemistry.Furthermore, through the use of a glow discharge is carried out surface hardening tool to increase its wear resistance, hardness, resistance to cavitation.
Among other possible applications of the described effects can be noted its use of special devices based on the effect of the glow discharge.They can be used to regulate current and voltage protection devices and amplification devices oscillator.However, the electric discharge can be undesirable phenomenon.For example, a corona electrical discharge from power lines cause electricity losses, but it is not a glow discharge, which now we are interested in.
Consideration of electric current in the gases allowed to establish the mechanism of its occurrence, including the understanding of what constitutes a glow discharge.Described embodiments of its use in industry and technology.
