Electric current flows not only in metals,but in liquids and gases. True, the mechanism of electric current flow in these cases is different. In gases everything begins with an electrical discharge. It by its nature can be of several kinds, one of them - the so-called glow discharge.
Чтобы понять, что это такое, можно ознакомиться с the description of an experiment conducted by scientists to demonstrate a similar phenomenon. For its carrying out use a glass tube of a certain length, which has two electrodes at the ends. A direct current source is connected to them. Here, two options for further experimentation are possible-either they begin to gradually increase the voltage to a value of several thousand volts, or they begin to pump air out of the tube to lower the pressure inside to a few mm. gt; post.
When the pressure is lowered to a certain value inA luminous cord from the electrode to the electrode flashes up the tube. It was a glowing discharge. Its appearance is promoted by a reduced pressure, and it is supported by the secondary emission of electrons from the cathode. The matter is that under normal conditions the gas does not conduct an electric current, but under special conditions, for example, such as described, an electric current flows between the electrodes. In this case, positive ions bombard the cathode and knock out electrons from there.
Current flow is caused by the formation of suchfree carriers, but the mechanism of their appearance is different. Now the following types of discharges in gases are known: spark, corona, arc and smoldering. The reasons for the current to flow are also different. When we evacuate air from a glass tube, we will eventually get a glow discharge, and when we increase the voltage at the leads of the electrodes - a spark.
In order not to return more to classification,we note that there are independent and non-self-sustaining categories. The types of independent discharges are already listed, and the non-self-sustaining ones arise with any additional external influences.
All kinds of categories are interesting and have an extremelycurious properties, but for now let us dwell on one of them. Let's see what the glow discharge is. If you study its external manifestation, you can establish two areas - non-luminous and luminous. Non-luminous is called the dark cathode space, and the luminous one is called the positive column, and it occupies practically the entire volume of the tube.
The color of the glow depends on the gas in whicha discharge occurs. Such luminous tubes are used as lamps, so-called fluorescent lamps. Yes, and advertising lights are also performed using similar tubes. And the process of decoration and lighting is almost impossible without such products.
However, this is not all possible areasuse of a glow discharge. There are such industries as laser technology and plasma chemistry. In addition, thanks to the use of a glow discharge, the surface of the tool is hardened to increase its wear resistance, hardness, cavitation resistance.
Из других возможных вариантов применения The described effect can be noted for its use in special devices based on the effect of a glow discharge. They can be used to regulate current and voltage, in device protection and amplification devices, oscillators. However, an electric discharge can also be an undesirable phenomenon. Thus, a corona electric discharge with a power line causes power losses, but this does not apply to a glow discharge, which we are now interested in.
Examination of the electric current in gasesallowed us to establish the mechanism of its occurrence, including understanding what the glow discharge is. The variants of its use in industry and engineering are described.
