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CHILDREN'S SCIENTIFIC LABORATORY
Underwater lightning. Children's Science Lab
Directory / Children's Science Lab They say that in the late 1940s of the last century, student Leva Yutkin waited out a thunderstorm on the shore of the lake. Suddenly, lightning struck the water, raising a huge fountain to the sky, dousing the young man from head to toe. I remember the strange event. The school teacher gave Leva a small electrostatic machine, and the student did not spare several years to experimentally reproduce what he saw. It would seem that everything is simple: throw one wire into a vessel with water, bring the other to its surface and turn the handle of the machine. But both the first and the hundredth spark did not give any effect ... And then it happened. A small aquarium suddenly split into several large pieces quietly, and water rushed into the room. This success determined the future life of Yutkin the inventor.
It turned out that if you correctly conduct an electric discharge in water, and even use a more powerful energy source for this than a school electrostatic machine, you get a powerful explosion. His power destroyed any materials. Everything spoke of pressures of thousands and tens of thousands of atmospheres. It is not surprising that in 1950, L.A. Yutkin, together with his wife Lidia Alexandrovna Goltsova, filed an application for a "Method for obtaining high and ultrahigh pressures." The application was crowned with a copyright certificate, however, after seven years ... (Later L.A. Yutkin and L.A. Goltsova made about 150 more inventions!) During an electric discharge, complex processes occur in water. At its first stage, which lasts for a microsecond, a plasma channel is formed with a temperature of up to 40000 ° C. The plasma expands at a speed comparable to the speed of sound in water (1410 m/s). This is how the first shock wave is formed and a cavity filled with hot steam and gas, which gradually completes its expansion, then begins to pulsate and finally collapses. There is a cumulative effect similar to that used in armor-piercing shells. The pressure arising at this stage, according to scientists, can reach 450 thousand atmospheres. Not surprisingly, there are no materials that can withstand an electric spark in water. Note that electric discharges in water were observed as early as the XNUMXth century. But scientists did not see anything remarkable in them. And L.A. Yutkin discovered a lot of interesting things. Therefore, the whole range of phenomena associated with an electric discharge in water and other liquids is commonly called the electrohydraulic effect (EGE), or the Yutkin effect. In the EGE, up to 30-80% of electrical energy is converted into mechanical work, and heat is sometimes released significantly, 2-3 times more. The reason is in the processes occurring at the moments of cavity collapse. Unfortunately, we know little about them. Most of them occur when the cavity is reduced to sizes that are not distinguishable in any microscope. In addition, the most interesting stage of the collapse lasts much less than a billionth of a second. However, the lack of theoretical knowledge does not prevent the practical application of the Yutkin effect. First of all, this is the crushing of a wide variety of materials, ranging from the simple transformation of stone blocks into rubble. So, during the reconstruction of one of the bridges in Moscow, old concrete parts were turned into crumbs using electric discharges, which were used to make new ones. But there are more subtle crushing processes. On the surface of steel parts cast into an earthen mold, a layer of earth and scale remains firmly ingrained into it. Removing it is extremely laborious if EGE is not used. And if you use it, the process is extremely simple. The details are placed in the bath, a few strokes of underwater lightning - and their surface is clean. The Yutkin effect allows not only to destroy, but also to create. Here is how, for example, it is used to stamp parts from a metal sheet. First, they make a matrix - a detail that is inverse in shape to the one they want to receive. It is placed at the bottom of the bath, a sheet of metal is firmly pressed on top and air is pumped out from under it. Then water is poured on top, and discharges are produced in it. The metal sheet bends and accurately fills the entire surface of the matrix. It must be said that sheet stamping can be done in many other ways, for example, by oil pressure or by hammering on a rubber layer. But here it is necessary to use a particularly ductile and soft metal, which means that the part is fragile. The Yutkin effect allows you to stamp parts from brittle and strong metals, and the part is very strong. Capable of EGE and drilling. Yutkin's drill consists of a plastic rod with an electrode inside and a crown made of any metal, such as copper. Both the crown and the shaft are stationary, only the light wire electrode rotates. Water is supplied through another of the channels in the rod. With each turn of the electrode, the teeth of the fixed crown go around a lot of sparks, crushing the rock lying below into dust, and the water carries it to the surface. And there are no breeds that can resist such a drill. Once, L.A. Yutkin and L.A. Goltsova subjected ordinary soil to EG shocks, blowing air through it. The fact is that the mineral salts contained in it come to the roots of plants, mainly from the surface of its particles. Microlightnings crushed them, the surface increased, and most of the salts contained in the soil became available to plant roots. Moreover, the nitrogen contained in the air has passed into the form of chemical compounds available to plants. Ordinary earth has turned into a wonderful environmentally friendly fertilizer!
You can talk about the Yutkin effect for a long time, but it's better to try it yourself. The main thing is a high voltage source capable of creating sharp, rapidly growing pulses. In industrial installations, a high-voltage transformer of 30-60 kV is used for this, which charges the capacitor through a rectifier. However, it is very difficult to make such a power source, and it is dangerous to work with it. The easiest way is to do the same as Yutkin himself: start experiments with a small school electrostatic machine that can give about 30000 V. With it you have to assemble a circuit consisting of two air dischargers and electrodes mounted on the bottom of the bath. But first, you need to put the electrostatic machine itself in full order - disassemble and thoroughly clean it from dust. Attention! All work on an electrical machine is dangerous! They can only be conducted in the presence of adults! For us, two high-voltage "Leyden jar" capacitors standing on its stand are very important. They are glasses covered with foil. They should be cleaned of dust especially carefully, while trying not to damage the foil, which is the lining of the capacitors: dust at high voltages is a good conductor. Closing the current generated by the machine, it will not allow you to gain high voltage. You should also pay attention to the small copper brushes - current collectors. They need to be cleaned of a dark coating of oxides. Finally, the electrostatic machine must be well dried. To do this, put it for a day near a hot heater. After that, she will begin to work so that you will not recognize her. Sparks will be large, sonorous and frequent. Now we proceed to obtain the electro-hydraulic effect. You will need a bathtub with transparent walls. A glass vessel is no good - it will not withstand water hammer. It is better to take the bottom of a five-liter plastic bottle. It should be connected to the electrostatic machine with a high-voltage wire, similar to that used in the ignition system of a car. To form a pulse, it is necessary to make two spark gaps. Each of them consists of balls with a diameter of 15-20 mm fixed on a piece of plastic. They can be found among old school appliances. Adjust the arresters so that the distance between the balls is 15-20 mm. Attach the paddles to the bottom of the bath. Their role is performed by the stripped ends of the high-voltage wire. The distance between them is 50-80 mm. After that, pour water into your bath - and start experimenting. Author: A.Ilyin
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