Power transmission remotely wirelessly. Research paper on the topic: “Wireless electricity. Will we get rid of the wires

Scientific and practical conference of students and teachers

"First steps into science".

Subject area - physics.

Research on the topic:

"Wireless electricity"

Performed: 9th grade student

MBOU SOSH №18

them. brothers Mogilevtsev, Bryansk

Malashenko Anastasia

Scientific adviser:

teacher of mathematics and physics

MBOU SOSH №18

Stepanova Olga Nikolaevna

Bryansk - 2012

C obsession

Introduction

1. The ability to transmit electricity through the air

1.1. Tesla's discovery

1.2. Electricity in Ancient Egypt

2. Is wireless electricity a reality in the 21st century ?!

3. The experimental part of the work

3.1. Development the simplest model devices for transmitting electricity through the air

3.2. Description of the device model

3.3. Experimental results

Conclusion

Clist of information resources

Applications

Introduction

9.

10.

ANNEXES

Table # 1

The wavelength of EM radiation approaches the visible region of the spectrum (from 10 μm to 10 nm), energy can be transmitted by converting it into a laser beam, which can then be directed to the photocell of the receiver.

A monochromatic light wave with a small angle of divergence allows a narrow beam to efficiently transfer energy over long distances. Compact size solid state laser - photoelectric semiconductor diode convenient for small items. The laser does not create radio frequency interference with existing communications. Disadvantages: Converting low-frequency EM radiation into high-frequency radiation, which is light, is ineffective. Converting light back into electricity is also ineffective, as the efficiency of photocells reaches 40-50%. Loss in the atmosphere. Requires line of sight between transmitter and receiver.

Illustration from Tesla's patent entitled "The art of transferring electrical energy through natural media", a diagram of the device and its external

view.

fig. one

Tesla Amplifying Transmitter Circuit

Source "B" feeds a two-turn primary winding, and a spiral coil in its middle. This apparatus was designed to transmit energy over long distances, so it also includes connections to the earth and sky. Element "E *" was connected to the ground, and element "E" was called by Tesla a "lifted capacity", and it had to be located on a balloon.This was the heart of the amplifying transmission system that Tesla tried to build in Wardencliffe (Fig. 3), in order to transmit energy to any point on the planet.

fig. 2

fig. 3 The Wardencliff Tower (1902) - a symbol of Nikola Tesla's unsuccessful attempt to tackle the problem of wireless power transmission.

fig. 4

fig. five

fig. 6

T1- transformer, VD1-VD5 - diodes, C1- capacitor (power supply for 12V 1A),

C2 capacitor - 100nF 250V, R1 resistor - 33K, R2 - variable resistor at 10K, VT1 - KT817G transistor (100V 3A 20W) on the radiator, L1-coil 7 turns (diameter 6 mm), L2 - coil ~ 900 turns (diameter 0 , 28 mm).

fig. 7

Table 2 History of wireless power transmission

1820: André Marie Ampere discovered Ampere's law showing that electricity produces a magnetic field.

1831 : Michael Faraday discovered the law of induction, an important basic law of electromagnetism.

1862: Carlo Matteuchi was the first to experiment with the transmission and reception of electrical induction using plane spiral coils

1864: James Maxwell systematized all previous observations, experiments and equations on electricity, magnetism, and optics into a coherent theory and rigorous mathematical description of the behavior of the electromagnetic field.

1888: Heinrich Hertz confirmed the existence of an electromagnetic field.

1891: Nikola Tesla improved the Hertz wave transmitter of radio frequency power supply in his patent No. 454.622, Electric Lighting System.

1893: Tesla demonstrates wireless fluorescent lighting in a project for the Columbian World's Fair in Chicago.

1894: Tesla wirelessly lights an incandescent light bulb in his Fifth Avenue laboratory, and later in the Houston Street laboratory in New York, using "electrodynamic induction," that is, wireless resonant mutual induction.

1894: Jagdish Chandra Bose remotely ignites gunpowder and strikes a bell using electromagnetic waves, indicating that communication signals can be sent wirelessly.

1895: A.S. Popov demonstrated the radio receiver he invented at a meeting of the physics department of the Russian Physicochemical Society on April 25 (May 7) 1895

1895: Boche transmits the signal over a distance of about one mile.

1896: Guglielmo Marconi applied for the invention of radio on June 2, 1896.

1896: Tesla transmits a signal over a distance of about 48 kilometers.

1897: Guglielmo Marconi transmits a text message in Morse code over a distance of about 6 km using a radio transmitter.

1897: Tesla registers the first of its patents for wireless transmission applications.

1901: Marconi transmits a signal across the Atlantic Ocean using Tesla's apparatus.

1917: The Vordencliff Tower, built by Nikola Tesla to conduct experiments on high-power wireless transmission, was destroyed.

1926: Shintaro Uda and Hidetsugu Yagi publish the first article on "High Gain Variable Directional Communication", well known as "Yagi-Uda Antenna" or "Wave Channel" antenna.

1961: William Brown publishes an article on the study of the possibility of transmitting energy through microwaves.

1968: Peter Glazer offers wireless transmission solar energy from space using the "Energy Beam" technology. This is believed to be the first description of an orbital energy system.

1975: The Goldstone deep space communications complex is conducting experiments on the transmission of tens of kilowatts of power.

2007: A research group led by Professor Marina Solyachich from the Massachusetts Institute of Technology transmitted wirelessly over a distance of 2 m, enough power to glow a 60 W light bulb, with an efficiency. 40%, using two coils with a diameter of 60 cm.

2008: Bombardier offers new Product for wireless transmission PRIMOVE, a powerful system for use in trams and light rail engines.

2008: Intel reproduces the experiments of Nikola Tesla in 1894 and the group of John Brown in 1988 on wireless power transmission for the glow of incandescent lamps with efficiency. 75%.

2009: Introduced an industrial flashlight capable of operating and recharging safely in a non-contact manner in an atmosphere saturated with flammable gas. This product was developed by the Norwegian company Wireless Power & Communication.

2009: The Haier Group unveiled the world's first fully wireless LCD TV based on Professor Marina Solyachich's research on wireless power transmission and wireless home digital interface (WHDI).

fig. 9

fig. 10

fig. 11

fig. 12

According to history, the revolutionary technological project was frozen due to Tesla's lack of adequate financial capabilities (this problem haunted the scientist almost all the time he worked in America). Generally speaking, the main pressure on him came from another inventor - Thomas Edison and his companies, which promoted DC technology, while Tesla was engaged in AC current (the so-called "War of currents"). History has put everything in its place: now alternating current is used in urban power grids almost everywhere, although echoes of the past reach our days (for example, one of the stated reasons for the breakdown of the notorious Hyundai trains is the use of direct current power lines on some sections of the Ukrainian railway).

The Wardencliff Tower, in which Nikola Tesla conducted his experiments with electricity (photo 1094)

As for the Wardenclyffe tower, according to legend, Tesla demonstrated to one of the main investors J.P. Morgan, a shareholder of the world's first Niagara hydroelectric power station and copper factories (copper, as you know, is used in wires), a working installation for wireless transmission of current, the cost of which for consumers would be (if such installations on an industrial scale) are much cheaper for consumers, after which he curtailed funding for the project. Be that as it may, they started talking seriously about wireless power transmission only 90 years later, in 2007. Although it is still far from the moment when power lines completely disappear from the cityscape, pleasant little things like wireless charging of a mobile device are available now.

Progress crept up unnoticed

If we look through the archives of IT news at least two years ago, then in such collections we will find only rare reports that certain companies are developing wireless chargers, and not a word about finished products and solutions (except for basic principles and general schemes ). Today, wireless charging is no longer something super-original or conceptual. Such devices are sold with might and main (for example, LG demonstrated its chargers at MWC 2013), tested for electric vehicles (Qualcomm is engaged in this) and even used in public places (for example, at some European railway stations). Moreover, there are already several standards for such transmission of electricity and several alliances promoting and developing them.

Similar coils are responsible for wireless charging of mobile devices, one of which is in the phone, and the other in the charger itself.

The most famous such standard is the Qi standard, developed by the Wireless Power Consortium, which includes such well-known companies as HTC, Huawei, LG Electronics, Motorola Mobility, Nokia, Samsung, Sony and about a hundred other organizations. This consortium was formed in 2008 with the aim of creating a universal charger for devices of various manufacturers and brands. In its work, the standard uses the principle of magnetic induction, when the base station consists of an induction coil, which creates an electromagnetic field when an alternating current is supplied from the network. In the device being charged, there is a similar coil that reacts to this field and is able to convert the energy received through it into direct current, which is used to charge the battery (you can learn more about the principle of operation on the consortium website http://www.wirelesspowerconsortium.com/what -we-do / how-it-works /). In addition, Qi supports a 2 kbps data transfer protocol between chargers and rechargeable devices, which is used to transfer data about the required amount of charging and the required operation.

Qi wireless charging is currently supported by many smartphones, and charging device universal for all devices supporting this standard

Qi also has a serious competitor - the Power Matters Alliance, which includes AT&T, Duracell, Starbucks, PowerKiss and Powermat Technologies. These names are far from being at the forefront in the world of information technology (especially the Starbucks coffee chain, which is in an alliance due to the fact that it is going to introduce this technology everywhere in its establishments) - they specialize in energy issues. This alliance was formed not so long ago, in March 2012, under one of the programs of the IEEE (Institute of Electrical and Electronic Engineers). The PMA standard promoted by them works on the principle of mutual induction - a particular example of electromagnetic induction (which should not be confused with the magnetic induction used by Qi), when when the current in one of the conductors changes or when the relative position of the conductors changes, the magnetic flux changes through the circuit of the second, created a magnetic field generated by the current in the first conductor, which causes an electromotive force in the second conductor and (if the second conductor is closed) induction current. Just like with Qi, this current is then converted to DC and fed to the battery.

Well, do not forget about the Alliance for Wireless Power, which includes Samsung, Qualcomm, Ever Win Industries, Gill Industries, Peiker Acustic, SK Telecom, SanDisk, etc. This organization has not yet presented ready-made solutions, but among its goals , including - the development of charges that would work through non-metallic surfaces and which would not use coils.

One of the goals of the Alliance for Wireless Power is the ability to charge without being tied to a specific location and type of surface.

From all of the above, a simple conclusion can be drawn: in a year or two, most modern devices can be recharged without the use of traditional chargers. In the meantime, the power of wireless charging is mainly enough for smartphones, however, for tablets and laptops, such devices will also appear soon (the same Apple recently patented wireless charging for the iPad). This means that the problem of discharging devices will be almost completely solved - you put or put the device in a certain place, and even during operation it charges (or, depending on the power, discharges much more slowly). Over time, there is no doubt that the range of their action will expand (now it is necessary to use a special rug or stand on which the device lies, or it should be very close), and they will be ubiquitously installed in cars, trains and even, possibly, airplanes.

Well, one more conclusion - most likely, it will not be possible to avoid another war of formats between different standards and alliances that promote them.

Will we get rid of the wires?

Wireless charging is a good thing, of course. But the powers that arise with it are sufficient only for the stated purposes. With the help of these technologies, it is not yet possible even to light a house, let alone the work of a large household appliances... Nevertheless, experiments on high-power wireless power transmission are underway and are based, among other things, on Tesla's materials. The scientist himself proposed to establish around the world (here, most likely, the developed countries at that time, which were much less than now), more than 30 transmitting and receiving stations that would combine the transmission of energy with radio broadcasting and directional wireless communication, which would allow getting rid of numerous high voltage transmission lines and facilitating the interconnection of electrical generators on a global scale.

Today there are several methods for solving the problem of wireless transmission of energy, however, all of them so far allow achieving globally insignificant results; it's not even about kilometers. Methods such as ultrasonic, laser and electromagnetic transmission have significant limitations (short distances, the need for direct visibility of transmitting devices, their size, and in the case of electromagnetic waves, very low efficiency and harm to health from a powerful field). Therefore, the most promising developments are associated with the use of a magnetic field, or rather, resonant magnetic interaction. One of them is WiTricity, developed by the WiTricity corporation, founded by MIT professor Marina Solyachich and a number of his colleagues.

So, in 2007, they managed to transmit a current with a power of 60 W at a distance of 2 m. It was enough for the glow of a light bulb, and the efficiency was 40%. But the indisputable advantage of the technology used was that it practically does not interact either with living things (the field strength, according to the authors, is 10 thousand times weaker than that which reigns in the core of the magnetic resonance imaging machine), or with medical equipment ( pacemakers, etc.), or with other radiation, which means that it will not interfere, for example, with the operation of the same Wi-Fi.

Most interestingly, the efficiency of the WiTricity system is influenced not only by the size, geometry and tuning of the coils, as well as the distance between them, but also by the number of consumers, and in a positive way. Two receiving devices, located at a distance of 1.6 to 2.7 m on either side of the transmitting "antenna", showed 10% better efficiency than separately - this solves the problem of connecting multiple devices to the same power source.

For many years, scientists have been struggling with the issue of minimizing electrical costs. there is different ways and suggestions, but still the most famous theory is the wireless transmission of electricity. We propose to consider how it is carried out, who is its inventor and why it has not yet been implemented.

Theory

Wireless electricity is literally the transfer of electrical energy without wires. People often compare wireless transmission of electrical energy to transmission of information such as radios, cell phones, or Wi-Fi Internet access. The main difference lies in the fact that from radio or microwave transmissions - this is a technology aimed at recovering and transporting information, and not the energy that was originally spent on transmission.

Wireless electricity is a relatively new area of \u200b\u200btechnology, but rather dynamic. Methods are now being developed on how to efficiently and safely transmit energy over a distance without interruption.

How wireless electricity works

The main work is based precisely on magnetism and electromagnetism, as is the case with radio broadcasting. Wireless charging, also known as inductive charging, is based on a few simple principles of operation, in particular the technology requires two coils. A transmitter and receiver, which together generate an alternating magnetic field of variable current. In turn, this field induces a voltage in the receiver coil; it can be used to power a mobile device or charge a battery.

If you direct an electric current through a wire, a circular magnetic field is created around the cable. Despite the fact that the magnetic field affects both the loop and the coil, it is most pronounced on the cable. When we take the second coil of wire, which does not receive the electric current passing through it, and the place where we place the coil in the magnetic field of the first coil, the electric current from the first coil will be transmitted through the magnetic field and through the second coil, creating an inductive coupling.

Take an electric toothbrush... In it, the charger is connected to an outlet that sends electrical current to a coiled wire inside the charger, which creates a magnetic field. There is a second coil inside the toothbrush, when the current begins to flow and, thanks to the formed MF, the brush starts charging without its direct connection to the 220 V power supply.

Story

Wireless power transmission as an alternative to the transmission and distribution of electrical lines was first proposed and demonstrated by Nikola Tesla. In 1899, Tesla introduced wireless transmission to power a field of fluorescent lamps located twenty-five miles from a power source without using wires. But at that time it was cheaper to make the wiring from copper wires by 25 miles, rather than building the special power generators that Tesla's experience requires. He was never given a patent, and the invention remained in the bins of science.

While Tesla was the first person who was able to demonstrate the practical possibilities of wireless communication back in 1899, today, there are very few devices on sale, these are wireless brushes, headphones, phone chargers, and more.

Wireless technology

Wireless power transmission involves the transmission of electrical energy or power over a distance without wires. Thus, the core technology lies in the concepts of electricity, magnetism and electromagnetism.

Magnetism

It is a fundamental force of nature that causes certain types of material to attract or repel each other. The only ones permanent magnets the poles of the Earth are considered. The flux current in the loop generates magnetic fields that differ from oscillating magnetic fields in the speed and time it takes to generate alternating current (AC). The forces that appear in this case are shown in the diagram below.

This is how magnetism appears

Electromagnetism is the interdependence of alternating electric and magnetic fields.

Magnetic induction

If the conductive loop is connected to an AC power source, it will generate an oscillating magnetic field in and around the loop. If the second conductive loop is close enough, it will capture some of this oscillating magnetic field, which in turn generates or induces an electric current in the second coil.

Video: how the wireless transmission of electricity occurs

Thus, there is an electrical transfer of power from one cycle or coil to another, which is known as magnetic induction. Examples of this phenomenon are used in electrical transformers and generators. This concept is based on Faraday's laws of electromagnetic induction. There, he argues that when there is a change in the magnetic flux connected to the coil by the EMF induced in the coil, then the quantity is equal to the product of the number of turns of the coil and the rate of change of the flux.

Power clutch

This part is necessary when one device cannot transfer energy to another device.

Magnetic coupling is generated when an object's magnetic field is capable of inducing an electric current with other devices in its field of reach.

Two devices are said to be mutually inductively coupled, or magnetically coupled, when they are designed such that the current changes while one wire induces a voltage at the ends of the other wire through electromagnetic induction. This is due to mutual inductance

Technology

Inductive coupling principle

The two devices, mutually inductively coupled or magnetically coupled, are designed so that a change in current while one wire induces a voltage at the ends of the other wire is produced by electromagnetic induction. This is due to mutual inductance.
Inductive coupling is preferred due to its ability to operate wirelessly as well as its shock resistance.

Resonant inductive coupling is a combination of inductive coupling and resonance. Using the concept of resonance, two objects can be made to work independently of each other's signals.

As you can see from the diagram above, resonance provides the inductance of the coil. The capacitor is connected in parallel to the winding. Energy will travel back and forth between the magnetic field surrounding the coil and the electric field around the capacitor. Here, radiation losses will be minimal.

There is also the concept of wireless ionized communication.

It is also realizable, but a little more effort is needed here. This technique already exists in nature, but there is hardly any expediency of its implementation, since it needs a high magnetic field, from 2.11 M / m. It was developed by the brilliant scientist Richard Volras, the developer of the vortex generator, which sends and transmits heat energy over great distances, in particular with the help of special collectors. The simplest example of such a connection is lightning.

Advantages and disadvantages

Of course, this invention has advantages and disadvantages over wired techniques. We propose to consider them.

The advantages include:

1. Complete absence of wires;
2. No power supplies needed;
3. The need for a battery is eliminated;
4. Energy is transferred more efficiently;
5. Significantly less maintenance required.

The disadvantages include the following:

• Distance is limited;
• magnetic fields are not so safe for humans;
• wireless transmission of electricity, using microwaves or other theories is practically impracticable at home and with your own hands;
• high installation costs.

At its appearance, alternating electric current seemed fantastic. Its inventor, the brilliant physicist Nikola Tesla, at the turn of the 19th and 20th centuries, investigated the problem of wireless transmission of electricity over long distances. So far, this problem has not been fully resolved, but the results are encouraging.

Ultrasound for energy transmission

Any wave carries energy, including high frequency sound waves. There are three approaches to wireless electricity transmission:

• transferring electrical energy through conversion to another form of energy at the source and reverse conversion to electricity at the receiving device;
• creation and use of alternative conductors of electricity (plasma channels, columns of ionized air, etc.);
• use of the conductive properties of the Earth's lithosphere.

The ultrasound method belongs to the first approach. In a special type of ultrasound source, when power is applied, a directed beam of high-frequency sound waves is generated. When they hit the receiver, the energy of the sound waves is converted into electric current.

The maximum distance for power transmission without wires is 10 meters. The result was obtained in 2011 by representatives of the University of Pennsylvania during a presentation at the exhibition "The All Things Digital". This method is not considered promising due to several of its disadvantages: low efficiency, low voltage obtained and limitation on the strength of ultrasound radiation by sanitary standards.

Application of electromagnetic induction

Although most people are not even aware of this, this method has been used for a very long time, almost from the very beginning of using AC. The most common AC transformer is the simplest wireless power transmission device, only the transmission distance is very short.

The primary and secondary windings of the transformer are not connected in one circuit, and when alternating current flows in the primary winding, an electric current arises in the secondary. In this case, the transfer of energy occurs through an electromagnetic field. Therefore, this method of wireless power transmission uses the conversion of energy from one type to another.

A number of devices have already been developed and are successfully used in everyday life, the operation of which is based on this method. These are wireless chargers for mobile phones and other gadgets, and household electrical appliances with low energy consumption during operation (compact CCTV cameras, all kinds of sensors and even LCD TVs).

Many experts argue that electric vehicles of the future will use wireless technologies to charge batteries or generate electricity for driving. Induction coils (analogs of the primary winding of the transformer) will be installed in the roads. They will create an alternating electromagnetic field, which, when a vehicle passes over it, will cause an electric current to flow in the built-in receiving coil. The first experiments have already been carried out and the results obtained give rise to restrained optimism.

The advantages of this method include:

• high efficiency for short distances (of the order of several meters);
• simplicity of design and mastered application technology;
• relative safety for human health.

The disadvantage of this method - the small distance at which the transmission of energy is effective - significantly reduces the area of \u200b\u200bapplication of wireless electricity based on electromagnetic induction.

Using different microwaves

This method is also based on the conversion of different types of energy. Ultrahigh frequency electromagnetic waves serve as a carrier of energy. For the first time this method was described and practically implemented in his installation by the Japanese physicist and radio technician Hidetsugu Yagi in the twenties of the last century. The frequency of radio waves for transmitting electricity wirelessly ranges from 2.4 to 5.8 GHz. An experimental setup has already been tested and received positive feedback, which simultaneously distributes Wi-Fi and powers low-power household electrical appliances.

The laser beam is also electromagnetic radiation, but with special property - coherence. It reduces energy losses during transmission and thus increases efficiency. Among the advantages are the following:

• the possibility of transmission over long distances (tens of kilometers in the Earth's atmosphere);
• convenience and ease of installation for low-power devices;
• the presence of visual control of the transmission process - the laser beam is visible to the naked eye.

The laser method also has disadvantages, namely: a relatively low efficiency (45-50%), energy losses due to atmospheric phenomena (rain, fog, dust clouds) and the need to find the transmitter and receiver in the field of view.

The intensity of sunlight outside the earth's atmosphere is several tens of times higher than on the earth's surface. Therefore, in the future, according to futurologists, solar power plants will be located in near-earth orbit. And the transfer of the accumulated electricity, in their opinion, will be carried out without live wires. A transmission method that copies lightning discharges will be developed and applied, and it is planned to ionize the air in one way or another. And the first experiments in this direction have already been carried out. This method is based on the creation of alternative wireless electric current conductors.

The wireless electricity produced in this way from near-Earth orbit is impulsive. Therefore, for him practical application powerful and inexpensive capacitors are needed, and it will be necessary to develop a way to gradually discharge them.

Most effective method

Planet Earth is a huge condenser. The lithosphere mainly conducts electricity, except for small areas. There is a theory that wireless transmission of energy can occur through the earth's crust. The bottom line is: the current source reliably contacts the earth's surface, an alternating current of a certain frequency flows from the source to the crust and spreads in all directions, electric current receivers are placed at certain intervals in the ground, from which it is transmitted to consumers.

The essence of the theory is to accept and use the current of only one given frequency. As in a radio receiver, the frequency of receiving radio waves is adjusted, so in such electrical receivers the frequency of the received current will be adjusted. Theoretically, by this method it will be possible to transmit electricity over very long distances if the frequency of the alternating current is low, on the order of several Hz.

Prospects for wireless electricity transmission

In the near future, the mass introduction of the PoWiFi system into everyday life is expected, consisting of routers with the function of transmitting electricity over several tens of meters, and household appliances, which are powered by receiving electricity from radio waves. Such a system is currently being actively tested and is being prepared for widespread use. Details were not disclosed, but according to available information, the "highlight" is that it uses the synchronization of the electromagnetic fields of the source and receiver of wireless electricity.

In a very distant future, the option of abandoning the use of traditional power plants on a global scale is being considered - solar stations will be used in near-earth orbitconverting the energy of sunlight into electrical energy. Electricity will presumably be transmitted to the planet's surface through ionized air or plasma channels. And on the earth's surface itself, ordinary power lines will disappear, their place will be taken by more compact and efficient systems transmission of electricity through the lithosphere.

The problem of energy transmission over a distance has not yet been solved. Although it was staged at the turn of the century. Nikola Tesla was the first to make this dream come true: "The transfer of energy without wires is not a theory or just a probability, as most people think, but a phenomenon that I have experimentally demonstrated for a number of years. The idea itself did not come to me right away, and as a result of a long and gradual development, it became a logical consequence of my research, which was convincingly demonstrated in 1893, when I first presented to the world a diagram of my wireless power transmission system for all sorts of purposes.My experiments with high frequency currents were the first ever conducted publicly, and they aroused keen interest because of the possibilities they opened up, as well as the amazing nature of the phenomena themselves. Few people familiar with modern equipment will appreciate the difficulty of the task when I had primitive devices at my disposal. "

In 1891, Nikola Tesla designed a resonant transformer (Tesla transformer), which allows obtaining high-frequency voltage fluctuations with an amplitude of up to a million volts, and was the first to point out the physiological effect of high-frequency currents. The standing waves of the electric field observed during a thunderstorm led Tesla to the idea of \u200b\u200bthe possibility of creating a system for providing electricity to power consumers remote from the generator without using wires. Initially, the Tesla coil was used to transfer energy over long distances without wires, but soon this idea was relegated to the last plan, since it is almost impossible to transfer energy over a distance, the reason for this is the low efficiency of the Tesla coil.

The Tesla transformer, or Tesla coil, is the only one of Nikola Tesla's inventions that bear his name today. It is a classic resonant transformer that produces high voltage at high frequency. This device was used by the scientist in several sizes and variations for his experiments. The device was claimed by patent No. 568176 of September 22, 1896 as "Apparatus for the production of electric currents of high frequency and potential."

There are 3 types of Tesla coils:

SGTC-spark gap Tesla coil - Tesla coil on the spark gap.
VTTC-vacuum tube Tesla coil - Tesla coil on a radio tube.
SSTC-solid state Tesla coil - Tesla coil on more complex parts.

Description of the construction of the transformer. In its elementary form, it consists of two coils - primary and secondary, as well as a strapping consisting of an arrester (a breaker, the English version of Spark Gap is often found), a capacitor and a terminal (shown as "output" in the diagram). Unlike many other transformers, there is no ferromagnetic core here. Thus, the mutual induction between the two coils is much less than that of conventional transformers with a ferromagnetic core. This transformer also has practically no magnetic hysteresis, the phenomenon of delay in the change in magnetic induction relative to the change in current, and other disadvantages introduced by the presence of a ferromagnet in the field of the transformer. The primary coil together with the capacitor forms an oscillatory circuit, which includes a non-linear element - a spark gap (spark gap). The spark gap, in the simplest case, is an ordinary gas; usually made of massive electrodes.

The secondary coil also forms an oscillatory circuit, where the capacitive coupling between the toroid, the terminal device, the turns of the coil itself and other electrically conductive elements of the circuit with the Earth plays the role of a capacitor. The terminal device (terminal) can be made in the form of a disk, a sharpened pin or a sphere. The terminal is designed to produce long, predictable spark discharges. The geometry and relative position of parts of a Tesla transformer strongly affect its performance, which is similar to the design problem of any high-voltage and high-frequency devices.

Another interesting device is the Van de Graaff generator. This is a generator high voltage, the principle of which is based on the electrification of a moving dielectric tape. The first generator was developed by the American physicist Robert Van de Graaf in 1929 and made it possible to obtain a potential difference of up to 80 kilovolts. In 1931 and 1933, more powerful generators were built, making it possible to achieve voltages up to 7 million volts. Van de Graaff generator circuit:

A large hollow metal electrode in the form of a hemispherical dome is mounted on a high-voltage insulating column. The upper end of the belt conveyor of electric charges, which is an endless rubber belt on a textile basis, stretched over two metal pulleys and usually moving at a speed of 20-40 m / sec, enters the electrode cavity. The lower pulley, mounted on a metal plate, is rotated by an electric motor. The top pulley is located under the high voltage dome electrode and is at full machine voltage. There is also the power supply system of the ion source and the source itself. The lower end of the tape passes an electrode supported by a conventional high-voltage source at a high voltage relative to earth up to 100 kV. As a result of a corona discharge, electrons from the ribbon are transferred to the electrode. The positive charge of the belt lifted by the conveyor is compensated at the top by the electrons of the dome, which receives a positive charge. The maximum achievable potential is limited by the insulating properties of the column and the air around it. The larger the electrode, the higher the potential it can handle. If the installation is hermetically sealed and the interior is filled with dry compressed gas, the dimensions of the electrode for this potential can be reduced. The charged particles are accelerated in an evacuated tube located between the high voltage electrode and ground, or between the electrodes if there are two. With the help of a Van de Graaff generator, a very high potential can be obtained, which makes it possible to accelerate electrons, protons and deuterons to an energy of 10 MeV, and alpha particles carrying a double charge up to 20 MeV. The energy of the charged particles at the output of the generator can be easily controlled with great accuracy, making accurate measurements possible. The proton beam current in the constant mode is 50 μA, and in the pulsed mode it can be increased to 5 mA.