RU2478974C2 - Method for replication of direct current force unit, and device for implementation thereof - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: method is implemented in a replicated current circuit on its vacuum-treated segment; a part of electrons predetermining replicated current force is directed from an electron cloud onto a cathode of an electronic amplifier under a potential difference. A pulse frequency recorded in an output of the electronic amplifier and an electron elementary discharge enable stating replicated direct current force. It enables recording directly each electron in replicated direct current flow and providing correlating a current force unit (Amper) and its physical meaning.

EFFECT: higher accuracy of current unit replication and extended range of direct current replication towards the lesser values, enabled direct recording of each electron.

2 cl, 1 dwg

Description

The group of inventions relates to measuring technique and metrology, namely to the technique of reproducing a unit of constant electric current strength by the absolute method.

In the first half of the 20th century, the generally accepted concept of direct current strength was that “electric current is generated by the movement of electric charges and can be defined as the number of electric charges passing through a conductor per unit time” [K.A. Krug, “Fundamentals of Electrical Engineering” . M.-L., 1936, p.13-14].

In the prior art, means for reproducing a unit of constant electric current directly in accordance with this definition are not known.

At the IX General Conference on Weights and Measures in 1948, it was accepted that Ampere is equal to the force of an unchanging current, which when passing through two parallel rectilinear conductors of infinite length and an insignificant small area of circular cross section located in vacuum at a distance of 1 m from one another , would cause in each section of the conductor 1 m long the interaction force equal to 2 · 10 ^-7 N. [International Committee of Weights and Measures, 1946, Resolution 2, approved by IX CGPM, 1948].

In accordance with this definition, the leading world metrological centers (USA, England, Germany, Japan) began work on creating a complex of equipment for reproducing a unit of current, which was called "current scales". In 1968, such a set of equipment, created in VNIIM them. D.I. Mendeleev, was approved by the USSR State Standard as the State primary standard of a constant electric current strength unit - Ampere (GET code 4-68), [GOST 8.022-72 GSI “State primary standard and all-Union calibration scheme for measuring instruments of constant electric power current ”] with a margin of error, as in other countries, 1 · 10 ^-5 .

In connection with the advent of quantum standards - the standard of constant electric voltage, based on the fundamental Josephson constant and the standard of electrical resistance, based on the fundamental Klitzing constant, it became possible to reproduce Ampere with an higher accuracy using the indirect method through Volt and Ohm.

Based on these provisions, in the range of 1 · 10 ^-3 - 1 A, in 1991 a set of measuring instruments was created and approved, which became part of the State primary standard of a unit of constant electric current strength - Ampere (GET code 4-91). [GOST 8.022-91 GSI "State primary standard and the State calibration scheme for measuring instruments of direct current in the range of 10 ^-16 - 30 A"]. The composition of the same standard in the range of 1 · 10 ^-16 -1 · 10 ^-9 A also included a complex of equipment based on electrometry methods [see D.I. Antonova, O.M. Pavlov and others. "Device for reproducing constant currents", A.S. No. 614724, Bull. fig. No. 25, 1978], in which indirect methods of reproducing Ampere are implemented and which, however, do not meet the current definition.

The error in reproducing a unit of current strength by the electrometric part of the GET 4-91 standard in the range of 1 · 10 ^-16 -1 · 10 ^-9 A is (5-0.1)% [ASKatkov, O.M. Pavlov, OPGalakhova, EDKoltik, "Primary Standard of Current Developed of VNIIM ", 2 ^nd ISEM'93, China, pp. 47-48].

The Advisory Committee on Electricity and Magnetism adopted recommendation E1 (2007) on proposed changes to the International SI Unit System and, in particular, the current definition of amperes. An example of an ampere definition is proposed:

- “an ampere is an electric current of an equivalent flux exactly equal to 1 / (1.60217653 × 10 ^-19 elementary charges per second (It follows from this that this definition fixes an elementary charge as equal to exactly 1.60217653 × 10 ¹⁹ A · c ) ”[RECOMMENDATION E1 (2007): Proposed changes to the International System of Units (SI). The Consultative Committee for Electricity and Magnetism (CCEM), CCEM / 2007-44].

The basis of the definition is made up of the following factors:

1) determination of the strength of direct electric current, as a phenomenon of directional movement of electric charges;

2) determination of the quantitative characteristic of this phenomenon - the strength of the electric current - as a quantity numerically equal to the amount of charge flowing through a certain surface per unit time;

3) discreteness of charge.

Thanks to the development of modern nanotechnology, it became possible to reproduce Ampere in accordance with the proposed definition. The General Conference appealed to leading metrology institutes with a call to begin work on the creation of equipment for reproducing Amperes in accordance with the recommended definition [XXIII General Conference of Weights and Measures, 2007, On the possible redefinition of some basic units of the International System of Units (SI). Resolution L].

To solve this problem, many leading metrological institutes in the world are working on the creation of a quantum standard of electric current based on the effect of single-electron tunneling. For a more successful solution to this problem, the European project COUNT was launched, within the framework of which two devices supplementing each other based on the effect of single-electron tunneling are developed for use in metrology of electric currents [N.E. van den Brom, O. Kerkhof, SV Lotkhov, SA Bogoslovsky, G.-D. Willenberg, H. Scherer, ABZorin, S. Pedersen, C. Kristoffersson, P. Delsing, M. Taslakov, Z. Ivanov, H. Nilsson, S. Giblin, P. Kleinschmidt, C. Hof, ALEichenberger, F.Overney, B. Jeanneret, G. Genevĕs, N. Feltin, L. Devolille, F. Gay, and F. Piquemal “Counting Electrons One by One - Overview of a Joint European Research Project ”, IEEE Trans. IM vol. 52, N2, pp. 584-587, 2003].

When using a single-electron pump to reproduce current, the basic measurement equation, depending on the material of manufacture and temperature, can be represented as follows:

i = ef or i = 2ef

where: e is the electron charge;

2e is the charge of the Cooper pair;

f is the frequency of the voltage applied to the gate of the device.

In the prior art, means for reproducing a unit of constant electric current directly in accordance with this definition are not known.

A known method of single-electron tunneling is a method of reproducing a unit of constant electric current, which, by its function and a set of essential features, is the closest analogue of the claimed method (Y. De Wilde, F Gay, FPMPiquemal, and G. Geneves, "Measurements of Single Electron Transistor Devices Combined with a CCC: Progress Report ", IEEE Trans. IM, vol.50, N2, pp. 231-234, 2001).

The effects of single-electron tunneling are manifested in systems that contain a small metal island weakly coupled (i.e., through tunnel junctions) to the external circuit. When the capacitance of the island C _Σ is small enough, the presence of an excess electron on the island can be detected. This effect is most obvious when energizes e ^2/2 · C _Σ is the dominant energy in the system: it must exceed the energy of the electrons associated with the applied voltage, e · V, and their thermal energy, k · T. In practice, this requires the use of metal structures with characteristic dimensions of less than 100 nanometers, operating at temperatures less than 50 micelvin (less than -223 ° C).

By means of a capacitive valve (shutter) connected to the island, the island charge can be controlled. The best known structure is a single-electron transistor, which has two tunnel junctions and one gate capacitance (IEEE Trans. IM vol. 52, N2, pp.584-587, 2003).

A known method of reproducing a unit of constant electric current strength is carried out by a device that contains a circuit reproducing a unit of current strength in the form of series-connected: source, "n" tunnel junctions, "n-1" islands located between them, drain supported by a substrate, certified reference measuring instrument and bias voltage source V _c . The positive pole of the bias voltage source is associated with a certified reference measuring instrument, and the negative - with the source. The fixed gate electrodes are located in the immediate vicinity of these quantum islands, forming a capacitive coupling between each gate electrode and each island. Each gate electrode, through a phase-shifting chain, is connected to one of the poles of the radio frequency generator, the other pole of the radio frequency generator is connected to a common source point and the negative pole of the bias voltage source V _c .

A known method of reproducing a unit of constant electric current is as follows.

The current i _in reproduced by the single-electron tunneling device under the influence of the applied voltage of the bias source will begin to flow only after the tunnel junction is unlocked, when the gate potential becomes greater than a certain threshold value, the Coulomb blockade. In a blocked state, the electron at the source has no available energy levels within the tunneling range. When the Coulomb blockade breaks, the electron passes through the barrier to the island. The breakthrough of the Coulomb blockade depends on the voltage at the gate. For the current to flow in the source-drain circuit, a voltage is supplied to each gate through a phase-shifting circuit from the radio frequency generator, which is ± π phase-shifted from the gate to the gate. In this case, the current in the circuit will flow in portions, which corresponds to the movement of individual electrons. Thus, by controlling the potential at the gate, it is possible to pass single electrons e or Coulomb pairs 2e through Coulomb barriers. When a positive potential is applied to the gate, the energy levels on the island decrease.

An electron e or Coulomb pair 2e can tunnel to an island, occupying the free energy level. Further, having passed the “n-1” islands, they can tunnel to the drain. The magnitude of the reproduced current i _in flowing between the source and drain depends on the frequency of the voltage generator f applied to the gates,

i _in = e · f or i _in = 2e · f.

where: e is the electron charge;

2e is the charge of the Cooper pair;

f is the frequency of the voltage applied to the gate of the device.

In the experiment, a current of 1 · 10 ^-12 A was obtained with an error of 0.1% with an electron transfer error of 0.15 ppm. The counting error of the main electron flux is estimated at ± 1 electron [MWKeller and JM. Martinic, NMZimmerman, AHSteinbach "Accuracy of electron counting using a 7-junction electron pump", Appl. Phys. Lett. v.69 N12, pp. 1804-1806, 1996].

The disadvantage of this method of reproducing direct current is that the reproducible current is determined indirectly by applying a voltage of a certain frequency to the gate. This raises the need to protect the electrons e and Cooper pairs 2e from tunneling to reduce the overall uncertainty of the passage of electrons, as well as the need to use high technology to create structures (sizes less than 100 nanometers) operating at ultra-low temperatures; and special equipment to ensure these conditions (at the units of Kelvin miles).

Devices for reproducing DC current, similar in technical essence and function performed, are not found by the applicant in the prior art.

The task to which the claimed group of inventions is directed is to further increase the accuracy of reproducing a unit of direct current strength and extend the range of reproduction of direct current to lower values, making it possible to create a standard of one of the main units of the international SI system - unit of direct current power of Ampere in the area of its fractional values.

The technical result obtained by the implementation of the claimed group of inventions is to provide the possibility of direct registration of each electron in the reproducible current circuit to ensure compliance with the recommended definition of Ampere with its physical meaning.

The specified technical result is achieved by the implementation of the claimed group of diverse inventions, which form a single creative concept and represent a method of reproducing a unit of constant electric current and a device for its implementation.

The specified technical result in the implementation of the claimed group of inventions is achieved by the fact that in the inventive method of reproducing a unit of constant electric current using a charge of electrons and moving them in a reproduced current circuit, in contrast to the known method, a portion of the reproduced current circuit is evacuated, a cathode is placed on this section emitting an electronic cloud, a control grid and an anode in the form of a cathode of an electron multiplier, an electronic cloud is created at the cathode and under the influence of a given p potential differences between the cathode and the control grid, the determined number of electrons determined by it, passed through the control grid to the anode, closes the reproduced current circuit, the number of electrons passed through the reproduced current circuit per unit time is converted in the electron multiplier into a train of pulses whose pulse repetition rate f determine the value of the unit force of the reproduced constant electric current i _In according to the formula:

i _B = e · f,

providing the possibility of direct registration of each electron in the circuit of the reproduced current,

where e is the elementary charge of the electron, exactly equal to 1.60217653 · 10 ^-19 C.

The specified technical result in the implementation of the claimed group of inventions is achieved by the fact that in the inventive device for reproducing a unit of constant electric current, consisting of a circuit reproducing a unit of current, made in the form of a measure of ramp, connected by one output to the connected first plates of two capacitors of equal nominal, another lining of one of the capacitors is connected to the cathode in the evacuated section of the circuit from sequentially located after the cathode control grid and anode connected to another output of the measure, and the anode in the current reproduction circuit is the cathode of the electron multiplier, the anode of which is connected to the pulse counter, while the second lining of the other capacitor is the output of the device, which displays the reproduced unit of the direct current strength.

In the device for implementing the method of reproducing a unit of current strength (drawing), a measure of a linearly varying voltage 1 is connected by one output to the common plates of capacitors 2 and 3 with an equal value of capacitance. Another lining of the capacitor 2 is connected to the cathode 4, located together with the control grid 5, the anode 6 (in the form of the cathode 6 of the electron multiplier 7) and the electron multiplier 7 in the vacuum cylinder 8. The control grid 5 and the anode 6 are connected to the other end of the ramp measure 1. The anode 9 of the electron multiplier 7 is connected to one of the ends of the load resistance 10 and one of the plates of the isolation capacitor 11. Another plate of the capacitor 11 is connected to the input of the pulse amplifier 12, the output of which is connected to the input of the counter pulses 13. The other end of the load resistance 10 is connected to the positive pole of the power source 14, with a common bus 15 of the pulse amplifier 12 and with the other end of the pulse counter 13. The bias resistance 16 is connected to the output 17 of the distributed voltage divider of the electron multiplier 7, and the other to with the positive pole of the power source 14. The negative output of the power source 14 is connected to the cathode 6 of the electron multiplier 7. Another lining of the capacitor 3 is connected to the high-impedance input of the certified reference Units measure 11%. The low-impedance input of the measuring instrument 18 is connected to the other end of the ramp measure 1 and to the negative pole of the power supply 14.

The inventive method of reproducing a unit of constant electric current is carried out by the device as follows.

The current strength i _B1 , reproduced by a measure of the ramp voltage 1 and capacitor C _B1 2, flows between the cathode 4 and the anode 6 (which is the cathode 6 of the electron multiplier 7) through the control grid 5, and automatically sets the voltage between the cathode 4 and the control grid 5, which is determined by the strength of the reproduced current i _B1 and does not depend on the load.

As a result, when reproducing the current strength i _B1 , the voltage between the cathode 4 and the control grid 5 remains constant. As a consequence, the emission of electrons from the cloud of the cathode 4 is proportional to the strength of the reproduced current i _B1 .

The electrons creating the reproducible current strength i _B1 flow from the cathode 4 under the influence of the electrostatic field formed by the high voltage voltage source 14 supplying the electron multiplier 7, are pulled by the anode 6, passing through the control grid 5. In this case, each electron falling on the cathode 6 of the electron multiplier 7, before closing the reproducible current circuit i _B1 , knocks out secondary electrons, which, multiplying, form on the anode 9 of the electron multiplier 7 a pulse that is released on the load resistance 10. This the pulse passes through the separation capacitor 11, is amplified by a pulse amplifier 12 and is supplied to the pulse counter 13. The bias resistance 16 is designed to establish the optimal operating mode of the electron multiplier 7.

Reproduced by the measure of linearly varying voltage 1 and the capacitor C _B1 2, the value of the unit current strength i _B1 , when the capacitance values of the two capacitors C _B1 2 and C _B2 3 are equal, the reproduced value of the unit current strength i _B2 through the capacitor C _B2 3 is displayed for further use with the transfer of the size of the unit of current to the standards of comparison 18.

With the exact equality of the capacitance values of the two capacitors C _B1 2 and C _B2 3, the strength of the reproduced current i _{B1 is} exactly equal to the strength of the reproduced current i _B2

i _B1 = i _B2 = e · f.

Since the current strength is determined by the magnitude of the charge, i.e., the number of electrons passing through the cross section of the conductor in 1 s, the basic equation for measuring the device will be:

i = e · f.

The value of the unit strength of the reproduced current i _B2 with the equality of the capacitance values of the capacitors C _B1 and C _B2 is determined from the ratio:

i _B2 = I _B1 = C _B2 · dV / dt = C _B1 · dV / dt = е · f,

where C _B1 and C _B2 are the capacitors of capacitors 2 and 3, to which a voltage V is applied, which varies linearly over a period of time t;

e is the elemental charge of an electron exactly equal to 1.60217653 · 10 ^-19 C;

f is the measured frequency (number) of pulses at the output of the electron multiplier 7.

In this case, the instability of the gain of the electron multiplier 7 does not play a role, since the amplitude of the pulse is not included in the main measurement equation.

In the prototype manufactured by the applicant, the fundamental possibility of counting the electrons forming the reproduced current was checked.

In the prototype were used:

- a measure of the ramp voltage 1 - a measure of the ramp voltage of the current calibrator NK1-4;

- capacitor C _B1 2 - with a capacity of ≈1 pF with leucosapphire insulation (own production);

- cathode emitting electrons 4, - gilded molybdenum disk with leucosapphire insulation (own production);

- control grid 5, the cathode of the electron multiplier 6, the electron multiplier 7, the anode of the electron multiplier 9, the output of the distributed voltage divider of the electron multiplier, 17 - secondary electron multiplier VEU-6;

- vacuum cylinder 8 - a cylinder made of molybdenum glass (own production);

- load resistance 10 - resistance type MVSG≈10 ⁸ Ohms;

- separation capacitor 11 - capacitor type FT ≈ 0.1 μF;

- power supply of the electron multiplier 14 - high-voltage power supply BPV-5;

- pulse amplifier 12 - pulse amplifier B3-2;

- pulse counter 13 - frequency meter Ch3-47;

- bias resistance 16, - resistance R _CM ≈10 ⁴ Ohms (selected during setup).

Thus, it is seen that the above information confirms the possibility of implementing the claimed invention, achieving the specified technical result and solving the problem.

Claims (2)

1. A method of reproducing a unit of constant electric current using a charge of electrons and moving them in a reproduced current circuit, characterized in that a portion of the reproduced current circuit is evacuated, a cathode emitting an electron cloud, a control grid and an anode in the form of an electron multiplier cathode are placed on this section , an electron cloud is created on the cathode and under the influence of a given potential difference between the cathode and the control grid, it determines the specified number of electrons passing through the con the grid to the anode, closes the reproducible current circuit, the number of electrons that have passed through the reproducible current circuit per unit time is converted in the electron multiplier into a sequence of pulses, according to the repetition rate of which f determine the value of the unit of force of the reproduced constant electric current i _V according to the formula:
i _B = e · f,
providing the possibility of direct registration of each electron in the circuit of the reproduced current,
where e is the elementary charge of the electron, exactly equal to 1.60217653 · 10 ^-19 C. 2. A device for reproducing a unit of constant electric current strength, consisting of a circuit reproducing a unit of current strength, made in the form of a measure of linearly varying voltage, connected by one output to the connected first plates of two capacitors of equal nominal value, the other plate of one of the capacitors is connected to the cathode in a vacuum a section of a circuit from successively located after the cathode of the control grid and the anode connected to another output of the measure, the anode in the current reproduction circuit being a method of an electron multiplier, the anode of which is connected to a pulse counter, and the second lining of the other capacitor is the output of the device, which displays the reproduced unit of direct current.