KR20110001214A - Coil current measurement apparatus of superconducting tokamak quench detection - Google Patents

Abstract

PURPOSE: A coil current measuring device is provided to improve the reliability of a superconducting tokamak device and to stably operate the device. CONSTITUTION: A measurement part(100) is installed in a normal bus bar which supplies a current to a superconducting coil and measures the current of the coil. A processing part(200) outputs a measurement value by analyzing the value through a mathematical algorithm. A central processing part(300) controls the superconducting are of a tokamak device by detecting a quench after receiving the detected measurement value.

Description

Coil current measurement apparatus for quench detection of superconducting tokamak devices

The present invention relates to a coil current measuring device for detecting the quench of a superconducting tokamak device, and more particularly, to detect the quench in real time by measuring means designed to be easily detachable for the purpose of measuring coil current on a normal busbar. It relates to a quench detection device for detecting.

Recently, as global interest in energy development has increased, KSTAR (Korea Superconducting Tokamak Advanced Research), a nuclear fusion experiment apparatus currently being developed in Korea to develop alternative energy in the future, is a toro for confining plasma deuterium to a strong magnetic field. It consists of a month-old (TF) coil (TF superconducting coil), a poroidal (PF) coil (PF superconducting coil) for generating plasma and controlling its position and shape, and a center coil (CS superconducting coil).

The superconducting coils developed to date can produce 13 Tesla fields, which are 260,000 times the Earth's magnetic field, which are necessary to create and trap the plasma required for fusion reactions. Therefore, the core technology of the superconducting coil is to manufacture the superconducting coil by forming coils by winding each wire known as a cable-in conduit-conductor (CICC).

In-line twisted pair conductor (CICC) is a magnet made of conductors of 360 or 486 strands surrounded by rectangular metal tubes for 35kA class high current operation. A supercritical helium of about 5 atm is forced to circulate in the stranded conductors for cooling to K.

1 is a diagram illustrating an example of a superconducting coil manufactured in Korea. As shown, a superconducting coil (SC magnet) is used to trap high-temperature plasma without touching the vacuum vessel wall, and has a main device, a tokamak device. The tokamak device is responsible for the generation, confinement, and control of plasma using a TF (Toroidal Field) and PF (Poloidal Field) coil.

TF superconducting coils 101 composed of TF (Toroidal Field) and PF (Poloidal Field) coils, CS superconducting coils 103 composed of Central Solenoid (CS) coils, and PF superconducting coils 102 composed of PF (Poroidal Field) coils ) And a connecting structure for connecting each superconducting coil.

The TF superconducting coil 101 (coil) is operated with a DC current of about 35KA, and the CS superconducting coil 103 and the PF superconducting coil 102 are pulse-driven to form a torus (donut) shape due to mutual magnetic field change. It is generated inside the vacuum chamber of the plasma to generate a plasma and serves to confine the plasma along with the plasma current and TF magnetic field.

These superconducting coils are characterized by AC losses during operation (losses caused by current generated by induction of voltage due to magnetic field changes; Faraday's law, Ohm's law), friction between wire and wire or friction between wire and support and contact resistance There is a continuous disturbance energy such as Joule heat generation. These phenomena lose superconductivity and change to phase conduction, the phenomenon is called quench, and the quench makes the wire rise in temperature and destroys the superconductivity of any part of the magnet.

If it is larger than the minimum propagation zone (MPZ) of the superconducting zone, the complex electrical and thermal phenomena such as heat generation in the phase conduction zone, heat transfer to the refrigerant, and heat absorption due to specific heat and thermal conductivity As a result, the phase conduction region expands the region.

During this process, the initial point of quench has the highest temperature rise since it is exposed to Joule heat generation for the longest time. Local temperature rise can have a serious effect on the magnet, and even if the temperature rise is limited to a certain range, the overvoltage of thousands to tens of thousands of volts in the phase conduction region can cause arcing between the windings.

In order to solve this problem, the superconducting coil of the tokamak device requires a quench detection system, and requires an active quench method in consideration of the shape and operating conditions of the superconducting coil.

Therefore, a device for detecting the quench generated by the elements described above is required for the stable operation of the superconducting tokamak device, and a system capable of monitoring whether or not the quench is generated in real time due to the characteristics of the tokamak device which is operated for 24 hours is required. Required.

Accordingly, the present applicant has filed the Republic of Korea Patent Application No. 2007-00085134 "Quench detection device and real-time quench monitoring system of the superconducting Tokamak device". This is to detect the energy dissipated through the voltage tap sensor. The quench detection method determines the quench by using the signal of the voltage tap sensor installed in the superconducting coil during operation.When the quench is detected, the stored energy is not a magnet but an external device. We have achieved technology development that will allow us to take appropriate steps to ensure rapid consumption.

However, the conventional quench detector uses a voltage tap sensor attached to the coil, so the relationship between the sensor signal and the coil current is not known. Therefore, in order to improve the stability of the quench detector, the mutual analysis of the coil current and the voltage signal must It is essential.

It is a device that measures the current of superconducting coil. The simplest form of shunt resistor is directly coupled to the normal busbar, so it is difficult to install. It also increases the size of the device due to Joule heat problem. The DC current transformer (DCCT) is also directly connected to the normal busbar. In order to measure high currents in a coupled form, there is a problem that very high cost is required.

The present invention for solving the above problems is to first detect the quench to lose the superconducting state of the superconducting coil in the superconducting tokamak device to secure the stability and reliability of the superconducting tokamak device operation.

Another object of the present invention is to provide a quench detection device which minimizes the detection device for quench detection and is very easy to install.

In addition, to monitor the generation of the quench in real time to achieve the stability and reliability of the operation of the Tokamak device.

In addition, the purpose is to allow a number of administrators to check whether or not the quench occurs anywhere to perform more accurate actions through the network.

The present invention for achieving the above object is a quench detection device for detecting the quench of the superconducting coil provided in the superconducting Tokamak apparatus, is installed in the normal bus bar for supplying a current to the superconducting coil to measure the current of the superconducting coil The measuring means, the processing means for interpreting the measured value measured by the measuring means through a mathematical algorithm and output the measured value and receiving the measured value detected by the processing means to determine whether the quench generation to determine the superconducting area of the tokamak device It characterized in that it comprises a central processing means for controlling.

In addition, the measuring means is characterized by using a Rogowski coil.

The processing means may include a terminal electrically connected to the measuring means, an amplifier for amplifying an analog signal provided from the terminal, a digitizer for converting an analog signal provided from the amplifier into a digital signal, and the digitizer. It is characterized by consisting of a computer to detect the generation of the quench by analyzing the voltage value provided through the mathematical modeling.

In addition, the processing means, the pulse current generated during one operation of the superconducting Tokamak apparatus, characterized in that the one operation time is up to 300 seconds.

In addition, the processing means and the central processing means, characterized in that connected to the network via Ethernet.

The processing means may be used for quench detection after calculating the pulse current flowing through the superconducting coil by numerical integration.

The processing means may convert the secondary voltage generated by the measuring means into a primary current corresponding to a normal bus bar.

In addition, the central processing means, characterized in that for controlling the MPS for supplying current to the superconducting coil through the superconducting bus line.

In addition, the measuring means is installed on the normal bus bar, characterized in that for detecting the current by forming a core-less transformer as magnetically coupled thereto.

를 통해 전압을 시간 적분하여 측정값을 산출하는 것을 특징으로 한다.In addition, the measuring means,

It is characterized by calculating the measured value by integrating the voltage over time.

Further, a quench detection device for detecting a quench of a superconducting coil provided in a superconducting tokamak device, comprising: measuring means for detecting a current flowing through a superconducting coil provided in a normal bus bar for supplying current to the superconducting coil; It is characterized in that it comprises a processing means for outputting the final value by interpreting the measured value measured from the mathematical algorithm.

In addition, the processing means, the terminal connected to the measuring means, the amplifier receiving the voltage provided from the terminal, the digitizer for digitizing the voltage value provided from the amplifier and the voltage value provided through the digitizer mathematically It is characterized by consisting of a computer that analyzes through modeling to detect the generation of quench.

In addition, the measuring means is characterized by using a Rogowski coil.

를 통해 전압을 시간 적분하여 측정값을 산출하는 것을 특징으로 한다.In addition, the measuring means,

It is characterized by calculating the measured value by integrating the voltage over time.

The present invention constructed and operated as described above greatly improves the stability of the conventional quench detection device due to various effects of quench generation of the superconducting coil due to various factors during operation of the superconducting tokamak device. It is effective to secure stable operation and reliability of the device.

In addition, since it is possible to detect the occurrence of the quench and monitor it in real time, it is possible to perform more accurate actions according to the situation because multiple managers can check it anywhere through higher stable operation and network.

Hereinafter, a preferred embodiment of the coil current measuring device for detecting the quench of the superconducting tokamak device according to the present invention with reference to the accompanying drawings in detail as follows.

Figure 2 is a schematic diagram showing a coil current measuring device for detecting the quench of the superconducting tokamak device according to the present invention, Figure 3 is a schematic diagram of a Rogowski coil as a measuring means for detecting the quench according to the present invention, Figure 4 is a Rogowski according to the present invention Figure 5 shows an equivalent circuit of the electrical characteristics of the coil, Figure 5 shows a model of the interlayer capacitance of the Rogowski coil according to the present invention, Figure 6 is a state diagram showing a state in which the measuring means is installed in the normal bus bar.

In the quench detection device for detecting the quench of the superconducting coil provided in the superconducting tokamak device of the superconducting tokamak device according to the present invention, the superconducting coil is provided in the normal bus bar 410 for supplying current to the superconducting coil 400 Measuring means (100) for detecting the current flowing through the processing means 200 for interpreting the measured value measured by the measuring means through a mathematical algorithm and outputting the final value and the measured value detected by the processing means is quenched It includes a central processing unit 300 for controlling the superconducting area of the tokamak apparatus by checking whether or not it occurs.

Measuring means 100 is to be installed in the normal bus bar 410 for supplying a current to the superconducting coil to measure whether the superconducting coil and the bus line quench generation, to measure the current of the superconducting coil, the main of the present invention As a technical point, the measuring means is to use a Rogowski coil which can be installed in a normal bus bar.

Rogowski coil is a coil consisting of a toroidal winding line and a rewinding line passing through it. It is mainly used for measuring AC current or pulse current. Compared to conventional current transformers (CTs), Rogowski coils do not have a magnetic core, so they do not have hysteresis, saturation, or magnetic loss, and are compact and lightweight.

2 is a conceptual diagram of a Rogowski coil, in which a normal bus bar through which a current to be measured flows is magnetically coupled to the Rogowski coil to form a core-less transformer. Therefore, normal busbars are called primary conductors, and the current to be measured is the primary current. In addition, the induced voltage generated in the Rogowski coil is a secondary voltage.

For Rogowski coils with a circular cross section, the winding axis has a permeability μ (H / m), the cross section radius of the winding axis is r (m), the main radius is R (m), and the number of turns of the conductor is N, The electromotive force e _s (V) generated in the Rogowski coil by the current I (A) is represented by Equation 1 below.

Where K _{R is} the mutual induction coefficient of the Rogowski coil. The primary current is expressed by Equation 2 below by integrating Equation 1 above.

If the primary current is a sinusoidal AC current, the primary current is simply calculated by measuring the secondary voltage as shown in Equation 1 using an AC voltmeter and converting the effective voltage into an effective current. On the other hand, if the primary current is not a sinusoidal alternating current, it is necessary to perform time integration as in Equation 2 using an integrator.

An equivalent circuit of the electrical characteristics of the Rogowski coil is shown in FIG. The resistance of the wound wire is r _c (Ω), the magnetic inductance is L (H), the distribution capacity of the wound wire is combined with the capacitance of the coaxial cable, C (F), and the damping resistance to prevent ringing at the coaxial cable end. Denotes R _d (Ω).

Rogowski coil's magnetic inductance L having a circular cross section is represented by Equation 3 below.

(m), 층수를 n으로 한다면, Rogowski코일의 층간용량 Cs(F)는 아래 수학식 4와 같이 표시된다.The wound wire portion of the Rogowski coil is modeled as shown in Fig. 4, and the permittivity of the wound wire portion is ε (F / m), the inner radius is α (m), the outer radius is b (m), and the length is

(m) If the number of floors is n, the interlayer capacity Cs (F) of the Rogowski coil is expressed as in Equation 4 below.

/코일에 발생하는 기전력

), 위상, 공진주파수 등의 주파수 특성에 주의가 필요 하다.As above, the Rogowski coil is not a pure voltage source, but has an RLC circuit inside itself. Especially in the high frequency range, gain (voltage at the end of coaxial cable)

EMF generated in the coil

Attention should be paid to the frequency characteristics such as), phase, and resonant frequency.

The numerical integration method is a method of multiplying the derivative value of a function by a weight and adding it numerically to find an answer. It is different from the algebraic integration method in which the differential equation is algebraically integrated to find an answer. Common techniques include the Newton-Cotes formulas and Gaussian quadrature. These are techniques based on the division rule strategy, and are obtained by dividing the integral over a large set by the integration over a small set. However, at higher order integrations, the calculations using these methods are enormous, so probabilistic algorithms such as the Monte Carlo method or optimization algorithms such as the sparse grid method are applied. In the present invention, a numerical integration method using general Newton-Cotes formulas is used.

Newton-Cotes formulas are the generic terms for the delimiter method, and there are two types of formulas in the Newton-Cotes formulas: "closed" and "open". In the present invention, the "closed case" is dealt with, and the nth-order formula in this case is represented by Equation 5 below using Lagrangian interpolation.

}에 관한 Lagrangian interpolation에 의한 보간다항식이다. 이 식은 Newton-Cotes formulas가 취한 값이 함수 f전체가 아닌

만으로 정하는 것을 의미한다. 1차에서 4차까지의 공식을 아래에 나타낸다. 적분치의 요소수는 미분치의 요소수의 (1/차수)가 되고, 예를 들면 4차의 공식이라면 1/4이 된다. 이 때문에 고차 공식에서는 요소수(시간해상도)의 감소에 주의할 필요가 있다.Where L (x) is a given element {(

} Is a Lagrangian interpolation of Lagrangian interpolation. This expression assumes that the value taken by the Newton-Cotes formulas is not a function

It means to decide only. The first to fourth formulas are shown below. The number of elements of the integral value is (1 / order) of the number of elements of the derivative value, for example, 1/4 of the fourth order formula. For this reason, attention must be paid to the reduction of the number of elements (time resolution) in higher order formulas.

1st order Trapezium fule

, 오차항

expression

, Error term

2nd Simpson's fule

, 오차항

expression

, Error term

3rd order 3/8 rule

, 오차항 -

expression

, Error term-

4th order Bool's rule

, 오차항

expression

, Error term

First, the impedance of the Rogowski coil is measured prior to application for quench detection of the superconducting coil and the superconducting bus line. The impedance is measured using a known RCL meter to measure the resistance R (Ω), magnetic inductance L (H) and mutual inductance M (H) of the Rogowski coil. The carrying current is about 10mA, and the frequency of alternating current is from 50Hz to 1MHz. An example of an RCL meter used in the present invention is PM6306 manufactured by FLUKE.

와 같다. 이 상호 유도계수

은 극히 작아 1차측에 전류 리드 1가닥을 통하게 하는 것만으로 측정할 수 없다. 그리하여 Rogowski코일의 1차측에 절연피복 도선을 100회 감아 상호 인덕턴스를 측정하고, 이 측정치의 1/00을 M 및

이라고 했다.Mutual inductance M is the mutual induction coefficient of Rogowski coil

Same as This mutual induction coefficient

Is extremely small and cannot be measured simply by passing a single current lead on the primary side. Thus, the mutual inductance is measured by winding the insulated conductor 100 times on the primary side of the Rogowski coil and measuring 1/00 of this measurement by M and

I said.

(H)를 산출해본다. 1차 전류의 실효치를 I(A), 2차 전압의 실효치를 V(V), 각 주파수를

(rad/s), 주파수를

(Hz)라고 한다면, 상기 수학식 1에서 Rogowski코일의 상호 유도계수

은 아래 수학식 6과 같이 나타난다.Where the mutual induction coefficient is based on the specifications shown in the table below

Calculate (H) The effective value of the primary current is I (A), the effective value of the secondary voltage is V (V), and each frequency

(rad / s), frequency

(Hz), the mutual induction coefficient of the Rogowski coil in Equation 1

Is represented by Equation 6 below.

= 60Hz를 상기 수학식 6에 대입하면,

=0.84

H이다. 단 이 값은 출고된 Rogowski코일의 기본 사양값에 근거한 계산치로, 만일 사양 이 틀릴 경우에는 이 계산치는 정확하지 않다.V = 0.2 V, I = 630 A,

= 60 Hz in Equation 6,

= 0.84

H. However, this value is based on the Rogowski coil's default specification, which is incorrect if the specification is incorrect.

Item Specifications Primary current 630A (*) Secondary voltage 200 mV (*) Current ratio error ± 1.0% Phase angle error ± 60 minutes Case material Nylon 6 GF 30% (black) Wire material Teflon Wire length 80 mm (twisted) Coil molding Epoxy (black)

As described above, the specification of the Rogowski coil used as the measuring means and the mathematical modeling for the interpretation thereof are merely an example and may be changed.

In this way, a small pulse current of about 100 A is measured over a long time of about 140 s using a Rogowski coil and a processing means described later for performing numerical integration. During the measurement of the Rogowski coil's secondary voltage, rather than in real-time integrating, the pulsed current is repeatedly flown through the primary conductor, and then the measured secondary voltage is processed using a computer. The length of the pulse current summit is about 3 s and the rate of change of the current is 20 to 500 A / s.

The processing means 200 receives a value (secondary voltage) measured by the Rogowski coil, which is the measuring means, and outputs a value through software for mathematical modeling as mentioned above. In addition, the processing means is a PXI system is applied, the value of the signal processing using a scanner method.

Further, it is preferable to receive and interpret the value measured by the measuring means by using a personal computer that executes the numerical integration described above. At this time, it is composed of a terminal 210, an amplifier 220, a digitizer 230 and a computer (240; PC) in order to electrically connect the measuring means 100 and the processing means, these are sequentially connected and measured Configure the means to receive the measured values measured. The terminal 210 is an electrical terminal block before the signal cable of the Rogowski coil flows into the processing means 200, and the amplification part 220 is an analog signal of the measuring means 100 before digital conversion for performing numerical integration. By amplifying the signal to improve the signal to noise ratio (SNR).

In addition, the digitizer 230 converts the analog signal amplified by the amplifier 220 into digital, which is finally analyzed / processed by the computer.

The waveform of the primary current is defined by the output voltage, the output current, their slew rates, and the latency. The Rogowski coil's voltage measurement and primary current energization are automatically coordinated by the LabVIEW program.

The detected sampling rate is 10 kS / s per channel, but averages every two points to drop the rate to 5 kS / s and then record the measurements on the computer. The reason for measuring at such a rate is to reduce aliasing noise as much as possible by sampling at a close rate that can be 10 kHz of the low-pass filter of the amplifier 220.

As such, the present invention detects the secondary voltage generated by the measuring means by the magnetic coupling according to the current flowing in the normal bus line through the measuring means and detects the current by the processing means to detect the current flowing in the superconducting coil. The measurement can be used for quench detection of superconducting coils and superconducting buslines.

In addition, in another embodiment according to the present invention is proposed a configuration for monitoring and controlling the generation of the quench in real time.

The central processing means 300 is connected to the processing means 200 and is provided to monitor and control whether or not a quench occurs in real time. The central processing means is a computer network of the processing means and a network via Ethernet. It can be monitored and controlled at a long distance by connecting to a LAN and is also responsible for controlling the MPS (magnet power supply) that supplies current to the superconducting coil.

Whether the quench is detected is transmitted to the processing means in real time, and the central processing means (central server) confirms through monitoring by the administrator and controls the MPS to quickly process the quench generation.

The central processing unit may be a general PC, and although not shown in the drawing, various functions such as a display unit, an interface for connecting to a network, and a setting unit for safety control according to quench generation are added.

The present invention configured as described above has the advantage that it is easy to detect the occurrence of the quench of the superconducting coil by installing a normal bus bar for detecting the quench of the superconducting coil and the superconducting bus line using the low-cost Rogowski coil. There is this.

In addition, the quench generated in the superconducting coil (magnet) of the tokamak device operated for 24 hours can be monitored and controlled by an administrator through a central processing unit in real time, and thus quick actions can be performed even in an emergency situation.

While the invention has been described and illustrated in connection with a preferred embodiment for illustrating the principles of the invention, the invention is not limited to the construction and operation as shown and described.

Rather, those skilled in the art will appreciate that many modifications and variations of the present invention are possible without departing from the spirit and scope of the appended claims. And all such modifications and changes as fall within the scope of the present invention are therefore to be regarded as being within the scope of the present invention.

1 is a partial cutaway view of a superconducting coil system constructed in a superconducting tokamak device,

Figure 2 is a schematic diagram showing a coil current measuring device for detecting the quench of the superconducting tokamak device according to the present invention,

3 is a schematic diagram of a Rogowski coil as a measuring means for detecting the quench according to the present invention;

4 is a view showing an equivalent circuit of the electrical characteristics of the Rogowski coil according to the present invention;

5 shows a model of the interlayer capacity of a Rogowski coil according to the invention,

Figure 6 is a state diagram showing a state in which the measuring means is installed on the normal bus bar.

<Description of the symbols for the main parts of the drawings>

100: measuring means 200: processing means

210: terminal 220: amplifier

230: Digitizer 240: Computer

300: central processing unit 400: superconducting coil

410: normal busbar

Claims (14)

A quench detection device for detecting a quench of a superconducting coil provided in a superconducting tokamak device, Measuring means installed in a normal bus bar for supplying current to the superconducting coil and measuring current of the superconducting coil; Processing means for interpreting the measured value measured from the measuring means through a mathematical algorithm and outputting the measured value; And Coil current measuring device for detecting the quench of the superconducting tokamak device, characterized in that it comprises a; central processing means for controlling the superconducting area of the tokamak device by receiving the measured value detected by the processing means to determine whether the quench is generated. . The method of claim 1, wherein the measuring means, Coil current measurement device for quench detection of a superconducting tokamak device, characterized by using a Rogowski coil. The method of claim 1, wherein the processing means, A terminal electrically connected to the measuring means; An amplifier for amplifying an analog signal provided from the terminal; A digitizer for converting an analog signal provided by the amplifier into a digital signal; And A quench detection device for a superconducting tokamak device, comprising: a computer for detecting whether a quench is generated by analyzing a voltage value provided through the digitizer through mathematical modeling. The method of claim 1, wherein the processing means, A coil current measuring device for detecting a quench of a superconducting tokamak device, wherein the pulse current generated during one operation of the superconducting tokamak device is measured, and the one time of operation is within a maximum of 300 seconds. The method of claim 1, wherein the processing means and the central processing means, Coil current measuring device for detecting the quench of the superconducting tokamak device, characterized in that connected to the network through the Ethernet. The method of claim 1 or 3, wherein the processing means, A coil current measuring device for detecting a quench of a superconducting tokamak device, characterized in that it is used for quench detection after calculating the pulse current flowing through the superconducting coil by the numerical integration method. The method of claim 1, wherein the processing means, A coil current measuring device for detecting a quench of a superconducting tokamak device, characterized in that the secondary voltage generated by the measuring means is converted into a primary current corresponding to a normal bus bar. The method of claim 1, wherein the central processing means, A coil current measuring device for quench detection of a superconducting tokamak device, characterized in that for controlling the MPS supplying current to the superconducting coil through the superconducting bus line. The method of claim 1, wherein the measuring means, The coil current measuring device for detecting the quench of the superconducting tokamak device, characterized in that the current is detected by forming a core-less transformer as installed in the normal bus bar and magnetically coupled thereto. The method of claim 1 or 2, wherein the measuring means, Equation

Coil current measuring device for detecting the quench of the superconducting tokamak device, characterized in that to calculate the measured value by integrating the voltage over time. A quench detection device for detecting a quench of a superconducting coil provided in a superconducting tokamak device, Measuring means installed in a normal bus bar for supplying current to the superconducting coil and measuring current flowing through the superconducting coil; And And a processing means for interpreting the measured value measured by the measuring means through a mathematical algorithm and outputting a final value. The coil current measuring device for detecting the quench of the superconducting tokamak device, comprising: a. The method of claim 11, wherein the processing means, A terminal connected with the measuring means; An amplifier receiving the voltage provided from the terminal; A digitizer for digitizing the voltage value provided by the amplifier; And A quench detection device for a superconducting tokamak device, comprising: a computer for detecting whether a quench is generated by analyzing a voltage value provided through the digitizer through mathematical modeling. The method of claim 11, wherein the measuring means, Coil current measurement device for quench detection of a superconducting tokamak device, characterized by using a Rogowski coil. The method of claim 11, wherein the measuring means, Equation

Coil current measuring device for detecting the quench of the superconducting tokamak device, characterized in that to calculate the measured value by integrating the voltage over time.

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