JPS6124802B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tubular resistor constituting a concentric double circular tube, and particularly to a tubular resistor for adjusting the current change time constant of a current transformer coil in a power supply circuit of a tokamak-type nuclear fusion device. This invention relates to a concentric tubular resistor applied to a variable resistor.

In recent years, research and development of tokamak-type nuclear fusion devices has progressed, and as the devices have become larger, toroidal magnetic field coils for confining plasma have become increasingly important.
Various performances are required of the power supply circuit for inducing the plasma current. FIG. 1 shows an example of this type of power supply circuit. The power supply circuit in the figure includes a DC power supply 1 for current transformer coils, a DC power supply 2 for vertical magnetic field coils, an air-core current transformer coil 4, a vertical magnetic field coil 5, a two-stage plasma excitation energy storage coil 6,
7. Variable resistor 8 for adjusting the time constant of current transformer coil 4, capacitor 9 and resistor 10 for voltage increase rate control, switch 1 for circuit interruption and polarity switching
1. Circuit interrupting switches 12, 13, current backflow preventers 14, 1 for energy storage coils 6, 7
5, a switch 16 for turning on the variable resistor 8 and changing the set resistance value, a current backflow preventer 17 for the vertical magnetic field coil 5, and a switch 1 for turning on the DC power supply 2;
8. 3 in the circuit is a magnetic path showing the electromagnetic coupling state of the formed plasma obtained by the air-core current transformer coil 4 disposed close to the periphery of the vacuum vessel.

The functions required of a power supply circuit having such a configuration are induction of plasma current, subsequent maintenance, control, and stopping of the plasma current. In particular, the plasma current is stored as electromagnetic energy by passing a direct current through the air-core current transformer coil 4 in advance, and when it reaches a predetermined current, this current is rapidly cut off to generate an induced voltage in the plasma. A plasma current can be induced. For this reason, a multi-stage inductive energy storage method is adopted, and the energy stored in each stage in the energy storage coils 6 and 7 is several times.
It reaches up to 10MJ.

In a power supply circuit that requires such a function, the variable resistor 8 plays an important role in adjusting the time constant of the change in the current flowing through the current transformer coil 4 and changing the rise time of the plasma current. be. Therefore, apart from the number of variable stages, this type of variable resistor is required to have the following performance.

(1) For each resistance value to be set, the inductance distributed in the resistor must be small. For example, several 10μ
H or less is desirable.

(2) There is little change in resistance value after setting due to temperature rise of the resistor. It is desirable that the increase rate be less than 10%. Therefore, the material used for the resistor must be selected in consideration of the temperature coefficient.

(3) A resistor whose temperature has risen can be quickly cooled down to the temperature before energization during the power supply interruption period.

This means that the input current is 2 to 2 times every 5 to 10 minutes of rest time.
This is because it is necessary to consider that the pulse is repeatedly applied for 5 seconds.

Here, some common resistors include those combined with so-called grid resistors of an air type manufactured for laboratory use. However, when a large resistor is constructed using this type of resistor, the influence of reactance becomes large, and it is extremely difficult to satisfy each of the conditions (1) to (3) above. This method could not be applied to the variable resistor of the power supply circuit shown in FIG.

Therefore, conventionally, a resistor constructed of concentric double circular tubes as shown in a vertical cross-sectional view in FIG. 2 has been used. FIG. 3 is a cross-sectional view of the resistor shown in FIG. 2--line. In each figure, an inner tubular resistor (hereinafter simply referred to as the inner tube) 21 and an outer tubular resistor (hereinafter simply referred to as the outer tube) 22 are arranged concentrically with a predetermined gap d. An inner tube 21 and an outer tube 22 are electrically connected in series to the lower ends of both inner tubes and outer tubes,
Moreover, an end plate 23 is provided to make it liquid-tight. The inner tube 21 has an upper opening as a refrigerant inlet 30 and a refrigerant flow hole 24 in the lower tube wall, while the outer tube 22 has a refrigerant outlet 31 in the upper tube wall. Further, an inner tube terminal 28 is provided on the outer wall of the upper end of the inner tube 21, and an outer tube terminal 2 is provided on the outer wall of the upper end of the outer tube 22.
9 are each welded. In the figure, numerals 32 and 33 are insulating tubes for supplying and discharging refrigerant for connecting the resistor to a cooling device (not shown). When the resistor with the above configuration is used as a variable resistor in the power supply circuit shown in Figure 1, a large number of these resistors are combined and the resistance value is variably set by switching the connection between each resistor with a changeover switch. It's becoming like that.

Now, in the conventional tubular resistor constructed in this manner, current is applied from the inner tube terminal 28 as shown by the solid arrow, and passes from the inner tube 21 through the end plate 23 and the outer tube 22. , flows in the directions of arrows A and B via the outer tube terminal 29. As a result, the heat generated during energization causes the inner tube 21 and outer tube 22 to
temperature increases. In order to cope with this temperature rise, the refrigerant 34 is supplied from the inlet 30 as shown by the broken line arrow, returns through the inside of the inner tube 21 and the refrigerant flow hole 24, and then flows between the inner tube 21 and the outer tube 22.
The inner tube 21 and the outer tube 22 are cooled by passing through the gap and flowing in the directions of arrows C and D through the outlet 31.

However, in this type of cooling mechanism, the inner tube 21 and the outer tube 22 are damaged due to the heat generated every time electricity is applied.
A temperature difference occurs, which manifests as a difference in elongation of the resistor material, which adversely affects the resistance value. This phenomenon occurs because the inner tube 21 and the outer tube 22 are not cooled uniformly due to the difference in cooling area. That is,
Since the refrigerant flow is in a folded manner, the inner pipe 2
This is due to the fact that one of the inner walls of the outer tube 22 is forcedly cooled, while the inner and outer walls of the outer tube 22 are cooled.

In order to prevent such adverse effects, conventionally, an insulating member 26 is attached to the metal bellows 25 whose one end is fixed to the inner tube 21, and one end is further attached to the insulating member 26 to cover the upper end tube wall of the outer tube 22. Although the thermal expansion difference absorbing structure is provided with a metal sleeve 27 fixed to the metal sleeve 27, this results in a decrease in reliability with respect to insulation properties and liquid tightness. Moreover, the inner tube terminal 28
Since the outer tube terminal 29 and the inflow port 30 and inflow port 31 associated with the folded refrigerant flow are concentrated at the upper part of the resistor and protrude, when configuring a large number of variable resistors in combination, each Connection wiring between the resistors and cooling piping between each resistor and the cooling device were mixed together at the top, causing an unreasonable device configuration and operational inconvenience.

It is therefore an object of the present invention to eliminate the above-mentioned drawbacks and to
It is an object of the present invention to provide a concentric tubular resistor that easily suppresses the difference in thermal expansion between an inner tube and an outer tube caused by repeated energization and cooling, has low inductance, and has good cooling efficiency.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 is a longitudinal sectional view of a concentric tubular resistor showing an embodiment of the present invention. In the figure, the inner tube 21 and the outer tube 22 are arranged so that their cross-sectional areas are approximately equal.
They are arranged concentrically close to each other with a gap that does not pose a problem compared to the diameter of each pipe, which is about 4 to 6 mm, and considering the specific resistance value and non-magnetic material, the material is made of, for example, austenitic material. Use stainless steel pipe. An end plate 23 made of, for example, austenitic stainless steel and having a refrigerant outlet 31 at its lower end is joined by welding to the inner tube 21 and the outer tube 22.
are electrically connected in series, and the lower end of each tube is sealed liquid-tight. The inner tube 21 has a refrigerant inflow hole 42 in the upper tube wall near where the upper end of the outer tube 22 overlaps.
A partition wall 41 having an orifice-like hole is provided near the bottom of the inflow hole 42, and a refrigerant outflow hole 43 is similarly provided near the end plate 23 of the lower end tube wall.
A partition wall 41 having an orifice-like through hole is provided in the upper vicinity of the outflow hole 43 . Furthermore, a flange 36 is provided at the upper part of the inner tube 21.
However, flanges 37 are welded to the upper ends of the outer tubes 22, respectively. Each flange 36,
Between 37 are an insulating ring 38 and packings 39, 39 made of a material such as ceramics or FRP.
are inserted and tightened with insulating bolts 40, thereby creating a liquid-tight and insulating structure between the upper portions of the inner tube 21 and outer tube 22. Moreover, the refrigerant used here is a liquid such as transformer oil, and cooling water or the like with good insulation is selected.

Next, the action will be explained.

In the concentric tubular resistor having the configuration shown in FIG. 4, when energized, the current flows through the inner tube terminal 28, the inner tube 21, and the end plate 2 as shown by the solid arrows, as in FIG.
3. Arrow A through the outer tube 22 and outer tube terminal 29;
Flows in direction B. In this case, the inner tube 21 and the outer tube 22
Since they are arranged close to each other in a concentric manner, the magnetic fields generated in each cancel each other out, and the inductance becomes small.

By pressurizing the refrigerant at the inlet 30 side, the refrigerant flows from the inner tube 21 through the refrigerant inlet hole 42, the gap between the inner tube 21 and the outer tube 22, the refrigerant outlet hole 43, and the outlet 31 as shown by the dashed arrow. It flows in the direction of arrows C and D. At this time, a part of the refrigerant flows inside the inner tube 21 through the orifice-like holes in the upper and lower partition walls 41 and 41, and the refrigerant flowing through the gap between the inner tube 21 and the outer tube 22 and the outlet 31 and flows out. That is, this part of the refrigerant flows through the partition walls 41, 41.
The inner wall of the inner tube 21 is cooled in the same way as the outer wall of the outer tube 22 is cooled by a slight natural convection in the atmosphere. Cooling makes the flow of refrigerant smooth and prevents insulation deterioration.

In this way, in the concentric tubular resistor, the outer wall of the inner tube 21 and the inner wall of the outer tube 22 are forcibly cooled by the refrigerant flowing through the gap between the inner tube 21 and the outer tube 22. Therefore, the inner tube 21 and the outer tube 22
Since these have the same cross-sectional area and are arranged concentrically close to each other, their cooling areas are approximately equal, so the cooling effect is the same, and the temperature difference due to the heat generated when energizing is small. The difference in elongation can be kept small. Furthermore, since the refrigerant is made to flow in one direction, it is possible to create a structure in which the refrigerant inlet and outlet are separated into an upper end portion and a lower end portion.

Next, another embodiment of the present invention is shown in FIG. In this case, the concentric tubular resistor is the inner tube 21 in FIG.
Instead of the partition walls 41, 41, partition walls 44, 44 of a single plate structure without orifice-like through holes are used,
The space between the partition walls 44, 44 is constructed to be airtight. Since the other parts are the same as those shown in FIG. 4, the weight of the refrigerant that conventionally flows through the inner pipe 21 is reduced, and a variable resistance is created by combining a large number of such resistors. This structure has the advantage that the support structure can be simplified in terms of the device configuration.

As described above, according to the present invention, the inner tube and the outer tube having substantially the same cross-sectional area are arranged concentrically close to each other, and the refrigerant ports are provided at both ends so that the refrigerant flows in one direction. The concentric tubular shape has low inductance, and since the forced cooling area is equal, there is no problem of thermal expansion difference, improving cooling efficiency, improving insulation properties and reliability of liquid tightness, and improving workability. You can get resistors.

[Brief explanation of the drawing]

Figure 1 is a connection diagram showing an example of a power supply circuit for inducing plasma current in a tokamak-type nuclear fusion device, Figure 2 is a partial vertical cross-sectional view of a conventional concentric tubular resistor, and Figure 3 is a 4 is a partial vertical sectional view showing one embodiment of the concentric tubular resistor according to the present invention, and FIG. 5 is a partial vertical sectional view showing another embodiment of the present invention. It is a diagram. 4... Air core current transformer coil, 21... Inner tube, 22
... Outer pipe, 23 ... End plate, 24 ... Refrigerant flow hole,
25... Metal bellows, 26... Insulating member, 27
...Metallic sleeve, 28...Inner tube terminal, 29...
...Outer tube terminal, 30...Refrigerant inlet, 31...Refrigerant outlet, 36...Inner tube flange, 37...Outer tube flange, 38...Insulation ring, 39...Packing, 40...Insulation bolt, 41... Partition wall having an orifice-like passage hole, 42... Refrigerant inflow hole, 4
3... Refrigerant outflow hole, 44... Partition wall.

Claims (1)

[Scope of Claims] 1. In a concentric tubular resistor in which inner and outer tubular resistors are arranged concentrically and electrically connected in series, and the inside is forcibly cooled with a refrigerant, both ends of the inner tubular resistor a refrigerant inlet and a refrigerant outlet provided in the inner tubular resistor; a refrigerant inlet and a refrigerant outlet provided in the tube wall of the inner tubular resistor near both the refrigerant inlet and the outlet; A concentric tubular resistor comprising: partition walls provided near the refrigerant inlet and outlet holes inside the refrigerant, and a liquid-tight mechanism for the refrigerant, so that the refrigerant flows in one direction. vessel. 2. The concentric tubular resistor according to claim 1, wherein both the partition walls are provided with through holes for dividing the flow of the refrigerant.