JPS5851636B2 - Plasma vacuum container tongue protection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for protecting a portion of a tongue of a plasma vacuum vessel used in a tokamak type nuclear fusion device.

A large current generated by plasma flows through the plasma vacuum vessel of a tokamak-type fusion device.

This large current flows in the circumferential direction of the vacuum vessel (if the vacuum vessel is considered as a ring, the circumferential direction along the ring), so there is usually one or more relatively large electric resistances in the vacuum vessel. By providing a portion of the tongue, a constant electric resistance can be obtained in the circumferential direction of the vacuum container.

However, when a sudden change in plasma current occurs in the plasma within the vacuum vessel, such as sudden plasma current extinction, a large induced current flows through the vacuum vessel.

In this case, a large current also flows through the tongue portion, generating an excessive electromagnetic force, and there is a risk that the relatively thin tongue portion may be deformed or damaged.

In addition, the current flowing through the thickness of the vacuum container is not uniform in the local direction (when considering the vacuum container as a ring, the circumferential direction around the axis of the members forming the ring), so this large induced current A current called a saddle current flows not only in the tongue part, but also in the flange of the tongue part in the direction of the small circumference of the vacuum vessel.

Since this saddle-shaped current interlinks with the toroidal magnetic field, an abnormal electromagnetic force is generated in the flange at a portion of the tongue, causing distortion or deformation of the flange.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a device for protecting the tongue portion of a plasma vacuum vessel, which keeps the electromagnetic force generated in the tongue portion of the plasma vacuum vessel below a predetermined value and prevents deformation and breakage of the tongue portion.

Next, the present invention will be described in accordance with an embodiment shown in the accompanying drawings.

FIG. 1 shows a plasma vacuum vessel 1 equipped with a tongue portion protection device of the present invention.

The vacuum container 1 is divided by, for example, four tongue portions 2 in the circumferential direction.

Each tongue part 2 consists of a bellows 3 and a bellows flange 4, each bellows flange 4 being connected to a vacuum vessel flange 5 of the vacuum vessel 1.

Each vacuum vessel flange 5 is provided with a first electrode 6.
A second electrode 7 and a third electrode 8 are provided at equal intervals in the circumferential direction of the vacuum capacity, and the first electrode 6. The second electrode 7 and the third electrode 8, and the first electrode 6° on the vacuum vessel flange 5 that faces the vacuum vessel flange 5 via the tongue portion 2. What are the second electrode 7 and the third electrode 8? They are located at positions facing each other in the circumferential cut direction.

In this way, the two electrodes that are opposed to each other in the circumferential direction with the tongue portion 2 in between are the first electrode pairs 9. A second electrode pair 10 and a third electrode pair 11 are configured.

To simplify the explanation, only one tongue part 2 is shown, but all the first electrode pairs 9 degrees and the second electrode pairs 10 degrees
A first switch circuit 12 is connected to the third electrode pair 11 and the third electrode pair 11, respectively.
．． A second switch circuit 13 and a third switch circuit 14 are connected in parallel to the tongue portion 2 in the circumferential direction.

Therefore, in the illustrated example, a total of 12 switch circuits are provided.

These switch circuits 12 to 14 respectively connect each electrode pair 9
, 10 and 11 is activated when a large potential difference exceeding a predetermined value occurs between the two electrodes 6, 6 or 7, 7 or 8, 8.

The switch circuits 12 to 14 are also provided in the vacuum vessel 1 and connected via a trigger generation circuit 16 so as to be operated by a plasma current sudden change detection device 15 such as a Rogowski coil that detects sudden changes in plasma current within the vacuum vessel. It is connected to a plasma current sudden change detection device 15.

The switch circuits 12 to 14 are further connected to each other so that when any one of them is actuated, the other two are immediately actuated, and at the same time the switch circuits 1 of the other set.
2 to 14 are also connected to operate them.

Therefore, when one switch circuit is activated, the other switch circuit is activated.
1 switch circuit is also activated.

FIG. 2 shows a first switch circuit 12, which is one of the switch circuits.

The first switch circuit 12 includes a pair of electrodes 6, 6 constituting a first electrode pair 9 connected to the bellows flange 4, and a first thyristor 17 and a first thyristor are connected in parallel between these electrodes, respectively.
A second thyrisk-18 and a resistor 19 are connected in antiparallel to the thyrisk-17.

The control poles of the first and second thyristors 17 and 18 are both connected to the output terminal of the OR circuit 20.

One of the two input terminals of the OR circuit 20 is connected to the plasma abnormality detection device 15 via the trigger pulse generation circuit 16.

The other input terminal is connected to the midpoint 21 of the resistor 19.

The output terminal of the OR circuit 20 is also connected to the second switch circuit 1, for example.
It is connected to the control pole of the thyristor of the other switch circuit No. 3.

The second switch circuit 13 and the third switch circuit 14 also
Furthermore, the other sets of switch circuits have substantially the same configuration as the first switch circuit 12 shown in FIG. When any one switch circuit is turned on, all other switch circuits are also turned on.

This relationship is electrically connected so that it holds true for all switch circuit groups connected between both ends of each flange 2.

The plasma vacuum container tongue portion protection device of the present invention constructed as described above operates as follows.

When the plasma in the plasma vacuum container is in a normal state, the protection device of the present invention does not operate and each switch circuit is open.

Therefore, although the current induced by the plasma flows in the circumferential direction along the wall of the vacuum chamber, it is kept below a predetermined value by the resistance of the tongue portion 2 and does not pose any particular problem.

When a sudden change in plasma current such as rapid extinction of plasma current occurs for some reason in the plasma confined in the plasma vacuum vessel, a large current flows in the direction of the circumferential gap in the tongue part 2, which has a relatively large electrical resistance. A large potential difference occurs between both ends of the tongue portion 2 in the global direction.

This potential difference also appears between both ends of the trigger voltage inducing resistor 19 of each switch circuit and between each end and the intermediate point 21, and a positive voltage signal is generated at the intermediate point 21.

Note that the positive voltage signal generated at the intermediate point 21 appears as a positive voltage regardless of which of the pair of electrodes has a higher potential.

This signal is supplied to an OR circuit 20, and the output of the OR circuit 20 is supplied to the control poles of the first thyristor 17 and the second thyristor to ignite the two thyristors 17 and 18, resulting in a potential difference in either direction. The switch is also in a closed state, that is, a conductive state.

Therefore, the potential difference generated between the ends of the bellows in the global direction becomes a current flowing through the switch circuit which is in a conductive state and disappears.

In this way, it is possible to prevent a large current from flowing through the vacuum container bellows.

The output of the OR circuit 20 is also connected to the control pole of the thyristor in the other switch circuits, so that if a signal is generated at the output terminal of the OR circuit 20 of any one switch circuit, all the other switches An ignition signal is also supplied to the thyristor in the circuit, making it conductive.

The occurrence of a sudden change in current in the plasma in the plasma vacuum vessel 1, such as sudden extinction of plasma current, may be detected before the detection of a large potential difference occurring between both ends of the tongue portion.

In this case, the sudden change in current is detected by a plasma current sudden change detection device 15 such as a Rogowski coil, which activates the trigger generation circuit 16 to apply a signal to the input terminal of the OR circuit 20, and sends a signal to the output terminal of Cyrisk-17 and 18. An ignition signal is generated.

In this case as well, that switch circuit becomes conductive, and at the same time, all of the remaining switch circuits also become conductive.

Further, even when a potential difference appears in the direction of the small circumference of the bellows flange portion and a so-called saddle type current attempts to flow, the current flows through another switch circuit 13 or 14 connected in parallel.

Therefore, in this case as well, the current in the small circumferential direction flows through the switching circuit to prevent extremely strong electromagnetic force from being applied to the bellows.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a plasma vacuum vessel tongue part protection device of the present invention, and FIG. 2 is a wiring diagram of the switch circuit shown in FIG. 1. 1... Plasma vacuum vessel, 2... Part of tongue, 12.13, 14... Switch circuit, 1
5... Plasma current sudden change detection device.

Claims (1)

[Claims] 1. A tongue portion of the plasma vacuum vessel is connected between both ends,
At least one switch circuit is provided that becomes conductive when a potential difference exceeding a predetermined value occurs between both ends of the tongue portion and short-circuits both ends of the tongue portion, and the switch circuit responds to a sudden change in plasma current. A device for protecting a part of a tongue of a plasma vacuum vessel, characterized in that the device is connected to a device for detecting sudden changes in plasma current so as to be in a conductive state. 2. In the plasma vacuum vessel tongue part protection device according to claim 1, the switch circuit is connected between both ends of the tongue part in parallel with each other and spaced apart from each other in a circumferential direction of the vacuum vessel. A plurality of switch circuits are electrically connected to each other so that when any one of the plurality of switch circuits becomes conductive, the remaining switch circuits simultaneously become conductive. Partial protection device for plasma vacuum container tongue. 3. In the plasma vacuum vessel tongue part protection device according to claim 2, each of the switch circuits includes a first thyristor connected between both ends of the tongue part, and the first thyristor. a second thyristor connected in antiparallel to the second thyristor, a resistor for inducing a trigger voltage connected in parallel to the second thyristor, an output terminal connected to the control pole of the first thyristor and the second thyristor;
A tongue portion of a plasma vacuum vessel characterized by comprising an OR circuit having a first input terminal connected to the midpoint of the resistor and a second input terminal connected to the plasma current sudden change detection device. Protective device.