JPH0569400B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to an electron beam device, and is particularly applicable to a simulation test of heat flux to the wall of a nuclear fusion reactor due to the plasma disruption phenomenon that occurs in a nuclear fusion reactor. The present invention relates to the electron beam device used.

(Prior Art) It is known that plasma in a tokamak-type fusion reactor causes a disruption phenomenon due to its instability. When this plasma disruption phenomenon occurs, the problem is that a large amount of energy from the collapsed plasma is locally injected into a part of the first wall of the fusion reactor facing the plasma, causing thermal damage to the first wall. It is becoming. This plasma disruption phenomenon is a serious problem for nuclear fusion reactors, and it is extremely important to take measures against it in the future.
Therefore, we irradiated a specimen of the material used for the fusion reactor wall with an electron beam as a simulated heat source, and obtained a heat flux approximately equivalent to the heat flux administered by the plasma disruption phenomenon that occurs in an actual fusion reactor. It is being considered to apply so-called simulation tests to assess the wear and deterioration of the material caused by this. Because the disruption phenomenon occurs in an extremely short period of time, the electron beam equipment used in this test must have the ability to irradiate the specimen with a high-power electron beam for an extremely short period of time. I can list a few things. One method is to place a disk on the irradiation path of the electron beam, form a slit with a constant width in a part of the disk to allow the electron beam to pass through, and rotate the disk. The electron beam is passed through the slit for a time corresponding to the rotational speed of the slit and the width of the slit, and the specimen is irradiated with the electron beam. The second method is to place an energized deflection coil in the middle of the electron beam path to deflect the electron beam, and then cut off the current for a predetermined period of time to irradiate the electron beam onto the test piece. Third, the electron gun has a built-in mechanism for pulsing the electron beam, and the test piece is irradiated with the pulsed electron beam.

(Problems to be Solved by the Invention) In the above-mentioned simulation test, it is required to irradiate the test piece with a high-energy electron beam of 50 KW or more within a very short period of time, usually on the order of 1/100 seconds. In the electron beam device that uses the above-mentioned slit disk, in order to make the electron beam high energy as described above, the output is generated at the initial stage of generating the electron beam, that is, due to the electrical transient phenomenon within the electron beam generator. When the output has not reached a steady state, the electron beam is irradiated onto parts of the disk other than the slit to shield the specimen from irradiation, and the disk starts rotating after the electron beam reaches a steady state output. As a result, the disk is subject to significant wear and tear due to the electron beam, requiring frequent disk replacement. Moreover, as mentioned above, the irradiation time of the electron beam is required to be extremely short, so if we try to determine the rotational speed of the disk in advance from the speed at which the slit crosses the electron beam, There is a problem in that after the slit crosses the electron beam, the slit crosses the electron beam again due to its inertial force, resulting in more irradiation of the test piece than necessary. In addition, in an electron beam device employing the above-mentioned deflection coil, when the electron beam in the deflected state moves to the irradiation path, and when the electron beam that has moved to the irradiation path returns to the deflected state, the electron beam irradiates the test piece. There is a problem in that the electron beam is forced to pass through parts other than the necessary parts, leaving traces of the electron beam scanning on the test piece. In addition, since an electron beam requires a certain amount of time to reach a steady output from its generation, the electron beam device with the built-in panel mechanism has the problem of not being able to accurately impart heat flux for an extremely short period of time. There is. Therefore, when the various electron beam devices described above are used in the simulation test, the obtained results will include errors caused by the above.

This invention was made in order to eliminate the above-mentioned drawbacks, and its purpose is to irradiate an object with an electron beam with high precision, and to achieve nuclear fusion by the plasma disruption phenomenon that occurs in a nuclear fusion reactor. An object of the present invention is to provide an electron beam device that can be suitably used for a simulation test of surface heat flux to a furnace wall.

(Means for Solving the Problems) In the electron beam device of the present invention, the electron beam is placed on the irradiation path of the electron beam that irradiates the irradiation target 1 while vibrating vertically and horizontally within a plane perpendicular to the irradiation direction. The electron beam is placed on a deflection coil 4 that deflects the electron beam toward a dummy target 17, and a rotary disk 2 that rotates and blocks the electron beam is placed on the side of the irradiation object 1 by the deflection coil 4.
A passage slit 3 for allowing the electron beam to pass is formed in a part of the rotary disk 2, and the electron beam is irradiated onto the rotary disk 2 by canceling the deflection toward the dummy target 17 by the deflection coil 4, The apparatus is characterized in that it is provided with a control section for controlling the deflection coil 4 and rotary disk 2 so as to irradiate the object 1 with the electron beam through the passage slit 3 for a predetermined period of time.

(Function) In the electron beam device of the present invention, the electron beam is irradiated onto the irradiation target 1 only during the period when the passing slit 3 crosses the irradiation path of the electron beam. This allows stable electron beam irradiation. In this way, it is possible to irradiate the irradiation target with an electron beam with high precision, and therefore it can be suitably used for simulation tests of the heat flux to the fusion reactor wall due to the plasma disruption phenomenon that occurs inside the fusion reactor. It is.

(Embodiments) Next, specific embodiments of the electron beam apparatus of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an embodiment of the present invention. In the figure, 5 is an electron gun, and a test piece 1 as an object to be irradiated is placed at a position facing the irradiation port of the electron gun 5. A rotating disk 2 is arranged on the irradiation path connecting the electron gun 5 and the test piece 1 to block the irradiation of the electron beam. The central axis of this rotating disk 2 is offset from the irradiation path, so that the edge of the rotating disk 2 is located on the irradiation path. Rotating disk 2
A passing slit 3 is formed extending from the outer periphery toward the center, and the electron beam passes through the passing slit 3 when the passing slit 3 is located on the irradiation path. A shaft 6 is attached to this rotating disk 2, and this shaft 6 has a first gear 7 at its base end.
It has a second gear 8 at its tip. The shaft 6 is supported by a support frame 9 so as to be rotatable about an axis. The first gear 7 is the motor 1
0 pinion 11, and the second gear 8 is meshed with a timing gear 12. This timing gear 1
The diameter of the second gear 8 is set to be n (n>1) times the diameter of the second gear 8, so that when the second gear 8, that is, the rotating disk 2 rotates n times, the timing gear 12 rotates once. is being used. Note that the value of n is determined in consideration of the time it takes for the electron beam to reach a steady output after its generation. A long slit 13 and a short slit 1 extending parallel to the circumferential direction are provided at the edge of the timing gear 12.
4 is bored. Reference numeral 15 denotes a first optical sensor, and a light emitter and a light receiver constituting the first optical sensor are arranged opposite to each other so as to sandwich the short slit 14 from both sides. Reference numeral 16 designates a second optical sensor, which is also disposed opposite to each other so that its emitter and receiver sandwich the long slit 13 from both sides. The first optical sensor 15 has a short slit 1
4 is detected, a deflection release signal is sent to a first deflection coil, which will be described later. Further, when the second optical sensor 16 detects the long slit 13 at the time of starting the motor 10, it sends a non-irradiation signal to the electron beam irradiation circuit (not shown) of the electron gun 5. When the sensor 16 is removed, this signal is canceled. That is, in a state where the second optical sensor 16 detects the long slit 13, the time until the first optical sensor 15 detects the short slit 14 is short, and when electron beam irradiation is started in this state, This is an attempt to eliminate this problem since the test piece 1 is irradiated before the beam output reaches a steady state. Note that once the electron beam is generated, the electron beam irradiation circuit is self-maintaining;
Even if the second optical sensor 16 detects the long slit again, the electron beam irradiation does not stop. On the other hand, in the middle of the electron beam irradiation path and above the rotating disk 2, a first deflection coil 4 is arranged as an irradiation blocking means. This first deflection coil 4 is a first deflection coil 4 arranged to sandwich the irradiation path from both sides.
A magnetic pole coil is attached to each of a pair of parallel magnetic plates, and when energized, the electron beam is deflected in the direction shown by the solid line in FIG. Note that 17 is a dummy target that receives the deflected electron beam, and 18 is a metal vapor screen interposed between the dummy target 17 and the test piece 1. This metal vapor screen 18 is for preventing metal vapor generated by irradiating the dummy target 17 from moving toward the test piece 1 side.

By the way, the electron beam employed in this example has a substantially rectangular cross section and a substantially rectangular energy distribution within this cross section in order to facilitate later analysis regarding the application of heat with a predetermined heat flux to the test piece 1. Those that are uniform will be adopted. Electron beams usually have a circular cross section and an approximately Gaussian energy distribution in the radial direction, but by vibrating a focused electron beam at a high frequency, it is possible to obtain an electron beam with a rectangular cross section and a uniform energy distribution. I can do it. The electron gun 5, which will be described in detail below, is provided with a second deflection coil (not shown), and this second deflection coil beams the electron beam in one direction It has an X deflection coil that vibrates the electron beam back and forth, and a Y deflection coil that vibrates the electron beam back and forth in the direction Y perpendicular to the X direction. Triangular waves from both directions are superimposed to vibrate in each direction. As a result, the electron beam oscillates within a rectangular region having one side each having a length twice the amplitude in each direction. Moreover, since the vibration trajectories of the electron beams within a rectangular region have different frequencies, they can be regarded as almost random, and if the frequency of vibration of each beam in the X and Y directions is made sufficiently high, Therefore, the energy distribution becomes approximately uniform.
FIG. 2 schematically illustrates the vibration locus of the electron beam at the irradiation part of the test piece 1. In the figure, the amplitude in the X-axis direction and the amplitude in the Y-axis direction are the same, and the frequency in the X-axis direction is 0.9 of the frequency in the Y-axis direction.
It shows that it has been doubled.

Next, the operating state of the electron beam device will be described, and the following series of operations are performed by a control section (not shown). First, the first deflection coil 4
energize. Next, by driving the motor 10, the rotating disk 2 is rotated, and an electron beam is generated from the electron gun 5. At this time, the electron beam is deflected by the second deflection coil 4 and irradiates the dummy target 17. When part of the long slit 13 of the timing gear 12 is not located within the second optical sensor 16, this electron beam operates as follows. As the rotating disk 2 rotates, the timing gear 1
By the time the second short slit 14 enters the first optical sensor 15, the rotating disk 2 is at least m (1<m<n)
Rotate. During this time, the output of the electron beam will increase to a steady output. When the short slit 14 enters the first optical sensor 15, a deflection release signal is issued from the first optical sensor 15 to the first deflection coil 4, and the first deflection coil 4 is de-energized. As a result, the passing slit 3 is located at the front of the irradiation path, and the electron beam is in a state where the edge of the rotating rotary disk 2 in front of the passing slit 3 is irradiated. When the rotating disk 2 further rotates and the passing slit 3 is located on the irradiation path, the electron beam passes through the passing slit 3 and irradiates the test piece 1. Then, the passage slit 3 passes through the irradiation path,
When the electron beam starts to irradiate the edge of the rotating disk 2, the short slit 14 is removed from the first photosensor 15, and the second deflection coil 4 is energized to deflect the electron beam and irradiate the dummy target 17 again. It becomes like this. Thereafter, if the timing gear 12 makes one revolution again and the generation of the electron beam is stopped before the first optical sensor 15 detects the short slit 14, the test is completed.

On the other hand, a part of the long slit 13 is connected to the second optical sensor 1.
When the rotary disk 2 starts rotating while positioned within the electron beam 6, a non-irradiation signal is issued from the second optical sensor 16 to the irradiation circuit of the electron gun 5, and the electron gun 5 does not generate an electron beam. In other words, immediately after startup (while the electron beam output is rising),
This prevents the test piece 1 from being irradiated with the electron beam. In this case, the rotating disk 2 is connected to the motor 1
0 drive makes it idle. Then, in a state where the long slit 13 is removed from the second optical sensor 16, an electron beam is generated, and thereafter, the electron beam device is The operation will be similar to the operation.

In the above electron beam device, the electron beam irradiates the rotating disk 2 only for the time period during which the short slit 14 passes through the first photosensor 15, excluding the time during which the electron beam passes through the passing slit 3. Therefore, wear and tear on the rotating disk 2 due to the electron beam is reduced. In addition, the electron beam moves to the irradiation path with the passing slit located in front of the irradiation path, and is deflected at the position where the passing slit has passed the irradiation path. Scanning marks caused by the electron beam are only generated at the edges, but no scanning marks are left on the test piece 1.

Further, since the long slit 13 is provided in the timekeeping gear 12 and is detected by the second optical sensor 16, only the electron beam at a steady output can be passed through the passage slit 3.

As described above, this electron beam device is capable of irradiating test 1 with an electron beam with high accuracy both in terms of time and amount of heat, and as a result, it is possible to irradiate test 1 with an electron beam with high precision in terms of time and calorific value. It can be suitably used for simulation tests of heat flux to the walls of a fusion reactor.

Although the embodiments of the electron beam device of the present invention have been described above, the electron beam device of the present invention is not limited to the above embodiments, and can be implemented with various modifications within the scope of the present invention. It is. For example, in place of the clock gear 12 or the like in the above embodiment, another type of counter mechanism for the number of disk rotations may be employed.

Further, in the above embodiment, the rotating disk 2 is used as the rotating disk, but there is no need to limit it to a disk as long as it can shield the electron beam while rotating.

In addition, in the above embodiment, the predetermined time for blocking electron beam irradiation is defined as at least the time until the electron beam reaches a steady output, but when multiple test pieces are irradiated continuously, one It is also possible to define it as the time from irradiation of a test piece to irradiation of the next test piece.

(Effects of the Invention) The electron beam device of the present invention irradiates the object with the electron beam only during the period when the passing slit crosses the irradiation path of the electron beam. It can be irradiated with high precision in both heat and calorific value, and therefore can be suitably used for simulation tests of the surface heat flux to the fusion reactor wall due to the plasma disruption phenomenon that occurs within the fusion reactor.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of the electron beam apparatus of the present invention, and FIG. 2 is a schematic diagram of the vibration locus of the electron beam on the test piece 1 in the present invention. 1... Test piece (irradiation target), 2... Rotating disk, 3
...passing slit, 4...first deflection coil.

Claims (1)

[Claims] 1. A deflection coil 4 for deflecting the electron beam toward the dummy target 17 is arranged on the irradiation path of the electron beam that irradiates the irradiation target 1 while vibrating vertically and horizontally in a plane perpendicular to the irradiation direction, and A rotary disk 2 that blocks the electron beam while rotating is arranged at a position closer to the irradiation object 1 than the deflection coil 4, and a passage slit 3 that allows the electron beam to pass is formed in a part of the rotary disk 2. Then, by releasing the deflection toward the dummy target 17 by the deflection coil 4, the electron beam is directed to the rotary disk 2.
A control unit is provided for controlling the deflection coil 4 and the rotary disk 2 so as to irradiate the electron beam onto the object 1 through the passing slit 3 for a predetermined period of time. electron beam equipment.