JP2002141200A - Electron beam device - Google Patents

Abstract

(57) [Summary] An object of the present invention is to adjust a synchronization phase by changing an installation position of a bending electromagnet. An electron emitted from an electron gun is guided to a high-frequency acceleration cavity, the electrons are accelerated in the high-frequency acceleration cavity, and the accelerated electrons are deflected outside the high-frequency acceleration cavity. In the electron beam apparatus that obtains high energy by repeatedly deflecting the beam trajectory by 180 degrees by the electromagnet 2 and then re-entering and accelerating the beam into the high-frequency accelerating cavity a plurality of times, the bending electromagnet is changed to the high-frequency accelerating cavity. The distance between the two is adjusted to adjust the synchronization phase of the electron beam.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam apparatus for generating high-energy electrons by accelerating electrons emitted from an electron gun.

[0002]

2. Description of the Related Art As shown in FIGS. 7 (a) and 7 (b), an electron beam device converts electrons 4 emitted from an electron gun 5 into a vacuum duct 17 as shown in FIGS.
To the high-frequency acceleration cavity 1 to accelerate electrons in the high-frequency acceleration cavity 1 to generate high-energy electrons.
Then, the electrons accelerated by the high-frequency acceleration cavity 1 enter the bending electromagnet 2 from the high-frequency acceleration cavity 1 through the vacuum duct 17, where the trajectory is deflected by 180 degrees and then accelerated again in the high-frequency acceleration cavity 1. The operation is repeated many times to obtain high energy, thereby achieving compactness and good power efficiency.

In this case, an accelerating electrode 3 called a ridge is provided so as to protrude from the left and right sides of the electron trajectory in the cavity, and an accelerating electric field is created between them. The accelerating electric field is excited by a sine wave between the orbits as shown in FIG.
After being deflected by 180 degrees, it is accelerated if the electric field is turned in the opposite direction.

Here, if the distance that the beam moves during one reciprocation is adjusted, distance / beam speed (determined by energy) = time, and the beam can be well synchronized with the phase of the sine wave. For example, if the distance 1 from the orbit, the time t between the orbit, and the velocity v of the electron are represented by l / v = t.

As a conventional deflection electromagnet for deflecting the trajectory of a charged particle beam, a C-shaped deflection electromagnet as shown in FIG. 8 is used.

[0008] That is, in FIG. 8, reference numeral 18 denotes a return yoke, reference numeral 12 denotes a main magnetic pole provided at an open end of the return yoke 18, and reference numeral 11 denotes an exciting coil wound around the main magnetic pole.

In the charged particle beam orbit bending electromagnet having such a configuration, when a uniform magnetic field is excited in the direction shown in FIG. The center trajectory of the charged particle 20 draws a circular trajectory by receiving Lorentz force perpendicular to the traveling direction.

Here, the momentum of the beam is represented by P [Gev /
c], the deflection magnetic field intensity is B [T], and the deflection radius is ρ [m], there is a relationship of P∝Bρ. Therefore, when the energy of the beam is deviated, the deflection radius does not change and the beam trajectory does not change if the deflection magnetic field is changed.

If the bending magnet deflects the beam horizontally, the horizontal transport matrix is

(Equation 1) It is expressed as

[0010] As shown in FIG. 9 (a), the angle with respect to the incoming / outgoing beam at the end of the bending electromagnet 2 is called an edge angle 21, which has a function of converging and diverging the electrons 4.

Considering FIG. 9 (a), the electron 4a deviated outward from the orbital center is bent too much due to the edge angle because the area where the magnetic field is felt less than the electron at the orbital center (the time to pass through the magnetic field is shorter). I can't.

Conversely, the inner electrons 4b are bent (because the time for passing through the magnetic field is longer) than the electrons at the center of the orbit, and consequently work as a diverging effect. The edge angle transport matrix is given by

(Equation 2) It is. Accordingly, the deflection angle of the deflection electromagnet body cannot be changed because the beam is deflected by 180 degrees, but the convergence force of the deflection electromagnet can be changed by changing the edge angle ε.

In electron beam devices, in order to reduce the size, a bending electromagnet is often provided with a quadrupole magnetic field component for converging and diverging a beam. Although there is an effect, etc., since the ratio of the effect of deflection and convergence is determined by the magnetic pole shape, it cannot be adjusted after the bending electromagnet is manufactured.

Therefore, the bending electromagnet of the electron beam device has an edge angle 21 as shown in FIG.
A convergent force is imparted by generating a reverse magnetic field and deflecting the magnetic field by the main magnetic pole 12 by 180 degrees or more.

[0015]

As described above, the conventional electron beam apparatus requires an adjusting method and a mechanism for synchronizing the beam with the accelerating electric field of the cavity in order to optimize the output beam. In order to prevent the beam from diverging and spreading and being lost on the way, a mechanism for adjusting the convergence force is required. Also, a function of monitoring the position and size of the beam for actually confirming the divergence / convergence state of the beam is required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and it is possible to adjust the synchronization phase by changing the installation position of a bending electromagnet, and make the magnetic pole end portion of the bending electromagnet a simple assembly type. It is an object of the present invention to provide an electron beam device that can easily change a convergence force depending on an edge angle.

[0017]

According to the present invention, an electron beam apparatus is constituted by the following means in order to achieve the above object.

According to a first aspect of the present invention, electrons emitted from an electron gun are guided to a high-frequency accelerating cavity, the electrons are accelerated in the high-frequency accelerating cavity, and the accelerated electrons are transferred to the high-frequency accelerating cavity. By deflecting the beam trajectory by 180 degrees by a bending electromagnet provided outside of the above, by repeatedly entering the high-frequency accelerating cavity and accelerating the beam, a plurality of times,
In the electron beam apparatus for obtaining high energy, the bending electromagnet is provided so that the distance between the bending electromagnet and the high-frequency accelerating cavity is variable to adjust the synchronization phase of the electron beam.

According to a second aspect of the present invention, in the electron beam apparatus according to the first aspect of the present invention, the bending electromagnet is connected to a transmission mechanism driven by a remotely controlled motor, and is connected to the high-frequency accelerating cavity. The distance between them is made variable.

According to a third aspect of the present invention, an electron emitted from an electron gun is guided to a high-frequency acceleration cavity, the electrons are accelerated in the high-frequency acceleration cavity, and the accelerated electrons are transferred to the high-frequency acceleration cavity. By deflecting the beam trajectory by 180 degrees by a bending electromagnet provided outside of the above, by repeatedly entering the high-frequency accelerating cavity and accelerating the beam, a plurality of times,
In an electron beam device for obtaining high energy, an iron piece having a desired edge angle with respect to an incoming / outgoing beam is detachably attached to a magnetic pole end of the bending electromagnet so that a convergence force can be adjusted.

According to a fourth aspect of the present invention, an electron emitted from an electron gun is guided to a high-frequency acceleration cavity, the electrons are accelerated in the high-frequency acceleration cavity, and the accelerated electrons are transferred to the high-frequency acceleration cavity. By deflecting the beam trajectory by 180 degrees by a bending electromagnet provided outside of the above, by repeatedly entering the high-frequency accelerating cavity and accelerating the beam, a plurality of times,
In an electron beam apparatus for obtaining high energy, a sub-pole is integrally formed on an electron beam input / output end face side of a main pole of the deflection electromagnet, and a desired edge angle with respect to the input / output beam is formed at an inner end of the sub-magnetic pole. The convergence force can be adjusted by a configuration in which a magnetic pole portion having a magnetic pole area is detachably attached.

According to a fifth aspect of the present invention, an electron emitted from an electron gun is guided to a high-frequency acceleration cavity, the electrons are accelerated in the high-frequency acceleration cavity, and the accelerated electrons are transferred to the high-frequency acceleration cavity. By deflecting the beam trajectory by 180 degrees by a bending electromagnet provided outside of the above, by repeatedly entering the high-frequency accelerating cavity and accelerating the beam, a plurality of times,
In an electron beam device that obtains high energy, the return yoke of each bending electromagnet is cut out, and a vacuum duct extends outside the return yoke in the same direction as the direction of incidence of the electron beam. In this case, the beam current can be measured.

According to a sixth aspect of the present invention, an electron emitted from an electron gun is guided to a high-frequency accelerating cavity, the electrons are accelerated in the high-frequency accelerating cavity, and the accelerated electrons are transferred to the high-frequency accelerating cavity. By deflecting the beam trajectory by 180 degrees by a bending electromagnet provided outside of the above, by repeatedly entering the high-frequency accelerating cavity and accelerating the beam, a plurality of times,
In the electron beam device that obtains high energy, the return yoke of each bending electromagnet is cut out, the vacuum duct extends outside the return yoke in the same direction as the electron beam incident direction, and a measuring device using a fluorescent plate is provided at the outer protruding end of this vacuum duct. It is a thing.

[0024]

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

FIG. 1 is a sectional view showing a bending electromagnet according to a first embodiment of the electron beam apparatus according to the present invention. The entire structure is the same as that shown in FIG. Are denoted by the same reference numerals, and description thereof is omitted. Here, different portions will be described.

In the first embodiment, as shown in FIGS. 1 (a) (horizontal sectional view) and (b) (longitudinal sectional view), it is provided near the beam entrance / exit of the high-frequency acceleration cavity 1, and A vacuum duct 1 in which a portion corresponding to a portion between a bending electromagnet 2 for deflecting the trajectory of electrons entering and exiting the acceleration cavity 180 degrees from the inside and outside of the acceleration cavity by 180 degrees and each beam entrance / exit port on the back of the acceleration cavity 1 is constituted by a bellows 17a.
7 and a U-shaped fixing tool 9 is attached to the back of the bending electromagnet 2, and a threaded shaft 8 screwed into a screw hole of the fixing tool 9 is connected to the rotating shaft of the motor 7. Configuration.

In this case, the motor 7 can be started and stopped by remote control, as well as controlling the number of revolutions.

In the electron beam apparatus having such a configuration, the deflection electromagnet 2 is moved by the expansion and contraction of the bellows 17a of the vacuum duct 17 by rotating the shaft 8 having a thread groove such as a ball screw by the motor 7, so that the deflection electromagnet is rotated. 2 and the distance L between the back of the acceleration cavity 1 can be changed.

Therefore, since the length of the beam trajectory changes twice as much as the change in the distance between the accelerating cavity 1 and the bending electromagnet 2, the acceleration phase of the beam synchronized with the electric field of the accelerating cavity 1 can be easily adjusted. Can be adjusted. Further, since the motor 7 can be controlled by remote control, it is possible to adjust the acceleration phase even during operation. Since the direction of movement of the bending electromagnet 2 must exactly match the direction of incidence and emission of the electron beam 4, it is necessary to use a precise threaded shaft 8 and the like.

FIG. 2 is a cross-sectional view showing a bending electromagnet according to a second embodiment of the electron beam apparatus according to the present invention. The whole structure is the same as that of FIG. Are denoted by the same reference numerals, and description thereof is omitted. Here, different portions will be described.

In the second embodiment, FIGS. 2 (a) (longitudinal sectional view) and (b) (horizontal sectional view as viewed from BB in (a))
As shown in FIG. 2, an iron piece 10 having a desired edge angle with respect to an incoming / outgoing beam is attached to an end of a main magnetic pole 12 of a bending electromagnet 2 with a bolt made of a magnetic material (not shown).

With the electron beam apparatus having such a configuration, the edge angle ε in the transport matrix shown in the above-described equation (2) can be changed by attaching the iron piece 10.
The convergence force of the bending electromagnet 2 can be adjusted.

FIG. 3 shows a bending electromagnet according to a third embodiment of the electron beam apparatus according to the present invention. The entire structure is the same as that of FIG. 7 described in the conventional example. Are denoted by the same reference numerals and description thereof is omitted, and different portions will be described here.

In the third embodiment, as shown in FIGS. 3 (a) (longitudinal sectional view), (b) (horizontal sectional view viewed from CC in (a)), and (b) as shown in FIG. A secondary magnetic pole 13 is formed integrally with the main magnetic pole 12 on the electron beam input / output end face side of the second main magnetic pole 12, a sub coil 14 is wound around the sub magnetic pole 13, and a magnetic pole is formed on the inner end of the sub magnetic pole 13. The configuration is such that the portion 15 is fixed by bolting. In this case, the magnetic pole portion 15 is formed of an iron piece having a desired edge angle and a magnetic pole area with respect to the incoming / outgoing beam.

In the electron beam apparatus having such a configuration, the magnetic pole portion 15 made of an iron piece having a desired edge angle and a magnetic pole area is attached to the inner end of the sub-magnetic pole 13, so that the above-mentioned expression (2) is obtained. Since the edge angle ε in the transport matrix can be changed, the convergence force of the bending electromagnet 2 can be adjusted.

FIG. 4 is a sectional view showing a bending electromagnet according to a fourth embodiment of the electron beam apparatus according to the present invention. The entire structure is the same as that of the conventional example shown in FIG. Are denoted by the same reference numerals, and description thereof is omitted. Here, different portions will be described.

In the fourth embodiment, as shown in FIGS. 4 (a) (horizontal sectional view) and (b) (longitudinal sectional view), the return yoke 18 of each bending electromagnet 2 is notched and the vacuum duct 17 is returned. The structure extends in the same direction as the electron beam incident direction outside the yoke, and a measuring device using a current transformer 16 is provided at an outer protruding end of the vacuum duct 17.

This measuring device includes a current transformer 16 provided on an outer peripheral portion of a measuring duct 17b connected to a vacuum duct 17, a simulated load 22 with a cooling device attached to a rear end of the measuring duct 17b. It has.

In the electron beam apparatus having such a configuration, the deflection transformer 2 is de-energized and electrons are injected into the accelerating cavity, so that the beam transformer after passing through each accelerating cavity by the current transformer 16 is used. Can be measured.
The electron beam is cooled after being converted into heat by the simulated load 22 with a cooling device.

FIG. 5 is a sectional view showing a main part of an electron beam apparatus according to a fifth embodiment of the present invention. The entire structure is the same as that of FIG. Are denoted by the same reference numerals, and description thereof is omitted. Here, different portions will be described.

In the fifth embodiment, as shown in FIG. 5, the return yoke 18 of each bending electromagnet 2 is cut out, and the vacuum duct 17 extends outside the return yoke in the same direction as the electron beam incident direction. 17 is provided with a measuring device using a fluorescent screen 24 at the outer protruding end.

This measuring device comprises a fluorescent plate 23 which is provided at an electron incident position in a substantially Z-shaped measuring duct 17c connected to the vacuum duct 17 and which is inclined so that the fluorescent state can be observed from below. A mirror 24 provided at a lower position in the duct 17c to reflect the light emitting state of the fluorescent plate 23
And a measuring unit 25 for measuring a beam profile from the light emission state projected on the mirror 24.

With the electron beam apparatus having such a configuration, the deflection electromagnet 2 is de-energized to inject electrons into the accelerating cavity, so that the fluorescent plate 23 emits light when hit by the electron beam, and the mirror 24 emits light. The beam profile after passing through each acceleration gap can be measured by capturing the light emission position projected on the measuring section 25. Therefore, the shape of the electron beam can be diagnosed. Since the fluorescent plate 23 generates heat when irradiated with an electron beam, it is desirable to provide a cooling mechanism. The measuring unit 25 is not limited, such as a CCD camera or an industrial camera, as long as the distribution of light can be identified.

FIG. 6 is a cross-sectional view showing a main part of an electron beam apparatus according to a sixth embodiment of the present invention. The entire structure is the same as that of FIG. Are denoted by the same reference numerals, and description thereof is omitted. Here, different portions will be described.

In the sixth embodiment, as shown in FIG. 6, the return yoke 18 of each of the bending electromagnets 2 is cut out to extend the vacuum duct 17 outside the return yoke in the same direction as the electron beam incident direction. 17 is provided with a measuring device using a fluorescent screen 24 at the outer protruding end.

This measuring device calculates a beam profile from a perforated fluorescent plate 26 provided at a rear position in a linear measuring duct 17c connected to the vacuum duct 17 and a light emitting state of a hole peripheral portion of the fluorescent plate 26. Measuring unit 27 for measuring
And

According to the electron beam apparatus having such a configuration, by injecting electrons into the accelerating cavity with the bending electromagnet 2 in a non-excited state, the peripheral edge of the hole of the fluorescent plate 23 emits light. The beam profile after passing through each acceleration gap can be measured by the measurement by the measuring unit 27. Therefore,
The electron beam shape can be easily diagnosed.

In this case, the adjustment can be easily performed by setting the current of the bending electromagnet to an intermediate current value at which the diagonally opposite ends of the hole periphery of the fluorescent plate shine.

Further, since the perforated fluorescent plate 23 is used, it is possible to measure from the incident direction of the electron beam without measuring from below the fluorescent plate. It is desirable that the size of the hole of the fluorescent plate 23 be a size obtained in advance by a calculation simulation.

[0050]

As described above, according to the electron beam apparatus of the present invention, the synchronous phase of the accelerating electric field can be changed by changing the distance between the bending electromagnet and the cavity, and the edge angle of the bending electromagnet can be changed. By changing, it is possible to change the focusing power of the beam. By installing a current transformer, the current value can be measured. Further, it is possible to diagnose the beam shape by using a fluorescent plate. By combining these, the extraction beam can be optimized.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view showing a first embodiment of an electron beam device according to the present invention, and FIG. 1B is a cross-sectional view taken along line AA in FIG.

FIG. 2A is a sectional view showing a second embodiment of the electron beam device according to the present invention, and FIG. 2B is a sectional view taken along line BB in FIG.

3A and 3B show a bending electromagnet according to a third embodiment of the electron beam apparatus according to the present invention, wherein FIG. 3A is a side view, and FIG. 3B is a cross-sectional view taken along line CC of FIG.

4A and 4B show a bending electromagnet according to a fourth embodiment of the electron beam apparatus according to the present invention, wherein FIG. 4A is a cross-sectional view, and FIG. 4B is a cross-sectional view taken along line DD in FIG.

FIG. 5 is a sectional view showing a bending electromagnet in an electron beam device according to a fifth embodiment of the present invention.

FIG. 6 is a sectional view showing a bending electromagnet according to a sixth embodiment of the electron beam apparatus according to the present invention.

FIG. 7A is a sectional view showing a conventional electron beam apparatus,
(B) is a cross-sectional view taken along line XX of (a), and (c) is a time chart of an accelerating electric field excited between each orbit by a sine wave.

FIG. 8 is a sectional view showing a conventional bending electromagnet.

9A is a diagram for explaining an edge angle of a conventional bending electromagnet, and FIG. 9B is a cross-sectional view showing a bending electromagnet of a conventional electron beam device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cavity 2 ... Bending electromagnet 3 ... Acceleration electrode 4 ... Electron 5 ... Electron gun 7 ... Motor 7a ... Motor support stand 8 ... Shaft 9 ... Fixture 10 ... Iron piece 11 ... Coil 12 ... Main magnetic pole 13 ... Secondary magnetic pole 14 ... Sub-coil 15 Sub-pole magnetic pole part 16 Current transformer 17, 17b to 17d Vacuum duct 17a Bellows 18 Return yoke 19 Excitation direction 20 Positive charged particles 21 Edge angle 22 Simulated load with cooling device 23 Fluorescent plate 24 Mirror 25, 27 Measurement part 26 Perforated fluorescent plate

Claims (6)

[Claims] An electron emitted from an electron gun is guided to a high-frequency acceleration cavity, the electrons are accelerated in the high-frequency acceleration cavity, and the accelerated electrons are deflected outside the high-frequency acceleration cavity. By an electromagnet, after deflecting the beam trajectory by 180 degrees, repeating the injection and acceleration of the beam into the high-frequency acceleration cavity a plurality of times to obtain high energy, in the electron beam apparatus obtaining high energy, the deflection electromagnet is connected to the high-frequency acceleration cavity. An electron beam apparatus, wherein the distance between them is variably provided to adjust the synchronization phase of the electron beam. 2. The electron beam apparatus according to claim 1, wherein the bending electromagnet is connected to a transmission mechanism driven by a remotely controlled motor so as to change a distance between the bending electromagnet and the high-frequency acceleration cavity. An electron beam apparatus characterized by the above-mentioned. 3. An electron emitted from an electron gun is guided to a high-frequency accelerating cavity, the electrons are accelerated in the high-frequency accelerating cavity, and the accelerated electrons are deflected outside the high-frequency accelerating cavity. After deflecting the beam trajectory by 180 degrees by the electromagnet, the electron beam is re-incident into the high-frequency accelerating cavity and accelerated a plurality of times to obtain high energy. An electron beam apparatus wherein an iron piece having a desired edge angle with respect to an output beam is detachably attached to adjust a convergence force. 4. An electron emitted from an electron gun is guided to a high-frequency acceleration cavity, and electrons are accelerated by being incident on the high-frequency acceleration cavity, and the accelerated electrons are provided outside the high-frequency acceleration cavity. Beam trajectory by the bending magnet
After deflecting by 0 degrees, the electron beam is re-entered into the high-frequency accelerating cavity and accelerated a plurality of times to obtain high energy. That the magnetic pole is formed integrally, and that the convergence force can be adjusted by a structure in which a magnetic pole portion having a desired edge angle and a magnetic pole area is detachably attached to the inner end of the sub-magnetic pole with respect to the incident / emitted beam. Characteristic electron beam device. 5. An electron emitted from an electron gun is guided to a high-frequency acceleration cavity, the electrons are accelerated in the high-frequency acceleration cavity, and the accelerated electrons are deflected outside the high-frequency acceleration cavity. After deflecting the beam trajectory by 180 degrees by means of the electromagnet, the electron beam is again injected into the high-frequency accelerating cavity and accelerated a plurality of times to obtain high energy. An electron beam apparatus characterized in that a vacuum duct extends outside the return yoke in the same direction as the electron beam incident direction, and a measuring device using a current transformer is provided at an outer protruding end of the vacuum duct so that a beam current can be measured. 6. The high-frequency acceleration cavity guides electrons emitted from the electron gun to accelerate the electrons in the high-frequency acceleration cavity and deflects the accelerated electrons outside the high-frequency acceleration cavity. After deflecting the beam trajectory by 180 degrees by means of the electromagnet, the electron beam is again injected into the high-frequency accelerating cavity and accelerated a plurality of times to obtain high energy. An electron beam apparatus, wherein a vacuum duct extends outside the return yoke in the same direction as the electron beam incident direction, and a measuring device using a fluorescent plate is provided at an outer protruding end of the vacuum duct.