JP2005085473A - Simultaneously accelerating cavity for a plurality of beam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To generate synchrotron radiations having sharp profiles by separating a plurality of electron beams to make them pass through uncombined tracks and separating a convergent magnet for converging each electron beam for every beam. <P>SOLUTION: Simultaneously accelerating cavity 120 for a plurality of beam of a linear accelerator 100 is composed by combining upper accelerating cavities 121, 123 and lower accelerating cavities 122, 124 combined altogether with coupled cavities 125, 126 at high frequencies. Convergent magnets 111, 113 are fitted around outer circumference of upper beam pipes 127, 129, and convergent magnets 112, 114 are fitted around outer circumference of lower beam pipes 128, 130. An accelerated electron beam B1 passes through a beam track in the upper accelerating cavities 121, 123, and a decelerated electron beam B2 passes through a beam track in the lower accelerating cavities 122, 124. Since the upper convergent magnets 111, 113 converge only accelerated beam B1 and the lower convergent magnets 112, 114 converge only decelerated beam B2, strength setting of the convergent magnets is made easy. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a multiple beam simultaneous acceleration cavity, and allows a plurality of electron beams to be accelerated or decelerated simultaneously while passing the plurality of electron beams in parallel.

  Synchrotron Radiation is a research tool that provides structural information at the atomic and electronic level as a research target in a wide range of fields such as biology, physics, chemistry, medicine, and engineering. In principle, this emitted light is generated as follows. That is, when a high-energy electron moves in a magnetic field, the electron receives a force toward the center of circular motion according to Fleming's left-hand rule, and the trajectory is bent. At this time, the electromagnetic wave is emitted in the tangential direction of the circular orbit of the electron so that the electromagnetic wave around the electron is shaken off. This emitted electromagnetic wave is called synchrotron radiation.

There is an energy recovery type accelerator as a device for generating synchrotron radiation. This energy recovery type accelerator will be described with reference to FIG. The electrons generated by the electron gun 1 are accelerated to a relatively low energy E _O by the incident accelerator 2 and input to the superconducting linear accelerator 3 to accelerate to a higher energy E. The accelerated electrons return to the superconducting linear accelerator 3 again through the trajectories 4, 5 and 6. The electrons that have orbited return to the superconducting linear accelerator 3 and other electrons generated by the electron gun 1 and accelerated by the incident accelerator 2 are input to the superconducting linear accelerator 3. When electrons pass through the circular orbit portions 4 and 6 and the straight orbit portion 5, emitted light is generated.

When the electrons return to the superconducting linear accelerator 3, the electrons are decelerated if the acceleration voltage is shifted by 180 ° from that during acceleration, and the electrons returned at the exit of the superconducting linear accelerator 3. The energy level returns to energy E _O , and the electrons are further decelerated by the decelerator 7 and then discarded by the beam dump 8. That is, each electron circulates only once.

  The energy consumed by the electrons during acceleration is recovered in the acceleration cavity when the electrons are decelerated by the superconducting linear accelerator 3, and used for accelerating the next electrons. For this reason, ideally, all of the energy input to the superconducting accelerator 3 is emitted as radiated light.

  By using the above-described energy recovery type accelerator, it is possible to realize a high-efficiency free electron laser system and a high-luminance and short-pulse radiation facility.

  Next, a conventional linear accelerator 10 constituting the superconducting linear accelerator 3 will be described with reference to FIG. A superconducting linear accelerator 3 shown in FIG. 8 is configured by connecting a large number (tens to hundreds) of the linear accelerators 10 in series.

  As shown in FIG. 9, in the conventional linear accelerator 10, the heat shield board 12 is arrange | positioned at the internal peripheral surface of the vacuum chamber 11 used as an exterior case. The heat shield plate 12 blocks radiant heat that enters the vacuum chamber 11 from the outside. A liquid helium tank 13 is disposed inside the vacuum tank 11.

  The accelerating cavity 14 and the accelerating cavity 15 formed of a superconducting material (for example, niobium) are linearly connected, and the internal spaces of the accelerating cavities 14 and 15 are connected to form a linear space. . The accelerating cavity 14 is a cavity resonator formed by connecting cells 14a to 14i in a hollow and flat spherical shape (just like a hollow “abacus ball”) in series. Is a cavity resonator formed by serially connecting cells 15a to 15i having hollow and flat spherical shapes. As will be described later, high-frequency power is supplied to the acceleration cavities 14 and 15, and standing waves are formed in the acceleration cavities 14 and 15 by a high-frequency electric field. The lengths of the cells 14a to 14i and 15a to 15i are equal to the length of the half wavelength (λ / 2) of the wavelength (λ) of the standing wave.

  The connected acceleration cavities 14 and 15 are disposed inside the liquid helium tank 13. Then, liquid helium is supplied to the space between the inner peripheral surface of the liquid helium tank 13 and the outer peripheral surfaces of the acceleration cavities 14 and 15. The acceleration cavities 14 and 15 are cooled by the liquid helium.

  A beam pipe 16 is connected to the left end (upstream end) of the acceleration cavity 14. The beam pipe 16 penetrates the left end surface of the liquid helium tank 13 and the left end surface of the vacuum tank 11 in a watertight and airtight state. ing. Similarly, a beam pipe 17 is connected to the right end (downstream end) of the accelerating cavity 15, and the beam pipe 17 connects the right end surface of the liquid helium tank 13 and the right end surface of the vacuum tank 11 in a watertight / airtight state. It penetrates with.

  A portion of the beam pipe 16 that protrudes outside the vacuum chamber 11 is provided with a converging magnet 18 on the input side, and a portion of the beam pipe 17 that protrudes outside the vacuum chamber 11 is disposed on the output side. A converging magnet 19 is mounted. The converging magnets 18 and 19 are each composed of a plurality of quadrupole magnets. The quadrupole magnet is a magnet having four magnetic poles of N pole, S pole, N pole, and S pole along the circumferential direction, and the two (upstream and downstream) quadrupole magnets are N poles along the circumferential direction. , The arrangement position of the S pole is shifted by 90 °, and the electron beam passing through the two quadrupole magnets is converged (strongly converged).

  A high frequency input coupler 20 formed of a coaxial waveguide supplies high frequency power to the acceleration cavity 14, and a high frequency input coupler 21 formed of a coaxial waveguide supplies high frequency power to the acceleration cavity 15. The high frequency power supplied to the accelerating cavities 14 and 15 via the high frequency couplers 20 and 21 is supplied from the same high frequency power supply, and both the high frequency powers have the same frequency and the phase is also adjusted. As a frequency of the high frequency power, for example, a frequency of 1.3 GHz is adopted.

  When high-frequency power is supplied to the accelerating cavities 14 and 15, a standing wave of an electric field having the same resonance frequency as the frequency of the high-frequency power is generated in the internal space of the accelerating cavities 14 and 15. Therefore, if the frequency of the high frequency power is, for example, 1.3 GHz, the resonance frequency of the standing wave of the electric field is also 1.3 GHz.

An accelerating electron beam B1 (shown by a black ellipse in the figure) sent from the incident accelerator (see FIG. 8) is input to the beam pipe 16 and passes through the beam pipe 16, and the focusing magnet 18 And travel straight through the internal space of the accelerating cavities 14 and 15, output to the utilization system via the beam pipe 17, and converged by the converging magnet 18 when passing through the beam pipe 17.
The decelerating electron beam B2 (shown by a white ellipse in the figure) recovered from the utilization system is input to the beam pipe 16 and is converged by the converging magnet 18 when passing through the beam pipe 16 to be accelerated. 14, 15 travels straight through the cavity internal space, is output toward the beam dump (see FIG. 8) via the beam pipe 17, and is converged by the focusing magnet 18 when passing through the beam pipe 17.

  In addition, in the cavity internal spaces of the acceleration cavities 14 and 15, the acceleration electron beam B1 and the deceleration electron beam B2 alternately go straight on the same track. The phases of the accelerating electron beam B1 and the decelerating electron beam B2 are shifted straight by 180 ° alternately.

  The accelerating electron beam B1 is accelerated by a standing wave formed in the cavity internal space, and the decelerating electron beam B2 is 180 ° out of phase with the accelerating electron beam B1 (ie, the phase with respect to the standing wave). Therefore, the energy of the decelerated portion is given to the standing wave. In other words, the standing wave decelerates the deceleration electron beam B2, thereby recovering the energy of the deceleration electron beam B2. The recovered energy is used to accelerate the acceleration electron beam B1. Since energy is recovered in this way, less high-frequency power is input.

Here, the reason why the electron beams B1 and B2 must be converged by the converging magnets 18 and 19 will be described.
Since each of the electron beams B1 and B2 is a collection of a large number of electrons, electrons having the same electrical characteristics (negative polarity) repel each other, and the electron beams B1 and B2 tend to spread due to the repulsive force. If the electron beams B1 and B2 spread greatly, electrons constituting the electron beam collide with the wall surfaces of the beam pipes 16 and 17 or the acceleration cavities 14 and 15, and acceleration and deceleration cannot be performed.
In order to suppress such spread of the electron beams B1 and B2, the converging magnets 18 and 19 converge the electron beams B1 and B2. Therefore, the electron beams B1 and B2 can pass through the cavity internal space without colliding with the wall surfaces of the acceleration cavities 14 and 15.

"Research report on future plans of synchrotron radiation-ERL light source and utilization research-" Published by High Energy Accelerator Research Organization March 2003 P1-P6, P128-P129

By the way, the strength of the focusing magnets 18 and 19 (the strength of the generated magnetic field) is optimized by the energy of the electron beam.
However, in the conventional linear accelerator 10 shown in FIG. 9, the accelerating electron beam B1 and the decelerating electron beam B2 alternately go straight on the same orbit in the cavity internal space of the accelerating cavities 14 and 15. Therefore, the acceleration electron beam B1 has a small energy because it is before acceleration on the upstream side (focusing magnet 18 side), and has a large energy because it is after acceleration on the downstream side (focusing magnet 19 side). The beam B2 has a high energy because it is before deceleration on the upstream side (convergence magnet 18 side), and has a low energy because it is after deceleration on the downstream side (convergence magnet 19 side).
That is, the acceleration electron beam B1 having a small energy and the deceleration electron beam B2 having a large energy pass at the position of the focusing magnet 18, and the acceleration electron beam B1 having a large energy and the deceleration electron beam B2 having a small energy are transmitted at the position of the convergence magnet 19. Pass through.
Furthermore, in order to sharpen the profile (temporal and spatial distribution shape) of the emitted light, it is required to suppress the spread of the accelerated electron beam B1 after acceleration as much as possible.

As a result, the focusing magnets 18 and 19 must converge the electron beams B1 and B2 having different energies while aiming to obtain a radiated light having a sharp profile, so that the intensities of the focusing magnets 18 and 19 are optimized. It was very difficult to set up.
In reality, priority is given to the fact that the electron beams B1 and B2 having different energies can pass through the cavity internal space without colliding with the wall surfaces of the acceleration cavities 14 and 15, so that the degree of convergence of the accelerated electron beam B1 after acceleration is slightly higher. In some cases, the radiation profile may be sacrificed to some extent.

In view of the above-described prior art, the present invention provides a multiple beam simultaneous acceleration cavity that allows a plurality of electron beams to pass in parallel to simultaneously accelerate or decelerate each electron beam.
It is an object of the present invention to make it possible to easily perform the optimum design of a converging magnet and to generate radiant light having a sharp profile.

In the configuration of the present invention that solves the above problem, when high frequency power is supplied, a standing wave of a monopole mode electric field in which one pole that maximizes the electric field in the beam traveling direction is formed in the cavity internal space. And a plurality of acceleration cavities connected to the ends of beam pipes around which the focusing magnets are mounted,
The acceleration cavities are arranged in parallel, and the acceleration cavities arranged in parallel are connected by a coupling cavity.

In addition, the configuration of the present invention has an acceleration cavity in which a standing wave of a multipole mode electric field is formed in a cavity internal space where a plurality of poles that maximize the electric field in the beam traveling direction are formed when high-frequency power is supplied. And
A plurality of beam pipes around which converging magnets are mounted are connected to the end of the acceleration cavity, and the number of beam pipes is the same as the number of poles, and the position where each beam pipe is connected is It is characterized in that it is aligned with the position where the pole of the electric field is formed.

Further, the configuration of the present invention forms a standing wave of a monopole mode electric field in which one pole maximizing the electric field in the beam traveling direction is formed in the cavity internal space when high-frequency power is supplied, and the focusing magnet The beam pipe to be mounted has a plurality of acceleration cavities connected to the ends,
The acceleration cavities are arranged in parallel, and each acceleration cavity is formed by connecting a plurality of cells in series. Adjacent acceleration cavities arranged in parallel are each of one of the adjacent acceleration cavities. The cell is connected to each cell of the other acceleration cavity adjacent to the cell.

  In the present invention, since a plurality of electron beams can be separated and passed in parallel, a converging magnet for converging each electron beam can be separated for each electron beam. As a result, the strength of the focusing magnet can be easily set. Further, it is possible to generate radiated light having a sharp profile.

  In the present invention, a plurality of parallel beam trajectories are formed inside the multiple beam simultaneous acceleration cavity, and a plurality of electron beams are separated and passed along each beam trajectory. In this way, by separating a plurality of electron beams and passing them parallel to the inside of the multiple beam simultaneous acceleration cavity, a converging magnet for converging each electron beam can be installed separately for each electron beam.

  A linear accelerator 100 using a multiple beam simultaneous acceleration cavity according to a first embodiment of the present invention will be described with reference to FIG. As shown in the figure, a heat shield plate 102 is disposed on the inner peripheral surface of the vacuum chamber 101, and a liquid helium chamber 103 is disposed inside the vacuum chamber 101. In addition, high-frequency input couplers 104 and 105 formed of coaxial waveguides are provided. The configuration so far is the same as that of the conventional linear accelerator 10 shown in FIG.

  In the present embodiment, the multiple beam simultaneous acceleration cavity 120 having a special structure is disposed inside the liquid helium tank 103, and the inner peripheral surface of the liquid helium tank 103 and the outer peripheral surface of the multiple beam simultaneous acceleration cavity 120 are Liquid helium for cooling is supplied to the space between the two. The multiple beam simultaneous acceleration cavity 120 is made of a superconductive material (for example, niobium).

  The multiple beam simultaneous acceleration cavity 120 includes four acceleration cavities 121, 122, 123, and 124. Each of the accelerating cavities 121 to 124 is a cavity resonator formed by connecting a plurality of cells in a hollow and flat spherical shape (just like a hollow “abacus ball”) in series, The length of the cell (length in the axial direction) is equal to the length of the half wavelength (λ / 2) of the wavelength (λ) of the standing wave of the electric field formed in the cavity internal space.

  The acceleration cavity 121 and the acceleration cavity 122 on the left side (upstream side) are arranged in parallel, and both the acceleration cavities 121 and 122 are coupled (coupled) “high-frequency” via the coupling cavity 125. Further, with respect to the longitudinal direction (axial direction) of the acceleration cavities 121 and 122, the position (phase) of each cell forming the acceleration cavity 121 and the position (phase) of each cell forming the acceleration cavity 122 coincide with each other. The acceleration cavities 121 and 122 are arranged in parallel.

Here, the meaning that the coupling cavity 125 couples the acceleration cavities 121 and 122 “high-frequency” will be described.
This is because, when the accelerating cavities 121 and 122 are coupled by the coupling cavities 125, the resonance frequency of the standing wave of the electric field formed in the internal space of each accelerating cavity is not coupled to each of the accelerating cavities 121 and 122 alone. This means that the coupling cavities 125 whose shapes and sizes are designed so as to be equal to the resonance frequency of the standing wave of the electric field formed in each of the cavity internal spaces. Note that the coupling cavity 125 may be disposed at any position.

  Similarly, the right (downstream) acceleration cavity 123 and the acceleration cavity 124 are arranged in parallel, and both acceleration cavities 123 and 124 are coupled (coupled) “high-frequency” via the coupling cavity 126. . Further, with respect to the longitudinal direction (axial direction) of the acceleration cavities 123 and 124, the position (phase) of each cell forming the acceleration cavity 123 and the position (phase) of each cell forming the acceleration cavity 124 are matched. Acceleration cavities 123 and 124 are arranged in parallel. The meaning of “high-frequency” coupling is the same as described above.

  Further, the upper accelerating cavity 121 and the accelerating cavity 123 are linearly connected, and the internal spaces of the accelerating cavities 121 and 123 are connected to form a linear space. Similarly, the lower accelerating cavity 122 and the accelerating cavity 124 are linearly connected, and the internal spaces of the accelerating cavities 122 and 124 are connected to form a linear space.

A beam pipe 127 is connected to the left end (upstream end) of the acceleration cavity 121. The beam pipe 127 penetrates the left end surface of the liquid helium tank 103 and the left end surface of the vacuum tank 101 in a watertight and airtight state. ing. A converging magnet 111 that is a quadrupole magnet is provided around the portion of the beam pipe 127 that protrudes outside the vacuum chamber 101.
A beam pipe 128 is connected to the left end (upstream end) of the acceleration cavity 122. The beam pipe 128 penetrates the left end surface of the liquid helium tank 103 and the left end surface of the vacuum tank 101 in a watertight and airtight state. ing. A converging magnet 112 that is a quadrupole magnet is provided around the portion of the beam pipe 128 that protrudes outside the vacuum chamber 101.

A beam pipe 129 is connected to the right end (downstream end) of the acceleration cavity 123, and this beam pipe 129 penetrates the right end surface of the liquid helium tank 103 and the right end surface of the vacuum tank 101 in a watertight and airtight state. ing. A converging magnet 113 that is a quadrupole magnet is provided around the portion of the beam pipe 129 that protrudes outside the vacuum chamber 101.
A beam pipe 130 is connected to the right end (downstream end) of the acceleration cavity 124, and the beam pipe 130 penetrates the right end surface of the liquid helium tank 103 and the right end surface of the vacuum tank 101 in a watertight and airtight state. ing. A converging magnet 114 that is a quadrupole magnet is provided around the portion of the beam pipe 130 that protrudes outside the vacuum chamber 101.

  High frequency (for example, 1.3 GHz) high frequency power is supplied to the upstream (left side) acceleration cavities 121 and 122 and the coupling cavity 125 via the high frequency input coupler 104, and the downstream (right side) acceleration cavities 123 and 124 are supplied. The coupling cavity 126 is supplied with high frequency power (for example, 1.3 GHz) via the high frequency input coupler 105. The high frequency power input through the high frequency input couplers 104 and 105 is supplied from the same high frequency power supply, and both the high frequency powers have the same frequency and the phase is adjusted.

  For this reason, a standing wave of an electric field having a resonance frequency (for example, 1.3 GHz) that is the same as the frequency of the high-frequency power is generated in the cavity internal space of the upper acceleration cavities 121 and 123, and the lower acceleration cavity 122. , 124 also generates a standing wave of an electric field having the same resonance frequency (eg, 1.3 GHz) as the frequency of the high-frequency power, and a standing wave generated in the upper cavity internal space. The phase of the standing wave generated in the inner space of the lower cavity is exactly 180 ° shifted. Furthermore, the standing wave of the electric field generated in the internal space of each of the accelerating cavities 121, 122, 123, and 124 is in a monopole mode in which one pole that maximizes the electric field is formed.

  In the linear accelerator 100 having such a configuration, the acceleration electron beam B1 is accelerated through the cavity internal space of the upper acceleration cavities 121 and 123, and the deceleration electron beam B2 is cavities of the lower acceleration cavities 122 and 124. Decelerate through the internal space. That is, the accelerating electron beam B1 and the decelerating electron beam B2 are separated and go straight along another orbit.

  That is, the acceleration electron beam B1 (shown by a black oval in the figure) sent from the incident accelerator (see FIG. 8) is input to the beam pipe 127 and converges when passing through the beam pipe 127. The beam is converged by the magnet 111, travels straight in the internal space of the upper acceleration cavities 121 and 123, is output to the utilization system via the beam pipe 129, and is further converged by the focusing magnet 113 when passing through the beam pipe 129. .

  Further, the decelerating electron beam B2 collected from the utilization system (indicated by a white oval in the figure: the phase is shifted by 180 ° with respect to the accelerating electron beam B1) is input to the beam pipe 128, and this When passing through the beam pipe 128, it is converged by the converging magnet 112, goes straight through the cavity internal space of the lower acceleration cavities 122, 124, and is output toward the beam dump (see FIG. 8) via the beam pipe 130, In addition, the beam is converged by the focusing magnet 114 when passing through the beam pipe 130.

  Since the cavity internal spaces of the upper acceleration cavities 121 and 123 and the cavity internal spaces of the lower acceleration cavities 122 and 124 are coupled at high frequencies by the coupling cavities 125 and 126, the deceleration electron beam B2 is decelerated. Thus, the energy recovered in the lower cavity internal space is used when the accelerated electron beam B1 is accelerated in the upper cavity internal space.

  In this embodiment, only the acceleration electron beam B1 passes through the cavity internal spaces of the upper acceleration cavities 121 and 123. Therefore, the accelerating electron beam B1 collides against the cavity wall surface, while the upper accelerating electron beam converging magnets 111 and 113 aim to obtain a radiated light with a sharp profile by suppressing the spread of the accelerating electron beam B1 as much as possible. Since it is only necessary to converge the acceleration electron beam B1 so that it can go straight in the cavity internal space of the upper acceleration cavities 121 and 123, the optimum intensity of the focusing magnets 111 and 113 can be easily set. As a result, it is possible to generate radiated light having a sharp profile.

  Further, only the decelerating electron beam B2 passes through the cavity internal spaces of the lower acceleration cavities 122 and 124. For this reason, the lower decelerating electron beam converging magnets 112 and 114 are arranged so that the decelerating electron beam B2 can go straight in the cavity internal space of the lower accelerating cavities 122 and 124 without colliding with the cavity wall surface. Since only B2 needs to be converged, the optimum strength of the converging magnets 112 and 114 can be easily set.

  Eventually, in the multiple beam simultaneous acceleration cavity 120 used in the first embodiment, the acceleration electron beam B1 and the deceleration electron beam B2 are allowed to pass along different parallel trajectories, and the acceleration electron beam B1 is accelerated and simultaneously the deceleration electron beam. B2 can be decelerated. Therefore, the converging magnets 111 and 113 for the accelerating electron beam and the converging magnets 112 and 114 for the decelerating electron beam can be separated, and the strength of the converging magnets 111 and 113 for the accelerating electron beam and the decelerating electron beam The strength of the converging magnets 112 and 114 can be optimally set individually and easily.

  A linear accelerator 100A using a multiple beam simultaneous acceleration cavity according to a second embodiment of the present invention will be described with reference to FIG. As shown in the figure, a heat shield plate 102 is disposed on the inner peripheral surface of the vacuum chamber 101, and a liquid helium chamber 103 is disposed inside the vacuum chamber 101. In addition, high-frequency input couplers 104 and 105 formed of coaxial waveguides are provided. Moreover, the convergence magnets 111-114 are provided. The configuration so far is the same as that of the linear accelerator 100 shown in FIG.

  In the present embodiment, the multiple beam simultaneous acceleration cavity 200 having a special structure is arranged inside the liquid helium tank 103, and the inner peripheral surface of the liquid helium tank 103 and the outer peripheral surface of the multiple beam simultaneous acceleration cavity 200 are Liquid helium for cooling is supplied to the space between the two. The multiple beam simultaneous acceleration cavity 200 is formed of a superconductive material (for example, niobium).

  The multiple beam simultaneous acceleration cavity 200 is configured by linearly connecting an acceleration cavity 201 and an acceleration cavity 202, and the cavity internal spaces of the acceleration cavities 201 and 202 are connected. Each acceleration cavity 201, 202 is hollow and flat when viewed in a longitudinal section (when viewed in the state shown in FIG. 2) (just like the shape of an “abacus ball”). The cavity resonator is formed by connecting a plurality of cells connected in series, and the length of each cell (axial length) is half the wavelength (λ) of the standing wave of the electric field formed in the cavity internal space. It is equal to the length of the wavelength (λ / 2).

  Moreover, as shown in FIG. 3B, which is a III-III cross section of FIG. 2, the accelerating cavity 201 (202) is elliptical or flat when viewed in cross section, and the high frequency input coupler 104 , 105, high-frequency power (for example, power having a frequency of 1.3 GHz) is supplied to the accelerating cavities 201 and 202, as shown in FIGS. Then, a standing wave (resonance frequency is, for example, 1.3 GHz) of a dipole mode (TM110 mode) electric field in which two poles that maximize the electric field in the beam traveling direction are generated. In the case of this figure, the electric field of the first pole and the electric field of the second pole are 180 degrees out of phase. By adjusting the shape of the cavity, it is possible to realize a mode in which there is no phase difference between the first pole and the second pole when high-frequency power having the same frequency is supplied. This mode can be regarded as a mode formed by combining two cavities, but such a mode can be used in principle.

  At this time, since the acceleration cavities 201 and 202 are elliptical or flat when viewed in cross section, the positions where the poles can be formed are constant in the circumferential direction. As a result, along the longitudinal direction (axial direction) of the accelerating cavities 201 and 202, the first pole formed in each cell is aligned to form the first beam trajectory, and the second pole formed in each cell. Are aligned in a row to form a second beam trajectory.

  In the first embodiment shown in FIG. 1, a monopole mode standing wave is generated in each cavity internal space of each of the accelerating cavities 121 to 124, with one pole having the maximum electric field. .

Returning to FIG. 2 and continuing the description, a beam pipe 203 is connected to a portion of the left end portion (upstream end) of the acceleration cavity 201 located in the first beam trajectory, and this beam pipe 203 is liquid helium. The left end surface of the tank 103 and the left end surface of the vacuum chamber 101 are penetrated in a watertight and airtight state. A converging magnet 111 that is a quadrupole magnet is provided around the portion of the beam pipe 203 that protrudes outside the vacuum chamber 101.
A beam pipe 204 is connected to a portion of the left end portion (upstream end) of the acceleration cavity 201 located in the second beam trajectory. The beam pipe 204 is connected to the left end surface of the liquid helium tank 103 and the vacuum chamber 101. It penetrates the left end surface of the watertight and airtight state. A converging magnet 112 that is a quadrupole magnet is provided around the portion of the beam pipe 204 that protrudes outside the vacuum chamber 101.

A beam pipe 205 is connected to a portion of the right end portion (downstream end) of the acceleration cavity 202 located in the first beam trajectory, and the beam pipe 205 is connected to the right end surface of the liquid helium tank 103 and the vacuum tank 101. It penetrates the right end surface in a watertight and airtight state. A converging magnet 113, which is a quadrupole magnet, is mounted on the portion of the beam pipe 205 that protrudes outside the vacuum chamber 101.
A beam pipe 206 is connected to a portion of the right end portion (downstream end) of the acceleration cavity 124 located in the second beam trajectory. The beam pipe 206 is connected to the right end surface of the liquid helium bath 103 and the vacuum chamber 101. It penetrates the right end surface of the watertight and airtight state. A converging magnet 114 that is a quadrupole magnet is provided around the portion of the beam pipe 206 that protrudes outside the vacuum chamber 101.

  In the linear accelerator 100A having such a configuration, the acceleration electron beam B1 is accelerated along the first beam trajectory in the cavity internal space of the acceleration cavities 201 and 202, and the deceleration electron beam B2 is accelerated. It decelerates along the second beam trajectory in the hollow space of 201, 202. That is, the accelerating electron beam B1 and the decelerating electron beam B2 are separated and traveled straight along different (first and second) beam trajectories in the same cavity internal space.

  That is, the acceleration electron beam B1 (shown by a black oval in the figure) sent from the incident accelerator (see FIG. 8) is input to the beam pipe 203 and converges when passing through the beam pipe 203. When the beam is converged by the magnet 111, travels straight along the first beam trajectory in the cavity internal space of the acceleration cavities 201 and 202, is output toward the utilization system via the beam pipe 205, and passes through the beam pipe 205. Is converged by the converging magnet 113.

  Further, the decelerating electron beam B2 collected from the utilization system (indicated by a white oval in the figure: the phase is shifted by 180 ° with respect to the accelerating electron beam B1) is input to the beam pipe 204, and this When passing through the beam pipe 204, the beam is converged by the focusing magnet 112, travels straight along the second beam trajectory in the cavity internal space of the acceleration cavities 122 and 124, and passes through the beam pipe 206 to the beam dump (see FIG. 8). And is converged by the converging magnet 114 when passing through the beam pipe 206.

  Since the first beam trajectory and the second beam trajectory are in the cavity internal space of the accelerating cavities 201 and 202 (the same cavity internal space), the decelerated electron beam B2 is decelerated to be recovered in the second beam orbit. The energy obtained is used when accelerating the accelerating electron beam B1 in the first beam trajectory.

  In this embodiment, only the acceleration electron beam B1 passes through the first beam trajectory in the cavity internal spaces of the acceleration cavities 201 and 202. For this reason, the accelerating electron beam B1 collides against the cavity wall surface while the converging magnets 111 and 113 for the accelerating electron beam aim to obtain the radiated light having a sharp profile by suppressing the spread of the accelerating electron beam B1 as much as possible. Since the accelerating electron beam B1 only needs to be converged so that it can travel straight along the first beam trajectory in the internal space of the accelerating cavities 201 and 202, the optimum intensity of the converging magnets 111 and 113 can be easily set. it can. As a result, it is possible to generate radiated light having a sharp profile.

  Further, only the decelerating electron beam B2 passes through the second beam trajectory in the cavity internal spaces of the acceleration cavities 201 and 202. Therefore, the decelerating electron beam converging magnets 112 and 114 decelerate electrons so that the decelerating electron beam B2 can go straight along the second beam trajectory in the cavity inner space of the accelerating cavities 201 and 202 without colliding with the cavity wall surface. Since only the beam B2 needs to be converged, the optimum strength of the converging magnets 112 and 114 can be easily set.

  Eventually, in the multi-beam simultaneous acceleration cavity 200 used in the second embodiment, the acceleration electron beam B1 and the deceleration electron beam B2 are passed along the parallel separate first beam trajectory and second beam trajectory, and accelerated. It is possible to accelerate the electron beam B1 and simultaneously decelerate the electron beam B2. Therefore, the converging magnets 111 and 113 for the accelerating electron beam and the converging magnets 112 and 114 for the decelerating electron beam can be separated, and the strength of the converging magnets 111 and 113 for the accelerating electron beam and the decelerating electron beam The strength of the converging magnets 112 and 114 can be optimally set individually and easily.

[Application example]
Note that the linear accelerator 100A shown in FIG. 2 has applications other than use as an energy recovery type linear accelerator. That is, in response to the need to use two electron beams having the same phase in synchronism, the two electron beams are input to the linear accelerator 100A in synchronism (in phase with each other), and the multiple beam simultaneous acceleration cavity 200 is obtained. Two electron beams can be accelerated at the same time by placing them on the acceleration phase of the standing wave of the electric field generated in the cavity internal space.

  Further, if the mode of the electric field formed in the cavity internal space of the multiple beam simultaneous acceleration cavity 200 is set to TM210 and TM410 and the mode order is made higher, simultaneous acceleration of four electron beams (or two are accelerated, 2 (decelerate 2) and (see FIG. 5C), simultaneous acceleration of 8 electron beams (or 4 accelerate and 4 decelerate) becomes possible.

  In addition, if a cavity having a rectangular cross section is adopted as the multiple beam simultaneous acceleration cavity, it is possible to simultaneously accelerate an odd number of electron beams (or partially accelerate and decelerate the rest) (see FIG. 5F).

FIG. 5 shows electric field modes that can be formed in a cylindrical cavity and a rectangular cavity.
For example, as shown in FIG. 5C, if the electric field mode is changed to the TM21 mode in a cylindrical cavity, it is possible to simultaneously accelerate (or accelerate two, decelerate two) four electron beams.
For example, as shown in FIG. 5G, if the electric field mode is TM31 in a rectangular cavity, the three electron beams can be accelerated simultaneously (or partially accelerated and the rest decelerated).

  FIG. 6 is a cross-sectional view showing a multiple beam simultaneous acceleration cavity 300 according to a third embodiment of the present invention. The multiple beam simultaneous acceleration cavity 300 has two acceleration cavities 301 and 302 arranged in parallel. In addition, each cell of the acceleration cavity 301 and each cell of the acceleration cavity 302 are connected in a one-to-one correspondence. Although not shown, a beam pipe having a converging magnet is connected to the end portions of the acceleration cavities 301 and 302.

  When high frequency power is applied to the multiple beam simultaneous accelerating cavity 300, a standing wave of a monopole electric field is generated in the cavity inner space of the accelerating cavity 301, and the monopole electric field is also determined in the cavity inner space of the accelerating cavity 302. Standing waves are generated. At this time, the electric field in the cavity internal space of the acceleration cavity 301 and the electric field in the cavity internal space of the acceleration cavity 302 are out of phase by 180 °. In other words, the electric field of the dipole is generated in the entire internal space of the multiple beam simultaneous acceleration cavity 300. Therefore, if a linear accelerator is configured using this multiple beam simultaneous acceleration cavity, two electron beams can be passed in parallel, and each electron beam can be accelerated or decelerated simultaneously. Furthermore, when the shape is changed, it is possible to obtain a condition in which the phase of adjacent cells is 0 ° when high-frequency power of the same frequency is applied. The use in such a state is also possible in principle.

  FIG. 7 is a cross-sectional view showing a multiple beam simultaneous acceleration cavity 400 according to a fourth embodiment of the present invention. The multiple beam simultaneous acceleration cavity 400 has four acceleration cavities 401, 402, 403, 404 arranged in parallel. Moreover, each cell of the acceleration cavity 401 and each cell of the acceleration cavity 402 are connected in a one-to-one correspondence, and each cell of the acceleration cavity 401 and each cell of the acceleration cavity 403 correspond one-to-one. And each cell of the acceleration cavity 402 and each cell of the acceleration cavity 404 are connected in a one-to-one correspondence, and each cell of the acceleration cavity 403 and each cell of the acceleration cavity 404 are They are connected in a one-to-one correspondence. Although not shown, a beam pipe with a converging magnet is connected to the ends of the acceleration cavities 401, 402, 403, and 404.

  When high-frequency power is applied to the multiple beam simultaneous acceleration cavity 400, a standing wave of a monopole electric field is generated in each of the cavity internal spaces of the acceleration cavities 401 to 404. At this time, the electric field in the cavity inner space of the acceleration cavities 401 and 404 and the electric field in the cavity inner space of the acceleration cavities 402 and 403 are out of phase by 180 °. In other words, electric fields of four poles (poles) are generated in the entire internal space of the multiple beam simultaneous acceleration cavity 400. Therefore, if a linear accelerator is configured using this multiple beam simultaneous acceleration cavity, four electron beams can be passed in parallel, and each electron beam can be accelerated or decelerated simultaneously.

  In each of the above-described embodiments, an acceleration cavity (cavity resonator) formed by connecting a plurality of hollow, flat spherical cells in series is employed. However, the present invention can be achieved using other types of acceleration cavities. Needless to say, it can be implemented. For example, an accelerating cavity (cavity resonator) formed by a cylindrical member (superconducting material) and a partition plate (superconducting material) spaced apart in the axial direction of the internal space of this cylindrical part is employed. The present invention can be implemented. In such an acceleration cavity formed by a cylindrical member and a partition plate, one cell is formed between one and the other of the adjacent partition plates, and a plurality of cells are connected in series. There is no difference in that.

  According to the multi-beam simultaneous accelerator of the present invention, since a plurality of electron beams can be separated and accelerated or decelerated, it can be used for next-generation synchrotron radiation equipment and the like.

It is a block diagram which shows the linear accelerator using the multiple beam simultaneous acceleration cavity which concerns on 1st Example of this invention. It is a block diagram which shows the linear accelerator using the multiple beam simultaneous acceleration cavity which concerns on the 2nd Example of this invention. It is explanatory drawing which shows the electric field of TM110 mode. It is explanatory drawing which shows the electric field of TM010 mode. It is explanatory drawing which shows TM mode of a cylindrical cavity and a rectangular cavity. It is a cross-sectional view showing a multiple beam simultaneous acceleration cavity according to a third embodiment of the present invention. It is a cross-sectional view showing a multiple beam simultaneous acceleration cavity according to a fourth embodiment of the present invention. It is a system configuration figure showing an energy recovery type accelerator. It is a block diagram which shows the conventional linear accelerator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electron gun 2 Incident accelerator 3 Superconducting linear accelerator 4, 5, 6 Orbit 7 Reducer 8 Beam dump 10 Molding acceleration cavity 11 Vacuum chamber 12 Heat shield plate 13 Liquid helium tank 14, 15 Acceleration cavity 16, 17 Beam pipe 18, DESCRIPTION OF SYMBOLS 19 Focusing magnet 20,21 High frequency input coupler 100,100A Linear acceleration cavity 101 Vacuum tank 102 Heat shield plate 103 Liquid helium tank 104,105 High frequency input coupler 111-114 Focusing magnet 120 Multiple beam simultaneous acceleration cavity 121-124 Acceleration cavity 125, 126 Coupling cavity 127-130 Beam pipe 200 Multiple beam simultaneous acceleration cavity 201, 202 Acceleration cavity 203-206 Beam pipe 300, 400 Multiple beam simultaneous acceleration cavity B1 Acceleration electron beam B2 Deceleration electron beam

Claims (3)

When a high frequency power is supplied, a standing wave of a monopole mode electric field in which one pole that maximizes the electric field in the beam traveling direction is formed in the cavity internal space, and a beam pipe in which a focusing magnet is mounted Has a plurality of acceleration cavities connected to the ends,
The accelerating cavities are arranged in parallel, and the accelerating cavities arranged in parallel are connected by a coupling cavity. When high-frequency power is supplied, the cavity has an accelerating cavity in which a standing wave of a multipole mode electric field is formed in which multiple poles that maximize the electric field in the beam traveling direction are formed.
A plurality of beam pipes around which converging magnets are mounted are connected to the end of the acceleration cavity, and the number of beam pipes is the same as the number of poles, and the position where each beam pipe is connected is A multi-beam simultaneous acceleration cavity characterized by being aligned with the position where the pole of the electric field can be formed. When a high frequency power is supplied, a standing wave of a monopole mode electric field in which one pole that maximizes the electric field in the beam traveling direction is formed in the cavity internal space, and a beam pipe in which a focusing magnet is mounted Has a plurality of acceleration cavities connected to the ends,
The acceleration cavities are arranged in parallel, and each acceleration cavity is formed by connecting a plurality of cells in series. Adjacent acceleration cavities arranged in parallel are each of one of the adjacent acceleration cavities. A multi-beam simultaneous acceleration cavity, wherein the cell and each cell of the other acceleration cavity adjacent to each other are connected to each other.

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