JP4719255B2 - High frequency accelerator - Google Patents

Description

  The present invention relates to a linear high-frequency accelerator that accelerates charged particles to high energy.

  In general, in order to efficiently accelerate charged particles with a high-frequency accelerator, it is necessary to adjust the timing when the charged particles pass through the acceleration gap and the phase of the high-frequency electric field, and the electric field strength of the accelerating electric field also has a predetermined magnitude. It is necessary to. Furthermore, when a linear type high frequency accelerator is configured by combining a plurality of high frequency acceleration cavity resonators (hereinafter simply referred to as “cavity resonators”), it is necessary to adjust each acceleration phase and acceleration electric field strength.

  Therefore, a conventional linear type high frequency accelerator is realized by connecting a high frequency power source to each individual cavity resonator and adjusting the strength of the high frequency electric field and the phase between the high frequency power sources with each high frequency power source. For example, in the related art described in Non-Patent Document 1 below, the high-frequency accelerator includes two cavity resonators, an RFQ cavity resonator and an APF-IH cavity resonator, and a high-frequency electric field is provided for each cavity resonator. In order to excite the power, a high frequency power supply is installed, and power is supplied to each cavity resonator through a high frequency transmission tube (coaxial tube).

  In addition, when a high frequency accelerator is configured by combining a plurality of cavity resonators, the coupling coefficient is also important. That is, if the coupling coefficient is small, the propagation speed between the cavity resonators is slow, and there is a possibility that a large voltage will stand up and discharge in the high-frequency transmission tube (coaxial tube) that supplies power to each cavity resonator. On the other hand, if the coupling coefficient is too large, the Q value seen in the entire cavity resonator is lowered, so that the power required for the high frequency power supply is increased.

  Therefore, for example, in the prior art described in Non-Patent Document 2 below, individual cavity resonators are slot-coupled (two cavities are coupled by making holes in the cavity resonators and leaking magnetic fields therefrom). In this case, the coupling coefficient is adjusted by finely post-processing and adjusting the slot hole size.

Y. Iwata, et. al. , Alternate-phase focused IH-DTL for an injector of heavy-ion medical accelerators, Nuclear Instruments & Methods in Physics Research A, 569, (2006), p685-696. Blue, et al., Development of bridge coupler for J-PARC ACS, 28th Linac Technical Meeting, (2003).

  When the charged particles are accelerated, so-called beam loading occurs in which kinetic energy is given to the charged particles. However, the energy also needs to be supplied from a high-frequency power source, and requires a larger power than when the charged particles are not accelerated. Since the phase of the beam loading and the phase of the high-frequency power source are different, it is necessary to make the power source phase different from when not accelerating when the charged particles are accelerated. Therefore, in the prior art of Non-Patent Document 1, a high-frequency power source is installed to excite a high-frequency electric field for each cavity resonator, and the strength of the high-frequency electric field and the phase between the high-frequency power sources are adjusted by each high-frequency power source. Since each acceleration phase and acceleration electric field intensity are adjusted, complicated control is required.

  In the prior art described in Non-Patent Document 2, the coupling coefficient is adjusted by slightly post-processing and adjusting the slot hole size. In this case, the cavity of the slot hole portion has a very complicated configuration, and adjustment of the coupling coefficient requires a great deal of labor. In addition, each acceleration cavity resonator is a cavity resonator having the same characteristics, and there is a problem that it is difficult to apply to acceleration cavity resonators having different characteristics.

  For these reasons, the conventional high-frequency accelerator has the following problems. That is, (1) it is difficult to individually supply different predetermined acceleration electric fields from one high-frequency power supply to a plurality of cavity resonators having different characteristics. (2) Complex control is required to adjust the acceleration phase between the plurality of cavity resonators. (3) Complex control is required to adjust the acceleration voltage between the plurality of cavity resonators.

  The present invention has been made in order to solve the above-described problems. In the case where a linear high-frequency accelerator is configured by combining a plurality of high-frequency accelerating cavities, a predetermined acceleration that is individually different from one high-frequency power source is provided. An object of the present invention is to be able to supply an electric field and to adjust the acceleration voltage and the acceleration phase very easily as compared with the conventional case.

  In order to achieve the above object, according to the present invention, in a high frequency accelerator having a plurality of cavity resonators, each of the high frequency acceleration cavity resonators is coupled to each other by a high frequency coaxial transmission line composed of an outer conductor and an inner conductor. In the high-frequency coaxial transmission line, a loop connecting the outer conductor and the inner conductor is formed at both ends thereof, and the plurality of high-frequency accelerating cavity resonators and the high-frequency coaxial transmission line have substantially the same resonance frequency. The cavity length of the high-frequency coaxial transmission line is set to a length different from (1/2) · N times the resonance wavelength (N is a natural number).

  According to the present invention, it is possible to supply different predetermined acceleration electric fields individually from a single high-frequency power supply to a plurality of high-frequency acceleration cavity resonators having different characteristics. In addition, since the acceleration phase between the plurality of high-frequency accelerating cavities is automatically adjusted, it is not necessary to adjust the phase by providing special means. This eliminates the need for complicated control for adjusting the acceleration voltage between the plurality of high-frequency accelerating cavity resonators.

Embodiment 1 FIG.
1 is a configuration diagram of a high-frequency accelerator according to Embodiment 1 of the present invention, FIG. 2 is an enlarged cross-sectional view showing a portion indicated by reference numeral P in FIG. 1, and FIG. 3 is a diagram showing the portion of FIG. It is the top view seen from the side.

  The high-frequency accelerator according to the first embodiment is a linear accelerator, particularly an H-mode accelerator, in which an ion source 1 and two-stage high-frequency accelerating cavity resonators (hereinafter simply referred to as cavity resonators) 2 and 3 are linear. These are arranged in a row and are sequentially connected to each other through the vacuum duct 4. In addition, one high-frequency power source 5 is connected to the front-stage cavity resonator 2 via a high-frequency transmission tube 6 made of a coaxial tube. Further, as a feature of the first embodiment, the front and rear cavity resonators 2 and 3 are coupled by a coaxial tube cavity 7 as a high-frequency coaxial transmission line.

  Then, the charged particles generated in the ion source 1 are transported in the vacuum duct 4 and accelerated through the front cavity resonator 2 and the rear cavity resonator 3. The high-frequency electric field generated in the front-stage cavity resonator 2 and the rear-stage cavity resonator 3 is supplied by a high-frequency power source 5, a high-frequency transmission tube 6, and a coaxial tube cavity 7.

  There are no particular restrictions on the types of the cavity resonators 2 and 3 before and after, for example, different types such as a combination of an RFQ acceleration cavity resonator and an APF-IH acceleration cavity resonator may be used. In addition, two RFQ accelerators or two APF-IH accelerators may be combined with the same type. The high-frequency transmission tube 6 only has a function of transmitting a high-frequency electric field, but the coaxial tube cavity 7 has not only a function as a high-frequency coaxial transmission line but also several hundreds to thousands of resonance sharpness (hereinafter referred to as “high-frequency coaxial transmission line”). , Which has a function as a cavity resonator having a Q value). The adjustment of the Q value will be described later.

  The coaxial tube cavity 7 is provided with a long lateral portion 7a extending along the cavity axial direction Z of the front and rear cavity resonators 2 and 3, and provided at both ends of the laterally elongated portion 7a. , 3 and a connecting portion 7b. And each connection part 7b is comprised so that it can rotate centering around an axial center, respectively by connecting with the horizontal elongate part 7a via a rotation flange etc. Thereby, each connection part 7b is comprised. The angle Φ of the loop 14 described later can be changed with respect to the cavity axial direction Z of the front and rear cavity resonators 2 and 3. Then, by changing the angle Φ, the amount of magnetic flux passing through the loop 14 changes, and the coupling coefficient κ changes accordingly, and this is used to adjust the coupling coefficient κ.

  Further, each connecting portion 7b is connected to the horizontally long portion 7a so as to be slidable along the axial direction by, for example, spline fitting or the like, whereby the entire cavity length of the coaxial tube cavity 7 can be varied. ing. Then, as described later, the resonance frequency is adjusted by changing the cavity length of the coaxial tube cavity 7.

  Both the horizontally long portion 7 a and the connecting portion 7 b of the coaxial tube cavity 7 include an outer conductor 11 and an inner conductor 12, and a high-frequency electric field is excited between the outer conductor 11 and the inner conductor 12. Each connection portion 7b is provided with a ring-shaped end plate 13 made of a conductive material and a substantially L-shaped loop 14 made of a conductive material. The loop 14 has one end connected to the inner conductor 12 and the other end connected to the end plate 13.

  The end plate 13 has an edge at the end in the figure, but since a high frequency high electric field is applied, the end plate 13 is actually formed in an arc shape so that the edge is eliminated. The loop 14 only needs to have one end connected to somewhere on the end face of the inner conductor 12 constituting the connecting portion 7 b, and the other end of the loop 14 is connected to any position of the end plate 13. May be. The connection position of the loop 14 can be arbitrarily changed depending on how the maximum value of the coupling coefficient is set.

  Further, in the first embodiment, the loop 14 has a rod shape and the cross-sectional shape is a quadrangle, but is not limited to this and may have a circular diameter. Furthermore, as shown in FIG. 4, the loop 14 may have a substantially sector shape that smoothly spreads from the inner conductor 12 toward the outer conductor 11. In this way, it is possible to prevent an increase in resistance due to local concentration of current flowing through the loop 14 when a high-frequency electric field is excited in each of the cavity resonators 2 and 3, and current loss is reduced. This is preferable because it is possible to avoid the increase and realize the coaxial tube cavity 7 having a large Q value.

  Further, in each of the cavity resonators 2 and 3 of the first embodiment, an angle Φ (in this example, each plane Sr that is surrounded by the loop 14 and the direction of the magnetic flux in the cavity resonators 2 and 3) A rotation angle measuring means 15 for measuring the angle formed between the cavity resonators 2 and 3 and the cavity axis direction Z is provided.

  The rotation angle measuring means 15 forms, for example, a graduation for angle measurement (not shown) on the outer peripheral surface of the outer conductor 11 of each connection portion 7b of the coaxial tube cavity 7, while the peripheral walls of the front and rear cavity resonators 2, 3 are formed. Protrusion 16 is provided in part facing the scale, and the scale is visually read with reference to the protrusion 16 so that the rotation angle Φ of the connecting portion 7b can be measured to adjust the angle of the loop 14. It has become. The rotation angle measuring means 15 is not limited to the configuration as in this example, and may be one that performs angle detection by an angle detection sensor.

  Next, the coupling coefficient with the cavity resonators 2 and 3 before and after the coaxial tube cavity 7 changes according to the angle Φ of the loop 14, and the Q value changes depending on the ratio occupied by the end plate 13. Since the resonance frequency varies depending on the cavity length of the tube cavity 7, the coupling coefficient, the Q value, and the resonance frequency are adjusted accordingly. This will be described in more detail below.

  FIG. 5 is a characteristic diagram showing changes in the coupling coefficient κ when the angle Φ of the loop 14 is changed. Here, as described above, the angle Φ of the loop 14 is the angle Φ between the plane Sr surrounded by the loop 14 and the magnetic flux direction in the cavity resonators 2 and 3 (in this example, each cavity resonator 2 , 3 is an angle formed with the cavity axial direction Z). The state in which the plane Sr is orthogonal to the magnetic flux direction Z in each of the cavity resonators 2 and 3, that is, the normal direction of the plane Sr coincides with the acceleration direction Z of the particle beam is “0 degree”. It is said. At that time, the cavity resonators 2 and 3 are excited by TE-mode high-frequency electromagnetic fields in the acceleration cavity.

  As can be seen from FIG. 5, when the loop 14 is rotated and the magnetic flux crossing the plane Sr is increased, the maximum value of the coupling coefficient is increased accordingly. Since the coupling coefficient depends on the amount of magnetic flux interlinked with the loop 14, the amount of magnetic flux interlinked can be changed by rotating the loop 14 with respect to the direction of the magnetic flux, thereby adjusting the coupling coefficient. At that time, the degree of adjustment of the coupling coefficient can be easily determined by measuring the rotation angle Φ of the loop 14 using the rotation angle measuring means 15.

  The coupling coefficient is preferably about 0.5% to 3%. If the coupling coefficient is small, the propagation speed between the cavity resonators 2 and 3 is slow, and a large voltage may be discharged in the high-frequency transmission tube 6. On the other hand, if the coupling coefficient is too large, the Q value seen by the three cavity resonators 2, 3, 7 as a whole is lowered, so that the required power of the high-frequency power source 5 is increased. Further, since the adjustment margin of the rotation angle Φ for adjusting the coupling coefficient is both +/−, the initial setting value of the rotation angle Φ is not an angle corresponding to the vicinity of the maximum value of the coupling coefficient, but more than that. An angle corresponding to a small coupling coefficient is set. For example, κa and Φa in FIG. 5 are examples of initial setting values.

  As described above, in the first embodiment, the coaxial tube cavity 7 that couples the front and rear cavity resonators 2 and 3 has a very simple configuration, and at the tip of each connection portion 7 b of the coaxial tube cavity 7. By attaching the loop 14 and rotating the loop 14, the coupling coefficient with each of the cavity resonators 2 and 3 can be easily adjusted independently. Therefore, even when the individual cavity resonators 2 and 3 have different parameters, the coupling coefficient can be easily adjusted. Then, by adjusting the coupling coefficient, the adjustment of the acceleration electric field strength of each of the cavity resonators 2 and 3 can be easily realized.

  FIG. 6 is a characteristic diagram showing changes in the Q value when the ratio of the ring-shaped end plates 13 provided at the connection portions 7 b at both ends of the coaxial tube cavity 7 to the end surface of the coaxial tube cavity 7 is changed. is there. Here, the symbol r is the inner diameter of the inner conductor 12, R is the inner diameter of the outer conductor 11, and a is the distance from the inner peripheral wall of the end plate 13 to the inner peripheral wall of the outer conductor 11.

  As can be seen from FIG. 6, when the proportion of the end plate 13 is increased, the Q value is increased accordingly. Therefore, the Q value of the coaxial tube cavity 7 can be adjusted by providing a ring-shaped end plate 13 at the end of each connection portion 7b of the coaxial tube cavity 7 and adjusting the area ratio. For example, according to the required characteristics of the cavity resonators 2 and 3, the Q value is adjusted to have a value of about several hundred to several thousand.

  Next, the relationship between the length of the coaxial tube cavity 7 and the resonance frequency, and the accompanying acceleration phases of the front and rear cavity resonators 2 and 3 will be described.

  When there are a plurality of cavity resonators 2 and 3, it is necessary to adjust the acceleration phase and the acceleration electric field strength. Therefore, in the prior art, as already described in the background art section, the high frequency power source 5 is connected to each cavity resonator, and the strength of the high frequency electric field and the phase between the high frequency power sources 5 are determined by the individual high frequency power sources 5. It was realized by adjusting.

  On the other hand, in the first embodiment, by changing the axial length of the coaxial tube cavity 7 and the angle of the loop 14, the resonance frequencies of the front and rear cavity resonators 2 and 3 and the coaxial tube cavity 7 are changed. Adjustment is made so that the acceleration phase is automatically locked to the desired value.

  That is, in the first embodiment, the plurality of cavity resonators 2 and 3 and the coaxial tube cavity 7 have substantially the same resonance frequency, but the axial length of the coaxial tube cavity 7 is equal to the resonance wavelength. It is set so that it is not (1/2) · N times (N is a natural number).

  The axial length of the coaxial tube cavity 7 is set to (1/2) · N times (N is a natural number) the resonance wavelength λ of the front and rear cavity resonators 2 and 3, and the front and rear cavity resonators 2 and 3 are set. When the loop 14 is connected between them, an inductance component is generated at the end of the cavity, so that the resonance frequency is shifted. In order to correct this, usually, a contrivance is provided such that a tuner for changing the inductance and capacitance is provided in the coaxial tube cavity 7, but in the first embodiment, the coaxial tube is simplified in order to simplify the configuration. By changing the length of the cavity 7 so that the cavity length is not (1/2) · N times (N is a natural number) of the resonance wavelength, the change in inductance or the like when the loop 14 is connected as a result. Therefore, the coaxial tube cavity 7 has a resonance frequency substantially the same as that of the cavity resonator.

FIG. 7 shows a specific example of a method for adjusting the resonance frequency of the coaxial tube cavity 7.
The distance D from the exit of the front cavity resonator 2 to the entrance of the rear cavity resonator 3 is determined by the acceleration phase of each of the cavity resonators 2 and 3 (in the case of the first embodiment, charged particles are high frequency). Since the phase of the electric field advances during π + 2nπ (where n is an integer), the horizontal length L1 of the horizontally long portion 7a of the coaxial waveguide cavity 7 cannot be changed. Therefore, in the first embodiment, the axial length L2 orthogonal to the surface in each of the cavity resonators 2 and 3 of the coaxial tube cavity 7 is adjusted.

Next, the physical mechanism of the present invention will be further described.
When a plurality of cavity resonators are electromagnetically coupled, each cavity resonator exhibits coupled characteristics. In the case of the first embodiment, the front-stage cavity resonator 2, the rear-stage cavity resonator 3, and the coaxial tube cavity 7 are electromagnetically coupled to each other. At that time, the acceleration frequency (resonance frequency) of the fundamental mode of the cavity resonators 2 and 3 and the resonance frequency of the lowest order of the coaxial tube cavity 7 deviate from the resonance frequencies that exist independently, and become three kinds of resonance frequencies. Specifically, there are three types: 0 mode, π / 2 mode, and π mode. Of these, in the case of the resonance frequency of π / 2 mode, the acceleration phase between the front cavity resonator 2 and the rear cavity resonator 3 is shifted by exactly π, and the acceleration electric field of the coaxial tube cavity 7 is almost “ 0 ”.

  Further, when the coupling coefficient between the front cavity resonator 2 and the coaxial tube cavity 7 is K1, and the coupling coefficient between the rear cavity resonator 3 and the coaxial tube cavity 7 is K2, the acceleration electric field E1 of the front cavity resonator 2 and the subsequent stage The ratio E2 / E1 of the acceleration electric field E2 of the cavity resonator 3 becomes E2 / E1 = √ (K1 / K2). This acceleration phase lock phenomenon (a phenomenon in which the acceleration phase is shifted by exactly π is referred to as a lock phenomenon) does not change even when there is beam loading. Therefore, when the coupling coefficients K1 and K2 are constant, if the input power to the cavity is increased, both the acceleration phase and the acceleration electric field become predetermined values, and the plurality of cavity resonators 2 and 3 can be connected without control. Can be used to achieve stable acceleration.

  FIGS. 8 and 9 are configuration examples in the case where a high-frequency acceleration electric field is excited using two front and rear cavity resonators 2 and 3. 9A is a plan view of the front cavity resonator 2 of FIG. 8 as viewed from the inside of the cavity, and FIG. 9B is a plan view of the rear cavity resonator 3 of FIG. 8 as viewed from the inside of the cavity. FIG.

  Here, the symbol Za is the direction of the high frequency magnetic field of the cavity resonator 2 in the previous stage, Zb is the direction of the high frequency magnetic field of the cavity resonator 3 in the subsequent stage, and Zc is the direction in which the charged particles travel. Symbol Ia is the direction of current flowing in the loop 14 provided on the front side of the coaxial tube cavity 7, and symbol Ib is the direction of current flowing in the loop 14 provided on the rear side of the coaxial tube cavity 7.

  In the first embodiment, the high-frequency magnetic field direction Za of the front-stage cavity resonator 2 and the high-frequency magnetic field direction Zb of the rear-stage cavity resonator 3 are opposite, and the lowest-order high-frequency resonance mode of the coaxial tube cavity 7 is used. Is (1/2) · N (where N is an odd number). For this reason, the current Ia flows from the outer conductor 11 toward the inner conductor 12 in the loop 14 provided on the front stage side of the coaxial pipe cavity 7, and the loop 14 provided on the rear stage side of the coaxial pipe cavity 7 A current Ib flows from the inner conductor 12 toward the outer conductor 11.

  With such a configuration, it is possible to excite a high-frequency electric field in which the phases of the front cavity resonator 2 and the rear cavity resonator 3 are accurately shifted by π, and the charged particle beam can resonate with each cavity. The acceleration phase between the two cavity resonators 2 and 3 does not shift even during beam loading in which the power of the high-frequency electric field in the acceleration cavities of the resonators 2 and 3 is changed to its own kinetic energy. However, the Q value of the cavity of the coaxial tube cavity 7 needs to be 100 or more.

  As described above, in the first embodiment, the cavity resonators 2 and 3 are coupled by the coaxial tube cavity 7, and the loop 14 that connects the outer conductor 11 and the inner conductor 12 is formed at both ends of the coaxial tube cavity 7. In addition, since the cavity length of the coaxial tube cavity 7 is set not to be (1/2) · N times the resonance wavelength of the cavity resonators 2 and 3 (N is a natural number), a plurality of acceleration cavity resonators Even when two and three have different characteristics, it is possible to supply different predetermined acceleration electric fields from one high-frequency power source 5 and to adjust the acceleration phase between the plurality of cavity resonators 2 and 3. Is no longer necessary. Therefore, complicated control for adjusting the acceleration voltage between the plurality of cavity resonators 2 and 3 is not required, and the cavity resonators 2 and 3 can be electromagnetically coupled with a simple configuration.

Embodiment 2. FIG.
FIGS. 10 and 11 are configuration examples in the case where a high-frequency acceleration electric field is excited using two front and rear cavity resonators. 11A is a plan view of the front cavity resonator of FIG. 10 viewed from the inside of the cavity, and FIG. 11B is a plan view of the rear cavity resonator of FIG. 10 viewed from the inside of the cavity. is there.

  Here, the symbol Za is the direction of the high frequency magnetic field of the cavity resonator 2 in the previous stage, Zb is the direction of the high frequency magnetic field of the cavity resonator 3 in the subsequent stage, and Zc is the direction in which the charged particles travel. Symbol Ia is the direction of current flowing in the loop 14 provided on the front side of the coaxial tube cavity 7, and symbol Ib is the direction of current flowing in the loop 14 provided on the rear side of the coaxial tube cavity 7.

  In the second embodiment, the high-frequency magnetic field direction Za of the front-stage cavity resonator 2 and the high-frequency magnetic field direction Zb of the rear-stage cavity resonator 3 are the same, and the lowest-order high-frequency resonance mode of the coaxial tube cavity 7 is used. Is (1/2) · N (where N is an even number). Therefore, currents Ia and Ib flow from the outer conductor 11 toward the inner conductor 12 through the loops 14 provided on the front side and the rear side of the coaxial tube cavity 7, respectively.

With such a configuration, it is possible to establish a high-frequency electric field in which the acceleration phases of the front cavity resonator 2 and the rear cavity resonator 3 are the same, and between the two cavity resonators even if there is beam loading. The acceleration phase is not shifted.
Since other operations and effects are the same as those in the first embodiment, detailed description thereof is omitted here.

Embodiment 3 FIG.
The high-frequency accelerator described in the first and second embodiments is an H-mode accelerator, and in this H-mode accelerator, the magnetic flux generated in each of the cavity resonators 2 and 3 is formed in the direction of the cavity axis. When the plane Sr at the position surrounded by 14 is orthogonal to the magnetic flux direction Z in the cavity resonators 2 and 3, it is defined as “0 degree”.

  On the other hand, in the case of the Alvare type accelerator, a magnetic flux is formed in a direction around the cavity axis of the cavity resonators 2 and 3. Therefore, in the case of this configuration, the plane Sr located at the position surrounded by the loop 14 is in a state where it coincides with the magnetic flux direction Z in each of the cavity resonators 2 and 3, that is, the normal direction of the plane Sr. Is perpendicular to the acceleration direction Z of the particle beam when the rotation angle Φ in FIG. 5 is “0 degree”.

As described above, where the reference “0 degree” is taken at the rotation angle Φ in FIG. 5 differs depending on the type of the high-frequency accelerator, and in any case, the above description is valid as it is, and the embodiment is described. The matters described in 1 and 2 are applicable.
Since other operations and effects are the same as those in the first and second embodiments, detailed description thereof is omitted here.

  The present invention is not limited to the configurations of the first to third embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, in each of the first and second embodiments, the cavity resonators 2 and 3 are provided in two stages before and after, but the present invention can also be applied to a high-frequency accelerator provided with cavity resonators in three or more stages.

It is a block diagram of the high frequency accelerator in Embodiment 1 of this invention. It is sectional drawing which expands and shows the part shown with the code | symbol P of FIG. FIG. 3 is a plan view of the portion of FIG. 2 viewed from the inside of the cavity of the high-frequency accelerating cavity resonator. It is a top view which shows the modification of a loop. FIG. 6 is a characteristic diagram showing a change in the coupling coefficient κ when the loop angle Φ is changed. It is a characteristic view which shows the change of Q value when the ratio for which the ring-shaped end plate provided in each connection part of the both ends of a coaxial tube cavity occupies the end surface of a coaxial tube cavity is changed. It is explanatory drawing which shows the specific example of the adjustment method of the resonant frequency of a coaxial pipe cavity. It is explanatory drawing which shows the structural example in the case of exciting a high frequency acceleration electric field using two high frequency acceleration cavity resonators before and behind. It is the top view which looked at each edge part of the coaxial tube cavity of FIG. 8 from the cavity inside side of the high frequency acceleration cavity resonator. In Embodiment 2, it is explanatory drawing which shows the structural example in the case of exciting a high frequency acceleration electric field using two front and back high frequency acceleration cavity resonators. It is the top view which looked at each edge part of the coaxial pipe | tube cavity of FIG. 10 from the cavity inside side of the high frequency acceleration cavity resonator.

Explanation of symbols

2 High-frequency accelerating cavity resonator (cavity resonator), 7 Coaxial tube cavity (high-frequency coaxial transmission line),
11 outer conductor, 12 inner conductor, 13 end plate, 14 loop, 15 rotation angle measuring means.

Claims (4)

In a high-frequency accelerator having a plurality of high-frequency accelerating cavities,
Each of the high-frequency accelerating cavity resonators is coupled to each other by a high-frequency coaxial transmission line composed of an outer conductor and an inner conductor, and the high-frequency coaxial transmission line is a loop that connects the outer conductor and the inner conductor to both ends thereof. The plurality of high-frequency accelerating cavity resonators and the high-frequency coaxial transmission line have substantially the same resonance frequency, and the cavity length of the high-frequency coaxial transmission line is (1/2) · A high-frequency accelerator characterized by being set to a length different from N times (N is a natural number). The loop is formed on a plane, and at least an angle formed by the plane surrounded by the loop and a magnetic flux direction in the high-frequency accelerating cavity resonator and an axial length of the high-frequency coaxial transmission line The high-frequency accelerator according to claim 1, wherein one of the two is variably configured. The rotation angle measuring means for measuring the angle formed by the plane surrounded by the loop and the magnetic flux direction in the high-frequency accelerating cavity resonator is provided. High frequency accelerator. 4. A ring-shaped end plate having an inner diameter of the ring larger than an outer diameter of the inner conductor is provided at each end of the high-frequency coaxial transmission line. The high frequency accelerator described in 1.

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