JP2520641B2 - Standing wave accelerator - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a standing wave accelerating tube that accelerates particles.

[Prior art]

FIG. 4 is a sectional view of a conventional side-coupling type standing wave type accelerating tube capable of accelerating particles to a wide range of energies. In FIG. 4, 1 is one acceleration cavity that constitutes an acceleration tube, 2a to 2d, 3 and 4 are coupling cavities, 5 is a short rod for stopping the propagation of microwaves, and 6 is an acceleration cavity 1 These particles are accelerated by the microwave energy stored inside. Next, the operation will be described. The size of the coupling hole of the coupling cavity with the short rod and the acceleration cavity 1 is different in the coupling cavities 3 and 4. The size of the coupling hole of the coupling cavity 3 is the same as that of the other coupling cavities, and the coupling hole of the coupling cavity 4 is smaller than the others. Now, when the short rod 5 is inserted into the coupling cavity 4 as shown in FIG. 5, the microwave propagates through the coupling cavity 3 as shown by an arrow A1, and the microwave propagates to the subsequent coupling cavities 2d. . Further, as shown in FIG. 6, when the short rod 5 is inserted into the coupling cavity 3, the microwave is coupled by the coupling cavity 4 as shown by an arrow A2.
And propagate the microwave to the subsequent coupling cavities 2d. Furthermore, when the short rod 5 is inserted into both the coupling cavities 3 and 4 as shown in FIG. 7, the microwave does not propagate to the subsequent coupling cavities 2d as indicated by an arrow A3. As a result, the electric field distribution in the acceleration tube is shown in FIG.
It becomes like FIG. 8 (c), and FIGS. 8 (a) to 8 (c) show the electric field distributions in the cases of FIGS. 5 to 7, respectively. Since the energy obtained by the electric field is different, the energy of the particles is different in FIGS. 8 (a) to 8 (c). The energy of the particles 6 accelerated by the insertion and removal of the short rod 5 as described above is adjusted.

[Problems to be Solved by the Invention]

Since the conventional standing wave type accelerating tube is configured as described above, if the short rod 5 is inserted to reduce the magnitude of the electric field in the cavity thereafter, or to eliminate it at all,
The electric field (converging electric field) in the direction perpendicular to the traveling direction of the particles 6 also becomes small or disappears. As a result, there is a problem in that the particles 6 diverge in the coupling cavity after the short rod and it is necessary to apply a magnetic field from the outside of the accelerating tube to converge the particles. The present invention has been made to solve the above problems, and an object thereof is to obtain a standing wave type accelerating tube capable of converging particles without applying a magnetic field from the outside.

[Means for solving problems]

The standing wave type accelerating tube according to the present invention is provided with accelerating and beam converging means for accelerating particles and generating a beam converging action in the accelerating cavity before or after the coupling cavity with a short rod.

[Work]

The accelerating and beam converging means in the present invention increases the electric field distribution in the direction perpendicular to the traveling direction of the particles in the acceleration cavity provided with the accelerating and beam converging means to accelerate the particles and exert a converging action.

【Example】

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1 (a), the same parts as those in FIG. 4 are designated by the same reference numerals to avoid redundant description, and the parts different from those in FIG. 4 will be mainly described. As is apparent from a comparison of FIG. 1 (a) with FIG. 4, the portions indicated by reference numerals 1, 3 to 6 are the same as in FIG. 4, and in the embodiment of FIG. 1 (a), A ring 7 is provided at the entrance of the next acceleration cavity 1a of the coupling cavity 3 in which the short rod 5 is inserted in the acceleration cavity 1 as means for accelerating and beam focusing. This ring 7 has the shape shown in FIG. 1 (b), and is for changing the electric field distribution in the acceleration cavity 1a, and is arranged at a few mm from the particle inlet of the acceleration cavity 1a. ing. Other configurations are the same as those in FIG. 2 and 3 show the electric field distribution in the acceleration cavity 1, respectively. In both figures 2 and 3, 8 is the strength of the electric field in the traveling direction of the particles 6 in the acceleration cavity 1, and 9 is the strength of the electric field in the direction perpendicular to the traveling direction of the particles 6. is there. Next, the operation will be described. The basic operation is the same as the conventional one, but the accelerating cavity 1a next to the coupling cavity 3 with a short rod has a ring 7 at the inlet as shown in FIG. 1 (a). The electric field distribution of the accelerating cavity 1a is different from the electric field distribution of the other accelerating cavities 1 (FIG. 2), and the electric field in the direction perpendicular to the traveling direction of the particles 6 as shown in FIG. It rapidly increases near the particle entrance, and a large converging action acts on the particle 6. Therefore, as shown in FIG. 8B, the coupling cavity 3 of FIG.
Even if the electric field suddenly weakens in the accelerating cavity 1a of Fig. 1 (a) by inserting the short rod 5 into it, the particle 6 will not diverge because it will undergo a large focusing action at the entrance of this accelerating cavity 1a Be accelerated. When the short rods 5 are inserted in the coupling cavities 3 and 4 on both sides as shown in FIG. 7, there is no electric field after the acceleration cavity 1a in FIG. It becomes like c). In such a case, it is advisable to provide a ring 7 at the entrance of the acceleration cavity 1 shown in FIG. That is, when the three types of short rods 5 are put in and out as shown in FIGS. 5 to 7 in the energy adjustment, both acceleration cavities 1 and 1a of FIG. 1 (a) are accelerated. At the entrance to the cavity,
It is necessary to provide the ring 7. Incidentally, when the short rod 5 is put in and out as shown in FIGS. 5 and 6, the ring 7 may be inserted into the acceleration cavity 1a. If such a ring 7 is provided at the entrance of all accelerating cavities, the particles 6 are always strongly focused at the entrance of the accelerating cavity.

【The invention's effect】

As described above, according to the present invention, since the particle accelerating and beam converging means are provided in the accelerating cavity before or after the coupling cavity with the short rod, it is not necessary to use an external magnetic field. Therefore, the accelerating tube becomes compact and inexpensive.

[Brief description of drawings]

FIG. 1 (a) is a sectional view showing the structure of the main part of a standing wave type acceleration tube according to an embodiment of the present invention, and FIG. 1 (b) is a plan view of a ring used in the embodiment. 2 and 3 are electric field distribution diagrams in the accelerating cavity in the above embodiment, FIG. 4 is a cross-sectional view showing the structure of the main part of a conventional standing wave type accelerating tube, and FIGS. 5 to 7 are FIGS. 8 (a) to 8 (a) to 8 (c) are diagrams of microwave propagation according to the position of the short rod inserted into the coupling cavity in the conventional standing wave type acceleration tube, respectively.
FIG. 6 (c) is an electric field intensity diagram in the standing wave type accelerating tube at the short rod insertion position of FIGS. 5 to 7, respectively. In the figure, 1 and 1a are acceleration cavities, 3 and 4 are coupling cavities, 5 is a short rod, 6 is a particle, and 7 is an acceleration and beam focusing means. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] 1. A plurality of accelerating cavities for accelerating particles and propagating microwaves, and a coupling cavity in which short rods which are coupled to the accelerating cavities via coupling holes to stop the propagation of microwaves are inserted. A standing wave type accelerating tube provided in the accelerating cavity before or after the coupling cavity into which the short rod is inserted, the accelerating and beam converging means for accelerating the particles and causing the beam converging action.