JPS6269499A - Incident device for magnetic resonance type accelerator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an injection device for a magnetic resonance accelerator that injects charged particles into a magnetic resonance accelerator having an orbit such as a synchrotron, storage ring, or collision ring. .

[Prior Art] A conventional magnetic resonance accelerator with an orbit uses an electromagnet called a kitker, which operates at high speed, or an electromagnet called a perturbator, as an injection device, and generates a magnetic field or an electric field in direct current. It had an inflector. An inflector guides charged particles into an incident trajectory. The kitker or perturbator displaces the equilibrium orbit so that even if a charged particle incident from the inflator travels around the orbit 11 degrees and comes to the inflator position, it will not hit the inflator.

In general, the Kitzker displaces the entire balanced track, while the Perturbator works in synchronization with two or three pieces to displace a partial section of the balanced track.

A conventional magnetic resonance type accelerator having an orbit will be explained with reference to FIGS. 8 to 10 showing specific examples.

The conventional magnetic resonance accelerator shown in Fig. 8 consists of an inflector INF that guides charged particles to an incident trajectory, a circular equilibrium orbit TR, and a bipolar electromagnet installed at multiple locations on the equilibrium orbit, each with a bipolar electromagnet and a A plurality of deflection recognition and focusing elements consisting of two sets of horizontal focusing quadrupole electromagnets QF and horizontal diverging quadrupole electromagnets QD arranged on both sides, and a balanced trajectory provided at the ends of the focusing elements on both sides of the inflector. There are Partabata P1 to P3 that move the parts. Partabaita P1~P3
As shown in FIG. 9, the balanced trajectory TR is displaced to provide a displaced balanced trajectory TR''.

While injecting a beam from the inflector INF into this displaced orbit TR', the perturbator is weakened, and the displaced orbit TR' is gradually returned to its original orbit TR.

This mechanism will be explained with reference to FIG. 10, which shows the phase space in a cross section taken along line AA' in FIG. 8. here 4
Consider the case of betatron oscillation, which rotates and returns to its original state. In FIG. 10, X represents the horizontal displacement from the original balanced trajectory TR, and X' represents the inclination of the trajectory. Furthermore, the reference number 0 is the equilibrium trajectory T displaced by the perturbator.
R', 1 is the incident orbit, and 2 is the orbit after being input and going around the orbit once. Orbit 2 oscillates as a betatron around the equilibrium orbit 0, so it is located at a position rotated around orbit 0 by an angle determined by the oscillation of the betatron. Reference number 3
, 4 and 5 represent the orbits after two, three, and four revolutions after incidence, respectively. The reason why trajectory 5 does not come to the position of incident trajectory 1 is because the displaced equilibrium trajectory 0 moves in the direction of the arrow as the perturbator weakens. The condition for not colliding with the inflector INF is that the gap between the incident trajectory 1 and the trajectory 5 is sufficiently large.

[Problems to be solved by the invention] In order to miniaturize the conventional magnetic resonance accelerator mentioned above and inject it with as high energy as possible, it is necessary to use a perturbator or kicker that generates a very high-velocity and high-intensity magnetic field. Become. In addition, the inflector requires a high-intensity magnetic field or electric field. However, there are technical limits to the strength and response speed of magnetic and electric fields that can be achieved with perturbators, kitskers, and inflectors. A method of injecting, accumulating, and accelerating with a very weak magnetic field is also possible, but
At low energies, the lifespan of stored charged particles is short, making it unsuitable for storing a sufficient amount of charged particles. These are obstacles to making magnetic resonance accelerators smaller and more efficient.

[Means for Solving the Problems] The injection device for a magnetic resonance accelerator according to the present invention applies a nonlinear magnetic field whose main component is an octupole magnetic field to the orbital surface around a centrally balanced orbit, and the effect of this nonlinear magnetic field is So that there exists a resonant orbit where the horizontal betatron frequency is 1/2,
Furthermore, it has a perturbator whose main component is a quadrupole magnetic field and which changes over time.

[Example 1] Referring to FIG.
1, an incident trajectory 12, an inflector 13, and a perturbator 14. In the conventional pertervater, the dipole magnetic field has the main function, whereas in the pertervater 14 of the present invention, the quadrupole magnetic field has the main function.

If we take a coordinate system as shown in Figure 2 for the balanced orbit 11, the magnetic field distribution on the r-6 plane is B (x) = 8 (1-nx + k x +
k x + ・・−)z zo
It can be expressed as 2 3x = (rr)/req eq. Here, B is the magnetic field in the Z direction O on the centrally balanced orbit, and r is the radius of the centrally balanced orbit. nq is an important parameter for focusing the beam, and in the present invention, parameter 3 has an essential function. The magnetic field distribution has eight components as shown in Figure 3.

In FIG. 2, the position of point 0 is assumed to be 0=0°, and the injection mechanism will be explained with reference to a phase plot diagram of the trajectory at this location. FIG. 4 shows a phase plot of r-direction motion without perturbator. In Fig. 4, the symbol X is the orbit proy) in which the amplitude of the betatron oscillation is small, and since the betatron oscillation frequency is greater than 1/2 of the margin below, the arrow Turn in the direction. When the magnetic field has eight components as shown in FIG. 3, as the amplitude of the betatron oscillations increases, the betatron frequency decreases. Betatron vibration frequency! /2, the orbit is the fourth
It is represented by the symbol Y in the figure, and it only oscillates between numbers 1' and 2'. As the betatron vibration amplitude further increases, the betatron frequency becomes smaller than 1/2, resulting in a trajectory indicated by the symbol Z in FIG.
It will rotate in the opposite direction than in the case of .

When a perturbator 14 with a quadrupole magnetic field is installed at the position of θ = 180°, the orbit Y that vibrates between two points will only have a node at the position of the perturbator 14, as shown in orbit -15 in Fig. 5. Become. In the phase plot, as shown in FIG. 6, the orbits are classified into two groups: non-moving orbits, Nigeloop orbits rotating around orbits, and orbits outside the stable region. The orbit 16 belongs to the group that rotates around the central equilibrium orbit 11 in state X in FIG. The group of tracks 17 rotates around the track 15 while oscillating between left and right closed areas. Orbit 18 is a group that rotates so as to surround orbits 16 and 17 in state Z in FIG. Trajectory 19 belongs to the group that flies away without being caught in the stable region. The size of the area of the trajectory 17 corresponds to the strength of the perturbator 14. Injection takes place from the outside along the trajectory 19. When it reaches point B, the inflector 13 moves it to point 0.

If the perturbator 14 is weakened as it approaches the orbit 16 while vibrating along the orbit 17, it will shift to a orbit in which it rotates while vibrating around the central equilibrium orbit 11 like the orbit 16. In this way, the trajectory captured in the area of the trajectory 16 does not increase in amplitude to the zero point position again, and therefore does not collide with the inflector 13. Incidentally, if only the incident trajectory is phase plotted, the result will be as shown in FIG. 7. However, the number represents the number of times the beam passes through θ=0° after incidence.

[Effects of the Invention] The injection device according to the present invention applies a nonlinear magnetic field whose main component is an octupole magnetic field, creates a resonant orbit with a betatron frequency of 172, and further has a quadrupole magnetic field as its main component and temporally It has a perturbator that generates a changing magnetic field, and by using an orbit that oscillates as a betatron around a resonant orbit for injection, it has the following effects.

(1) The burden on the inflector is reduced.

(2) The strength and speed of time change of Perturbator is reduced.

(3) It is possible to inject the beam into a small storage ring with a strong magnetic field.

(4) The uj gap between the incident orbit and the orbit after the injection is large, leading to a reduction in the incidence efficiency.

Note that the present invention is applicable to weakly focused and strongly focused magnetic resonance accelerators. Further, the octupole magnetic field may exist only in one section or i number of positions along the orbit. Furthermore, the perturbator can be divided into those that change over time and those that do not, and these can be used by superimposing them at a plurality of different positions or at the same position.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is a diagram showing a balanced orbit, Fig. 3 is a diagram showing a magnetic field distribution, Fig. 4 is a phase plot diagram of the orbit, and Figs. 7 is a phase plot diagram of the incident trajectory, FIG. 8 is a diagram showing a conventional accelerator, and FIGS. 9 and 10 are FIG. 2 is an explanatory diagram of the operation of a conventional accelerator. 11...Equilibrium orbit, 12...Incidence orbit, 13...
Inflector, 14... Partabaita. Agent (7783) Kashi 111. Ike January Noriyasu ('1st
Figure 2

Claims (1)

[Claims] In an injection device for injecting charged particles into a magnetic resonance type accelerator having a circular orbit, a nonlinear magnetic field having an octupole magnetic field as a focusing component is formed on the orbital plane around a central equilibrium orbit, and horizontal beta The frequency of tron vibration is 1/2
An injection device for a magnetic resonance accelerator, characterized in that it has a resonant orbit, and further includes a perturbator that generates a magnetic field that has a quadrupole magnetic field as its main component and changes over time.