JPH01217900A - Accelerator - Google Patents

Abstract

PURPOSE:To make it possible to centralize particles having extents with two- pole deflection electromagnet at the center of orbit designed by providing a focusing eight-pole electromagnet having a large focusing function and a dispersing eight-pole magnet at the outlet of the two-pole deflection magnet. CONSTITUTION:At the outlet of two-pole deflection magnet 2, a focusing eight- pole electromagnet 7, and a dispersing eight-pole magnet 8 are arranged sequentially. The eight-pole magnet has a property to give strong focusing and dispersing forces by the arrangement of magnets forming the eight-pole magnet. Particles accelerated by means of a high frequency acceleration cavity (not shown) lose energy when they pass along the outer periphery side of orbit in the two-pole deflection magnet 2, and have extents when they pass along the inner periphery side of orbit therein. By the adoption of the electromagnets 7 and 8, the orbits of particles having respective extents can be resumed to those approximately equal to the original orbit designed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an accelerator suitable for accelerating large currents.

[Conventional technology]

Conventionally, in a synchrotron accelerator, as shown in FIG. 2, the trajectory of particles injected from an injector 1 is bent by a bending electromagnet 2, and the particles are deflected by a converging quadrupole electromagnet 3 and a divergent quadrupole electromagnet 4. It revolves around the designed orbit 5 while being subjected to convergence and divergence effects.

When the particles pass through the high-frequency acceleration cavity 6, they are accelerated or decelerated due to the difference in the phase of the high-frequency waves, but each time they make a turn, they are accelerated and their energy increases.

[Problem to be solved by the invention]

As described above, the energy of the particles is accelerated by the high-frequency acceleration cavity 6 and increases with each rotation.

If the trajectory of a particle having electric charge (e) and moving at a speed close to that of light flux is bent by a bending electromagnet, then if the momentum at this time is PO and the magnetic flux density of the bending electromagnet is BO, then the radius of curvature ρ is It is given by equation (1).

eB.

When a particle is accelerated in the high frequency acceleration cavity 6, its energy increases and its momentum increases by Po+ΔPO.

The radius of curvature increases by (2) a large amount.

eB.

Therefore, the particles pass outside the center of the bending electromagnet 2 by the amount that their momentum has increased compared to the Po particle. As a result, the particles spread within the bending electromagnet 2 and begin to be displaced from the designed trajectory in the horizontal direction. Therefore, when the energy of a particle changes significantly due to syntarotron oscillation, the horizontal displacement increases,
Since the particles move in a spread manner within the designed trajectory 5, they collide with the inner wall of the vacuum vessel 5, causing a large loss of energy and making it impossible to maintain a large current.

An object of the present invention is to solve the above problems and provide an accelerator that can obtain a large current.

[Means to solve the problem]

The above problem involves storing particles accelerated with high energy,
a vacuum container having a closed orbit; a two-pole bending electromagnet that deflects the trajectory of particles within the vacuum container; a converging quadrupole electromagnet that converges particles that have passed through the two-pole bending electromagnet; and the converging quadrupole electromagnet. In an accelerator consisting of a divergent quadrupole electromagnet that makes particles converged by the electromagnet diverge into a horizontal beam; and a high-frequency acceleration cavity that accelerates particles emitted from the divergent quadrupole electromagnet; A converging octupole electromagnet that converges the passing particles; and a diverging octupole electromagnet that diverges the particles converged by the converging octupole electromagnet and converts them into a horizontal beam at the center of the orbit at the exit of the two-pole bending electromagnet. This problem can be solved by providing an octupole electromagnet for divergence in the front and an octupole electromagnet for convergence in the rear with respect to the traveling direction of the particles on the sides.

[Effect]

A converging octupole electromagnet and a diverging octupole electromagnet with a large convergence force are provided at the exit portion of the 2-pole bending electromagnet, and the 2-pole bending electromagnet narrows the spread particles to the center of the designed trajectory.

〔Example〕

Embodiments of the present invention will be described with reference to FIGS. 1, 3, and 4.

FIG. 3 shows the operation of the converging octupole electromagnet. The figure shows the arrangement of N and S poles in a plane perpendicular to the designed trajectory, and the arrows indicate the direction of the magnetic field. On the X-axis (horizontal direction) of the vertical plane of the design trajectory, the magnetic field (By) is oriented in the y-direction (vertical direction), but the direction of the magnetic field (By) differs depending on whether it is positive or negative on the X-axis. Therefore, when a charged particle passes along the X-axis in the Z direction (Xs y+2 is right-handed).

The particles are converged in the direction of x=O.

The dx/dz at the entrance of the octupole electromagnet can be approximated as PXo, and the dx/dz after passing through the octupole electromagnet as Px can be approximated as shown in equation (3).

P x = P xo + A x 3- (3) Here, A: constant.

In a converging 8-pole electromagnet where A is negative, X regardless of whether X is positive or negative.
The larger the value, the greater the convergence effect.

On the other hand, if you change the polarity in the figure from N pole to S pole and sl to N pole, the directions of the magnets will all be reversed, so on the X axis
It receives a divergent effect regardless of whether it is positive or negative.

FIG. 1 shows the operation of the present invention. Electromagnets having two functions as shown in FIG. 3, that is, an octupole electromagnet 7 for convergence and an octupole electromagnet 8 for divergence, are placed on the exit side of the bipolar bending electromagnet 2 in the forward direction with respect to the traveling direction of the particles. An octupole electromagnet 8 for divergence is installed behind the polar electromagnet 7. First, high frequency acceleration cavity 6
When the particles are accelerated, their energy increases, and when they pass through the bipolar bending electromagnet 2, they pass on the outer circumference of the orbit of the bipolar bending electromagnet 2, and lose energy and move toward the inner circumference of the orbit of the bipolar bending electromagnet 2. pass through. After the particles with this spread pass through the two-pole bending electromagnet 2, by shortening the distance to the focusing eight-pole electromagnet 7, collisions with the inner wall of the designed orbit 5 are reduced.
Energy loss is also reduced. Further, by using the converging octupole electromagnet 7 and the divergent octupole electromagnet 8, the trajectories of the particles having their respective spreads can be returned to trajectories approximately equal to the original designed trajectories. Furthermore, the same effects can be applied to particles passing on the y-axis in FIG.

Due to the above effects, even if energy oscillations occur due to synchrotron oscillations, the displacement of one particle in the X direction (horizontal direction),
Directional (vertical) displacement can be kept small, and large current acceleration is possible.

FIG. 4 shows an embodiment in which the deflection is made larger than that shown in FIG. Two dipole bending electromagnets 2 (radius of curvature: 0.6 m) were used to deflect the particles 180', and the particles were deflected from 10 M e V to 600 M e
This shows a part of the accelerator that accelerates to V. The high frequency acceleration cavity 6 has an amplitude of 5k in terms of electron energy.
A high frequency of eV is applied. Therefore, when particles pass through the high-frequency acceleration cavity 6, due to the difference in the high-frequency phase, a maximum of 5
An increase or decrease in energy of keV occurs. This phenomenon occurs repeatedly, and the particles move around in a circular orbit while changing energy (vibrating). The period (time) of this energy oscillation (synchrotron oscillation) varies approximately 200 times in terms of the number of revolutions of the circular orbit. That is, after changing the zoO times, the energy returns to its original value. Due to this effect, for example, when a particle is injected into an accelerator at 10 MeV, its average energy increases while the energy changes from approximately 9.7 to 10.3 MeV. The trajectory for an energy of 10.3 M e V is shown by a broken line in FIG. 4, and the trajectory for an energy of 9 and 7 M e V is shown by a dashed line. Energy 10.3MeV, 9.7Me
The displacement of the particles V in the X direction (horizontal direction) at the exit side of the bipolar bending electromagnet 2 is ±2.4C each! It becomes l. Therefore,
Using equation (3), PK at the exit part of the converging 8-pole electromagnet 7
seek. Here, if parameter A is set as approximately 380, then
Since Pxo when entering the converging octupole electromagnet 7 is approximately zero even if the energy changes from 10, 3 to 9, or 7 M e V, P8 at the exit of the converging octupole electromagnet 7 is , 6 mra for energy 9,7 MeV
d, energy 10, −6 m for 3 M e V
It becomes rad. A straight section with a length of 1.5 m without a magnetic field is provided between the converging 8-pole electromagnet 7 and the divergent 8-pole electromagnet 8.

As a result, the 8-pole electromagnet 8 for 1 divergence has energy 9, 7
The particle of M e V is P x at the position x=-1,5an
Incident at o = 6 mrad, energy 10,3
In the case of M e V, Px at the position of x = 1.5al.

= -6 mrad. Therefore, for the 9-diverging 8-pole electromagnet 8, by setting the parameter A in equation (3) to 1900, the particle at the exit of the 1-diverging 8-pole electromagnet 8 will have a displacement in the X direction of 1.5 an. It can be rotated with small displacement. In addition, the above-mentioned energy change also occurs in the process in which the average energy of particles increases, but this can also be solved by changing the magnetic field strengths of the converging octupole electromagnet 7 and the divergence octupole electromagnet 7, ) By adjusting the parameter A in the equation, acceleration can be achieved while suppressing the displacement in the X direction.

〔Effect of the invention〕

According to the present invention, by providing a converging octupole electromagnet with a large convergence force and a diverging octupole electromagnet at the exit part of a 2-pole bending electromagnet, particles having a large spread can be moved to the center of the designed orbit by the 2-pole bending electromagnet. Since it can be narrowed down to a small size, there is less energy loss due to collision with the inner wall of the vacuum container, and large current acceleration can be achieved.

[Brief explanation of the drawing]

Fig. 1 is a diagram explaining the present invention in detail, Fig. 2 is a diagram showing a conventional accelerator, Fig. 3 is a diagram showing a focusing octupole electromagnet, and Fig. 4 is a diagram showing an embodiment of the present invention. It is. 1... Injector, 2... 2-pole bending electromagnet, 3... 4-pole electromagnet for convergence, 4... 4-pole electromagnet for divergence, 5...
Design trajectory (vacuum vessel), 6... High frequency acceleration cavity, 7.
... 8-pole electromagnet for convergence, 8... 8-pole electromagnet for divergence.

Claims (1)

[Claims] 1. A vacuum container that stores particles accelerated with high energy and has a closed orbit; A dipolar bending electromagnet that deflects the trajectory of the particles in the vacuum container; Converges the particles that have passed through the dipole bending electromagnet. a converging quadrupole electromagnet; a diverging quadrupole electromagnet that makes the particles converged by the converging quadrupole electromagnet diverge into a horizontal beam; a high-frequency acceleration space that accelerates the particles passing through the divergent quadrupole electromagnet; In an accelerator having a body; a focusing octupole electromagnet that focuses the particles that have passed through the two-pole bending electromagnet; and a focusing octupole electromagnet that causes the particles focused by the focusing octupole electromagnet to diverge and form a beam centered on the designed trajectory and in a horizontal direction. An accelerator characterized in that an octupole electromagnet for divergence and an octupole electromagnet for convergence are provided at the exit side of the two-pole bending electromagnet in front with respect to the traveling direction of particles, and an octupole electromagnet for convergence at the rear.