JPH02142099A - Incident device for charged particle beam - Google Patents

Abstract

PURPOSE:To take incident beams in with no influence on accumulated beams by providing an electro-magnet which generates magnetic fields with multi- magnetic field components so as to deflect the orbit of charged particles. CONSTITUTION:A generated magnetic field is furnished with an electro-magnet 16 accompanied with multi-magnetic field components. The direction of a magnetic field to be generated by the electro-magnet 16 is opposite about a center axis with respect to the axis of symmetry, an incident beam is subjected to the more intensive force of the magnetic field as it is parted from the center axis so that it is thereby pressed back toward the center axis. Which situation thereby prevents the beam on the center axis from being affected much, the orbit 4 of accumulated beams is not changed even when the electro-magnet 16 is in operation, and the capacity of a power supply can thereby be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Practical Application] The present invention relates to a charged particle beam injection device used for, for example, injection of a charged particle beam into a circular accelerator.

[Prior art] Figure 3 shows, for example, "Design of UV Storage Ring" (UVSOR-9), published by the Institute of Molecular Science, December 1982.
This is the conventional charged beam injection device shown on page 67. In the figure, (1) is the vacuum chamber of the electromagnet, (2) is the coil, (3) is the yoke of the coil, (4) is the storage beam trajectory, ( 5) shows the incident trajectory.

FIG. 4 shows the situation at this time on a phase plane. In the figure, circles (5) to (11) indicate the positions of the incident beams. The horizontal axis represents the deviation from the center orbit, and the vertical axis represents the inclination of the beam with respect to the center @1. In FIG. 5, (12) shows the incident magnet, and (13) shows the wall of the vacuum chamber.

(14) shows the trajectory of the incident beam, and (15) shows the trajectory of the @ product beam.

A conventional charged particle beam injection device is constructed as described above, and the current generated by the pulse 'l[is is an electric current.

flows into the magnet. As shown in the drawing, the electromagnet generates only a magnetic field in the vertical direction and deflects the beam trajectory by a certain amount. The reason why pulsed electromagnets are necessary is that, according to physics, when only a temporally constant magnetic field force acts on a beam, for example in Figure 4, the beam moves on an arc centered on the central axis. In other words, the beam (
5) will move on the arc that passes through the position of (5), and will eventually return to the original position (5) tK. As can be seen in Figure 5, this beam is located at the incident magnet (1
It collides with the vacuum wall (13) of 2) and becomes unable to enter. This is because in order to keep the incident beam inside, it is necessary to apply orbital deflection to the beam using a pulsed electromagnet for only a certain period of time.

FIG. 4 shows this situation. First, consider the incident beam. Before the electromagnet is driven, the beam is (5
) is located off the central axis.

When the beam next reaches the electromagnet after one rotation, the beam position has changed to position (6). At that position, it changes by tK by K(7) due to the magnetic field of the pulsed electromagnet. Then, due to the effect of the magnetic field generated by the electromagnet,
- (81, (9), (1o) for each revolution.

It will pass through position (11). Next, if the ILF flow of the pulsed electromagnet is cut off at this time, the subsequent beam will move on an arc centered on the central axis in FIG. 4, as taught by accelerator physics. Therefore, in FIG. 4, the incident beam traces a trajectory inside the initial position, and never goes outside.

[Problem to be solved by the invention]

In the conventional charged particle beam injection device as described above, for example, the magnetic field generated by the electromagnet also affects the stored beam. This may cause extra vibrations to the beam and cause it to become unstable. Also,
Considering the power source of the electromagnet, the electromagnet generates an unnecessary magnetic field, and a power source capacity that is larger than necessary is required.

The present invention has been made to solve these problems, and aims to provide a loaded particle beam injection device that does not disturb the stored beam and can reduce the power supply capacity.

[Means to solve the problem]

The charged particle beam injection device according to the present invention includes an electromagnet with a multipolar magnetic field component in the generated magnetic field.

[For production]

In this invention, the direction of the magnetic field generated by the electromagnet is
They are opposite with the central axis as the axis of symmetry. Therefore, as the incident beam moves away from the central axis, it receives a stronger magnetic field force and is pushed back onto the central axis.

〔Example〕

FIG. 1 shows an embodiment of the present invention, with symbols (1) to (1)
5) is exactly the same as the conventional device described above.

(16) is, for example, a quadrupole electromagnet. FIG. 2 is a diagram showing a phase plane, and the symbols are exactly the same as in the conventional device.

In the charged particle beam injection device configured as described above, the generated magnetic field takes a value proportional to X. For this reason, the beam on the central axis is hardly affected, and the trajectory of the stored electron beam does not change even if the electromagnet is operated. If we consider the incident beam, as shown in Figure 2, by appropriately selecting the angle at which the beam rotates per rotation, we can see that it converges as it receives a stronger force as it moves away from the central axis.

In the above embodiment, a quadrupole electromagnet was considered as the electromagnet, but a similar operation can be expected with a multipole electromagnet for generating a higher-order magnetic field.

〔Effect of the invention〕

As explained above, in this invention, by using a multipolar electromagnet instead of the conventional incident pulse electromagnet for generating a vertical magnetic field, the incident beam can be taken in with almost no effect on the accumulated beam.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an embodiment of the present invention, FIG. 2 is a line diagram showing the behavior of the beam in phase space in this embodiment, and FIG. 3 is a cross-sectional view of a conventional charged particle beam injection device. ,
FIG. 4 is a diagram showing the behavior of the beam on the phase plane, and FIG. 5 is a sectional side view of the main part of the slow-rising incidence magnet and the vacuum vessel, which are used simultaneously with the pulse electromagnet. (1)...Vacuum container, (2)...Magnetic coil,
(3)...magnet yoke, (4)...storage beam trajectory, (5)...injection trajectory, (16)...quadrupole electromagnet. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] A charged particle beam injection device comprising an electromagnet that generates a magnetic field having a multipolar magnetic field component and deflects the trajectory of a charged particle by the magnetic field, and a power source for causing a pulse current to flow through the electromagnet.