JPS63116400A - Knockout electrode of accelerator - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a knockout electrode for an accelerator used in ultra-LSI@fine processing and the like.

(Prior art) Circular accelerators are used to accelerate beams of electrons, protons, ions, etc. to a high energy state of about 1 billion electron volts (IGaV), and have been used in the field of elementary particle research as an example of this accelerator. Large ones with a diameter of 11a+ or more have been constructed. Recently, relatively small accelerators with a diameter of about 10 meters have been constructed for application in new fields such as ultra-LSI microfabrication (lithography) that utilizes synchrotron radiation from electrons (called SOR light). It's starting to look like this.

Now, various types of beam monitors are used in accelerators depending on the purpose. The betatron frequency (tune) of the beam must be known well enough to determine where the operating point is and to ensure proper conditions of incidence. There is a tune monitor as a monitor for this purpose, which consists of a knockout electrode for exciting the beam and a pickup monitor for detecting the displacement of the beam (detailed explanation will be omitted).

Here, a conventional knockout electrode will be explained with reference to FIG. 2. Knockout electrode.

A vacuum chamber 3 through which a beam 2 of electrons, protons or ions passes, and a coaxial terminal 5 vacuum-connected by silver brazing or the like to an electrode base 4 mounted on the vacuum chamber 3.
and an electrode vibro attached to this coaxial terminal 5.

Note that this electrode vibro produces the same effect even if it is rod-shaped or plate-shaped.

Moreover, FIG. 3 is a side view of the knockout electrode. Each electrode vibro is connected to coaxial terminals 5 at both left and right ends,
One side of it is further connected to termination 7, where the input power is consumed.

A method of measuring tune using such a knockout electrode will be briefly described. That is, high frequency power is input from each coaxial terminal 5 to energize the electrode vibro, thereby generating a high frequency magnetic field in the vacuum chamber 3. At this time, when measuring a tune in the horizontal direction, the current is applied so that the magnetic field is in the vertical direction, and when measuring a tune in the vertical direction, the current is applied so that the magnetic field is in the horizontal direction1. In Figure 2, l! The polar vibros a and 6b are made to have in-phase currents, and the electrode vibros c and 6d are made to have currents that are 180 degrees out of phase.

When the frequency f of the magnetic field is f=(m±q)fr, the beam resonates and its amplitude increases. where m is zero or a positive integer, q is the non-integer part of the tune, and fr is the rotational frequency of the beam. The non-integer part q of the tune is determined by detecting the amplitude of the beam with a pickup monitor and checking the frequency at which the amplitude increases. On the other hand, since the integer part of the tune can be known with sufficient accuracy when designing the accelerator, the beam tune can be determined after all.

However, if the characteristic impedance of each electrode does not match the impedance of the high-frequency power source, the input power will be reflected, so power will not be effectively transmitted to each electrode vibro, and a magnetic field will be generated in the vacuum chamber 3. becomes small.

Furthermore, if the characteristic impedances of the electrodes are not uniform, the direction of the generated magnetic field will not be the desired direction, making it difficult to accurately measure the tune.

However, in the conventional knockout electrode shown in FIG. 2, the vacuum chamber 3, the electrode base 4, the coaxial terminal 5. Since the electrode vibros are fixed to each other, the characteristics of the W1 pole cannot be matched.

(Problems to be Solved by the Invention) As described above, in the five conventional knockout electrodes, the characteristics of each electrode cannot be matched.

In this case, the input power is not effectively transferred to each electrode, and sufficient magnetic fields are not generated to swing the beam.

Also, since a magnetic field is not generated in the desired direction, accurate tune measurement is difficult.This difference in characteristics is due to the mismatch between the characteristic impedance between the vacuum chamber 3 and the electrode vibro and the impedance of the high frequency power source.

Therefore, the present invention has a configuration in which the characteristics of each electrode can be easily matched, effectively utilizing the high frequency power source for tune measurement, increasing the accuracy of tune measurement, improving the beam incidence efficiency, and improving the beam incidence efficiency. The purpose is to avoid betatron oscillations and improve beam life.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a vacuum connection between an electrode base and a bellows support attached to the outer edge of a coaxial terminal using a bellows. , nut etc. to make it adjustable? By making it possible to change the position of the 11-pole pipe, the characteristic impedance between the vacuum chamber and the electrode can be matched with the impedance of the high frequency ff1M.

(Function) With this structure, the characteristic impedance of each electrode of the knockout electrode can be adjusted.

Reflection of power input from a high frequency power source can be reduced.

By doing this, it is possible to effectively utilize the capacity of the power supply to generate a high magnetic field within the vacuum chamber, and also to generate the magnetic field in the desired direction.

Tune measurement accuracy can be improved.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a cross section of the knockout electrode. This electrode is connected by a bellows 10 between a bellows support 9 attached to the outer edge of a coaxial terminal 5 and an electrode base 4, and a plurality of adjustment studs 11 erected on the electrode base 4 and a bellows. The support body 9 is adjustable and fixed with a nut 12 or the like.

In the knockout electrode configured in this way, the position of the electrode vibro is changed by turning the nut 12, and the characteristic impedance between the vacuum chamber 3 and the electrode can be easily matched with the impedance of the high frequency power source. Tune can be determined accurately by effectively utilizing the power supply capacity.

Furthermore, it is possible to increase the beam incidence efficiency and to avoid unstable betatron oscillations, thereby improving the beam life.

〔Effect of the invention〕

As described above, according to the present invention, the characteristic impedance of each electrode can be easily made equal, so the capacity of the power supply can be effectively utilized to improve tune measurement accuracy, increase the beam incidence efficiency, and prevent unstable Beam life can be improved by avoiding betatron oscillations.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a knockout electrode according to an embodiment of the present invention, FIG. 2 is a sectional view of a conventional knockout electrode, and FIG. 3 is a partially cutaway side view of a conventional knockout electrode. 2... Beam 3... Vacuum chamber 4... Electrode base 5... Coaxial terminal 6, 6a, 6
b, 6c, 6d... Electrode pipe 7... Termination 9... Bellows support 1o...
・Bellows 11...adjustment stud 12・
...Natsuto's agent Patent attorney Nori Chika Yudo Hirofumi Mitsumata Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] An electrode base fastened around a hole drilled in a wall of an accelerator vacuum chamber, a stud erected on the electrode base, a bellows support adjustable on the stud, and the bellows support. and the electrode base, and a coaxial terminal fixed to the bellows support and passing through a hole in the vacuum chamber wall to hold the electrode tip in the vacuum chamber. Features a knockout electrode for the accelerator.