JPH01700A - High frequency acceleration cavity using superconductor - 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 [Industrial Field of Application 1] This invention relates to a high frequency acceleration cavity for accelerating charged particles in a circular accelerator.

[Prior Art] FIG. 2 shows a system diagram of a conventional high frequency accelerator. 1 is a beam duct in a circular accelerator that accumulates charged particles, and 2 is an acceleration cavity for accelerating charged particles using a high-frequency electric field, which is a cylindrical hollow body with both ends closed. , is located coaxially with the beam duct 1, and the beam duct 1 penetrates inside the acceleration cavity 2 from both end surfaces, and the duct ends 1a of the beam duct 1 that have penetrated therethrough face each other through a predetermined gap G. ing.

When the high frequency wave oscillated by the high frequency oscillator 3 is supplied into the acceleration cavity 2 through the waveguide 4, the high frequency wave is supplied to both ends 1a of the beam duct 1.
In addition, an electric field E is generated in a direction that accelerates the charged particles. 5 is a water load for absorbing high frequency reflected waves from the acceleration cavity 2, and is provided in the middle of the waveguide 4.

This acceleration cavity 2 is generally made of a cladding material of oxygen-free copper and stainless steel, or an iron material with a copper-plated inner surface, or aluminum, but when an electric field E is set up inside such an acceleration cavity 2, the inside of the cavity is A circulating current flows across the surface.

Since this current is a high-frequency current, it flows at a surface depth that depends on the material of the inner surface of the cavity, but if the cavity is made of copper, aluminum, etc., the Joule loss due to this current will be large, and the characteristics of the cavity will be affected. Since the expressed Q value is generally as low as about 105, energy loss becomes large relative to the required electric field, and a high-power high-frequency oscillator 3 is required.

[Problem to be Solved by the Invention J] Therefore, it is conceivable to form the acceleration cavity 2 with a superconductor so that no loss occurs even when a high-frequency current flows inside the cavity. In this case, niobium (Nb) is used as the superconducting material.
A sheet of several mm is formed using a 10'' T
It is annealed at a temperature of several hundred to 1,000 degrees Celsius in a vacuum atmosphere of about 300° C. to release welding distortion. As for the surface treatment inside the cavity, a method is used in which electrolytic polishing is applied and a thin oxide film is applied and then removed with hexachloric acid.

An accelerating cavity made of such a superconductor has a Q value of 4.2 and approximately 109, and its characteristics are greatly improved compared to a normal conducting cavity, but the formed superconductor may be locally contaminated with impurities. There is a problem in that there are places where the magnetic field tends to concentrate, such as existing places and welding places, where the superconducting state is broken and a local temperature rise is caused.

This invention was made to eliminate the above-mentioned problems, and aims to provide a high-frequency acceleration cavity using a superconductor that reduces energy loss and enables stable operation.

[Means for Solving the Problems] A high-frequency acceleration cavity using a superconductor of the present invention is a high-frequency acceleration cavity for accelerating charged particles in a circular accelerator, and the inner surface of the high-frequency acceleration cavity has approximately The present invention is characterized in that a thin film is formed of a high temperature superconductor exhibiting a superconducting phenomenon of 90 or higher.

[Effect 1] According to the above configuration, the high frequency wave introduced for accelerating charged particles flows into the superconductor layer formed on the inner surface of the high frequency acceleration cavity, but no Joule loss occurs, so the operating efficiency is improved.

[Example] FIG. 1 shows an example of a high frequency acceleration cavity using the superconductor of the present invention.

Reference numeral 11 denotes a beam pipe made of stainless steel, which is drawn to form a cavity X at the center, and has an inner diameter B (-) at both ends Y than the inner diameter A at the center X. It has been narrowed down to <A). The inner diameter B at both end openings Y is the same as the inner diameter of the beam duct 1 shown in FIG.

Then, a layer 13 having a uniform thickness is formed on the inner surface of the cavity X of the beam pipe 11 using a thin film forming apparatus using a high-temperature superconductor that exhibits a superconducting phenomenon at approximately 90 K (absolute temperature) or higher. Further, in order to cool the superconductor layer 13 to a critical temperature at which it becomes superconductive, a coolant container 14 is provided to cover the outer periphery of the beam pipe 11, and liquid nitrogen is sealed in the coolant container 14. Further, an introduction port 15 for introducing high frequency waves into the cavity X is provided at a predetermined portion of one eyelet Y, and this introduction port 15 is connected to a high frequency oscillator 3 shown in FIG. A waveguide 4 is connected.

In the high frequency acceleration cavity configured as described above, if microwaves are introduced into the cavity X from the introduction port 15,
Charged particles from the beam duct 1 are accelerated in the cavity X by an electric field formed by the introduced high frequency wave. Also, at this time, a part of the supplied high frequency flows as a circulating current to the superconductor layer 13 on the inner surface of the cavity X, but since the superconductor layer 13 is in a superconducting state due to cooling of the liquid nitrogen, Since almost no Joule loss occurs, the characteristic value Q in this high frequency acceleration cavity becomes large, and the output capacity of the high frequency oscillator 3 can be reduced. In addition, since the superconductor layer 13 is formed into a uniform thin film, there is no need for a subsequent polishing process, which eliminates the contamination of impurities, and since there are no welding points and the specific heat of the superconductor layer is large, There is no longer any breakage in the superconducting state as in conventional systems, resulting in stable operation and improved reliability.

[Effects of the Invention] According to the present invention, operating efficiency is improved because Joule loss is eliminated, and stable operation is possible and reliability is improved because the superconducting state is no longer broken due to defective parts.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of a high frequency acceleration cavity using the superconductor of the present invention, and FIG. 2 is a schematic system diagram of a conventional high frequency acceleration device. 1... Beam duct, 3... High frequency oscillator, 4...
- Waveguide, 11... Beam pipe, 12... 7 runs, 13... Superconductor layer, 14... Refrigerant container, 15
...Introduction port. Patent applicant: Sumitomo Electric Industries, Ltd. Representative: Patent attorney: Aohaku Ao and 1 other person

Claims (1)

[Claims] (1) A high-frequency acceleration cavity for accelerating charged particles in a circular accelerator, the inner surface of the high-frequency acceleration cavity having approximately 9
A high-frequency acceleration cavity using a superconductor, characterized in that a thin film is formed of a high-temperature superconductor that exhibits a superconducting phenomenon at temperatures above 0K.