JPS5820120B2 - Sengata Denshika Sokki - Google Patents

Description

[Detailed description of the invention] This invention relates to improvements in linear electron accelerators.

FIG. 1 is a vertical cross-sectional view showing the configuration of the main parts of a conventional linear electron accelerator tube, which is heated to a high temperature by a heater 12 provided inside an electron gun 1 connected to an accelerating tube 2 through a flange 11.21. A high voltage (usually 5 to 1 ooKV) is applied between the hot cathode 13 and the anode 14 insulated by the insulator 16, and the electrons emitted from the hot cathode 13 are converged by the Wehnelt electrode 15, and then the electrons in the acceleration cavity 24 are It is accelerated by a microwave electric field.

In the linear electron accelerator configured in this manner, the smaller the accelerating tube 2 is, the larger the ratio of the electron gun 1 to the accelerating tube 2 becomes, which is an obstacle to downsizing.

Furthermore, the electron gun 1 requires a high-voltage pulse source to be applied between the positive and negative electrodes, which is an obstacle to simplifying the device.

This invention was made in view of the above-mentioned conventional difficulties, and integrates the accelerator tube 2 and the electron gun 1, and provides a compact and simple structure that does not require a high-voltage pulse source for the electron gun, and is an inexpensive linear The purpose is to provide an electron accelerator.

In this invention, the center of the end plate inside the resonant cavity is made of a cathode material, and the shape of the resonant cavity is such that electrons are emitted by the microwave electric field within the resonant cavity. The electron group is set to form a convergent electron beam.

FIG. 2 is a longitudinal cross-sectional view showing the configuration of essential parts of an embodiment of the present invention, in which 22 is a convergence cavity and 23 is a disk.

That is, the linear electron accelerator of this embodiment includes an acceleration tube 2 and an electron emission source.

This acceleration tube 2 has a plurality of resonant cavities 2 whose interior is partitioned by disks 23 at appropriate intervals along the longitudinal direction.
2 and 24 are formed sequentially.

An opening is formed in the disk 23.

In other words, each adjacent resonant cavity 22, 24 of the acceleration tube 2
An opening is formed in the wall between the two.

Among the plurality of resonant cavities, one end of the acceleration tube 2 (the left end in the figure) is used as the convergence cavity 22, and the other resonant cavities following the convergence cavity 22 are used as the acceleration cavities 24. It will be done.

An electron emission source is integrally formed on the wall surface of one end of the acceleration tube 2, that is, on the wall surface of the convergence cavity 22.

This electron emission source includes a heater 12 and a hot cathode 13.

A Wehnelt electrode (so-called convergence electrode=15) is formed in a protruding cylindrical shape around the hot cathode 13 on the convergence cavity 22 side.

Next, the operation when a focused electron beam is derived using the linear electron accelerator of this embodiment will be described.

Now, when microwaves are supplied to the acceleration tube 2 from a microwave input end (not shown), a microwave electric field is generated in the axial direction by the TMolo resonance mode of the convergence cavity 22.

Electrons are emitted from the hot cathode 13 heated by the heater 12 by this microwave electric field.

The emitted electron group becomes a focused electron beam due to the convergence effect of the electric field distribution in the convergence cavity 22, and is accelerated by the microwave electric field in the acceleration cavity 24.

FIG. 3 shows another embodiment of the invention, in which a cold cathode 25 is provided in place of the hot cathode 13 and heater 12 of the embodiment of FIG.

In this embodiment as well, electrons are extracted by the microwave electric field within the focusing cavity 22 and a focused electron beam is formed, as in the previous embodiment.

This invention uses a microwave electric field in the convergence cavity 22 to extract a group of electrons from an electron emission source and converge them to form an electron beam, so an electron gun is not required, and the configuration of a linear electron accelerator tube is therefore simplified. It is simple and compact.

Furthermore, since a high-voltage pulse power source for the electron gun is not required, the device can be made simple and inexpensive.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing the configuration of the main parts of a conventional linear electron accelerator, FIG. 2 is a longitudinal sectional view showing the structure of the main parts of an embodiment of the present invention, and FIG. FIG. 3 is a longitudinal cross-sectional view of the embodiment. . In the figure, 2 is an acceleration tube, 12 is a heater, 13 is a hot cathode, 22 is a convergence cavity, 23 is a disk, 24 is an acceleration cavity, and 25 is a cold cathode.

Claims (1)

[Scope of Claims] 1. An acceleration tube in which a plurality of resonant cavities are sequentially formed along its longitudinal direction, and openings are formed in the wall between adjacent resonant cavities, and - the acceleration tube. integrally formed on the wall at one end of the and an electron emission source for emitting electrons, a resonant cavity on one end side of the acceleration tube is used as a convergence cavity, and another resonant cavity following the convergence cavity is used as an acceleration cavity. , A linear electron accelerator characterized in that a microwave electric field in the acceleration tube extracts electrons from the electron emission source, converges the electrons to generate an electron beam, and accelerates the electron beam. . −