JPS6040659B2 - ion generator - Google Patents

Description

[Detailed description of the invention] The present invention relates to an ion generator.

For example, PIG type ion generators are widely used in ion accelerators, etc., but they have an anode and a cathode placed opposite each other under high vacuum, and a discharge is generated between the two to supply the inside. This method generates ions by ionizing the gas.

The generated ions are usually extracted to the outside by an electric field based on the voltage applied between the external electrode and the anode, but generally they are extracted to the outside through an ion extraction port formed in the ion extraction part. . Incidentally, there has recently been a demand for an increase in the ion current, and as one measure to this end, it has been considered that the shape of the ion extraction port should be oval instead of a dot-like small hole. According to this, a larger amount of beam passes through the ion extraction port than through the small hole, which is convenient. However, when such an oval ion extraction port is used, the cross-sectional area of the ion beam passing through it also becomes wider according to the cross section of the ion extraction port, compared to when a small-hole ion extraction port is used. The ion density becomes low, making it impossible to obtain a high-quality ion beam. Even though it is sufficient to concentrate the ion beam that has passed through the ion extraction port in order to increase the ion density,
As mentioned above, an ion beam with a large cross-sectional area cannot be expected to have much of a convergence effect due to the beam. The object of this invention is to increase the ion current and at the same time increase the density of the ion beam.

The present invention is characterized in that a plurality of small holes having a small area are used as ion extraction ports, and these are formed in an elongated ion extraction port formation region.

In this case, the formation area of all the small holes should be approximately equal to the area of the oval ion extraction port formed in order to increase the ion beam current as described above. The total amount of ion beam current passing through the hole is not inferior in quantity to the ion beam current passing through the elliptical ion extraction port described above. This makes it possible to increase the ion beam current in the same way as when using an oval ion extraction port. In addition, the cross-sectional area of the ion beam passing through each small hole decreases according to the area of the small hole, and the electric field for extraction shows a uniform distribution for each small hole. Since the same homogeneous beam can be obtained in an amount equivalent to the total number of small holes, a large amount of beam with better quality (less divergence) can be obtained than with an oval shaped ion extraction port. It will be done. In other words, the ion beam current is highly concentrated. The ion beams that pass through each small hole then merge with each other and collide with the target. The present invention will be explained below based on the drawings.

In FIG. 1, 1 is a cathode and 2 is an anode, in which an ionic gas supplied from behind the cathode 1 is ionized by a discharge generated based on the voltage applied between the cathode 1 and the anode 2. Also, the anode 2 and the external electrode (not shown)
The ions generated as described above by the electric field formed between the ions and the ions are extracted through the ion extraction port of the ion extraction section 3. Note that the cross-sectional shape of the anode 2 is an oval shape. However, according to the present invention, the ion extraction port of the ion extraction section 3 shown in FIG.

Since the ion extraction port is constituted by a plurality of small holes 4, they are formed in a long horizontal line in the cross-sectional area.
With this configuration, when using the ion extraction cap A in which only one oval ion extraction port S is formed as described above, the equipotential of the electric field for ion extraction is reduced as shown in FIG. While the surface P is formed in a concave shape at the center, the equipotential surfaces P exhibiting a peak shape are formed in a number equal to the number of holes 4, as shown in FIG. Note that the arrow in the figure indicates the direction of ion extraction. In the case of FIG. 3, ions traveling between adjacent small holes 4 pass through the small holes 4 as if being drawn toward the holes 4. Therefore, the existence of the ion extraction group located between the adjacent small holes 4 does not become an obstacle to the passage of the ion beam. In other words, such a configuration does not cause a decrease in the ion beam current. On the other hand, in the case of Fig. 3, as mentioned above, ions directed between adjacent small holes 4 are drawn into the small holes 4, so for one ion beam passing through one hole 4, It is natural that the density (the amount of ions per unit cross-sectional area) is greater than that in the case of FIG. Then, as shown in Figure 3, the equipotential surface becomes a regular shape, similar to the superposition of electric fields due to unit holes, so the second
The arrangement shown eliminates the possibility of a beam being drawn out with non-uniform or large divergence angles. In addition, since the ion extraction port is made into a small hole, it becomes difficult for the gas of the supplied ionic substance to flow out through the ion extraction port, and the gas flow is slowed accordingly, so the discharge conditions between the negative and intestinal poles are improved. It's good that it's stabilized now. The small holes 4 shown in FIG. 1 are arranged in ~ rows,
They may be formed in two rows as shown in FIG. Further, the small holes 4 may be rectangular or triangular as shown in FIGS. 5, 6, and 7, or may be arranged in a staggered manner as shown in FIG. 8. FIG. 9 shows a structure in which the small holes 4 are formed in the shape of thin grooves and a plurality of these are arranged in parallel. In any case, the ion extraction port consisting of a plurality of small holes may be formed within the elongated cross-sectional area of the ion beam. As described in detail above, according to the present invention, the ion beam current can be increased quantitatively, the density of the ion beam can be increased, and the discharge conditions for ion generation can be stabilized.

[Brief explanation of drawings]

Figure 1 is a perspective view showing an embodiment of the invention, Figures 2 and 3.
The figure is a sectional view for explaining the operation, and FIGS. 4 to 9 are diagrams showing embodiments of the ion extracting section. 1... cathode, 2... anode, 3...
...Ion extraction part, 4...Small hole. Younger brother' figure 2 figure beauty 3 younger brother Buddha figure younger brother Ta figure longevity o design 7 figure 8 younger brother q figure

Claims (1)

[Claims] 1 comprising an anode electrode, a cathode electrode, and an ion extraction section having an ion extraction port consisting of a plurality of holes through which ions ionized by the discharge between the two electrodes pass, and from the anode electrode to the ion extraction section. The inner surface of the anode electrode is formed into an elongated rectangular parallelepiped so that the ion beam facing toward the ion beam has an elongated rectangular cross section, and the ion extraction port is formed within a cross-sectional area of the ion beam facing the ion extraction portion. An ion generator.