JPH0326520B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is characterized by a cooling mechanism for accelerating electrodes of a particle accelerator arranged vertically in a particle accelerator tube.

As shown in Figure 1, a conventional particle accelerator has a large number of annular accelerating electrodes 2 arranged concentrically at very precisely centered intervals inside a particle accelerating tube 1 that uses high-power, high-frequency waves. The structure is such that they are positioned in a straight line by alignment such as angle and inclination, and are suspended at regular intervals.

In addition, in the above-mentioned particle accelerator, in order to obtain a high accelerating electric field at a resonant frequency, the inner diameter D of the particle accelerating tube 1 and the dimensions of each part of the accelerating electrode 2 (D ₁ , D ₂ , D ₃ shown in FIG. , D ₄ , T ₁ , T _{2 ,} etc.) are electrically determined by themselves.

Furthermore, the acceleration electrode 2 has an outer flat disk portion.
It has an electrode A portion consisting of A ₁ and a truncated conical column portion A ₂ (nose cone portion) with a hole A′ on the center side,
In the electrode A, heat is generated due to wall loss of high power and high frequency, and the amount of heat generated becomes a heat generation curve as shown in FIG. part (nose cone part)
A High heat generation occurs in the ₂ part.

Therefore, it is necessary to cool the electrode A in order to prevent the temperature from rising due to the heat generation, but the inside of the particle accelerator tube 1 is maintained at an ultra-high vacuum, and the electrode A cannot be cooled from the outer surface due to its function. Since this is possible, it is necessary to flow a fluid (generally pure water) inside to keep the temperature constant.

Therefore, the conventional structure for cooling the accelerating electrode 2 under the above conditions is to supply cooling water from the inlet passage a provided in the support neck A ₃ attached to the electrode A, as shown in FIGS. 4 and 5. flows into semicircular arc-shaped both channels a ₂ provided in the truncated conical column part A ₂ , and the flat disc part A ₁
After flowing as shown by the arrows through semicircular arc-shaped water channels _a1 provided in the upper and lower sides, the water is discharged from an outlet passage S.

However, in the conventional accelerating electrode 2 described above, (1) As shown in FIGS. 4 and 5, there are few water channels in the flat disk portion _A1 , and the heat transfer area is small;
The temperature of the flat disk portion _A1 increases.

(2) The perforated truncated conical column A ₂ , that is, the nose cone, has a large waterway cross-sectional area and a low cooling water flow rate, so under a constant flow rate, the heat transfer coefficient is small, and the nose generates the most heat. The cone cannot be cooled efficiently. (Since the number of accelerating electrodes is very large, the equipment cost of the pump becomes high, so it is practically impossible to increase the flow rate.) Due to these reasons, there is a drawback that thermal stress and thermal deformation due to temperature deviation occur over the entire surface of the accelerating electrode. be.

The present invention was developed to eliminate the above-mentioned drawbacks of accelerating electrodes of conventional particle accelerators. Multiple substantially circular or semi-circular water channels centered around the truncated conical column are provided in the electrode, and adjacent ends of the water channels are connected by a bent passage, and the channels are provided adjacent to the electrode. A cooling water channel is provided in which an inlet passage provided in the support neck part is directly connected to the innermost side of the water channel, and an outlet passage surrounding the inlet passage is directly connected to the outermost side of the water channel, and the cooling water channel in the truncated conical column part is provided. It is characterized in that it has a small cross-sectional area and is arranged in large numbers close to the outer surface, and its purpose is to provide a wall loss as shown in Fig. 3, and Under conditions where the dimensions of the accelerating electrode are determined electrically and the amount of cooling water must be kept as low as possible, (a) the temperature of the accelerating electrode is kept as low as possible so that the cooling water does not boil, and (b) the accelerating electrode In addition to making the temperature distribution as uniform as possible and minimizing thermal stress and local deformation, (c) the accelerating electrode can be manufactured at low cost, so it can be manufactured from the most common material (steel) with low material and processing costs. The purpose of this invention is to provide an accelerating electrode for a particle accelerator.

The present invention has the above-mentioned configuration, in which cooling channels are rationally arranged over the entire surface of the accelerating electrode,
In particular, the cooling channels in the truncated conical column, which generates the largest amount of heat, have a small cross-sectional area and are arranged in large numbers close to the outer surface, so the temperature of the truncated conical column (nose cone) can be controlled extremely efficiently. In addition, it is possible to cool substantially uniformly over the entire surface, and thermal stress and thermal deformation due to temperature deviation can be significantly reduced. Therefore, instead of using expensive materials with high thermal conductivity (such as copper and brass), it is possible to make an inexpensive accelerating electrode by using a steel material with relatively low thermal conductivity.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. 6 to 11 show each part of an accelerating electrode 12, which is an embodiment of the present invention, which is aligned and vertically arranged inside the particle accelerating tube 1 as shown in FIG. As shown in FIG. 7, the electrode 12 is a portion of the electrode A that is generally annular in its entirety, consisting of an outer flat disk portion A ₁ and a central truncated conical portion A ₂ with a hole A′. and a support neck portion A ₃ (see FIG. 6) attached to the electrode A, and a cooling water channel extending over the entire surface as described later is disposed inside them.

That is _, as shown in the cross- _section in FIG.
Multiple approximately circular or paired semicircular arc-shaped waterways g to m, m' centered on the axis of the truncated conical column are provided to reduce the wall thickness in the radial direction between the waterways to ensure transmission over the entire surface. The thermal area is greatly increased, and the adjacent ends of the water channels g to m' are connected via the bent passage as shown in the figure, and the inlet passage a provided in the support neck A ₃ attached to the electrode A is A support neck part A ₃ is directly connected to the innermost end of the water channel and surrounds the inlet passage a.
A cooling water channel is provided over the entire interior of the accelerating electrode 12 by directly connecting the outlet passage S provided in the cooling water channel to the outermost end of the water channel.

Further, the above-mentioned cooling water channel is arranged inside the nose cone portion, that is, the truncated conical column portion _A2 , as shown in the cross section of FIG. 7 and further shown in the cross sections of FIGS. 8 to 10, and generally The waterway is formed with a small cross-sectional area, and the truncated conical column part _A2 is divided into three parts in the thickness direction (the number of divisions can be increased), and the approximately shaped waterways m and m' on both sides, and the semi-circular waterway. g, increases the flow rate of cooling water, improves the heat transfer coefficient, and reduces the temperature difference between the cooling water and the inner wall.
Furthermore, the wall thickness δ between the outer surface and the waterway is made as thin as possible,
In addition, the structure is placed close to the hole A' to reduce the temperature difference due to heat transfer, etc., and overall the cooling water channel arranged inside the truncated conical column part _A2 is
The route is water channels b to m and m' as shown in Fig. 11.

An embodiment of the present invention shown in FIGS. 6 to 11 is as described above, and the accelerating electrode 1
The structure of the cooling water channel disposed inside the cooling water passage 2 will be explained in detail as well as its function.

Cooling water is introduced into the truncated conical column part A ₂ from the inlet passage a that passes through the support neck part A ₃ and the flat disk part A ₁ shown in FIG. The flow rate is divided into two. Note that since the water channel a' side has the same structure as the branch water channel a side, a portion of the explanation will be omitted in favor of the explanation of the branch water channel a side.

The cooling water in the branch waterway a of the inlet passage a shown in the cross-section of FIG. 8 passes through the waterway b shown in the cross-section of FIG.
The cooling water that exits the waterway c shown in the cross-section of Figure 0 passes through the waterway m, passes through the waterway e, passes through the waterway f shown in the cross-section of Figure 9, and exits the waterway g shown in the cross-section of Figure 8. , flows through waterway g, passes through waterway h shown by the arrow in the cross section of FIG. 7, and exits to waterway i. Here, it merges with the cooling water that has flowed from the other waterway a'' that has branched off from the inlet passage a (details are omitted, see Figure 11), and branches into a semicircular waterway again to form waterways i, j, and k. , l and is discharged from the outlet passage S.

Therefore, in the above-mentioned embodiment, inside the truncated conical column part _A2 of the electrode A which generates an extremely large amount of heat, both the substantially circular water channels m and m' formed in a small cross-sectional area and the central part are formed. The cooling water flows through a pair of semicircular arc-shaped channels g, increasing the flow rate and significantly improving thermal conductivity, and lowering the temperature evenly over the entire surface in the thickness direction and lowering the temperature on the outer surface. The temperature difference between the cooling water and the inner wall becomes better, and the temperature difference between the cooling water and the inner wall becomes smaller.Furthermore, even in the outer flat disk part _A1 , the multiple semicircular arc-shaped water channels form a plurality of pairs to reduce the temperature difference between each water channel. The wall thickness in the radial direction is thinner, the thermal conductivity is improved, and a uniform temperature-lowering effect can be obtained.

Therefore, according to this embodiment, it is possible to significantly reduce thermal stress and thermal deformation due to temperature deviation over the entire surface of the accelerating electrode 12, and in particular, to reduce the temperature of the truncated conical column portion _A2 that generates the highest amount of heat. This also makes it possible to use steel materials with low thermal conductivity instead of using expensive materials with high thermal conductivity (e.g. copper, brass), making it possible to provide inexpensive accelerating electrodes. can.

In the above embodiment, the water channel of the truncated conical column (nose cone) is divided into three parts in the thickness direction, but the present invention is not limited to three parts.

Although the present invention has been described above with reference to embodiments, it goes without saying that the present invention is not limited to such embodiments, and that various design modifications can be made without departing from the spirit of the present invention. .

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing an overview of a conventional particle accelerator, Figure 2 is a longitudinal cross-sectional view showing only the electrode portion of a conventional accelerating electrode, and Figures 3A and B are partial positions of the electrode in Figure 2. Figure and state diagram of calorific value, 4th
The figure is an explanatory diagram of the cooling water channel arranged inside the electrode in Figure 2, Figure 5 is a cross-sectional view of Figure 4, and Figure 6 is a cross-sectional view of an accelerating electrode showing an embodiment of the present invention (Figure 5). Figure 7 is a cross-sectional view of Figure 6.
8 is a sectional view of FIG. 7, FIG. 9 is a sectional view of FIG. 7, FIG. 10 is a sectional view of FIG. 7, and FIG. 11 is a water channel in the truncated conical column of the embodiment. FIG. 1: particle acceleration tube, 12: acceleration electrode, A: electrode,
A ₁ : flat disk part, A ₂ : truncated conical column part, A ₃ : support neck part, A': hole, a: entrance passage, b to m, m': water channel,
S: Exit passage.

Claims (1)

[Claims] 1. Multiple approximately circular or semi-circular water channels centered around the axis of the truncated conical column are provided in an electrode consisting of an outer flat disk portion and a perforated truncated conical column portion at the center. , the adjacent ends of the water channel are connected by a bent passage, an inlet passage provided in a support neck attached to the electrode is directly connected to the innermost side of the water channel, and an outlet passage surrounding the inlet passage is connected to the outlet passage. A cooling water channel directly connected to the outermost side of the water channel is provided, and the cooling water channels in the truncated conical column part have a small cross-sectional area and are arranged in large numbers in close proximity to the outer surface of the particle acceleration tube. Accelerating electrode of a particle accelerator installed vertically.