Control gate for electron curtain accelerator

Abstract

The utility model relates to a control grid for an electron curtain accelerator. Specifically, the utility model relates to a honeycomb-shaped control grid on an electron curtain accelerator. The grid comprises a grid body which is a rectangular metal plate, and a grid electrode is arranged on the grid body. The grid electrode is an array grid electrode, and the array grid electrode is composed of hexagonal small holes which are arranged in a staggered mode. The lower surfaces of the two longitudinal sides of the grid body are connected with reflecting electrodes with semicircular cross sections. By adopting the control grid for the electron curtain accelerator, the beam current loss can be reduced, and the beam current transmission efficiency can be improved.

Description

Technical Field

[0001] This utility model relates to a control grid for an electron accelerator. Specifically, it relates to a honeycomb control grid on an electron curtain accelerator. Background Technology

[0002] In the electron accelerator manufacturing and application industry, it is well known that an electron curtain accelerator contains a stainless steel cylinder, shielded by a lead layer. Inside, it houses a cathode grid assembly, a vacuum chamber, insulating components, and an anode. The cathode grid assembly is a crucial part of the electron curtain accelerator, consisting of a cathode filament, a reflector, and a grid, all housed as a single unit within the vacuum chamber. At the bottom of the stainless steel cylinder is a beam extraction window, which, together with the cylinder, forms the anode. This beam extraction window, constructed of a metal foil and a supporting copper grid, is used to maintain the vacuum and extract the beam. During accelerator operation, the cathode filament potential is -80 to -300 kV. A high-voltage electric field is created between the cathode grid assembly and the beam extraction window using a high-voltage power supply. After the filament is heated, it generates a long, strip-shaped electron cloud. This electron cloud, influenced by the high-voltage electric field, moves against the direction of the field, passes through the grid, and is accelerated by the high voltage, forming a long, strip-shaped, rain-like electron beam. When the electron beam reaches the beam extraction window, it passes through the titanium film and loses part of the beam, which is converted into heat. The remaining beam enters the radiation zone and irradiates the sample.

[0003] The grid is located below the cathode and has a voltage slightly higher than the cathode (100V to 1000V). It is used to extract electrons emitted by the cathode and spread the electron beam evenly. Its shape and control voltage play a key role in the beam current flux and uniformity.

[0004] like Figure 1 As shown, most commonly used gates are long-slit array gates. These long-slit array gates have no reflectors. Due to the absence of reflectors, both the beam current loss rate and the beam current loss rate of the supporting copper gate are relatively high, reaching 0.0294 and 0.2968, respectively. Because of these high beam current loss rates, both the long-slit array gate and the supporting copper gate result in significant beam current loss and low transmission efficiency. Utility Model Content

[0005] The problem this invention aims to solve is to provide a control grid for an electron curtain accelerator. Using this control grid can reduce beam loss and improve beam transmission efficiency.

[0006] The above-mentioned problems to be solved by this utility model are achieved by the following technical solutions:

[0007] The control grid for the electron curtain accelerator of this invention includes a grid body, which is a rectangular metal plate with a grid on it. Its key feature is that the grid is an array grid, which consists of staggered hexagonal holes.

[0008] A further improvement of this utility model is that a reflector with a semi-circular cross-section is connected to the lower sides of both longitudinal sides of the grid body.

[0009] The planar side of the semi-circular reflector is connected to the lower surface of the corresponding longitudinal side of the grating.

[0010] The grid is made of molybdenum plate or stainless steel plate.

[0011] As can be seen from the above technical solution, since the gate is an array gate composed of staggered hexagonal apertures, it provides good shielding against the high-voltage electric field in the acceleration region. This ensures that electrons emitted from the cathode to the reflector can essentially reach the gate, significantly reducing beam loss at the reflector. Furthermore, since semi-circular reflectors are connected to the lower sides of the gate along its longitudinal direction, beam diffusion in the Y direction is effectively prevented, ensuring that all electron beams passing through the gate reach the anode, further reducing beam loss. Therefore, using this type of control gate for electron curtain accelerators can reduce beam loss and improve beam transmission efficiency. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the long-slit array gate structure in the background art;

[0013] Figure 2 This is a schematic diagram of the control grid structure for the electron curtain accelerator of this utility model.

[0014] Figure 3 yes Figure 2 A diagram showing the view from the right. Detailed Implementation

[0015] like Figure 2 and Figure 3 As shown, the control grid for the electron curtain accelerator of this invention includes a grid body 2, which is a rectangular molybdenum or stainless steel plate. In this embodiment, the grid body 2 is a molybdenum plate. A gate is processed on the grid body 2, which is an array gate, and the array gate is composed of hexagonal holes 1 arranged in an alternating pattern.

[0016] To reduce beam loss and improve beam transmission efficiency, a semi-circular reflector 3 is attached to the lower surface of both longitudinal sides of the grid 2. The planar side of the semi-circular reflector 3 is welded to the lower surface of the corresponding longitudinal side of the grid 2.

[0017] This invention provides effective shielding against the high-voltage electric field in the acceleration region, ensuring that electrons emitted from the cathode to the reflector can essentially reach the grid, significantly reducing beam loss at the reflector. Furthermore, the presence of semi-circular reflectors 3 on both sides of the grid 2 effectively prevents beam diffusion in the Y direction, ensuring that all electrons passing through the grid reach the anode, further reducing beam loss. Therefore, this control grid for electron curtain accelerators effectively reduces beam loss and improves beam transmission efficiency.

Claims

1. A control grid for an electron curtain accelerator, comprising a grid body (2) which is a rectangular metal plate having a grid electrode thereon; characterized in that: The grid is an array grid, which is composed of hexagonal small holes (1) arranged in a staggered manner.

2. The control grid for an electron curtain accelerator of claim 1, wherein: The grid body (2) is connected with a semicircular reflecting pole (3) in cross section at the lower surface of each longitudinal side.

3. The control grid for an electron curtain accelerator of claim 2, wherein: The plane side of the semicircular reflecting pole (3) is connected with the lower surface of the corresponding longitudinal side of the grid body (2).

4. The control grid for an electron curtain accelerator according to any one of claims 1 to 3, characterized in that: The grid body (2) is a molybdenum plate or a stainless steel plate.

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