A direct-heated thermal emission electron source

Abstract

The utility model discloses a direct-heated thermal emission electron source, which includes a base, a shielding cover, a heating element, and a support assembly; the support assembly includes two support rods fixed on the base, the support rods are made of conductive high-temperature resistant material, and the base is made of insulating high-temperature resistant material; the left and right ends of the heating element are respectively connected to the two support rods, and the heating element has a spiral heating body; the shielding cover is connected to a support rod of the support assembly, the shielding cover shields the front and back sides and the bottom side of the heating element, and the shielding cover is made of conductive high-temperature resistant material. The direct-heated thermal emission electron source of the utility model has the advantages of large emission current and stable use.

Description

Technical Field

[0001] The utility model relates to the field of electron sources, in particular to a direct-heated thermal emission electron source. Background Art

[0002] In electron microscopes, mass spectrometers and other detection instruments, the electron source is a key component and largely determines the performance of the instrument.

[0003] At present, low-power electron sources (typical emission current 1mA ~ 5mA) generally adopt a direct heating structure, that is, based on the thermal electron emission effect, the heating element is heated to a sufficiently high temperature, so that the energy of the electrons inside the heating element increases with the increase of temperature, and the energy of some of the electrons is large enough to overcome the obstacles that prevent them from escaping (i.e., work function) and enter the vacuum from the heating element. The heating of the heating element is generated by the thermal effect generated by the power supply.

[0004] Although the greater the current flowing through the heating element, the higher the temperature of the heating element, the more electrons escape from the electron source, and the greater the emission current generated, which is beneficial for use, excessive temperature of the heating element will affect other components of the electron source, resulting in unstable use.

[0005] In view of the above problems, it is necessary to develop a direct-heated thermal emission electron source with large emission current and stable use. Utility Model Content

[0006] The utility model aims to provide a direct-heated thermal emission electron source which has large emission current and stable use.

[0007] In order to achieve the above purpose, the solution of the utility model is:

[0008] A direct-heated thermal emission electron source comprises a base, a shielding cover, a heating element, and a supporting assembly; the supporting assembly comprises two supporting rods fixed on the base, the supporting rods are made of conductive high-temperature resistant material, and the base is made of insulating high-temperature resistant material; the left and right ends of the heating element are respectively connected to the two supporting rods, and the heating element has a spiral heating body; the shielding cover is connected to a supporting rod of the supporting assembly, the shielding cover shields the front and back sides and the bottom side of the heating element, and the shielding cover is made of conductive high-temperature resistant material.

[0009] The two support rods of the support assembly are connected to the base by brazing.

[0010] The shielding cover is connected to the supporting rod by fusion welding.

[0011] The left and right ends of the heating element are respectively connected to the two support rods by fusion welding.

[0012] The support rod is made of stainless steel.

[0013] The heating element is made of tungsten wire or tungsten-rhenium wire.

[0014] The shielding cover is made of stainless steel.

[0015] The diameter of the support rod is more than 5 times the diameter of the heating element.

[0016] The base is made of ceramic.

[0017] After adopting the above scheme, the heating element of the utility model has a spiral heating body, which can increase the effective length and resistance of the heating element, concentrate the heat of the heating element, make the heating speed of the heating element fast and reduce the preheating time, and at the same time increase the emission area of ​​the heating element and increase the emission current; and the setting of the shielding cover can make the electrons emitted by the heating element go in the expected direction, reduce the loss of the emitted electrons and help increase the emission current. In addition, the base, shielding cover, heating element and supporting assembly are all resistant to high temperature, making the direct-heated thermal emission electron source of the utility model reliable to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural exploded view of the utility model.

[0019] Figure 2 The structure of the utility model is shown in FIG. Figure 1 .

[0020] Figure 3 The structure of the utility model is shown in FIG. Figure 2 .

[0021] Figure 4 It is a cross-sectional view of the utility model.

[0022] Description of labels:

[0023] Base 1,

[0024] Shield 2,

[0025] Heating element 3, heating body 31,

[0026] Support assembly 4, support rod 41,. DETAILED DESCRIPTION

[0027] In order to further explain the technical solution of the present utility model, the present utility model is described in detail below through specific embodiments.

[0028] like Figures 1 to 4As shown, the utility model discloses a direct-heated thermal emission electron source, which includes a base 1, a shielding cover 2, a heating element 3, and a supporting assembly 4; wherein the supporting assembly 4 includes two supporting rods 41 fixed on the base 1, the supporting rods 41 are made of conductive high-temperature resistant material, and the base 1 is made of insulating high-temperature resistant material; the left and right ends of the heating element 3 are respectively connected to the two supporting rods 41, and the heating element 3 has a spiral heating body 31; the shielding cover 2 is connected to a supporting rod 41 of the supporting assembly 4, the shielding cover 2 shields the front and back sides and the bottom side of the heating element 3, and the shielding cover 2 is made of conductive high-temperature resistant material.

[0029] In the present utility model, the two support rods 41 of the support assembly 4 can play the role of supporting the heating element 3 and the shielding cover 2, and the two support rods 41 of the support assembly 4 can also play the role of energizing the heating element 3; and the heating element 3 has a spiral heating body 31, which can increase the effective length and resistance of the heating element 3, so that the heating of the heating element 3 is concentrated, so that the heating speed of the heating element 3 is fast and the preheating time is reduced, and at the same time, the emission area of ​​the heating element 3 is increased, and the emission current is increased; and the setting of the shielding cover 2 can make the electrons emitted by the heating element 3 face the expected direction, reduce the loss of the emitted electrons and help increase the emission current. In addition, the base 1, the shielding cover 2, the heating element 3 and the support assembly 4 are all resistant to high temperatures, so that the direct-heated thermal emission electron source of the present utility model is reliable to use, and high temperature resistance means that it can withstand temperatures above 1000°C.

[0030] In the embodiment of the present invention, the base 1 is made of ceramic.

[0031] In the embodiment of the utility model, the support rod 41 of the support assembly 4 is made of stainless steel; the two support rods 41 of the support assembly 4 are brazed and connected to the base 1, so that the two support rods 41 are firmly and reliably connected to the base 1. In addition, the diameter of the support rod 41 is more than 5 times the diameter of the heating element 3. Such a setting can ensure the support strength of the support rod 41 to ensure long-term use, while reducing the resistance of the support rod 41 to reduce the heat generation of the support rod 41 and reduce power loss.

[0032] In the embodiment of the present utility model, the shielding cover 2 is made of stainless steel, and the shielding cover 2 is connected to a support rod 41 by fusion welding, so that the connection between the shielding cover 2 and the support rod 41 is firm and reliable.

[0033] In the embodiment of the utility model, the heating element 3 is made of tungsten wire or tungsten-rhenium wire, and the left and right ends of the heating element 3 are respectively welded to the two support rods 41 , so that the connection between the heating element 3 and the two support rods 41 is firm and reliable.

[0034] The above embodiments and drawings do not limit the product form and style of the present utility model. Any appropriate changes or modifications made by ordinary technicians in the relevant technical field should be deemed to be within the patent scope of the present utility model.

Claims

1. A direct-heated thermal emission electron source, characterized in that: It includes a base, a shielding cover, a heating element, and a supporting component; The support assembly includes two support rods fixed on the base, the support rods are made of conductive high temperature resistant material, and the base is made of insulating high temperature resistant material; The left and right ends of the heating element are respectively connected to two support rods, and the heating element has a spiral heating body; The shielding cover is connected to a supporting rod of the supporting assembly, and the shielding cover shields the front and rear sides and the bottom side of the heating element, and the shielding cover is made of conductive and high temperature resistant material.

2. A direct-heated thermal emission electron source as claimed in claim 1, characterized in that: The two support rods of the support assembly are connected to the base by brazing.

3. A direct-heated thermal emission electron source as claimed in claim 1, characterized in that: The shielding cover is connected to the supporting rod by fusion welding.

4. A direct-heated thermal emission electron source as claimed in claim 1, characterized in that: The left and right ends of the heating element are respectively connected to the two support rods by fusion welding.

5. A direct-heated thermal emission electron source as claimed in claim 1, characterized in that: The support rod is made of stainless steel.

6. A direct-heated thermal emission electron source as claimed in claim 1, characterized in that: The heating element is made of tungsten wire or tungsten-rhenium wire.

7. A direct-heated thermal emission electron source as claimed in claim 1, characterized in that: The shielding cover is made of stainless steel.

8. A direct-heated thermal emission electron source as claimed in claim 1, characterized in that: The diameter of the support rod is more than 5 times the diameter of the heating element.

9. A direct-heated thermal emission electron source as claimed in claim 1, characterized in that: The base is made of ceramic.

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