High-power pulse magnetron cathode

Abstract

The invention discloses a high-power pulse magnetron cathode, and belongs to the technical field of magnetrons. The cathode comprises a heating substrate, an upper end cap, a lower end cap and a cathode emitter, the upper end of the heating substrate is connected with the upper end cap, and the lower end penetrates through the lower end cap and extends out of the magnetron tube core to be connected with a power supply; the heating substrate positioned between the upper and lower end caps is spiral-line-shaped; and the cylindrical cathode emitter is sleeved on the outer side of the spiral linear part of the heating substrate. The cathode emitter is heated through the heating substrate, so that the cathode emitter emits electrons, and the emitted electrons back bomb the surface of the cathode emitter under the action of an external electromagnetic field of the magnetron to generate new secondary electrons. According to the invention, the probability of electron bombardment on the surface of the cathode emitter can be greatly increased, that is, secondary emission electrons can be bombarded continuously, the overall electron emission density of the cathode is improved, and a high-power pulse magnetron is supported to provide higher power output.

Description

Technical Field

[0001] The invention belongs to the technical field of magnetrons, and in particular relates to a high-power pulse magnetron cathode. Background Art

[0002] As a mature source device for generating microwave energy, magnetron is widely used in microwave heating, medical imaging, radar detection, aerospace and other fields. Among them, the cathode, as the core component of the magnetron, plays a vital role in its working performance.

[0003] At present, the mainstream magnetron cathodes are basically thoriated tungsten cathodes or oxide cathodes, and their structures are usually spiral-shaped. However, in order to adapt to the working mode of high-power pulse magnetrons, traditional spiral-shaped hot cathodes have shortcomings such as limited emission performance and severe electron back bombardment. Therefore, a cathode that is more suitable for high-power pulse magnetrons is needed. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a high-power pulse magnetron cathode structure.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A high-power pulse magnetron cathode, characterized in that it comprises a heating substrate, an upper end cap, a lower end cap, and a cathode emitter;

[0007] The upper end of the heating substrate is connected to the upper end cap, and the lower end passes through the lower end cap and extends outside the magnetron core to connect to the power supply; the heating substrate located between the upper end cap and the lower end cap is configured as a spiral line;

[0008] The cathode emitter is cylindrical and is sleeved outside the spiral part of the heating substrate. The cathode emitter emits electrons outward after being heated by the heating substrate. The emitted electrons bounce back to the surface of the cathode emitter under the action of the electromagnetic field applied by the magnetron to generate new secondary electrons.

[0009] Furthermore, the outer surface of the cathode emitter is impregnated with an active substance required for electron emission or coated with a thin film containing an active substance required for electron emission.

[0010] Furthermore, the active substance is a compound containing the elements magnesium, barium, lanthanum, cerium, iridium and scandium.

[0011] Furthermore, a plurality of circular ring structures or a plurality of banner-shaped structures arranged at equal intervals are embedded in the outer side surface of the cathode emitter; the materials used for the circular ring structures and the banner-shaped structures are easier to heat and emit electrons than the materials of the cathode emitter.

[0012] Furthermore, the surface area of ​​the annular structure or the strip-shaped structure accounts for 40-60% of the surface area of ​​the outer side of the cathode emitter.

[0013] Furthermore, there is a distance of 0.1-1 mm between the cathode emitter and the heating substrate.

[0014] Furthermore, the cathode emitter has a height of 10 to 35 mm and a radius of 2 to 20 mm.

[0015] Furthermore, the diameter of the heating substrate is 0.8-1.2 mm.

[0016] Furthermore, the material of the heating substrate is tungsten, molybdenum or titanium.

[0017] The beneficial effects of the present invention are as follows:

[0018] In the present invention, the cylindrical cathode emitter is heated by a spiral heating substrate to emit electrons. The emitted electrons are emitted toward the anode of the magnetron under the high electric field generated by the anode voltage of the magnetron, and then return to the cathode under the action of the external magnetic field of the magnetron, and finally bombard the surface of the cathode emitter to generate secondary electrons. Since the surface area of ​​the cylindrical cathode emitter of the present invention is much larger than the surface area of ​​the traditional spiral emitter, the probability of electron bombardment on the surface of the cathode emitter can be greatly increased, that is, the secondary emitted electrons can be bombarded continuously; at the same time, the present invention also uses active substances as cathode emitter materials to increase the emission probability of secondary electrons.

[0019] Due to the limitations of existing materials, materials that are conducive to heating and emitting electrons are usually not easy to emit secondary electrons under electron bombardment; therefore, in order to balance the heating and emitting electrons and the secondary electrons emitted by bombardment, the present invention uses materials that are easier to heat and emit electrons as cathode emitters, so that the initial heating and emitting electrons are sufficient; then, a ring-shaped structure or a banner-shaped structure that is easier to produce thermal electron emission materials is embedded on the surface of the cathode emitter to increase the probability of secondary electron emission, thereby improving the overall electron emission density of the cathode.

[0020] Compared with the traditional magnetron cathode, the present invention can ensure that the magnetron provides a larger emission current density under lower heating power by increasing the secondary emission electrons, thereby supporting a high-power pulse magnetron to provide a larger power output, and the cathode of the present invention can be applied to high-power pulse magnetrons with different cavity structures and different output structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the magnetron cathode structure of Example 1;

[0022] Figure 2Schematic diagram of the magnetron cathode structure of Example 2;

[0023] Figure 3 Schematic diagram of the magnetron cathode structure of Example 3.

[0024] Explanation of the accompanying drawings: 1. heating substrate, 2. cathode emitter, 31. upper end cap, 32. lower end cap, 41. ring structure, 42. banner-shaped structure. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is further described in detail below in conjunction with the embodiments and drawings.

[0026] Embodiment 1:

[0027] A high-power pulse magnetron cathode in this embodiment, such as Figure 1 As shown, it includes a heating substrate, an upper end cap, a lower end cap, and a cathode emitter.

[0028] Among them, the heating substrate is a cylindrical filament, the upper end of which is connected to the upper end cap, and the lower end passes through the lower end cap and extends outside the magnetron core to connect to the power supply; the upper end cap and the lower end cap are cylindrical structures with a diameter of 0.72 mm, and the heating substrate located between the upper end cap and the lower end cap is set to a spiral line shape to better heat the cathode emitter.

[0029] The cathode emitter is cylindrical and is sleeved outside the spiral part of the heating substrate; the cathode emitter emits electrons outward after being heated by the heating substrate, and at the same time, the electrons emitted under the action of the electromagnetic field applied by the magnetron generate new secondary electrons by bouncing back on the surface of the cathode emitter.

[0030] In this embodiment, the heating substrate is a metal molybdenum filament with a diameter of 2 mm; the outer diameter of the cathode emitter is 2.2 mm, the thickness is 0.5 mm, and the height is 0.88 mm. The distance between the cathode emitter and the spiral heating substrate is 0.2 mm; the outer surface of the cathode emitter is coated with a Ni-NiO-Ba film so that more secondary electrons can be generated.

[0031] In this embodiment, the cathode of the magnetron heats the cathode emitter by heating the substrate, so that the cathode emitter emits electrons. The emitted electrons undergo electron back-bombardment under the action of the external electric field and magnetic field of the magnetron. Since the surface area of ​​the cathode emitter is increased, the back-bombarded electrons can basically fall on the surface of the cathode emitter, bombarding to obtain secondary electrons, and finally complete the energy exchange under the common modulation of the electromagnetic field, so that the magnetron successfully starts to oscillate and begin to radiate microwaves. The present invention can obtain a larger emission current density under the condition of lower heating power by increasing the way of secondary emission electrons, thereby improving the output power of the magnetron.

[0032] Embodiment 2:

[0033] A high-power pulse magnetron cathode in this embodiment, such as Figure 2 As shown; compared with the cathode in Example 1, the difference between this cathode and the cathode in Example 1 is that: the outer side of the cathode emitter is embedded with 5 circular ring structures arranged at equal intervals, the width of the circular ring structure is 0.8mm, the interval is 1mm, and the total area accounts for 46.7% of the outer surface of the cathode emitter.

[0034] The material of the circular ring structure in this embodiment is thoriated tungsten material, and the material of the cathode emitter is a nickel substrate with a Ni-NiO-Ba active material impregnated on the surface; therefore, the cathode emitter can emit more electrons by heating, and the circular ring structure is easier to generate secondary electrons by electron back bombardment than the cathode emitter.

[0035] Embodiment 3:

[0036] A high-power pulse magnetron cathode in this embodiment, such as Figure 3 As shown; compared with the cathode in Example 1, the difference between this cathode and the cathode in Example 1 is that: five banner-shaped structures arranged at equal intervals are embedded in the outer side of the cathode emitter, and the total area of ​​the banner-shaped structures accounts for 50% of the outer surface of the cathode emitter.

[0037] The material of the banner-shaped structure in this embodiment is thoriated tungsten material, and the material of the cathode emitter is a nickel substrate with a surface impregnated with Mo-MoO2-Ba active material; therefore, the cathode emitter can emit more electrons by heating, and the banner-shaped structure is easier to generate secondary electrons by electron back bombardment than the cathode emitter.

Claims

1. A high-power pulsed magnetron cathode, characterized in that: It includes a heating substrate, an upper end cap, a lower end cap, and a cathode emitter; The upper end of the heating substrate is connected to the upper end cap, and the lower end passes through the lower end cap and extends outside the magnetron core to connect to the power supply; the heating substrate located between the upper end cap and the lower end cap is configured as a spiral line; The cathode emitter is cylindrical and is sleeved outside the spiral part of the heating substrate. The cathode emitter emits electrons outward after being heated by the heating substrate. The emitted electrons bounce back to the surface of the cathode emitter under the action of the electromagnetic field applied by the magnetron to generate new secondary electrons.

2. A high-power pulse magnetron cathode as claimed in claim 1, characterized in that: The outer surface of the cathode emitter is impregnated with active materials required for electron emission or coated with a thin film containing active materials required for electron emission.

3. A high-power pulse magnetron cathode as claimed in claim 2, characterized in that: The active material is a compound containing the elements magnesium, barium, lanthanum, cerium, iridium and scandium.

4. A high-power pulse magnetron cathode as claimed in claim 3, characterized in that: There is a distance of 0.1-1 mm between the cathode emitter and the heating substrate.

5. A high-power pulse magnetron cathode as claimed in claim 4, characterized in that: The cathode emitter has a height of 10 to 35 mm and a radius of 2 to 20 mm.

6. A high-power pulse magnetron cathode as claimed in claim 5, characterized in that: The diameter of the heating substrate is 0.8-1.2 mm.

7. A high-power pulse magnetron cathode as claimed in claim 6, characterized in that: The material of the heating substrate is tungsten, molybdenum or titanium.

8. A high-power pulse magnetron cathode as claimed in any one of claims 2 to 7, characterized in that: The outer side surface of the cathode emitter is embedded with a plurality of circular ring structures or a plurality of banner-shaped structures arranged at equal intervals; the materials used for the circular ring structures and the banner-shaped structures are easier to heat and emit electrons than the materials of the cathode emitter.

9. A high-power pulse magnetron cathode as claimed in claim 8, characterized in that: The surface area of ​​the circular ring structure or the strip-shaped structure accounts for 40-60% of the surface area of ​​the outer side of the cathode emitter.

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