CN110752130B - A composite heat dissipation method for instantaneous pulse ultra-high power electron collection stage - Google Patents

Abstract

The invention relates to a composite heat dissipation method of instantaneous pulse super-power electronic collection level, belonging to the field of instantaneous pulse super-power heat dissipation. channel; step 3, attaching a graphite layer to the inner wall of the metal body; step 4, adjusting the position of the metal body to realize the electron beam deposition heating area where the external electron beam is irradiated on the inner wall of the graphite layer; step 5, flow heat dissipation in the double-spiral microchannel Step 6: The external electron beam is directed to the graphite layer along the axial direction of the metal body; the heat is absorbed by the graphite layer and transferred to the metal body through the graphite layer, and finally the heat is taken away by the heat dissipation working medium flowing through the double helix microchannel, Realize heat dissipation; the present invention makes the collector always work within the normal temperature range by utilizing the characteristics of different materials, and ensures the reliability and stability of the high-power klystron.

Description

A composite heat dissipation method for instantaneous pulse ultra-high power electronic collection stage

technical field

The invention belongs to the field of instantaneous pulse super-power heat dissipation, and relates to an instantaneous pulse super-power electronic collection-level composite heat dissipation method.

Background technique

High-power klystron is a microwave vacuum device that converts electron beam energy into microwave energy based on the principle of velocity modulation. It has the advantages of high power and high gain. However, the conversion efficiency of the klystron is low. The high-energy electron beam still has high kinetic energy after the high-frequency interaction section surrenders part of the energy and converts it into microwave. The collector is used to collect these high-speed electron beams. The collector is used to collect the electron beam bombarded by the instantaneous pulse during the working process of the klystron. The high-energy electron beam of the instantaneous pulse is deposited on the collector to convert the energy into a large amount of heat, which causes the temperature on the collector to rise and becomes the klystron. One of the worst parts of the fever. If its temperature is too high, it will cause the desorption of the adsorbed gas on the surface of the collector material and even the evaporation and vaporization of the material itself, which will not only seriously affect the reliability and stability of the entire high-power klystron; Continued accumulation, the continuous melting of the collector material will cause it to melt through, which will destroy the vacuum environment and cause the failure of the klystron. Moreover, due to the working characteristics of the klystron, the electron beam heating characteristics of the collector are very harsh, not only the average heating power is as high as several tens of kW, but the instantaneous pulse heating power is as high as several GW, which puts forward very strict requirements for the heat dissipation design of the collector. requirements. There is currently no relevant effective solution.

SUMMARY OF THE INVENTION

The technical problem solved by the present invention is: to overcome the deficiencies of the prior art, a composite heat dissipation method for instantaneous pulse ultra-high power electron collectors is proposed. Reliability and stability of power klystrons.

The technical solution of the present invention is:

A composite heat dissipation method for instantaneous pulse ultra-high power electron collection level, comprising the following steps:

Step 1. Place the metal main body vertically in the axial direction;

Step 2, processing double helix microchannels in the side wall of the metal body;

Step 3, attaching a graphite layer to the inner wall of the metal body;

Step 4: Adjust the position of the metal main body to realize the electron beam deposition heating area where the external electron beam is irradiated on the inner wall of the graphite layer;

Step 5. Flow heat dissipation working medium in the double helix microchannel;

Step 6: The external electron beam is directed to the graphite layer along the axial direction of the metal body; the heat is absorbed by the graphite layer and transferred to the metal body through the graphite layer, and finally the heat is taken away by the heat dissipation working medium flowing through the double-spiral microchannel to realize heat dissipation. .

In the above-mentioned composite heat dissipation method of instantaneous pulse ultra-high power electron collection level, in the first step, the metal main body is a circular structure; the metal main body is made of stainless steel or titanium material; the diameter of the outer wall of the metal main body is 60-150 mm, The axial length is 10-50mm; the wall thickness is 3-5mm.

In the above-mentioned composite heat dissipation method of instantaneous pulse super-power electron collection level, in the second step, the double-spiral microchannel includes a first spiral microchannel and a second spiral microchannel; the first spiral microchannel and the second spiral microchannel The microchannels are all spiral annular channels; and the first spiral microchannel and the second spiral microchannel are alternately arranged; the inlet of the first spiral microchannel is at the axial bottom end of the metal body; the outlet is at the axial top end of the metal body; the second spiral microchannel The inlet of the microchannel is at the axial top end of the metal body; the outlet is at the axial bottom end of the metal body; the helical directions of the first helical microchannel and the second helical microchannel are opposite.

In the above-mentioned composite heat dissipation method of instantaneous pulse ultra-high power electron collection stage, the pipe cross-sections of the first spiral microchannel and the second spiral microchannel are rectangular structures, and the pipe cross-section size is 3mm*1mm.

In the above-mentioned composite heat dissipation method of instantaneous pulse ultra-high power electron collection level, in the step 3, the graphite layer is an annular layered structure; the axial length of the graphite layer is 10-50mm; the wall thickness is 1-2mm; the melting point is 3000 °C.

In the above-mentioned composite heat dissipation method of instantaneous pulse super-power electron collection level, in the step 4, the electron beam deposition heating area is arranged in the middle position of the inner wall of the graphite layer; the electron beam deposition heating area is an annular area; the axial length is It is 5-25mm; the side area of the electron beam deposition heating area is half of the inner wall area of the graphite layer.

In the above-mentioned composite heat dissipation method of instantaneous pulse ultra-high power electron collection level, the metal body and the graphite layer are welded by molecular diffusion welding; the contact thermal resistance between the metal body and the graphite layer is reduced; the contact heat transfer coefficient is 5000~ 10000W/(K·m ² ).

In the above-mentioned composite heat dissipation method of instantaneous pulse super-power electron collection level, in the step 5, the heat dissipation working medium is ionized water, the thermal conductivity is 0.6W/(K·m), and the specific heat capacity is 4183J/(kg·K) .

In the above-mentioned composite heat dissipation method of instantaneous pulse super-power electron collection level, in the step 6, the external electron beam adopts the instantaneous pulse emission mode, the single pulse emission power is 1-9GW; the single emission time is 100-500ns; The emission frequency is 10 to 50 Hz.

In the above-mentioned composite heat dissipation method of instantaneous pulse ultra-high power electron collection stage, the whole heat dissipation mechanism achieves a single electron pulse heat flux density of 10 ¹² -2×10 ¹² W/m ² , and an average heat flux density of 5×10 ⁶ -10 The heat dissipation of ⁷ W/m ² ; the maximum temperature of the graphite layer does not exceed 2000℃; lower than the melting point of the graphite layer; the maximum temperature of the metal body is reduced from 2600℃ to 650℃.

The beneficial effects of the present invention compared with the prior art are:

(1) In the present invention, graphite with a large electron penetration depth and a high melting point is used as the absorbing material of the electron beam. Compared with the traditional single-material collector heat dissipation method, it can avoid the super power loading in the limited area during the instantaneous pulse electron deposition process. melting of collector material;

(2) In the present invention, a metal material with high thermal conductivity and easy processing and welding is used as the collector body, and the countercurrent spiral cooling channel is processed in the metal body, and the electron beam is continuously deposited by the continuous flow of the working medium through the two spiral cooling channels. The average heat is dissipated to ensure that the temperature of the collector as a whole is always within the allowable range during long-term operation; at the same time, the working fluid adopts the reverse flow method in the two spiral channels to control the temperature of the electron deposition surface near the outlet of the channel to increase, Make the collector temperature distribution more uniform.

Description of drawings

Fig. 1 is the schematic diagram of the double helix microchannel in the metal main body of the present invention;

Fig. 2 is the schematic diagram of graphite layer of the present invention and electron beam deposition heating area;

3 is a schematic cross-sectional view of the metal body and the graphite layer of the present invention.

Detailed ways

The present invention will be further elaborated below in conjunction with the examples.

The invention provides a composite heat dissipation method of instantaneous pulse ultra-high power electron collection stage, which improves the volume and heat capacity of the collector to absorb the instantaneous pulse electron beam, and solves the problem that the local temperature rises too high after the electron collector is heated by the instantaneous pulse ultra-high power. Part of the material is melted; the heat dissipation capability of the collector is improved, and the problem of ultra-high average heat flow dissipation is solved; the temperature uniformity of the collector is improved, and the power consumption required to drive the working medium to flow through the radiator is reduced. It mainly includes the following steps:

Step 1: The metal main body 1 has a circular structure; the metal main body 1 is made of stainless steel or titanium; the outer wall diameter of the metal main body 1 is 60-150 mm, the axial length is 10-50 mm, and the wall thickness is 3-5 mm. Place the metal body 1 axially upright; as shown in Figure 1.

Step 2: Process a double helical microchannel in the side wall of the metal body 1; the double helical microchannel includes a first helical microchannel 2 and a second helical microchannel 3; It is a spiral annular channel; and the first spiral microchannel 2 and the second spiral microchannel 3 are alternately arranged; the inlet 21 of the first spiral microchannel 2 is at the axial bottom end of the metal body 1; the outlet 22 is at the axial top end of the metal body 1 The inlet 31 of the second spiral microchannel 3 is at the axial top end of the metal body 1; the outlet 32 is at the axial bottom end of the metal body 1; The pipe sections of the first helical microchannel 2 and the second helical microchannel 3 are rectangular structures; the size of the pipe section is 3mm*1mm.

Step 3, attaching a graphite layer 4 to the inner wall of the metal body 1; the graphite layer 4 is an annular layered structure; the axial length of the graphite layer 4 is 10-50 mm; the wall thickness is 1-2 mm; and the melting point is 3000°C. as shown in picture 2. In terms of improving the heat capacity of the endothermic volume, graphite is used as the electron beam absorption layer of the collector. The penetration depth of the electron beam in the graphite is 6 times that of stainless steel and 3 times that of titanium. The kinetic energy of the electron beam is converted into heat energy after entering the graphite. When the graphite in the penetration area is heated, the heat absorption volume is large due to the large electron penetration depth of the graphite. Moreover, the melting point of graphite is as high as 3000 ° C, which is much higher than the melting point of stainless steel of 1400 ° C and the melting point of titanium of 1660 ° C, so the temperature of graphite heated by the electron beam still has a large distance from its melting point. Therefore, by using the characteristics of graphite's high melting point and large electron penetration depth, the problem of melting of the collector part material caused by the local temperature rise caused by instantaneous ultra-high-power electron deposition can be solved. The metal body 1 and the graphite layer 4 are welded by molecular diffusion welding; the contact thermal resistance between the metal body 1 and the graphite layer 4 is reduced; the contact heat transfer coefficient is 5000-10000W/(K·m ² ), as shown in Figure 3 .

Step 4: Adjust the position of the metal body 1 to realize the electron beam deposition heating area 41 where the external electron beam is shot on the inner wall of the graphite layer 4; the electron beam deposition heating area 41 is arranged in the middle position of the inner wall of the graphite layer 4; the electron beam deposition heating area 41 is An annular area; the axial length is 5-25 mm; the side area of the electron beam deposition heating area 41 is half of the inner wall area of the graphite layer 4 .

Step 5: Flow a heat-dissipating working medium in the double-spiral microchannel; the heat-dissipating working medium is ionized water, the thermal conductivity is 0.6W/(K·m), and the specific heat capacity is 4183J/(kg·K).

Step 6: The external electron beam is directed to the graphite layer 4 along the axial direction of the metal body 1; the external electron beam adopts the instantaneous pulse emission mode, and the single pulse emission power is 1-9GW; the single emission time is 100-500ns; the emission frequency is 10～50Hz. The heat is absorbed by the graphite layer (4) and transferred to the metal body 1 through the graphite layer 4, and finally the heat is taken away by the heat-dissipating working medium flowing through the double-spiral microchannel to realize heat dissipation. In terms of improving the heat dissipation capacity of the collector and reducing the flow resistance of the heat dissipation device, the structural parameters such as channel height, channel width and fin width of the metal microchannel structure are optimized to balance the thermal conductivity and thermal conductivity of the fins during the internal heat transfer process of the metal microchannel. Through the ratio of convective heat transfer of the working medium, the flow resistance of the working medium in the microchannel is reduced while the heat transfer capacity of the metal microchannel is improved, and the pump work required to drive the flow of the working medium is reduced. The whole heat dissipation mechanism realizes the heat dissipation with a single electron pulse heat flux density of 10 ¹² -2×10 ¹² W/m ² and an average heat flux density of 5×10 ⁶ -10 ⁷ W/m ² ; Over 2000°C; lower than the melting point of the graphite layer 4; the maximum temperature of the metal body 1 is reduced from 2600°C to 650°C.

The ultra-high-power electron beam emitted by the instantaneous pulse is loaded on the graphite layer and absorbed by the graphite. Due to the extremely short heating time, the heat cannot diffuse outward during the heating time of the pulsed electron beam, so only the area of the graphite that absorbs the electron beam increases in temperature immediately. After that, in the interval of electron beam pulse heating, the heat is gradually transferred from the graphite to the working medium in the heat dissipation channel through the metal microchannel, and the temperature of the graphite absorbing electron beam area decreases rapidly, so that the temperature of the graphite does not exceed the ultra-high power instantaneous pulse heating. The allowable temperature of graphite, and due to the contact thermal resistance between the metal microchannel and the graphite, the temperature of the metal microchannel is much lower than that of the graphite, and the maximum temperature is also far from the melting point of the metal. Therefore, the collector heat-sinking device of graphite and metal microchannels can maintain safe and stable operation under the condition of instantaneous pulse heating of ultra-high-power electron beams.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can use the methods and technical contents disclosed above to improve the present invention without departing from the spirit and scope of the present invention. The technical solutions are subject to possible changes and modifications. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solutions of the present invention belong to the technical solutions of the present invention. protected range.

Claims (4)

1. an instantaneous pulse super-power electron collection-level composite heat dissipation method, is characterized in that: comprise the steps: Step 1, place the metal body (1) vertically in the axial direction; Step 2, processing double helical microchannels in the sidewall of the metal body (1); Step 3, attaching a graphite layer (4) to the inner wall of the metal body (1); Step 4, adjusting the position of the metal body (1) to realize the electron beam deposition heating area (41) in which the external electron beam is irradiated on the inner wall of the graphite layer (4); Step 5. Flow heat dissipation working medium in the double helix microchannel; Step 6: The external electron beam is directed towards the graphite layer (4) along the axial direction of the metal body (1); the heat is absorbed by the graphite layer (4) and transferred to the metal body (1) through the graphite layer (4), and finally passes through the double The heat dissipation working medium flowing in the spiral microchannel takes the heat away and realizes heat dissipation; In the step 1, the metal main body (1) is an annular structure; the metal main body (1) is made of stainless steel or titanium material; the diameter of the outer wall of the metal main body (1) is 60-150 mm, and the axial length is 10-50 mm ;Wall thickness is 3-5mm; In the second step, the double helical microchannel includes a first helical microchannel (2) and a second helical microchannel (3); the first helical microchannel (2) and the second helical microchannel (3) are both. a spiral annular channel; and the first spiral microchannel (2) and the second spiral microchannel (3) are alternately arranged; the inlet (21) of the first spiral microchannel (2) is at the axial bottom end of the metal body (1); The outlet (22) is at the axial top of the metal body (1); the inlet (31) of the second helical microchannel (3) is at the axial top of the metal body (1); the outlet (32) is at the axial bottom of the metal body (1). end; the helical directions of the first helical microchannel (2) and the second helical microchannel (3) are opposite; The pipe sections of the first helical microchannel (2) and the second helical microchannel (3) are rectangular structures; the size of the pipe section is 3mm*1mm; In the step 5, the heat dissipation working medium is ionized water, the thermal conductivity is 0.6W/(K·m), and the specific heat capacity is 4183J/(kg·K); The graphite layer (4) has an annular layered structure; the axial length of the graphite layer (4) is 10-50 mm; the wall thickness is 1-2 mm; the melting point is 3000° C.; In the fourth step, the electron beam deposition heating area (41) is arranged in the middle position of the inner wall of the graphite layer (4); the electron beam deposition heating area (41) is an annular area; the axial length is 5-25 mm; the electron beam The lateral area of the deposition heating area (41) is half the area of the inner wall of the graphite layer (4). 2. A kind of instantaneous pulse super-power electron collection-level composite heat dissipation method according to claim 1, characterized in that: the metal main body (1) and the graphite layer (4) are welded by molecular diffusion welding; ) and the graphite layer (4), the contact thermal resistance is reduced; the contact heat transfer coefficient is 5000-10000 W/(K·m ² ). 3. A kind of instantaneous pulse ultra-high power electron collection-level composite heat dissipation method according to claim 2, characterized in that: in the step 6, the external electron beam adopts the instantaneous pulse emission mode, and the single pulse emission power is 1～9GW ;Single transmission time is 100-500ns; transmission frequency is 10~50Hz. 4. A kind of instantaneous pulse super-power electron collection-level composite heat dissipation method according to claim 3, characterized in that: the whole heat dissipation mechanism realizes a single electron pulse heat flux density of 10 ¹² -2×10 ¹² W/m ² , Heat dissipation with an average heat flux density of 5×10 ⁶ -10 ⁷ W/m ² ; the maximum temperature of the graphite layer (4) does not exceed 2000°C; lower than the melting point of the graphite layer (4); the maximum temperature of the metal body (1) Decrease from 2600℃ to 650℃.

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