RU2539973C2 - Compact magnetron structure having forced air cooling - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention relates to electronic engineering and is intended for use in high- and ultra high-power magnetrons in the millimetre and sub-millimetre wavelength range. In a magnetron consisting of an anode block and a cathode placed coaxially inside the anode block and located in the interaction space of electromagnetic fields, a magnetic conductor is placed coaxially on the housing of the anode block and a cooling radiator is placed coaxially on said magnetic conductor. All three elements are mounted with cylindrical heat-conducting rods. One end of each rod is attached in the anode housing and the other end passes through an opening in the magnetic conductor and is attached in the cooling radiator which is cooled by an air stream. In another version of the magnetron, which consists of an anode block and a cathode placed coaxially inside said anode block and located in the interaction space of electromagnetic fields, the anode block with a cooling radiator is placed inside an external magnetic conductor with a cylindrical structure which has entrance and exit windows for a cooling air stream passing through the cooling radiator.

EFFECT: high efficiency of heat transmission and diffusion.

2 cl, 2 dwg

Description

The invention relates to electronic equipment and can be used in microwave devices of the M-type, in particular in powerful and (or) heavy-duty magnetrons of millimeter and submillimeter wavelength ranges.

[1, 2], которое является постоянной величиной для конкретной конструкции магнетрона и определяет его энергетику, где P_н - выходная мощность (в нагрузке) в МВт, f_о - частота генерируемых колебаний в ГГц. Этот параметр используется для классификации магнетронов по мощности (табл.1).In order to compare magnetrons with each other, we used the relation known from the literature $$P_n\cdot f_{{}_{\mathrm{about}}}^2$$

[1, 2], which is a constant value for a particular magnetron design and determines its energy, where P _n is the output power (in load) in MW, f _о is the frequency of generated oscillations in GHz. This parameter is used to classify magnetrons by power (Table 1).

When advancing into the short-wavelength part of the millimeter and submillimeter wavelength ranges, the dimensions of the interaction space decrease and the losses in the anode slowdown system increase. As a result of this, there is a sharp decrease in the coefficient of performance (COP) of the magnetron to values less than 10%. The supplied power in the anode circuit is converted by more than 90% into heat, which must be dissipated in order to avoid overheating of the anode block, other structural elements and the troubles associated with the deterioration of the vacuum state in the device, sparks, breakdowns, reduction of the magnetron uptime. An important problem that arises in the design of magnetrons of this class is the provision of the required minimum possible temperature of the anode block in a working device.

It is known that at present, a special fluid is used to cool the structural elements of the device, pumped through the channels of the anode block [3]. However, such systems with liquid forced cooling of the anode block have serious drawbacks in operation:

- The liquid used to cool the anode block must retain its properties and operate efficiently in the range of operating temperatures from minus 60 ° C to plus 100 ° C. However, the used liquid compositions at minus temperatures tend to thicken, have a high viscosity, and it is not possible to start the cooling system without additional heating of the liquid.

- A known magnetron design [4], in which the authors strive to use liquid in the system for simultaneous cooling of the anode block and the cathode, which is at high potential. Since the liquid forced cooling system is a closed volume in which the pump constantly pumps liquid through the channels of the anode block and cathode, the liquid must have a high electrical resistance and maintain it during the entire operation of the magnetron. Otherwise, large leakage currents appear during operation and the modes and electrical parameters of the device change.

- The used cooling systems are bulky, energy-consuming, inconvenient to operate.

The problem to which the invention is directed, is the creation of a powerful and (or) heavy duty magnetron of the indicated wavelength ranges, providing high reliability and stability of operational parameters when working with forced air cooling.

The technical result achieved in the claimed invention is to increase the efficiency of heat transfer and dissipation.

The specified technical result is achieved by the fact that in a magnetron, consisting of an anode block and a cathode coaxially placed inside it, located in the space of interaction of electromagnetic fields, according to the invention, a magnetic circuit is coaxially mounted on the casing of the anode block and a cooling radiator is mounted coaxially on it. All three elements are fixed by cylindrical heat-conducting rods. One end of each rod is fixed in the anode casing, the other is passed through the hole of the magnetic circuit and is fixed in a cooling radiator cooled by air flow.

In another embodiment of the magnetron, consisting of an anode block and a cathode coaxially placed inside it, located in the space of interaction of electromagnetic fields, according to the invention, the anode block with a cooling radiator is placed inside an external magnetic circuit of a cylindrical structure, in which there are inlet and outlet windows for cooling air flow, passing through a cooling radiator.

In FIG. Figure 1 shows the design model of the anode block with an integrated magnetic circuit, that is, on the casing of the anode block (4) made of copper, a magnetic circuit (3) made of steel or other iron-containing material is coaxially mounted with it, and a cooling radiator is mounted coaxially on it (5 ), made in the form of ribs, or needle rods or any other configurations made of copper or other material that conducts heat well, all three elements are fixed by cylindrical heat-conducting rods (2), made mi of copper or other good heat conductive material. One end of the rod is soldered or secured in any other way that provides contact in the anode body, the other is passed through the hole of the magnetic circuit and soldered or secured in any other way that provides contact in the cooling radiator, which allows efficient heat removal by directed air flow formed, for example, by a fan. Heat transfer is carried out from the heating source, which is the cathode (1), to the body of the anode block (4), then along the heat-conducting structural elements - rods (2) entering the hole of the magnetic circuit (3), to the cooling radiator (5) with their further cooling air flow.

To create effective heat transfer, the rods (2) are cylinders whose junction length in the housing is related by the ratio with their diameter, as L = D / 2. The total cross-sectional area of the heat-conducting elements is at least 10% of the lateral surface area of the anode block housing.

In FIG. Figure 2 shows a model of the magnetron design, in which the anode block body (4) and the cylindrical cooling radiator (5) are integral, made of copper or other heat-conducting material and are located inside the external magnetic circuit (3) made of steel or other iron-containing material having an inlet window with a connected duct (7) and an outlet window (8) for the passage of air flow, cooling the housing of the device. The cooling radiator (5) can be made in the form of ribs, or needle rods or any other configurations that allow efficient heat removal by directed air flow. Heat transfer is carried out from the heating source - the cathode (1) to the anode block body (4) and the cooling radiator (5) with further cooling by their air flow. The surface area of the outlet window is 1.3-1.4 times larger than the inlet to ensure the necessary air flow. The total area of the windows should be no more than 15% of the surface area of the external magnetic circuit.

S ₁ + S ₂ ≤0.15 · πD _in

Where

S ₁ - surface area of the input window;

S ₂ - surface area of the output window;

D _c , h are indicated in FIG. 2.

With this ratio, the loss of magnetic field due to windows is not more than 2.5%.

Practical implementation of the invention.

Example 1. To study the process of heat transfer efficiency and determine the temperature on the body of the anode block, 2 ^x mm magnetrons were used. wavelength range with parameters:

Anode voltage 14.6 kV Pulse anode current 15 A Impulse power 5 kW Goodness 1100 Current pulse duration 0.085 μs

The model corresponded to the constructive version depicted in Fig 1. To create an air flow, a fan of 20VTs-10-2A brand was used. The temperature taken for blowing air was + 25 ° C. The magnetron was placed in a cylindrical closed chamber, in which on one side there was an inlet window with a flange for connecting a fan, and on the other diametrically opposite side there was a window for air outlet. The mounting location of the thermocouple (6) is indicated in figure 1.

In the generation mode with the fan running, after about 15 minutes the temperature on the case at the attachment point of the thermocouple was no more than 55 ° C.

Example 2. To study the process of heat transfer efficiency and determine the temperature on the body of the anode block of the constructive embodiment depicted in FIG. 2, magnetrons with identical electrical parameters and the same fan connected to the duct flange were used. In the generation mode with the fan running, at approximately the same time intervals, the maximum temperature at the indicated point (6) was no more than 68 ° C.

Information sources

1. Petrochenkov V.I. Calculation of the electrical characteristics of a magnetron based on an approximate analytical model. - Radio engineering and electronics, 1994, No. 11, p. 1825-1844.

2. Petrochenkov V.I. Optimization of magnetron characteristics. - Electronic technology, ser. 1, Microwave technology, vol. 2 (505), 2010.

3. Japan patent No. 192459 (priority 29.09.2011).

4. A.V. Lyashenko, A.A. Solopov, E.A. Fedorenko, V.P. Eremin, A.V. Pastukhov, E.I. Buldakov. “Powerful, pulsed 2 mm magnetron with a durability of 2000 hours.” Tantal OJSC, Saratov. Materials of the XVII coordination scientific and technical seminar on microwave technology. Nizhny Novgorod Region, Khakhaly, September 2011

Explanations for the figures.

1. Figure 1. Anode block.

1 - heating source - cathode; 2 - heat-conducting structural elements - rods; 3 - magnetic circuit; 4 - anode body; 5 - cooling radiator; 6 - place of attachment of the thermocouple.

2. Figure 2. Anode block.

1 - heating source - cathode; 3 - external magnetic circuit; 4 - anode body; 5 - cooling radiator; 6 - place of fastening of the thermocouple; 7 - inlet with air duct; 8 - outlet.

Claims (2)

1. A magnetron, consisting of an anode block and a cathode coaxially placed inside it, located in the space of interaction of electromagnetic fields, characterized in that a magnetic circuit is coaxially mounted on the casing of the anode block, and a cooling radiator is mounted coaxially on the magnetic circuit, and all three elements are mounted cylindrical heat-conducting rods, each of which has one end fixed in the anode body, the other passed through the hole of the magnetic circuit and fixed in the radiator of cooling, cooled by air shny flow. 2. A magnetron, consisting of an anode block and a cathode coaxially placed inside it, located in the space of interaction of electromagnetic fields, characterized in that the anode block with a cooling radiator is placed inside an external magnetic circuit of a cylindrical structure, in which an input and output window for cooling air flow is provided, passing through a cooling radiator.

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