2010-12-15 what is a microwave generator and what is its function? Is there any way to change the microwave frequency of the microwave generator (there is a specific operation flow)? If you don't know, ask the professionals around you. I reward 100 points! The microwave generator can be a transistor, and the high power is an electron tube. The following is a detailed introduction. Microwave energy is generated by a microwave generator, which includes a microwave tube and a microwave tube power supply. Among them, the function of microwave tube power supply (referred to as power supply or microwave source) is to convert commonly used AC energy into DC energy and create conditions for the work of microwave tubes. Microwave tube is the core of microwave generator, which can convert direct current energy into microwave energy and provide stable continuous wave microwave power. It is used in grain and oil, food, agricultural and sideline products processing, pharmaceutical products, rubber vulcanization, ceramic sintering, chemical products processing and high-tech applications. Advantages: continuously adjustable power, stable performance and perfect safety protection measures. It can work continuously for a long time, with high energy conversion efficiency and simple operation. Different manufacturers and models vary greatly. He generally has: power switch, frequency adjustment knob, output power adjustment, frequency meter and so on. Electromagnetic vibration in the magnetron produces microwaves. The anode voltage controls the frequency of microwave, which can't remove the buried plastic. His puncture ability is the ability to guide the coupling of electrical substances. For example, microwave ovens only couple food and not dishes. Just change the input frequency! Microwave energy is usually obtained by a special device with direct current or 50 MHz alternating current. There are many kinds of devices that can generate microwaves, but they are mainly divided into two categories: semiconductor devices and electric vacuum devices. Electric vacuum device is a device that uses electrons to move in vacuum to complete energy conversion, or called electron tube. Actually, it's just one kind: transistor, or electron tube. It can be applied to various industrial activities, as well as aerospace industry and so on. Regarding the core question you asked, I don't know if what I want to answer is irrelevant, just for your reference. There is a microwave RF multi-frequency generator. It has a power measurement and control display, a temperature measurement and control display, a timing display, a pulse modulator and a radiator, and is characterized by also having a controller, various groups of power supplies controlled by the controller, two or more oscillation sources with different frequencies, a Qualcomm device, a band-pass device, a low-pass device, an attached board, a switch circuit, a synthetic radiator, a radiator handle switch and a combined foot switch. Its principle is simply to add a similar modem to realize the function of single frequency conversion and multi-frequency I can give you a schematic diagram if you want. If it is a microwave oven, the microwave generator, which is usually an electron tube, adopts the principle similar to "cyclotron", except that a resonant cavity and other devices are added to extract the electromagnetic waves emitted by the electron cyclotron (the fact that the cyclotron emits electromagnetic waves is ignored in the high school textbooks). So find the resonant cavity and add the deflection magnetic field to change the frequency. But this method is not suitable for changing the frequency greatly. After all, the original product was designed to work under the best conditions. What is a microwave generator? How to use it? The microwave generator can be a transistor, and the high power is an electron tube. The following is a detailed introduction. Microwave energy is generated by a microwave generator, which includes a microwave tube and a microwave tube power supply. Among them, the function of microwave tube power supply (referred to as power supply or microwave source) is to convert commonly used AC energy into DC energy and create conditions for the work of microwave tubes. Microwave tube is the core of microwave generator, which converts direct current energy into microwave energy. Microwave tubes are divided into microwave transistors and microwave tubes. Microwave transistors have low output power and are generally used in measurement and communication fields. There are many kinds of microwave tubes, such as magnetron, klystron and traveling wave tube. They have different working principles, different structures and different performances, and are widely used in radar, navigation, communication, electronic countermeasures and heating, scientific research and other fields. Magnetron is especially suitable for microwave heating and other microwave energy applications because of its simple structure, high efficiency, low working voltage, simple power supply and strong ability to adapt to load changes. Magnetron can be divided into pulse magnetron and continuous wave magnetron due to different working conditions. Microwave heating equipment mainly works in continuous wave state, so continuous wave magnetron is often used. Magnetron is an electric vacuum device for generating microwave energy. It is essentially a diode placed in a constant magnetic field. Under the control of constant magnetic field and constant electric field perpendicular to each other, electrons in the tube interact with high-frequency electromagnetic field to convert the energy obtained by constant electric field into microwave energy, thus achieving the purpose of generating microwave energy. There are many kinds of magnetrons. This paper mainly introduces multi-cavity CW magnetron. Magnetron consists of tube core and magnetic steel (or electromagnet). The structure of the tube core includes anode, cathode, energy output and magnetic circuit system. The tube is kept in a high vacuum state. The structure and function of each part are introduced below. 1 anode is one of the main parts of magnetron. Together with the cathode, it forms a space where electrons interact with high-frequency electromagnetic fields. Under the action of constant magnetic field and constant electric field, electrons complete the task of energy conversion in this space. The anode of magnetron not only collects electrons like the anode of ordinary diode, but also plays a decisive role in the oscillation frequency of high-frequency electromagnetic field. The anode is made of metal material with good conductivity (such as oxygen-free copper) and is provided with a plurality of resonant cavities, the number of which must be even. The higher the operating frequency of the lamp, the more resonant cavities there are. The types of anode resonant cavities are usually slot-shaped, fan-shaped and slot-fan-shaped, and each small resonant cavity on the anode is equivalent to a 2c oscillating circuit in parallel. Taking the slot sector cavity as an example, it can be considered that the slot part of the cavity mainly constitutes the capacitance of the oscillation circuit, while the sector part mainly constitutes the inductance of the oscillation circuit. According to the theory of microwave technology, the resonant frequency of a resonant cavity is inversely proportional to the geometric size of the cavity. The larger the cavity, the lower its working frequency. So we can estimate its working frequency band according to the size of the cavity. The anode of magnetron is coupled by many resonant cavities, forming a complex resonant system. The resonant frequency of this system is mainly determined by the resonant frequency of each small resonant cavity, and we can also estimate the working frequency band of magnetron according to the size of small resonant cavity. The anode resonance system of magnetron can not only produce the required electromagnetic oscillation, but also produce electromagnetic oscillation with different characteristics. In order to make the magnetron work stably in the required mode, "spacer" is often used to isolate the interference mode. Spacer strips connect the anode fins one by one to increase the frequency interval between the working mode and adjacent interference modes. In addition, because the electrons after energy exchange still have a certain amount of energy, these electrons hit the anode to raise the anode temperature. The more electrons collected by the anode (that is, the greater the current) or the greater the energy of the electrons (the lower the energy conversion rate), the higher the anode temperature. Therefore, the anode needs to have good heat dissipation capacity. Generally, the power tube is forced air-cooled, and the anode has fins. Most high-power tubes are water-cooled, and the anode has a cooling water jacket. Cathode and its lead The cathode of the magnetron is an emitter of electrons and a part of the interaction space. The performance of cathode has a great influence on the working characteristics and service life of CRT, and it is regarded as the heart of the whole CRT. There are many kinds of cathodes with different properties. The directly heated cathode commonly used in CW magnetron is made of tungsten wire or pure tungsten wire wound into a spiral shape, which has the ability to emit electrons after being heated to a specified temperature by current. This cathode has the advantages of short heating time and strong electron bombardment resistance, and is widely used in continuous wave magnetron. This kind of cathode has a large heating current, which requires short and thick cathode leads and good contact between the connecting parts. The cathode lead of high-power tube works at high temperature, so forced air cooling is often used to dissipate heat. When the magnetron works, the cathode is connected with negative high voltage, and the lead wire should have good insulation performance to meet the requirements of vacuum sealing. In order to prevent the anode from overheating due to electron recoil, the cathode current should be reduced according to regulations after the magnetron works stably to prolong its service life. 3 Energy Exporter The energy exporter is a device that transports microwave energy generated in the interaction space to the load. The function of the energy output device is to ensure that the vacuum seal of the pipeline is not lost or broken through by microwaves, and at the same time, it is convenient to connect with external systems. Low-power CW magnetron mostly uses coaxial output in the place where the high-frequency magnetic field of anode resonator is the strongest. When the coupling ring is placed, when the magnetic flux passing through the torus changes, high-frequency induced current will be generated on the torus, thus leading high-frequency power out of the ring. The larger the area of the coupling ring, the stronger the coupling. The axial energy output device is often used in high-power CW magnetron, and the output antenna is connected to the anode fin through the hole of the pole shoe. Antennas are usually made into bars or rods or cones. The whole antenna is sealed by the output window. The output window is usually made of glass or ceramics with low loss characteristics. It does not need to ensure the lossless passage of microwave energy, and has good vacuum tightness. Forced air cooling is often used in the output window of high-power tubes to reduce the heat generated by dielectric loss. Magnetron of magnetic circuit system needs a strong constant magnetic field when it works normally, and its magnetic field induction intensity is generally thousands of gauss. The higher the operating frequency, the stronger the applied magnetic field. The magnetic circuit system of magnetron is a device that generates a constant magnetic field. Magnetic circuit system can be divided into two categories: permanent magnet and electromagnetic. The permanent magnet system is generally used for small power tubes, and the magnetic steel and the mold are firmly combined to form the so-called package type. High-power electron tubes use electromagnets to generate magnetic fields. The tube core and electromagnet are used together, and there are upper and lower pole shoes in the tube core to fix the distance of magnetic gap. When the magnetron is working, the output power and working frequency can be easily adjusted by changing the magnetic field intensity. In addition, anode current can also be fed into the electromagnetic coil to improve the working stability of the electron tube. The correct use of magnetron is the heart of microwave application equipment, so the correct use of magnetron is a necessary condition to maintain the normal work of microwave equipment. The following problems should be paid attention to when using magnetron: First, the load should be matched. No matter what equipment, the output load of magnetron should be matched as much as possible, that is, its voltage standing wave ratio should be as small as possible. Standing wave not only has high incident power, which reduces the actual power obtained by the processed material, but also leads to magnetron jumping and cathode overheating, which will damage the lamp tube in serious cases. When the dice jump, the anode current suddenly drops. In addition to the small mode separation degree of the pipeline itself, the reasons for mode jump mainly include the following aspects: (1) The internal resistance of the power supply is too large and the no-load is too high, resulting in non-π mode. (2) The load is badly mismatched, and the reflection of unfavorable phase weakens the interaction between high-frequency field and electron flow, which makes the normal π -mode oscillation impossible to maintain. (3) Insufficient emission due to insufficient filament heating, or insufficient emission due to cathode poisoning due to outgassing in the tube, which cannot provide the tube current required for π mode oscillation. In order to avoid mode jump, it is required that the internal resistance of power supply should not be too large, the load should be matched, and the filament heating current should meet the requirements of the manual. Cooling is one of the conditions to ensure the normal operation of magnetron. The anode of high-power magnetron is often water-cooled, and the lead-out part of cathode filament and the output ceramic window are forced to be air-cooled at the same time. Some electromagnets are also air-cooled or water-cooled. Poor cooling will cause the pipeline to overheat and fail to work normally, and in severe cases, it will burn out the pipeline. It is forbidden to work under insufficient cooling. Third, adjust the cathode heating power reasonably. After the magnetron starts to vibrate, the cathode temperature will rise and become overheated due to the unfavorable electrons returning to the cathode. Cathode overheating will aggravate the evaporation of substances, shorten the life, and even burn out the cathode in serious cases. The way to prevent cathode overheating is to adjust and reduce cathode heating power according to regulations. 5. Electrode materials of magnetron for storage and transportation include oxygen-free copper and kovar alloy. It is easy to oxidize in acid, alkali and moisture. Therefore, the preservation of magnetron should be moisture-proof and avoid acid-base atmosphere. Prevent high temperature oxidation. Because the encapsulated magnetron is equipped with magnetic steel, the magnetic change of the magnetic steel should be prevented. When ferromagnetic substances exist, there should be no ferromagnetic substances around the pipeline 10 cm. Pipes should be put into special shockproof packing boxes during transportation to prevent damage due to vibration and impact.