Improve the ability to receive weak signals, in addition to increasing the antenna aperture, but also need to improve the sensitivity of the receiving system to achieve. Since the manufacturing cost of a large-diameter antenna is very high and subject to certain restrictions, it is particularly important to develop receiver sensitivity in a receiving system.
The receiver sensitivity depends on the noise figure of the preamplifier. Generally, the noise figure of the amplifier at 20K (-253°C) ambient temperature is only about one-tenth of the normal temperature, which can greatly improve the receiver's sensitivity index. However, in order to maintain a low temperature operating environment, a vacuum dewar is used to encapsulate the cryogenic amplifier. A waveguide vacuum window must be introduced between the feed output and the cryogenic amplifier. The magnetic brake vacuum window is a key component in the refrigeration receiver dewar assembly.
At present, domestic and foreign refrigeration receivers have been widely used in deep space detection systems and radio astronomy systems. For the first time, a cat cable low loss waveguide vacuum window was developed in China. The waveguide vacuum window not only has low loss to the input microwave signal, but also has the ability to vacuum seal, heat insulation, and pressure.
Because the microwave loss of the waveguide vacuum window is directly superimposed on the noise of the low noise amplifier, its insertion loss and standing wave performance are the key indicators that directly affect the receiver sensitivity. At the time of initial measurement, it may be considered to design two dedicated waveguides for coaxial conversion. Before testing, it is necessary to repeatedly calibrate the insertion loss and return loss of the coaxial conversion of the two waveguides. This method is difficult to measure accurately. Generally, the vacuum window is installed in the Dewar module. After the low-temperature amplifier is connected, the noise value of the window is calculated by using the noise difference between the amplifier with and without the window to calculate the actual loss. .
Cobalt-based alloy powders are commonly used in plasma transfer arc welding (PTAW) due to their excellent high-temperature properties and resistance to wear and corrosion. These alloys are typically composed of cobalt as the base metal, with various alloying elements such as chromium, tungsten, nickel, and carbon added to enhance specific properties.
The use of cobalt-based alloy powders in PTAW offers several advantages, including:
1. High-temperature strength: Cobalt-based alloys exhibit excellent strength and resistance to deformation at elevated temperatures, making them suitable for welding applications that involve high heat.
2. Wear resistance: These alloys have a high hardness and resistance to wear, making them ideal for welding applications where the welded parts are subjected to abrasive or erosive conditions.
3. Corrosion resistance: Cobalt-based alloys offer good resistance to corrosion, making them suitable for welding applications in aggressive environments, such as those involving chemicals or saltwater.
4. Thermal conductivity: Cobalt-based alloys have good thermal conductivity, allowing for efficient heat transfer during welding and reducing the risk of heat-affected zone (HAZ) defects.
5. Compatibility with other materials: Cobalt-based alloys can be easily welded to a wide range of base metals, including stainless steels, nickel alloys, and other cobalt-based alloys, providing versatility in welding applications.
To use cobalt-based alloy powders for PTAW, the powder is typically fed into the plasma arc using a powder feeder. The powder is then melted by the high-temperature plasma arc and deposited onto the workpiece, forming a weld bead. The specific welding parameters, such as arc current, travel speed, and powder feed rate, will depend on the specific alloy and application requirements.
It is important to note that the selection of the cobalt-based alloy powder should be based on the specific welding application and the desired properties of the final weld. Different cobalt-based a
Co Powder,Cobalt 6 Powder,Cobalt 12 Powder,Cobalt 21 Powder
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