vacuumpump真空泵ppt課件(參考版)
2025-05-08 18:28本頁面
【正文】 otherwise the molecules will pass through the rotor regions without being struck. Lighter molecules are more difficult for turbomolecular pumps to pump, because they are more likely to pass through the rotors without being hit by a blade, increasing the likelihood of back diffusion of the gas. Pump performance depends on blade design as well as rotor speed. Variables include the pitch angle, blade width and the distance between blades. Overall performance is optimized by varying the blade geometry through the pump. Ingestion（ 攝 ?。? of foreign objects into any turbomolecular pump during operation will cause severe damage to the rotor and stator blade. In order to reduce this risk most pumps are provided with a wire mesh inlet guard. 05/10/2022 Title 35 Pumping selectivity Pumping speed depends on the types of gas (molecular weight, momentum transfer) for the operation principle 05/10/2022 Title 36 ADVANTAGES 1. Fast recovery from “Dumping” 2. Fast startup 3. Constant speed 4. Clean ( No oil ) 5. Operating costs 6. High throughput 7. Small to large size DISADVANTAGES 1. Sensitive to particulates 2. Requires mechanical pump 3. High rpm ( Noise/Vibration ) 4. Low speed for hydrogen and helium 5. High maintenance cost 6. 1 ? 103 Torr upper limits 7. High initial cost Advantages and disadvantages of the turbomolecular pump 05/10/2022 Title 37 ? Vapor pump: ejector pump and diffusion pump ? Distinction： mean free path at the intake port vs. throat width ? In relation to 關于 涉及 ? boiler ? Mercury ? Chimney ? Deflect 偏轉 ? Umbrella 傘形鐘罩 ? Pressure gradient ? viscous drag and turbulent mixing ? Diminish, crosssection ? Orifice 孔 ? vapor booster pump: bination the diffusion and ejector pump 05/10/2022 Title 38 1 Nozzle (Laval) 2 Diffuser nozzle (Venturi) 3 Mixing chamber 4 Connection to the vacuum chamber 1 Steam inlet 2 Jet nozzle 3 Diffuser 4 Mixing region 5 Connection to the vacuum chamber 。 102 ~ 103 l/sec ? Applications 。Unit Ⅱ . Vacuum Pumps 05/10/2022 Title 2 Vacuum pumps ? be concerned with 與 … 相關 ?pumping mechanism: lowering the molecules number ? pressionexpansion: piston pump（活塞） liquid ring pump（液環(huán)） rotary pump Root’s pump ? Drag by viscosity(黏性） : vapor ejecting pump ? Drag by diffusion effect: vapor diffusion pump ? molecular drag: molecular pump ? ionization effect: ion pump ? physical/chemical sorption pump: sorption pump, cryopump(低溫） , gettering(吸氣） pump Principles of pumping 05/10/2022 Title 3 A sort of pump I. Gas transfer pumps remove gas particles from the system. There are rotary vane pump, turbomolecular pump and diffusion pump in gas transfer pumps. II. Entrapment pumps in which gas particles that have entered from the system are trap
教學課件相關推薦
鄂ICP備17016276號-1