论文部分内容阅读
对于确实不存在碳氢化合物的真空过程，到目前为止主要是使用溅射离子泵，它常和钛升华泵组合，称之为“干”泵系统。研制用氦作为致冷剂的高效率、操作安全的低温致冷器就有可能产生封闭循环的低温泵结构。采用这种真空泵也同样能获得“干”式真空。此外，这种泵的优点是能在大于１０－４毫巴的较高压强和较高气体量下得到应用。 氢在１２至２０Ｋ的工作温度下仍具有高的蒸汽压强，为了获得对氢的高抽速和低的分压强，就有必要研制合适的吸附剂。对固体吸附剂上的物理吸附和在２０Ｋ温度下的冷凝ＣＯ２层上的低温捕集效应作了比较，其结果表明，第一种方法在应用中比较简单。应用活性碳就能吸附大量的分压强极低的氢。 在这些经验的基础上研究了致冷器型低温泵的各种不同的解决方法。采用这一些方法，在２０Ｋ和约 １瓦特致冷功率下达到最佳抽速。 无论如何，处于最低温度的低温面用一个较高温度（约８０Ｋ）辐射屏来屏蔽，屏的型式采用透气性好的人字形挡板，这样，易冷凝气体（水蒸汽）就冷凝于挡板上。对于这种屏所需要的致冷功率与决定水蒸汽抽速的几何尺寸和辐射热量有关。若环境温度接近于室温，则低温泵就完全可以构成一个整体式系统，这两级温度的致冷功率由同一致冷器提供。可是，假如所要求?
For the vacuum process in which hydrocarbons do not actually exist, a sputtering ion pump is used so far, often in combination with a titanium sublimation pump, called a “dry” pump system. Developed with helium as a refrigerant of high efficiency, safe operation of the cryogenic refrigerator may have a closed cycle cryogenic pump structure. This type of vacuum pump also gives a “dry” vacuum. In addition, this pump has the advantage of being able to be used at higher pressures and gas volumes of more than 10-4 mbar. Hydrogen still has a high vapor pressure at an operating temperature of 12 to 20K. In order to obtain a high pumping speed and a low partial pressure of hydrogen, it is necessary to develop a suitable adsorbent. The physical adsorption on the solid adsorbent and the cryogenic trapping effect on the condensed CO2 layer at 20K were compared. The results show that the first method is simple in application. Application of activated carbon can absorb a lot of very low partial pressure of hydrogen. Based on these experiences, various solutions to cryogenic pump cryogenic pumps have been studied. Using these methods, the optimum pumping speed is achieved at 20 K and about 1 Watt of refrigeration power. In any event, the lowest temperature surface is shielded with a higher temperature (~ 80K) radiating screen, which uses a well-ventilated chevron baffle so condensable gas (water vapor) condenses on the baffle on. The cooling power required for this screen is related to the geometry and radiant heat that determine the water vapor pumping speed. If the ambient temperature is close to room temperature, the cryogenic pump can completely form a one-piece system, the two-stage temperature cooling power provided by the same cooler. However, if requested?