原文：
低温抽气是目前获得洁净真空环境的一种快捷而有效的方法。随着双级高可靠性小型制冷机的日臻完善，制冷机低温泵得到迅速发展，已成为获得洁净、无污染、抽速大、工作压力范围宽、抽气效率高、结构简单、使用方便，能长期工作及可任意方向安装的真空获得设备。 一典型的气氦制冷机低温抽气系统。该抽气系统不需要前级泵，仅需要在粗抽过程中开动机械泵进行预抽。它不需要用液氮冷阱来防止低温泵的返流，但可在真空室内安装冷阱、水冷障板或室温障板来屏蔽工作过程中的热载荷，但是这些障板也会降低系统的总抽速。低温泵可以用氢蒸气压规来监测第二级冷阵的温度。 低温泵的抽速大，通常用在不能高温烘烤除气的真空系统。从抽气系统结构来看，低温泵系统类似于离子泵系统。为了无污染粗抽真空，还可以配接吸附泵。但是这种结合并不适用于抽除大量的惰性气体，例如氩气。而且虽然低温板易抽气，但当低温泵需要再生时，会给吸附泵造成困难。由于前级泵只在起始抽气期间使用，所以污染极少，如果使前级泵工作在粘滞流范围，即用机械泵粗抽到200Pa，然后 再用吸附泵接力抽到1Pa，可进一步减少污染。但是除了额外气体负载外，低温泵在200Pa下开始冷却时会导致可凝结性气体，例如CO2和水汽，凝结在低温板上而不是周围屏蔽板上。在低温板上涂覆适量活性碳可有效地降低这种凝结效应。因为低温泵对氢气的抽速很小，所以低温泵抽氢气时应与钛升华泵结合。低温泵也可以和其它的超高真空泵，例如离子泵或涡轮分子泵进行组合。 低温泵真空系统的操作 低温泵抽气系统不需要前级泵，仅需要粗抽泵，低温抽气的真空室在到达切换压力之前是用粗抽泵进行抽气的。当达到切换压力后关掉粗抽阀并打开高真空阀。真空室可在安全的压力范围内地被转换上低温泵抽气。如果用机械泵粗抽，则真空室切换到低温泵抽气转换所允许的{zd1}压力是由防止机械泵返油的要求决定的。对直径为4到6cm的粗抽管道来说，{zd1}压力约为10到20Pa。对直径非常大的粗抽管道来说，其切换的{zd1}压力值更低；但其数值要大于克努曾数为0.01时的压力值。{zg}切换压力取决于低温抽气表面的几何形状和制冷机的制冷量。泵的低温抽气表面应具有相当大的热容量，它们 能接纳“突发”的气体而不产生不可逆升温。在一次气体突发中导入低温泵中的{zd0}气体量Qi的允许数值可由低温泵的制造厂家得到，当打开高真空阀时瞬间导入的气体量可由Qi＝PcV求出，由此可见，{zd0}切换压力为 Pc=Qi/V 式中Pc———切换压力，Pa V———真空室容积，m3 Qi———某一瞬时突发进入低温泵内的{zd0}气体量（例如打开高真空阀时瞬间导入的气体量）；V为真空室容积。 对典型的小型制冷机低温泵，由粗抽转换到低温泵抽气的切换压力范围为 10小于等于Pc小于等于Qi/V 假如由（4）式求得的值低到在切换前就会有机械泵油返流现象的话，那就说明相对于真空室容积尺寸来说低温泵的抽速太小了。 由（4）式求得的低温泵的切换压力要比扩散泵的高几个数量级。如果突发产生的气体很多，则在粘滞流或过渡流时，突发气体中的水蒸气就会到达吸附剂处，覆盖在吸附剂上或使之饱和，从而防碍了对氢气和氦气的抽除。在大部分低温抽气系统中，切换压力接近100Pa。为了尽量减少油的返流，{zh0}是采用尽可能高的并避免吸附剂出现饱和现象的切换压力。

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译文：
Low access to clean exhaust is a quick vacuum and effective way. With the two-stage high-reliability small refrigerator is improving daily, refrigerator cryopump rapid development, has become the access to clean, non-polluting, pumping speed large, working pressure range, high pumping efficiency, simple structure, easy to use, long-term work and can be installed in any direction the vacuum obtain equipment. A typical low-temperature exhaust gas helium refrigerator system. The exhaust system does not require pre-pump, only the process needs to start pumping crude pre-pumping mechanical pump. It does not require liquid nitrogen cryogenic pump cold trap to prevent thereflux, but can be installed in the vacuum chamber cold trap, water-cooled baffle or baffle to shield the work at room temperature during the heat load, but these barriers will reduce the system board The total pumping speed. Low-temperature hydrogen vapor pressure pump can be regulated to monitor the temperature of the second stage cold front. Cryopump pumping speed large, usually not high-temperature baking in a vacuum degassing system. From theexhaust system structure, the cryogenic pump system similar to the ion pump system. To clean coarse vacuum, the pump can also be connected with adsorption. But this does not apply to extraction combined with large amount of inert gas, such as argon. And although the board easy to exhaust temperature, but low pump needs regeneration, the adsorption pump will cause difficulties. Since the former pump only used during the initial pumping, so little pollution, if the work of the former pump viscous flow in the range, that is pumped by mechanical pump crude 200Pa, and then use the adsorption pump Relay pumped 1Pa, can to further reduce pollution. But apart from the additional gas load, the low temperature cooling pump started under 200Pa will lead to condensation of gases, such as CO2 and water vapor, condensation in the cold shield around the board instead of board. In the low amount of activated carbon coated board can effectively reduce this condensation effect. Because the temperature of the hydrogen pump pumping speed is small, so low temperature pumping of hydrogen should be combined with titanium sublimation pump. Cryopump can and other ultra-high vacuum pumps, such as ion pumps or turbo-molecular pump combination. Cryopump vacuum system operation Cryopump exhaust system does not require pre-stage pump with only rough pumping, low-temperature exhaust of the vacuum chamber before reaching the pressure switch is used for extraction of crude pumping. When the pressure reached after switching off Roughing valve and open the high vacuum valve. Vacuum chamber can be in a safe pressure range is converted on the mainland at low temperature pump exhaust. If mechanical pump Roughing, then switch to low-temperature vacuum chamber pump exhaust pressure to change the minimum allowed by the mechanical pump to prevent oil back to the requirements of the decision. 4 to 6cm in diameter pipeline pumping crude, the minimum pressure of about 10 to 20Pa. Very large diameter pipeline pumping crude, its lowest pressure switch lower; but its value is greater than 0.01 on several occasions when Cinu pressure value. The maximum pressure depends on the low-temperature exhaust switching surface geometry and the cooling capacity. Surface temperature exhaust pump should have a considerable heat capacity, they can accept the "sudden" in the gas without producing irreversible warming. In a burst of gas into low-temperature gas pump maximum allowable amount of Qi values can be obtained at low temperature pump manufacturer, when the high vacuum valve to open when the instantaneous amount of gas imported by Qi = PcV obtained, we can see that the maximum switching pressure Pc = Qi / V Type in the Pc --- switch pressure, Pa V --- vacuum chamber volume, m3 Qi --- an instantaneous burst into the low-temperature gas pump the maximum amount (for example, when the moment to open high vacuum valve into the gas volume); V for the vacuum chamber volume. The typical small refrigerator cryopump, the crude extract of conversion to low pressure pump exhaust the range of switching 10 Pc less than equal to less than or equal Qi / V If by (4)-type low value obtained before the switch will have mechanical pump oil reflux phenomenon, it shows that relative to the size of the vacuum chamber for the low volume pump pumping speed is too small. By (4) obtained low-temperature pump-type switching high-pressure pump than the diffusion of several orders of magnitude. If the burst of gas produced by many in the viscous flow or transition flow, the sudden arrival of gas in the water vapor adsorption Department, covering the adsorbent or so saturated, thus hindering the hydrogen and helium gas extraction. In most low-temperature exhaust system, the pressure switch close to 100Pa. In order to minimize reflux of oil is best used as high as possible and to avoid the phenomenon of switching adsorbent saturated pressure.