Development of a cryogenic air sampling system for unmanned aircraft observation.

为了利用无人飞行器研究平流层大气痕量气体的分布和变化，有必要研制一种小型、轻量化的大气采样系统。为此，我们开发和测试了一种新的低温空气采样器使用氖焦耳-汤姆逊（JT）冷却器。主要研究结果如下：1.实验测定了氖JT制冷机的制冷量。结果表明，氖JT制冷器在氖气压力为130 kgf/cm ^2时产生的制冷量约为23焦耳/秒，在50 kgf/cm ^2时几乎为零。还证实了在引入氖50至150秒后氖液化。将低压氮气引入一种新的低温空气取样系统中，测量了氮气的取样速率。在氮压为100 hPa时，采样率为0.7 - 1.0正常窝/分钟，在氮压为5 hPa时，采样率为0.3 - 0.7正常窝/分钟。这些结果表明，要实现实用的采样系统，需要提高采样率.为了检测低温采样系统采样后的空气成分，将已测定甲烷浓度的空气基标准气体引入低温采样系统中进行低温采样。结果表明，在测量精度范围内，样品的甲烷浓度与标准气体的甲烷浓度一致.采用断管刀、冷焊和N-S连接技术成功地研制了一种高导阀系统。由于阀系统仅由直管组成，即使使用相对较细的管也容易获得高电导。

In order to clarify distributions and variations of atmospheric trace gases in the stratosphere using an unmanned aircraft, it is necessary to develop a small and light weight air sampling system. For this purpose, we developed and tested a new cryogenic air sampler using neon Joule-Thomson (JT) cooler. The results are summarized as follows :1. An refrigeration capacity of neon JT cooler was experimentally determined. The results showed that the neon JT cooler produced refrigeration of about 23 Joule/second at neon gas pressure of 130 kgf/cm^2 and of nearly zero at 50 kgf/cm^2. It was also confirmed that the neon gas was liquefied after 50 to 150 seconds of the neon gas introduction.2. Low pressure nitrogen was introduced into a new cryogenic air sampling system in which the JT cooler was equipped, and sampling rate of nitrogen were measured. the sampling rate was between 0.7 and 1.0 normal litter/minutes at nitrogen pressure of 100 hPa and between 0.3 and 0.7 normal litter/minutes at 5 hPa. these results indicate that it is necessary to increase the sampling rate to realize a practical sampling system.3. To examine the composition of air after sampled by the cryogenic sampling system, an air-base standard gas, of which methan concentration was already determined, were introduced into the sampling system and sampled cryogenically. As a result, the methan concentration of the sample was confirmed to be identical to that of the standard gas within the measurement precision.4. A high conductance valve system was successfully developed using a pipe breaking cutter, cold weld and N-S joint techniques. Because the valve system was composed only by straight tubes, high conductance was easily attained even if relatively thin tube was used.