D R A F T. Testing of performance of precooling refrigerator in the fill/vent line at Indiana. Revision: 0.00

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1 D R A F T Testing of performance of precooling refrigerator in the fill/vent line at Indiana Revision: 0.00 Prepared: Z. Tang, Indiana University, Nov Checked: Hermann, Nann, Indiana University, yyyy Approved: Mike Snow, Indiana University, yyyy 1. Scope One of the largest modifications to the target system operated at LANSCE was the 10 m long vacuum/fill/vent line and addition of the precooling refrigerator. The function of the vacuum/vent line is to connect the cryostat isolation vacuum to pump system and relief system located outside the experimental cave. Inside the vacuum/vent line is coaxially the hydrogen fill/vent line that connects the LH2 vessel to the gas handling and the relief system. The precooling cryo- refrigerator is connected to the fill/vent system at the 6 way cross. Its first stage is connected to a thermal radiation shield, and its second stage is connected to the copper sleeved elbow part of the hydrogen fill/vent line. Its purpose is to cool down the incoming hydrogen gas and thus help to shorten the target filling process. The vacuum/fill/vent line was designed and built at Indiana University. Because of its length, it was not possible to test the line and the precooling cryo- refrigerator with the cryostat at Indiana, instead, a separate test was performed to verify the performance of the precooling system. This document summarizes the results of the test. 2. Set up and measurement The performance of the precooling system was estimated and results presented in the document Filltimeestimate.pdf that can be found at Figure 1 and 2 show the setup for the performance test. The long pipe is in its transportation box, in the foreground pump lines for the vacuum can be seen and also the helium gas input, in the test helium gas was used. Figure 2 shows the other end of the system where the cry- refrigerator is and the gas outlet. During the test the cryo- refrigerator was cold and the helium gas flow rate was varied and the temperature of the outgoing gas and the refrigerator was monitored. 3. Results A thermometer, which measured the gas temperature, was located about 6.5 away from the end of the fill/vent line (see attachment). Two different helium flow rates

2 were used. We found that when there is no helium flow, the base temperature of the fill/vent line was 28 K, and with 6.4 SLPM flow the temperature stabilized to 26 K, and at 14 SLPM the temperature reached 101 K. Even though with 6.4 SLPM flow, the temperature of gas is actually less than the base temperature of 28 K, we did notice an increase in the heat load from second stage of the refrigerator which temperature changed from 14.5 K to 20 K. Attached is a copy from the logbook. The pre- cooling system performed as expected. Fig. 1. The vacuum/fill/vent line in its transport box and with the test components. In the foreground is the vacuum flex line and the inlet of helium gas.

3 Fig. 2. The cryo- refrigerator end of the vacuum/fill/vent line. The cryo- refrigerator is behind the vertical pipe section. On the top of the vertical pipe section is the outlet of the helium gas. The temperature sensor for the gas is inside about 6 from the end flange of the tube.

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