R&D (Cryogenic)
ORishabhBajpai - 17:40, Wednesday 29 May 2024 (3577)
Testing Parallel Cryocooler Operation

With Matsuo-san

Overview: Today, we tested if the cryocooler in our Lab can be operated in parallel with Matsuo-san cryocooler.

Conclusion: We cannot operate them together.

Deatils: One of the cryocolers in Matsuo-san's lab was already operating. At first, we closed the valve connected to the input of the GWSP cryocooler and observed the water pressure in Matsuo-sans lab.

The pressure with the valve open was: 0.25 MPa

After closing the valve, the pressure was: 0.28 MPa

Based on this we concluded that water was flowing into the GWSP cryocooler. After confirming this, we opened the valve again and turned on the cryocooler. At this point, I realized I had made some errors in the temperature sensor cabling as the readings were all over. Since the goal was to confirm the parallel operation, I continued with cooling. The cryocooler was turned on at 11:28 and was atleast working until 11:50 when I left the lab. When I returned around 12:50, the cryocooler was off and showed "Motor Temp: Err", so I concluded that the water pressure was insufficient for parallel operation and the compressor overheated. However, the compressor was not too hot to touch but may have just turned off a while ago. One thing to note is that the manual suggests using the arrow key and confirming that the LED display also shows "Water Flow Err" to confirm the issue is low water pressure, but I forgot to do this. In any case, the conclusion is that two cryocoolers can't be operated in parallel.

Side Note: As previously reported, there are two sensors somewhere inside the cryostat, but I could not see them (I asked about it to Satoshi Tanioka at GWADW but he doesn't remember). However, since the temperature of this sensor did not drop drastically, I concluded they are not connected to the cold-head. I will look for them again when I open the cryostat.

Next Step: I am now discussing with Matsuo-san to have standalone test for our cryocooler to confrim if the water pressure is enough. Also, we should try to install a pressure guage near the water supply for our cryocooler.