2013/10/14
| 0100 | Commence helium transfer. Helium liquid level 11.1%. |
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| 0140 | Cease helium transfer. Helium liquid level 89.9%. |
| 0155 | Stop 1 K pot and open valve V5 on IGH to start recovering mixture from both sides of the fridge. |
| 0220 | Fill N2 cold trap full. |
| 1100 | Fill N2 cold trap full. |
| 1715 | Recovered 674 mbar of mixture. Increase mixing chamber heater power to 10 mW to aid recovery. |
| 1820 | Mixing chamber temperature 17.9 K. Recovered 675 mbar of mixture. Having trouble getting the rest of the mixture out, but hopefully this doesn't mean we've lost any of it. The laboratory is a little cooler today at 23 degrees Celsius, so we may have recovered most of the mixture. Turn off mixing chamber heater. |
| 1930 | Turn on 1 K pot, temperature 1.83 K. |
| 1940 | Cease mixture recovery. Commence manual condensation procedure through nitrogen cold trap 1. |
| 2150 | Valve V12A full open on IGH: manual condensation procedure complete. |
| 2220 | Mixing chamber temperature 2.4 K. Commence manual circulation procedure. |
| 2320 | Fill N2 cold trap full. |
681 mbar Single Shot Test
The single shot test performed today gave results shown in Figure 1 below. From the figure, which shows pressure in G2 (mbar) and mixing chamber temperature (mK) as a function of time, it can be seen that the single shot test was started at 61 seconds which resulted in a rapid decrease in G2 due to V9 opening up to the empty dump. This rapid increase subsided at 169 seconds with G2=14 mbar. Once the test has been started, the mixing chamber temperature began to decrease. This decrease is due to the He3 being pumped from the fridge to the dump. From 169 seconds (mixing chamber temperature of 86.5 mK) to 3037 seconds (mixing chamber temperature of 45.7 mK) the temperature in the mixing chamber decreases, allowing us to assume that the pressure increase during this time range is due to the accumulation of He3. During this total time of the single shot test (169 seconds to 3037 seconds) G2 increases from 14 mbar to 163 mbar, and thus 149 mbar if He3 was collected. This is roughly 22% He3 in the mixture.
From this we predict that we want 16% He3 so we must extract 40mbar of He3 from the mixture. According to the rate measured, this would take 770 seconds or almost 13 minutes.
| Figure 1: Single Shot Test Results |
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