2013/10/04

1120	Filled LN2 coldtrap full.
1705	Began single shot test with mixing chamber temperature at 56.9 mK and G2= 68 mbar. Results of test included below.
1810	Stopped single shot test. Stopped 1K pot and begin recovering mixture to the dump.
1900	Commence helium transfer. Helium liquid level 16.7%.
1935	Cease helium transfer. Helium liquid level 92.3%.
2245	Fill N2 cold trap full.
	Recovered 683 mbar of mixture. Start 1 K pot; initial temperature 1.67 K (expect to rise by 200 mK after a while). Commence manual condensation procedure through nitrogen cold trap 1.
2300	Temperature of 1 K pot has risen to 1.88 K.
2315	Valve V12A fully open: manual condensation procedure complete. Dump pressure of 450 mbar in fridge.

Single Shot Test : 400 mbar of Mixture

The single shot test performed today gave results shown in Figures 1 and 2 below. From Figure 2, which shows pressure in G2 (mbar) as a function of time, it can be seen that the single shot test was started at 136 seconds which resulted in a rapid increase in G2 due to V9 opening up the dump. This rapid increase subsided at 160 seconds with G2=260 mbar. Once the test has been started, the mixing chamber temperature remains relatively constant for a few seconds before beginning to decrease. This decrease is due to the He3 being pumped from the fridge to the dump. From 186 seconds (mixing chamber temperature of 56.9 mK) to 2138 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 time range (from the time the mixture has flown from the dump to the time the temperature begins to increase) G2 increases from 260 mbar to 316 mbar, and thus 56 mbar if He3 was collected. This is roughly 14% He3 in the mixture.

Figures 1 and 2: Single Shot Test Results