| Line 24 was replaced by line 24 |
| - !Cool down |
| + !Cool Down |
| Line 26 was replaced by lines 26-45 |
| - There are two possibilities, each has advantages and drawbacks. |
| + # Connect helium pump to the pumping port (P). Switch on the pump and wait until |
| + the pressure stabilizes (should be less than a few millibars). Make sure that |
| + the warm valve (W) is closed, open cold valve (C) a little, the pressure at the |
| + pump should not exceed 20 mbar (30 on a maxi cryostat). |
| + In SEA, this could be done by switching the needla valce control to automatic |
| + and set 20 - 30 for the flow maximum. |
| + # Put a setpoint of 10 K on the heat exchanger. |
| + # When the heat exchanger is at 10 K and the sample near 10 K, reduce the pressure |
| + by closing the cold valve gradually until the heating power the temperature controller |
| + needs to keep 10 K has reached a value between 100 and 200 mW. |
| + With SEA, the regulation of the needle valve is done automatically, but the value |
| + for "flow set" should be optimized if not known form an earlier run. |
| + # Put the temperature setpoint to zero. The cryostat should cool to 1.6 K within 10 minutes. |
| + If the base temperature can not be reached or the "nv_Set" is oscillating, most probably |
| + the value for "flow set" was not determined properly, and must be increased slighly. |
| + |
| + ''Cool Down with warm valve'' |
| + In principle there is the possibility to cool down with the use of the warm valve, |
| + without He pump. As this is not recommended, it mentioned only for information, |
| + and that it has to be made sure that the warm valve has to be closed always. |
| Removed line 28 |
| - *With He pump |
| Removed lines 30-47 |
| - ** Connect helium pump to the pumping port (P). Switch on the pump and wait until |
| - the pressure stabilizes (should be less than a few millibars). Make sure that |
| - the warm valve (W) is closed, open cold valve (C) a little, the pressure at the |
| - pump should not exceed 40 mbar (20 on the ILL cold valve controller). |
| - ** Put a setpoint of 10 K on the heat exchanger. |
| - ** When the heat exchanger is at 10 K and the sample near 10 K, reduce the pressure |
| - by closing the cold valve gradually until the heating power the temperature controller |
| - needs to keep 10 K has reached a value between 100 and 200 mW. Wait half an hour |
| - and check or change the cold valve setting again. |
| - ** Put the temperature setpoint to zero. The cryostat should cool to 1.6 K within 10 minutes. |
| - |
| - *With warm valve |
| - |
| - ** Open cold valve (C), open warm valve (W) by about 3 turns. Close the valve (R) going |
| - to the He recovery. |
| - ** When the heat exchanger and the sample temperature have stabilized around at 4.2 K, |
| - close the warm valve and reopen a little bit, just enough to held 4.2 K. |
| - |
| Line 54 was replaced by line 54 |
| - * Dry the sample stick. |
| + * Dry the sample stick with a hair blower (not a hot gun!) |
LIN