| At line 2 added 2 lines. |
| + For some general remarks on cryogenic handling at the Neutron guide hall [see|http://lns00.psi.ch/sinqwiki/Wiki.jsp?page=CryogenicHandling]. |
| + |
| At line 3 added 1 line. |
| + This is normally done by a sample environment technician |
| Line 18 was replaced by line 21 |
| - * Increase the temperature of the heat exchanger to 100 K. |
| + * Increase the temperature of the heat exchanger to 100 K. (The better part of air will not condense at this temperature) |
| Line 22 was replaced by lines 25-27 |
| - * Pump down and flush again with He gas, then pump down to a pressure between 10 and 50 mbar. |
| + * Pump down and flush again with He gas. To remove all contaminants you should repeat this procedure an infinite number of times (at least 2x). |
| + * If you cannot reach 0 mbar (or -1 bar) on the mechanical gauges you might be faced with a leak into the sample chamber or with an offset on the gauge. |
| + * Pump down to a pressure between 10 and 50 mbar. |
| Line 30 was replaced by line 35 |
| - In SEA, this could be done by switching the needla valce control to automatic |
| + In SEA, this could be done by switching the needle valve control to automatic |
| Line 37 was replaced by line 42 |
| - for "flow set" should be optimized if not known form an earlier run. |
| + for "flow set" should be optimized if not known from an earlier run. |
| At line 42 added 1 line. |
| + |
| Lines 44-45 were replaced by lines 50-51 |
| - 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. |
| + without He pump. As this is not recommended, it is mentioned only for information. |
| + Make sure that the warm valve is always closed except for preparation. |
| At line 54 added 15 lines. |
| + |
| + !He Flow Schematics |
| + |
| + [OrangeCryostatCooldownProcedure/NeedleValveControl.png] |
| + |
| + !Automatic Cryostat Control and Monitoring |
| + |
| + All our cryostats are monitored and controlled with [SEA|http://lns00.psi.ch/sinqwiki/Wiki.jsp?page=Sea].\\ |
| + All instruments are equipped with a temperature controller (Lakeshore 340) for the temperature control \\ |
| + and a cryostat control unit (CCU) for the control of pressures, levels and valves.\\ |
| + The CCU will only work with a correctly configured SEA instance. It can read the pressure in the Helium gas pumping line and set the needle valve accordingly.\\ |
| + It reads the analog output of AMI Helium level meters and serves as a level indicator for our 2 point liquid Nitrogen level meter.\\ |
| + The Unit is used to energize the electromagnetic valves involved in the automatic Nitrogen/Helium refill. |
| + |
| + [CCU|CCU.png] |
LIN