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]. |
+ |
Line 19 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 23 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. |
At line 60 added 11 lines. |
+ |
+ !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] |