| Line 1 was replaced by lines 1-12 |
| - * fill the cold trap with liquid nitrogen and make sure that |
| + !Condensing the Mixture |
| + |
| + It is highly recommended to use the automatic condensing scripts in SEA. |
| + Click on "sorbpump", when "readyforpump", make sure that the IVC is connected |
| + to a running turbo pump, and the valve and the IVC space is open. |
| + |
| + The automatic script is doing a sligthly different condensing procedure than |
| + described below. |
| + |
| + * If not yet done, the IVC has to be pumped. Do not do that before the sorb T |
| + is at 4K. |
| + * Fill the cold trap with liquid nitrogen and make sure that |
| At line 2 added 49 lines. |
| + * Make sure that all tubes are connected correctly |
| + * Cool the VTI ("1 K pot" thermometer) to a temperature below 3 K. With the |
| + Variox 2 K may be reached, with MA09 about 2.5 K. |
| + Open the needle valve to get a pressure at the 65 m3 |
| + pump of about 12 mbar. |
| + * Open the valves in the pumping line and in |
| + the condenser line. |
| + * Open the green valves marked "out" and "in" on the dump. The dump is the |
| + grey cylinder in the center of the gas handling system rack. |
| + * Switch on the 3He pump (while pressing on the 3He button, press |
| + RAISE). |
| + * Make sure that the heater on the mixing chamber is off and that |
| + the setpoint is zero. Switch off the still heater also. |
| + * Open valve 9 (while pressing on the valve button, press |
| + RAISE). |
| + * The reading on G2 is proportional to the amount of mixture in the |
| + dump. It should read something around 660(DIL1) or 400(DIL2) mbar. |
| + * Open valves 1 and 6 (Valve 6 is a motor valve, while pressing |
| + the red valve button, press RAISE until a value of 99.9 is shown). |
| + * Open valve 13A |
| + * Open V12A a little (4 %) to allow the mixture pass the trap slowly. |
| + * When the pressure reading on G1 stabilizes or decreases, open valve 12A |
| + completely. |
| + * During condensation, the 1 K pot temperature might raise to more than 3 K, |
| + especially when the pressure on G1 is high. Adjusting the needle valve |
| + is only necessary, when this temperature get too high and prevents |
| + the condensation to progress. |
| + * After some time (depends on the temperature of the mix. chamber) |
| + the mixing chamber should reach about 1 K, and then |
| + the pressure on G1 stabilizes at a low value. |
| + Now you may start to pump out the dump: close valve 9, |
| + and open valve 14 for a short time |
| + (close it when P1 raises above 50 mbar). |
| + As soon as the pressure on P1 drops down, you might open |
| + and close valve 14 again. Do that several times. |
| + * At some stage, when opening valve 14, the pressure on P1 does no longer |
| + raise above 50 mbar. Leave the valve open until P1 drops below 1. |
| + * The temperature in the mixing chamber goes down in steps during the |
| + condensation process. It takes some time until the temperatures start |
| + to move downwards, and goes then quickly below 1 K. Then it stays there |
| + or decreases slowly to about 0.8 K, for about half an hour or more, before |
| + going down by more than 0.01 K per minute. |
| + * Once the temperature has stabilized in the region of 0.1 K or less, |
| + the flow on the condenser line might fall below 100 (black display below |
| + the valve panel, on DIL1 only). |
| + Setting the still heater to a power of 3-5 mW, the flow can be increased |
| + back to about 100, and the temperature should go down more. Good luck! |
| + |
| + [DIL1/igh.png] |
LIN