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Electronics | Mr. Freeze (dilution refrigerator) | Mrs. Astra

Principle of Operation | Cooling Down | Starting the Circulation | Warming Up |

Pumping the Transfer Tube and the Top Loading Stick | Loading and Unloading the Sample

 

n. b. This is not a foolproof guide. It is very important that one has to know what he is doing, why he is doing it, and what’s happening in Mr. Freeze if he does it.

 

STOPPING THE CIRCULATION

1.      If the BOOSTER PUMP is being used, do the following:

a.      Switch off the QSB valve.

b.      Close valve #13.

c.      Turn off the BOOSTER PUMP.

2.      If only the 3He ROTARY PUMP is in use, do the following:

a.      Close #12.

b.      Turn off the ROTARY PUMP.

3.      Open valve #2.

4.      Close the C needle valve on top of the refrigerator.

5.      Turn off the 4He ROTARY PUMP.

6.      Open #31.

 

RETURNING He MIXTURE TO THE DUMPS

The best time to do this is when the temperature reaches 4.2 K.

 

1.      Close 8.

2.      Open 1.

3.      3 should be open.

4.      Close 5.

5.      Open 9.

6.      Turn on the He3 ROT PUMP.

7.      Slowly open 12 until it is fully open.

8.      Make sure dumps valve are open.

9.      When 12 is fully open, wait a few minutes.

10. Close 1,  7, and 9 in that order.

11. Turn off the He3 ROT PUMP.

12. Close dumps valve.

 

CLEANING/PUMPING NITROGEN TRAP

  1. Remove the N2 trap from the N2 dewar.

  2. Turn on the ROT A PUMP.

  3. Make sure the following valves are closed: 1, 1A, 4, 4A, 8, 8A, 9, 10, 26 and 28. Make sure the He3 PUMP is turned off.

  4. Wait for a few minutes until the mechanical pump has stabilized.

  5. Open 35 and check pressure on P3. Wait until pressure is below 10-1 mbar.

  6. Close 35.

  7. Open 34, and switch pressure meter to P4.

  8. Open 4 or 4A depending upon which trap needs cleaning. Optimal pumping time is overnight since it takes some time for trap to warm up to room temperature.

  9. When cleaning is finished, close 4 or 4A.

  10. Close 34.

  11. Turn off ROT A PUMP.

Updated:   August 9, 2004, Ian Jasper Agulo

 
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