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Venting, bake-out and degassing

Bake-out of the analysis chamber

  1. Disconnect all cables and water-cooling tubes from the equipment on the analysis chamber except for the turbopump, the titanium sublimation pump and gauges. Typically (from top to bottom):
    • sample manipulator (thermocouple connector, 2 heating connectors, 4 z- and Θ-control unit cables, Θ-motor connector, grounding banana plug and crocodile clip),
    • quadrupole mass spectrometer (2 connectors),
    • sputter ion gun (1 connector),
    • LEED (2 connectors+grounding on the flange and 2 on the camera),
    • evaporators (2 grounding cables on the CF63 viewport, all filaments, high voltages, thermocouples, water cooling tubes; blow out the residual cooling water using compressed air),
    • X-ray source (2 water tubes of the anode cooling circuit and a high voltage banana plug under the protective cover fixed with 6 screws; filament connector outside with the feedthrough to be covered with a small protective cap, another 2 water tubes of the head cooling circuit; blow out the residual cooling water using compressed air),
    • electron analyzer (detector box data connector, 2 high voltage connectors, lens connector, thick grounding cable).
    Blow out water from the cooling tubes using compressed air.  Write down which cable was connected where.
  2. Completely remove all other components that cannot be baked-out, typically:
  3. Place the thermocouples to the following positions (or check them if already there):
    • manipulator bellows (1),
    • analysis chamber (2),
    • electron analyzer detector flange (3),
    • pumping sextion at the bottom of the chamber (4).
    The thermocouples should have a thermal contact but not the electric contact with the chamber, otherwise the bake-out controller will not work properly.
  4. Cover the bellows on the manipulator with a single layer of aluminum foil and wind a 3 m-long heating tape starting from the CF160 flange passing around the xy stage, Θ rotary feedthrough, z bellows up to the feedthroughs at the top.
  5. Cover sensitive areas (viewports, bellows, feedthroughs, leak valves, X-ray source ceramic insulator) with aluminum foil.
  6. Place one or two heating tapes where missing (evaporators, X-ray source).
  7. Cover the whole chamber including all bakeable parts with several layers of aluminum foil. Be careful that the cables that remain connected (gauges and pumps) stay outside. Fix also holes around the heating shield of the big flange at the bottom of the chamber.
  8. Check that heating tapes contacts are not grounded to the chamber and connect them to the socket box of the bake-out controller using extension cables. Use (as in step 3):
    • channel 1 for the manipulator (1 tape),
    • channel 2 for the chamber (5 tapes + that ones added in step 6),
    • channel 3 for the electron analyzer (3 tapes),
    • channel 4 for the pumping section (2 tapes).
  9. Connect the socket box to the electric line and to the bake-out controller unit (grey cable).
  10. Connect the thermocouples to the bake-out controller unit and switch it on. Set the program to temperatures 130 °C for the channels 1 to 4. The total time should be at least 36 hours (usually 40-48; it is convenient if the bake-out stops at very early morning, so the chamber cools down a bit before you arrive to work).
  11. If the pressure is in low 10-6 mbar order and the water cooling of the turbopump is on you can switch on the bake-out on the bake-out controller.
  12. Switch on the heating jacket on the turbopump on the analysis chamber.
  13. Check regularly temperatures and the pressure, at least in the first hours after the start, until the desired temperatures are reached. To monitor the pressure you can use the Pressure Watcher software.
  14. When the bakeout is finished switch off the heating jacket on the turbopump on the analysis chamber.
  15. Degas the titanium sublimation pump using the corresponding controller (25 A for 15 min).
  16. Close the gate valve towards the preparation chamber - bottom.
  17. Remove the aluminum foil, heating tapes and thermocouples added in steps 3-7.
  18. Install and connect back all parts removed in steps 1-2.

Bake-out of the preparation chamber (and load lock, if needed)

  1. Disconnect all cables and water-cooling tubes from the equipment on the preparation chamber - bottom (and eventually preparation chamber - top and/or load lock) except for the turbopump, the titanium sublimation pump and gauges. Typically (from top to bottom): Blow out water from the cooling tubes using compressed air.
  2. Place 2-4 thermocouples in different heating zones.The thermocouples should have a thermal contact but not the electric contact with the chamber, otherwise the bake-out controller will not work properly.
  3. Cover the bellows on the manipulator with a single layer of aluminum foil and wind a 3 m-long heating tape starting from the CF160 flange passing around the xy stage, Θ rotary feedthrough, z bellows up to the feedthroughs at the top (if applicable)
  4. Cover sensitive areas (viewports, bellows, feedthroughs, leak valves) with aluminum foil.
  5. Place other heating tapes where missing (evaporators, transfer rod if applicable).
  6. Cover the whole chamber(s) including all bakeable parts with several layers of aluminum foil. Be careful that the cables that remain connected (gauges and pumps) stay outside. The load lock door and both full-range gauges (if applicable) should be covered less than the all-metal parts in order to lower the temperature.
  7. Check that heating tapes contacts are not grounded to the chamber and connect them to the socket box of the bake-out controller using extension cables. Use the heating channels consistently with the thermocouples (as in step 2).
  8. Connect the socket box to the electric line and to the bake-out controller unit (grey cable).
  9. Connect the thermocouples to the bake-out controller unit and switch it on. Set the program to the temperatures 100-130 °C. The total time should be at least 12 hours depending on the desired final pressure. It is convenient if the bake-out stops at very early morning, so the chamber cools down a bit before you arrive to work.
  10. If the pressure is in low 10-6 mbar order switch on the bake-out on the bake-out controller.
  11. Switch on the heating jacket on the turbopump on the preparation chamber - bottom.
  12. Check regularly temperatures and the pressure, at least in the first hours after the start, until the desired temperatures are reached.
  13. When the bakeout is finished switch off the heating jacket on the turbopump on the preparation chamber - bottom.
  14. Degas the titanium sublimation pump using the corresponding controller (25 A for 15 min).
  15. Remove the aluminum foil, heating tapes and thermocouples added in steps 2-6.
  16. Install and connect back all parts removed in step 1.

Some equipment in the vented chambers must be properly degassed before use, as described on the next page.



Last Updated on Monday, 12 August 2019 15:50