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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. Write down which cable was connected where. Usually (from top to bottom):
    • sample manipulator (thermocouple connector, 2 heating connectors, 4 z- and Θ-control unit cables, Θ-motor connector, grounding banana plug),
    • quadrupole mass spectrometer (2 connectors),
    • sputter ion gun (1 connector),
    • LEED (2 connectors+grounding on the flange10 and 2 on the CCD camera),
    • evaporators (2 grounding cables on the CF63 viewport13, all filaments, high voltages, thermocouples, water cooling tubes12-15; then blow out the residual cooling water using compressed air),
    • X-ray source (2 water tubes of the head cooling circuit, then disconnect the cover interlock connector, remove the protective cover fixed with 3+3 screws2+4, inside disconnect 2 water tubes of the anode cooling circuit and a high voltage banana plug; filament connector outside with the feedthrough1.5 to be covered with a small protective cap; blow out the residual cooling water using compressed air),
    • electron analyzer (detector box data connector, 2 high voltage connectors, lens connector).
  2. Completely remove all other components that should not be baked-out, typically:
    • sample manipulator Θ-controller (2 screws13), Θ-motor (4 screws3), LN2 cooling inlet tank and outlet bottle13-15,
    • quadrupole mass spectrometer (the whole white electronics unit, 2 screws4),
    • sputter ion gun fan (tied with a wire),
    • LEED covering sheet, its holder and camera holder with camera (4 nuts13),
    • lights on viewports,
    • electron analyzer detector electronics (2 clips).
  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 section 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. The bellows on the manipulator usually requires more layers otherwise it might not reach the desired temperature.
  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 + those added in step 6),
    • channel 3 for the electron analyzer (4 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 it finishes 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 (parameter 001 on the control unit).
  13. Check regularly temperatures and pressure, at least in the first hours after the start, until 130 °C is reached. To monitor the pressure trend you can use the Pressure Watcher software.
  14. When the bakeout is finished switch off the heating jacket on the turbopump (parameter 001 on the control unit).
  15. Degas the titanium sublimation pump using the corresponding controller (25 A for 15 min).
  16. Remove aluminum foil, heating tapes and thermocouple (4) that you added in steps 3-7.
  17. 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. Usually (from top to bottom):
    • sample manipulator (thermocouple connector, 2 heating connectors) if applicable,
    • quartz crystal microbalance (1 connector, 2 water tubes13-14; then blow out water from the cooling tubes using compressed air),
    • sputter ion gun (1 connector),
    • lights on viewports,
    • evaporators (if applicable).
  2. Place 2-4 thermocouples in different heating zones (including the manipulator bellows if applicable). 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 of 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 (see 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 it finishes 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 of the preparation chamber - bottom (and load lock if applicable) - parameter 001 on the control unit.
  12. Check regularly temperatures and pressure(s), at least in the first hours after the start, until the set temperatures are reached.
  13. When the bakeout is finished switch off the heating jacket(s) started in step 11.
  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, 21 December 2020 14:33