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 guns (2 connectors),
   • LEED (3 connectors and 1 USB on the CCD camera),
   • evaporators (2 grounding cables on the CF63 viewport13, all filaments, high voltages, thermocouples, water cooling tubes12-14; 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 and 1 USB on the CCD camera).
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 (2 nuts10),
   • LEED camera holder with camera (4 nuts13) and paper shielding cone,
   • lights on viewports,
   • electron analyzer detector electronics (2 clips) and camera (2 clips).
3. Place the thermocouples to the following positions (or check them if already there) and connect them to the bake-out controller:
   • 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 bake-out controller grey sockets using extension cables. Use (as in step 3):
   • channel 1 for the manipulator (1 tape),
   • channel 2 for the chamber (6 tapes + those added in step 6),
   • channel 3 for the electron analyzer (4 tapes),
   • channel 4 for the pumping section (2 tapes).
   Additionally, connect the grey cable from the turbopump heater switching box to the blue socket TIMED (because the turbopump has internal temperature check so none of our thermocouples is used) for this.
9. Switch the bake-out controller on (by the switch next to the mains socket near the beamline entrance slit.
10. If the pressure is in low 10^-6 mbar order and the water cooling of the turbopump is on you can start the bake-out. The temperatures should be set to 130 °C for the channels 1 to 4 and the total time 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. Switch on the heating jacket on the turbopump (parameter 001 on the control unit).
12. 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 Display software.
13. When the bakeout is finished switch off the heating jacket on the turbopump (parameter 001 on the control unit).
14. Degas the titanium sublimation pump using the corresponding controller (25 A for 15 min).
15. Remove aluminum foil, heating tapes and thermocouple 4 that you added in steps 3-7.
16. 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 selected channel ob the bake-out controller using extension cables. Use the heating channels consistently with the thermocouples (see step 2).
8. Switch the bake-out controller on (by the switch next to the mains socket near the beamline entrance slit.
9. If the pressure is in low 10^-6 mbar order and the water cooling of the turbopumps is on you can start the bake-out. The temperatures should be set to 130 °C (preparation chambers) or 100 °C (load lock) and the total time 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. Switch on the heating jacket(s) on the turbopump(s) of the preparation chamber - bottom (and load lock if applicable) - parameter 001 on the control unit. No timing nor thermocouple is used in this case.
11. Check regularly temperatures and pressures, at least in the first hours after the start, until the set temperatures are reached.
12. When the bakeout is finished switch off the heating jacket(s) started in step 10.
13. If you want to lower the pressure using titanium sublimation pump degas the filament using the corresponding controller (25 A for 15 min).
14. Remove the aluminum foil, heating tapes and thermocouples added in steps 2-6.
15. Install and connect back all parts removed in step 1.

Bake-out controller

• START/STOP to start/stop the bake-out (long press)
• TIMER to set the total time (red number); use SET and up/down to adjust, 2×SET to confirm; the blue number has no effect)
• TIMED blue socket on while bake-out is on, no temperature control, to be used for turbopump of the analysis chamber
• grey sockets 1-5 on while bake-out is on and the temperature of the correstonding thermocouple (red number) is lower than the set temperature (green number)
• to set the desired temperature use SET and up/down to adjust, SET to confirm