Preparing the SPELEEM bake-out

Preparing the chamber

  • Remove the big threads fixing the microscope optical table on the granite block. The table must be free to expand during bake out! You can leave only one, that clode to the e-gun.
  • Remove all water cooling pipes that are stil connected to the evaporators. Use tissue to avoid dropping water from the evaporator onto the MCH ion pump high voltage connector.
  • Remove also the electrical cables from the evaporators and from the sputter gun.
  • Make sure MCP and Screen Voltages are down; disconnect the channelplate cables.
  • Remove the CCD camera from the channel plate flange and mount the protection disk. Protect the fiber optics cable with the orange lids.
  • Cover all windows and feedthroughs with Al foil. It is important to protect the soft bellow between the MCH and the beamline pipe and the magnetisation stage; protect also the small ion pump in PCH.
  • Check that the VAT valve separating MCH from PCH is open. The valve between MCH and COL should stay closed.
  • When the MCH is in the low 10-7 mbar range, switch off the MCH ion pump (if on), and open the ionpump-to-MCH VAT valve.
  • Open the PCH-ionpump-to-PCH VAT valve.
  • Remove the manipulator micrometers

Preparing the tent

  • Place the tent frame (without the tent) on the optical table.
  • Place a heater (baker) on the right hand side of the optical table and connect it to the socket on the back of the table (bake-out temperature controller no. 2). It is important that the baker doesn't touch the microscope chamber, nor the tent.
  • Mount the tent, taking care not to put force on the linear motion feedthroughs, e.g. analyser slit, MCH-to-COL vavle, illumination and field limiting apertures.
  • Check that the column bake out heaters are NOT connected to the Bake-out Time Control socket, as you don’t want to bake the column out.
  • Connect the Variac to the heating tapes (Vat valves, turbo support, beamline pipe). Initially set the Variac to 160 V, then, after few hours, increase it up to 210 V.
  • Start the bake out with the Elmitec bakout control unit. Set an appropriate duration, typically 48 hours are enough.
  • The pressure at the end of the bake out should be in close to 1.5 · 10-7 mbar.

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Last Updated on Monday, 28 September 2020 12:30