{"id":406,"date":"2019-08-30T13:42:26","date_gmt":"2019-08-30T20:42:26","guid":{"rendered":"http:\/\/www.rbdinstruments.com\/blog\/?p=406"},"modified":"2025-03-04T06:09:25","modified_gmt":"2025-03-04T14:09:25","slug":"bake-out-procedure-to-improve-base-vacuum","status":"publish","type":"post","link":"https:\/\/www.rbdinstruments.com\/blog\/bake-out-procedure-to-improve-base-vacuum\/","title":{"rendered":"PHI 5600 XPS system Bakeout procedure to improve base vacuum"},"content":{"rendered":"

Updated 8-30-19<\/p>\n

This post explains the bakeout procedure to improve base vacuum in a PHI 5600 X-ray photoelectron spectrometer. The procedure is basically the same for most of the older PHI (Physical Electronics) Spherical Capacitive Analyzer XPS surface analysis systems.<\/p>\n

PHI X-ray photoelectron spectrometers generally have built-in radiant heaters as well as heaters under the magnets in the ion pumps that heat the system up to a maximum of 200 degrees Celsius. After the system is prepared for bake-out, a heat-insulating blanket is put over the vacuum chamber to trap the heat generated by the heaters.\u00a0 Bakeout times are typically 12 to 20 hours depending on the amount of water vapor in the chamber, which in turn is directly proportional to how long the vacuum chamber has been up to air.<\/p>\n

The system should be pumped down with the ion pumps and the vacuum should be in the low 10-7<\/sup> Torr range or better before starting a bake-out. The only exception is when you are baking out new ion pumps into the turbo pump; this is explained in more detail below. Just follow these steps and refer to the pictures:<\/p>\n

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  1. Remove any samples from the chamber that should not be baked out. These include samples that are mounted with carbon or silver tape, and gassy samples. Metals and semiconductors are OK to leave in the chamber.<\/li>\n
  2. Make sure that all the valves on the AVC are closed, and that the turbo pump is off.<\/li>\n
  3. Turn off the card rack power<\/li>\n
  4. Turn off the ion gun control, X-ray source control, and any other controls that may have filament or high voltage. The only units that should still have power are the Boostivac ion pump control, AVC (auto valve control) and the DGC III ion gauge control.<\/li>\n
  5. Remove all of the cables to all optics units on the vacuum chamber, with the exception of the ion gauge control cable, which is bake-able and remains connected at all times. The cables that should be disconnected include those for the X-ray source, ion gun, neutralizer, and electron gun if so equipped.<\/li>\n
  6. If the system has motors on the stage, remove them. If your system is a 5000 series LS (large sample) put the stage in the bake-out position before you remove the motors.<\/li>\n
  7. Drain the water out of the standard X-ray source (if so equipped) by first disconnecting the IN water line from the source but keeping the OUT water line connected. Then, remove the IN water coupler. Gravity will draw the water out of the X-ray source in about 20 seconds.\u00a0 Once the water is drained out of the source, disconnect the OUT water line and reconnect the IN water coupler to the source.<\/li>\n
  8. Remove the water cooling lines and HV connection on the standard source and the second half of the shroud.\u00a0 Cover the water swag lock fittings with aluminum foil.<\/li>\n
  9. If the system has a monochromator, set the shield aperture to mid-range. This will help prevent any coating during bake-out to occur on the monochromator crystals and will also help reduce to direct radiant heat on the surface of the crystals.<\/li>\n
  10. Remove the 10-610 monochromator X-ray source cover, Teflon block, base (first remove the HV connector), and water o-ring seals.\u00a0\u00a0\u00a0 Note that a stubby 3\/4″ open end wrench works best to remove the nut on the HV connector.\u00a0 Home Depot carries the Tekton brand 3\/4″ stubby combination wrench.\u00a0 The O-ring seals on the mono anode need to be removed or they will dry out during the bake-out, which in turn may cause a variety of problems including water leakage and leakage current on the mono X-ray source. Removing the O-rings before bake-out and coating them with some vacuum grease will prevent them from drying out and causing these leaks.\u00a0 This is VERY IMPORTANT!<\/strong>\u00a0 See the pictures below which show how the Teflon block can get burned and cause electrical leakage if the O-rings are not removed for the bake out. \u00a0\u00a0 \u00a0\"\"