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Thermo Fisher Scientific

Ring Collapse


Question about why low extraction voltage reduce tip life


Titan G2 60-300, Titan G2 80-200


These are possible resolutions for the issue:

  • Always run at V standby


These are possible causes for the issue:

  • Unbalance of electron flux and electrical field.


This TA is a question if whether using Vstandby (base on mono-XFEG spec of 20nA) will reduce the tip life? For XFEG it is higher recommended and SFEG as high as possible. Otherwise the consequences will be

  1. Ring collapse
  2. Beam instability
  3. Beam current drop
  4. Tip geometry change and life time reduce

Unless it has specific application like EELS which low Vstandby result in low energy spread. Our SW allow maximum 12 hours of working at < Vstandby. It will automatic raise back to Vstandby. Always consult the customer what is their requirement.

See doc.106134 for more information.