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Thermo Fisher Scientific

Ring Collapse

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Issue

Question about why low extraction voltage reduce tip life

Environment

Titan G2 60-300, Titan G2 80-200

Resolution

These are possible resolutions for the issue:

  • Always run at V standby

Cause

These are possible causes for the issue:

  • Unbalance of electron flux and electrical field.

Details

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.