CO2 Pressure on Modules

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• CO2 Pressure on Modules
• Chiho Wang
• Duke University

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Possible Effects of CO2 Pressure

• Pressure in purging volume can deform shell and
• pull divider to one side, thus bend straws.
• break glue bond between shell and divider - an
  even larger pull of divider.
• if shell touches neighboring module, it can
• mechanically deform/displace neighboring modules.
• electrically connect neighboring modules.
• (not a problem.)

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Measurement Method Notations

• Dial gauge and module are mounted on stepping
  motor for Bridgeview control readout.
• Purging volume outlet is dipped in a water column
  to set pressure.
• 2 points at one HV plate and 1 point at the other
  are used to align module with dial gauge.
• Scanning is 2cm grid, back to front, and lower
  edge to upper edge.

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Module 2.09, Side A
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Module 2.09, Side B
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Module 2.09, Side D
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Module 2.09, Shell Peaks

• Red line is module theoretical boundary.
• Measurements are relative to HV plate edge.

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Module 3.06, Side B
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Module 3.06, Side C
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Module 3.06, Side D
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Module 3.06, Shell Peaks
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Summary

• We have measured a type 2 and a type 3 module for
  shell deformation with pressurized purging
  volume.
• Some modules are very likely to touch its
  neighbors even with minimal pressure in purging
  volume!
• Purging volume pressure should be kept as low as
  possible to avoid straw deformation and
  structural damage.