Vacuum Pressure Calculations

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Vacuum Pressure Calculations
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Vaccalc

• The program vaccalc was used for all
  calculations.
• The program required three pieces of information
  for each chamber pumping, conductance, and
  outgassing.
• Using the given information, the program
  calculates the pressure at any point along the
  entire tube.

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Chamber Design
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69.33 m
HER downstream
LER downstream
4
plot
plot
Q5 NEG
ST plot
1
2
Support chamber
Q5 NEG
plot
plot
5
6
LER upstream
HER upstream
66.114 m
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Assumptions

• Bertollinis numbers on outgassing were true.
• 2000 (l/s)/m pumping for all NEG pumps with B or
  C screens.
• 1000 (l/s)/m pumping for all NEG pumps with A or
  D screens
• 1000 (l/s)/m pumping for all ion pumps (150 l/s
  pump over 0.15 m)

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Data

• Conductance remains a constant throughout the LER
  tubes.
• Lengths were taken from drawings and tables.
• This is a work in progress, making it difficult
  to draw final conclusions from the plots.

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Cases

• Baseline Design
• No Radial Pumps
• No C Pumps
• No Upstream Q4 Pump
• No Q4 pump with Ion pump
• LER Q5 not pumping
• LER Q5 outgassing
• No Q4 pump with Ion pump and frangible pump
• LER Q5 not pumping with Frangible Link Pump
• LER Q5 outgassing with Frangible Link Pump
• No C Pumps
• Q4 and Q5 outgassing
• No Q4 and Q5 outgassing

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Baseline Design (Support Tube)
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Upstream HER
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Upstream LER
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Downstream HER
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Downstream LER
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No radial pumps
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No C Pumps Upstream (support tube)
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Upstream LER
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No Upstream Q4 Pump (support tube)
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Upstream LER
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No Q4 pump with ion pump
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Q5 not pumping
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Q5 Outgassing
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No Q4 pump with ion and frangible pump
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Q5 not pumping with Frangible Link Pump
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Q5 outgassing with Frangible Link Pump
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No C Pumps Upstream (support tube)
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Upstream LER
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Q4 and HER Q5 outgassing (support tube)
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Upstream HER
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Upstream LER
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No Q4 and HER Q5 outgassing (support tube)
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Upstream HER
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Upstream LER
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Next Steps

• Test other possible combinations
• Finish the HER
• Upstream
• Downstream
• Recalculate outgassing numbers
• Check pump speed numbers
• screen conductances