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Vacuum Pressure Calculations. Vaccalc. The program vaccalc was used for all calculations. The program required three pieces of information for each chamber: pumping, conductance, and outgassing.
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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.
Chamber Design 3 69.33 m HER downstream LER downstream 4 plot plot Q5 NEG ST plot 2 1 Support chamber Q5 NEG plot plot 5 6 LER upstream HER upstream 66.114 m
Assumptions • Bertollini’s 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)
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.
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
Next Steps • Test other possible combinations • Finish the HER • Upstream • Downstream • Recalculate outgassing numbers • Check pump speed numbers • screen conductances