Pumpdown using mech pump through turbo
Answers to Exercises

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Exercise 1: Pump down the reaction chamber through the turbo pump, with just the mechanical pump.

  1. What base pressure does the reaction chamber reach?
    The reaction chamber pumps down to the base pressure of the mech pump, about 2x10-3 torr. The reaction chamber eventually reaches the lowest pressure obtainable using the mech pump only.

  2. Roughly how long does it take to reach approximate base pressure?
    The mech pump reaches its base pressure in about 1 min 30 sec. The pumpdown speed depends mainly on the volume and initial pressure of the reaction chamber and on the effective pumping speed of the mech pump as realized through the turbo chamber. Details of the turbo pump design and turbo pump chamber volume also influence the system dynamics.