Decision

1
Decision 30 - Maintenance Unit Length

• Options
• Half the distance between refrigerators 3km
  sector
• 0.5km units (requires 6 U-tubes or 24 valves
  at each location)
• BCD 3Km sector
• Pro
• Minimizes the component count
• Minimizes the heat load.
• Con (500m units provide)
• Reduced thermal cycles on CMs. (factor 5)
• Reduced warm up times (factor gt2)
• Reduced cooldown times (factor 10)
• Reduced He storage (factor 5)
• Refrigeration load sharing
• Modular upgrade elements
• ACD If the component reliability can not be
  reached change design to 500m maintenance units.

2
Decision 38 - Refrigerator Spacing

• Drivers T. Petersons presentation 5km
• 2K temperature (pressure), Gradient, Q, cavity
  shape 300 mm pipe diameter determine the
  maximum length of the pumping line.
• Maximum coldbox size 25kW of 4.5 K equivalent
• Options
• Pair of refrigerators at common locations each
  feeding a 3.5km sector (Pipe limited)
• Single larger refrigerator each feeding two
  2.8km sectors (Refr limited)
• BCD Single refrigerator spaced 5.6km
• Pro
• Option B minimizes the pressure drops in the CM
• This reduces the baseline warm-up unit length.
• Con
• The TESLA design used option A it permitted an
  initial half refrigeration installation
• Increases the number of utility systems required
  Purifiers, LN2 systems, LHe systems, GHe systems,
  ICW, etc
• Required task After the Decisions 3, 10 25
  etc are chosen the 5.6Km needs to be verified