Loads on the 5 K shield

1
Loads on the 5 K shield
lead to increase on static not the same MLI!

• provide thermal intercepts
• on the many penetrations!
• couplers x 8 (9)
• leads
• cables
• Shield surface provides
• surface for thermal
• strapping with small braids

2
What is the price to pay _at_ 2K?

• From Tom Cryo spreadsheet (Feb07)
• 2K 11.4 (1.7 s 9.7 d) _at_ 700 W/W
• 5K 15.0 (10.6 s 4.4 d) _at_ 200 W/W
• 40K 153.5 (59.2 s 94.3 d) _at_ 16 W/W
• Sum 14.4 kW plug power for each module (no
  overcapacity)
• If all 5K load goes into 2K as is
• Plug power increased by 56
• Need to provide same efficient radiation shield
  for the 2K mass, with at least 10 layers MLI
  protecting the 2K cold mass
• If only radiation flow into 2K (consider factor 2
  increase for worse MLI protection) and all
  conduction intercepted
• Plug power increased by 15
• 5K thermalizaton for 3 posts, 8-9 couplers, HOM,
  leads, cables

3
Metric of comparison

• Range of effect on plug power (operation cost) is
  15 to 55 under rather optimistic conditions
  given the many penetrations that the module has
  to the 2 K environment, and located at different
  positions along the transverse section (top
  support, side couplers)
• Main difference with LHC case
• Couplers would not support weight of bulky braids
• To be on the lower side we need anyway a 5K cryo
  circuit for 90 of the conduction heat removal
• What is the metric for the comparison of this
  operating cost hit?
• The presence of the 5 K shield is in the module
  capital cost
• if any, still questionable if many thermalization
  are needed

4
5 K thermal anchors
5
Modeling issues

• Exchanging info with Norihito to decide
  simulation comparison metrics
• INFN Type III ANSYS Model
• Used for transient cooldown simulations
• 2 Shields HeGRP / No vessels
• Non linear material data
• Convective time dependent heat load on integrated
  piping
• Used so far to benchmark previous cooldown models
• Not all conduction paths included (no couplers
  yet)
• KEK STF Model

6
MLI

• CERN data used so far
• From r.t. to neglibible temperatures using 30
  layers MLI
• 1 W/m2
• From 80 K to neglibible temperaturs using 10
  layers MLI
• 0.05 W/m2
• Taking out 5 K shield how many layers of MLI?
• What shielding efficiency?

7
From J.Weisend book

• From Cry 3 DWGs
• 30 MLI sheets in 24 mm, 32 layers/inch
• 10 MLI sheets in 9 mm, 28 layers/inch
• In literature (perfect installation of best
  blanket material)
• 200 mW/m2 from r.t. 30 layers
• 20 mW/m2 for 77 K 10 layers
• 50 mW/m2 for 77 K 5 layers
• Should we use?
• 1 W/m2 30lay from r.t.
• 50 mW/m2 10lay from 77K
• 100 mW/m2 5lay from 77K

8
Shield temperature variations

• Th is the hot boundary temperature

9
Validating model results
10
Thermal loads and boundaries
11
Exploring max gradient during cooldown
12
Gradient on 70 K shield
13
Heat flow on 70 K pipe during cooldown