SRF Vertical Test Cryostat Design Review

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SRF Vertical Test CryostatDesign Review

• 16 May 2006
• IB1

2
Introduction

• Welcome and introductions
• Charge to the committee
• Assess the technical design of the ILCTA IB1 SRF
  Vertical Cryostat and its readiness for the
  procurement/fabrication process
• Comment on all technical aspects of the Cryostat
  design, including integration to the IB1
  cryogenic system
• Provide a written report.

3

• not a facility safety review
• Focus on
• Cryostat technical specifications
• Readiness for procurement
• Review outline
• Location of and purpose of facility in IB1 (Joe
  Ozelis)
• Cryostat system requirements (Mayling Wong)
• Integration with IB1 Cryogenic System, PID, and
  Cryogenic Design Parameters
• (Roger Rabehl and Yuenian Huang)
• 3D model overview (Clark Reid / Mayling Wong)
• Documentation requirements (Mayling Wong)
• Cost estimate, procurement plan, and schedule
  (Cosmore Sylvester)

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• Goals of the ILC Vertical Cavity Test Program
• Verify cavity processing improvements by
  quantifying cavity performance in a reliable,
  reproducible, and efficient manner.
• Measure Q0 vs Temperature
• Measure Q0 vs E
• Measure Field Emission (radiation)
• Investigate effect of low temperature externally
  performed bakeout on Q-drop
• Initial throughput expected to be 2
  cavities/month, increasing to 2 cavities/week.
  Multiple tests/cavity (Q-drop) increase this.
• System is to be capable of testing cavities
  designed for the ILC Main Linac cryomodule.
• Baseline Design Tesla cell shape, 9 cells, 1.3
  GHz. Alternate geometries, cells,
  superstructures, may also be evaluated.

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Cavity Test Facility Location
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Cavity Test Facility Location
Existing cryogenic services
Approx size/location of cryostat pit/hole
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• Cavity Test Facility Cryostat/Cryogenic
  Requirements
• LHe bath capable of operation between 4.3 and
  1.6K
• Cooldown rate from 300K to 4K that minimizes
  Qdisease susceptibility (minimize time spent
  between 100-150K)
• Sufficient volume of LHe above cavity to preclude
  need for active LHe level control during testing
  (190-200cm 165cm to top cavity flange)
• Instrumentation to provide readout of Dewar
  pressure, temperature, and LHe level
• Fast turnaround
• Cooldown fill 4-6 hours
• Pumpdown 2-4 hours (can be concurrent w/ fill
  if not performing Q0 vs T measurements)
• Remnant LHe boiloff 3-5 hours (150-180W for
  800L)
• Warmup to 300K 10-12 hours (400K He gas at
  2g/s)

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Example Test Cycle (w/ Q0 vs T measurement) Inser
t stand into Dewar Leak check Dewar seal Leak
check test stand Attach RF instrumentation
cables Pump/purge Dewar w/ GHe, check for
contamination Cooldown Fill _at_ 4K Cable
calibrations _at_ 4K Measure cavity frequencies (all
modes) Perform low field (2-3 MV/m) Q0
measurement (1W amplifier) Begin pumpdown to
1.5K, take low field Q0 data Warm back up to
2K Perform Q vs E measurements at 2K Boiloff
remnant LHe Warm Dewar
0.5hr 0.5hr 1hr 0.25hr 1hr 1.5hrs 4hrs 0.5hr 0.25h
r 0.5hr 3hrs 0.5hr 2hrs 4hrs 12hrs
Total warm-warm cycle time 31.5hrs
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Example Test Cycle (w/o Q0 vs T
measurement) Insert stand into Dewar Leak check
Dewar seal Leak check test stand Attach RF
instrumentation cables Pump/purge Dewar w/ GHe,
check for contamination Cooldown Fill _at_ 4K, begin
pumping to 2K when LHE collects Cable
calibrations _at_ 2K Measure cavity frequencies (all
modes) Perform Q vs E measurements at 2K Boiloff
remnant LHe Warm Dewar
0.5hr 0.5hr 1hr 0.25hr 1hr 1.5hrs 4hrs 0.5hr 0.25h
r 2hrs 4hrs 12hrs
Total warm-warm cycle time 27.5hrs
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Example Test Schedule (includes Q0 vs T
msmt) Day 1 Load test stand, all checkouts,
cooldown fill to 4K Day 2 Q0 vs T, Q0 vs E,
boiloff Lhe and begin Dewar warmup Day 3 Remove
test stand, setup for 120 C bake 24 hours Day
4 Load test stand, all checkouts, cooldown
fill to 4K Day 5 Q0 vs T, Q0 vs E, boiloff LHe
and begin Dewar warmup This scenario supports 2
tests per week of the same cavity, with a 24hr
120 C bake between tests. If Day 3 is a Friday,
can do a 48hr bake over a weekend.
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Example Test Schedule (w/o Q0 vs T msmt) Day 1
Load test stand, all checkouts, cooldown, fill,
pump to 2K, Q vs E, start boiloff warmup script
(long day) Day 2 Remove test stand, setup for
120 C bake 48 hours, swap cavities Day 3
Load test stand, all checkouts, cooldown, fill,
pump to 2K, Q vs E, start boiloff warmup script
(long day) Day 4 Remove test stand, setup for
120 C bake 48 hours, swap cavities (baked
one) Day 5 Load test stand, all checkouts,
cooldown, fill, pump to 2K, Q vs E, start boiloff
warmup script (long day) This scenario
supports 3 tests per week, 2 different cavities,
one of which gets a 48hr 120 C bake between
tests.
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• Conclusions
• The aggressive test schedules described here can
  be fully supported by a
• cryostat/cryogenic system that provides
• LHe bath capable of operation between 4.3 and
  1.6K
• Cooldown rate from 300K to 4K that minimizes
  Qdisease susceptibility (minimize time spent
  between 100-150K)
• Fast turnaround
• Cooldown fill 4-6 hours
• Pumpdown 2-4 hours (can be concurrent w/ fill
  if not performing Q0 vs T measurements)
• Remnant LHe boiloff 3-5 hours (150-180W for
  800L)
• Warmup to 300K 10-12 hours (400K He gas at
  2-4g/s)
• The present design will be shown to meet these
  requirements.
• Additionally, it does not preclude testing of
  alternate cavity designs or
• more extensive (RD) testing.

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Cryogenic System Requirements
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Cryogenic System Requirements
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IB1 Refrigeration Capability

• Calculated cooling capacity of 125 W at 2 K.
• Assumes 88-90 efficient J-T heat exchanger
  pre-cooling the supplied LHe. This HX is
  identical to one used in the MTF LHC quadrupole
  feed box.
• Assumes 3 Torr pressure drop through the pumping
  line between the new test facility and the Kinney
  pumps.

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ILCTA-IB1 Vertical Dewar PID
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Integration with IB1 Refrigerator

• LHe supplied across the roof of IB1 through the
  existing transfer line from the 10 kl dewar.
  Drawn off a phase separator, 5 K boiloff will
  cool a dewar intercept and a baffle.
• GHe pumped away via Kinney pumps, returned
  directly to compressor suction, or vented to
  atmosphere. The first option requires a new
  pumping line, the last two options will use
  existing VMTF piping.
• LN2 supplied from 10 kgal dewar, tying into
  existing VMTF piping.
• GN2 vented to atmosphere, tying into existing
  VMTF piping.

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Helium Vessel Thermal Design

• Heat load to 2 K helium bath is controlled 80 K
  shield and heat intercepts at 80 K and 5 K level
• 80 K shield and intercept will be cooled by LN2
• 5 K heat intercept will be cooled by GHe vapor
  from phase separator, 10 W heater to control
  vapor flow
• Heat load to 2 K from other sources (pumping line
  and instrumentations wired) will be estimated
  later, however, it should be around 2 W or so
  level

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Helium Vapor Pressure Drop

• The total vapor pressure drop will be about 3
  torr and thats our design goal
• 2 line is 150 ft and 6 line is 300 ft
• Total vapor pressure drop breaks down to three
  parts in the pumping line in our calculation
• Pressure drop within JT heat exchanger, lt 1 torr
• Pressure drop along 150 ft, 2 insulated piping,
  3.5 K inlet and 5 K outlet, the average pressure
  drop is 1.01 torr
• Pressure drop along 300 ft, un-insulated 6
  piping, 5 K inlet and 300 K outlet, the average
  pressure drop is estimated to be 0.843 torr

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Cryostat Layout
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Helium Vessel

• ASME BPVC vessel
• Dimensions - 304SS shell
• 28-inch OD
• 0.094-inch thick
• Thickness driven by external pressure (due to
  leak in insulating vacuum)
• To minimize thickness ( conduction heat load)
  use Stiffeners every 30-inch along length
• L1X1X1/4-inch angle bent intermittently welded
• 16-feet long

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Helium Vessel (contd)

• Relief system
• Burst disc
• 65-psig set pressure
• 1.5-inch - Sized assuming complete helium
  vaporization during leak of insulating vacuum
  (resulting flux of 0.6 W/cm2)
• Code Relief valve
• 50-psig set pressure
• Connected to top plate of removable insert (not
  part of this assembly/procurement)
• Heater for dewar warm-up
• Temperature of helium 420K
• Helium pressure 3-psig

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Top flange of helium vessel

• Thickness 1-inch
• Sized to ensure welded joint to the helium vessel
  shell is adequate, following guidelines of ASME
  BPVC

Top flange of Helium vessel
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Status of Documentation

• Engineering drawings
• 75 exist for initial design iteration
• Engineering notes
• Helium vessel 75 complete
• Vacuum vessel
• Pressure drop calculations
• Heat load analysis
• Relief valve sizing
• Technical specification for vendor (required at
  the time the RFP is issued)

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Cost Estimate
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Procurement Plan

• Complete the Design of the Cryostat assembly and
  release via. an RFP. Select the best qualified
  vendor based on a technical evaluation of the
  vendors proposal - not solely on lowest bid.
• While cryostat Procurement is underway-
• Continue to work towards a final design of the
  magnetic shielding and release these drawings for
  fabrication (estimated del 6 weeks ARO)
• Continue to work on the final design of the top
  plate and suspension components and then release
  these for fabrication
• located a supplier of the Lead and has a quote
  and estimated delivery (6 weeks ARO)
• located a supplier for an encapsulant (rated for
  4.5K use) which could be used on the exposed lead
  surfaces

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Schedule