1. ILC Cryogenic Systems Draft EDR Plan
T. Peterson
With input from RDR co-authors
13 September 2007

2. ILC Engineering Design Phase
A year effort to create a more complete ILC design
Starting now
Precise scope not yet defined and will depend on funding
Will do what we can afford to do, starting with highest priorities
Work will be internationally distributed
ILC cryogenic systems design for each area must be integrated with designs of cooled devices (cryomodules, magnets)
13 Sep Tom Peterson
EDR draft plan

3. Towards the EDR -- summary
Continue to refine heat load estimates and required plant sizes
Contract with industry for main linac cryogenic plant conceptual designs and cost studies
Need to integrate plant cycle with cryomodule conditions
Will feed back to system design and cryomodule design
Refine system layout schemes to optimize plant locations and transfer line distances
Particularly for the sources, damping rings, and beam delivery system
Develop cryogenic process, flow, and instrumentation diagrams and conceptual equipment layouts
Develop more detailed conceptual designs for the various end boxes, distribution boxes, and transfer lines
Refine liquid control schemes so as to understand use of heaters and consequent heat loads (allowed for in Fo = 1.4)
13 Sep Tom Peterson
EDR draft plan

4. Towards the EDR -- summary - 2
Consider impact of cool-down, warm-up and off-design operations
Evaluate requirements for loss-of-vacuum venting
Conceptual designs for large 2 kelvin heat exchangers
Not distributed as in LHC
Consider how to group surface components to reduce surface impact
Compliance with engineering standards, particularly in cryogenic modules
Damping ring cryogenic system
Beam delivery cryogenic system
13 Sep Tom Peterson
EDR draft plan

5. Near term goals
Review the following list of work packages for completeness
Review work package priorities
Important to understand priorities in order to allocate limited resources
Begin associating work packages with names of people and institutions
13 Sep Tom Peterson
EDR draft plan

6. Work Package 1 Main linac heat loads (6 man-months)
Heat load estimates and uncertainty and overcapacity factors all need refinement.
We should quantitatively evaluate uncertainties for dynamic and static heat at each temperature level and incorporate those uncertainties into the plant sizing spreadsheets.
Dark current, HOM loads, etc., need another look
Present estimate is largely just scaled from TESLA TDR
High priority
Collaborative effort with main linac experts
Who? (So far Peterson, Parma, ML people. A role for CERN here?)
13 Sep Tom Peterson
EDR draft plan

7. Work Package 2
Main linac plant design (6 man-months lab labor plus industrial study)
An ILC refrigeration study should be done with industry as soon as funds (~$100K) are available.
Integration of the refrigeration cycle with the required flows, pressures, and temperatures in ILC requires some study.
Changing heat loads at all temperature levels affect cold box operation, so some special features and control strategies will have to be implemented.
Cryogenic unit pressure drops, temperature rises, and flow rates need to be re-evaluated and integrated with cryogenic plant cycles.
High priority
Who? (KEK or Fermilab should manage a contract with industry for this study)
13 Sep Tom Peterson
EDR draft plan

8. Work Package 3 Reliability, maintenance, and repair (6 man-months)
Methods and cost for providing redundancy, such as load sharing among cryogenic plants, should be investigated.
Warm-up and cool-down of the 2.5 km long cryogenic units need to be studied.
Segmentation of the cryogenic unit for warm-up and repair of short sections might be desired. A feasibility study on segmentation has to be carried out with corresponding impacts on filling factor, cost, operation and reliability.
High priority
Who? (this is open)
13 Sep Tom Peterson
EDR draft plan

9. Work Package 4 Emergency venting (6 man-months)
Protection from over pressurization due to abnormal operating conditions, such as loss of beam tube or insulating vacuum, power outage, etc., needs to be studied.
Vacuum isolation, lengths of vacuum units, and fast-acting vacuum valves all need further investigation.
All the cryogenic circuits need study. The 2 K cavity-cooling circuit is most critical due to the low pressure limits imposed by the niobium RF cavities, but the thermal shield flow circuits may be difficult to protect due to the relative high initial pressure.
Work has been done for XFEL, providing some basis
High priority
Who? (wide open)
13 Sep Tom Peterson
EDR draft plan

10. Work Package 5 Grouping major surface components (6 man-months)
The cryogenic system, particularly compressors and associated cooling towers, will be one of the most visible parts of the ILC. Studies of how to minimize the surface impact by means of consolidating as much of the cryogenic system as possible on the central campus and other areas would be valuable.
These studies could look at pipe sizes required for grouping compressors, transfer line sizes for grouping 4 Kelvin refrigeration with distributed 2 K cold boxes, etc. Cost tradeoffs for these options should be evaluated.
High priority for conceptual designs, lower for detailed design since regional implementation
Who? Parallel efforts to develop concepts in both US and Japan would be fine
13 Sep Tom Peterson
EDR draft plan

11. Work Package 6
Mitigation of oxygen deficiency hazards needs to be studied (3 man-months)
Interface with civil engineering, all three regions, addressed locally
Medium priority
Who? Each region with CF&S people
13 Sep Tom Peterson
EDR draft plan

12. Work Package 7
Cryogenic box design (36 man-months, including significant designer time)
We need conceptual design layouts and 3-D models for the many cryogenic boxes in ILC.
Cryogenic distribution design should be a major EDR effort.
These component designs feed back to alcove sizes as well as to cryogenic system design and costs.
Interface with DESY for XFEL input
Medium priority
Who? Open, can be divided
13 Sep Tom Peterson
EDR draft plan

13. Work Package 8 Liquid control (6 man-months)
Control of the 154 meter long strings of 108 helium vessels filled by means of series flow will present some unique problems due to the large dynamic heat loads and due to very long time constants. Dynamic heat loads much larger than static will result in large 2 Kelvin heat load changes with changes in RF power. Electric heaters will be required to help offset the impact of sudden changes in dynamic heat loads. The two-phase superfluid helium flow pattern and cooling limitations with respect to slope and string length should be studied and validated. Electric heaters should be sized, a conceptual design developed (where are the heaters, how are they powered, etc.), and their impact on total heat load evaluated.
Medium priority. Self-contained project. Could be student.
13 Sep Tom Peterson
EDR draft plan

14. Work Package 9 Cryomodule thermal optimization (12 man-months)
Costs of the cryomodules per meter are much larger than the costs of the cryogenic system per meter. Optimization studies for capital and operating costs should consider tradeoffs of cryomodule complexity with heat loads. For example, thermal shields, thermal intercepts, and MLI can perhaps be simplified for efficient production. At a minimum, the 5 Kelvin thermal shield bridges at cryomodule interconnects can probably be eliminated.
Lower priority
Who? Open, close collaboration with cryomodule people
13 Sep Tom Peterson
EDR draft plan

15. Work Package 10
2 K heat exchangers (6 man-months plus industrial study)
Subcooling to 2.2 K by heat exchange with the returning, saturated 30 mbar pumped flow will not be done locally in tunnel feed boxes as in LHC but centrally at the cryogenic plant. Therefore, sub-cooling heat exchangers with capacity 10 times larger than the present state of the art have to be developed. (Possible collaborative study with industry/university.)
Lower priority, self-contained project.
13 Sep Tom Peterson
EDR draft plan

16. Work Package 11
Compliance with engineering standards and the associated component design pressures needs to be studied with respect to cost, operability and reliability (3 man-months)
For example, a plan to handle (non-) compliance with the ASME boiler and pressure vessel code should be developed.
Regional issues may differ, also would like common set of standards
Lower priority
13 Sep Tom Peterson
EDR draft plan

17. Other Area Work Packages
Sources, including the undulators, will require significant cryogenic design work (6 man-months)
Medium priority, require interfacing with area people.
Damping ring cryogenic system needs some very fundamental design work (12 man-months)
We need a conceptual flow schematic, cryogenic distribution plans, concepts for cool-down and warm-up, and a re-evaluation of system heat loads. Like for main linacs, cryogenic distribution design is a major effort. This work would be done in close collaboration with the damping ring area leaders.
Medium priority, requires interfacing with area people.
Beam delivery cryogenic system needs some very fundamental design work (6 man-months)
Same comments as for Damping Rings
13 Sep Tom Peterson
EDR draft plan

18. Excerpts -- work package table
13 Sep Tom Peterson
EDR draft plan

19. Work package table - part 2
13 Sep Tom Peterson
EDR draft plan

20. Work package table - part 3
13 Sep Tom Peterson
EDR draft plan

21. Conclusions
Work list is certainly not comprehensive; other topics will no doubt be added.
A total of ~10 man-years of engineering and design labor are identified for EDR cryogenics.
The RDR cryogenic system effort had less than 1 FTE of effort.
Would like an FTE in each region through the EDR phase.
If cryogenic experts around the world all continue to have other, local commitments in addition to ILC, this work will require part-time (but significant fraction) efforts from at least 2-3 people in each region.
13 Sep Tom Peterson
EDR draft plan