SCU Layout Concept - Minimal Segmentation Joel Fuerst (ANL) SCU 3-Lab Review Meeting Dec. 16, 2014.
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Transcript of SCU Layout Concept - Minimal Segmentation Joel Fuerst (ANL) SCU 3-Lab Review Meeting Dec. 16, 2014.
SCU Layout Concept -Minimal Segmentation
Joel Fuerst (ANL)
SCU 3-Lab Review MeetingDec. 16, 2014
SCU 3-Lab Review Meeting, Dec. 16, 2014
Introduction
“Segmentation” refers to the layout strategy for connecting an array of individual cryostats.
The downtime associated with removal of an individual cryostat is highly dependent on the layout.Component reliability and redundancy contribute to the expected frequency of cryostat removal.System cost increases with increased segmentation.
compared to
SCU 3-Lab Review Meeting, Dec. 16, 2014
Minimally segmented layout concept
Individual 5.5-m cryostats are arrayed in some number of continuous multi-cryostat strings.Strings are separated by 1 or 2 room-temperature self-seeding sections.Within a string, cryostat interconnect strategy is similar to the LCLS-II SC linac.The cryogenic distribution system is internal to the cryostats except at a warm bypass or at the cryoplant interface.
SCU 3-Lab Review Meeting, Dec. 16, 2014
Cryostat geometry
The vacuum vessel is standard 16” pipe.Thermal radiation shield is cooled by helium gas at ~50 K.Cold mass is cooled by saturated LHe at 4.3 K.Flanged sub-assemblies contain independent conduction-cooled current leads for each magnetic element.
Cold mass
Thermal shield
Vacuum vessel
Current lead/instrumentationassemblies
Retractable inter-cryostat vacuum bellows
SCU 3-Lab Review Meeting, Dec. 16, 2014
Cold mass geometry
Three 1.5-m SCU magnets plus quads, phase shifters, and bpms (not shown) are aligned to a rigid strongback.SCU magnet cooling channels are fed by a LHe reservoir pipe running the length of the string.Other elements are conductively cooled at 4.3 K.
Heliumpipe Magnet with
Horizontal field
SCU 3-Lab Review Meeting, Dec. 16, 2014
Alignment/subsystem access
Magnetic elements are precision aligned to the strongback. The cold mass assembly is suspended from the vacuum vessel using adjustable low-heat-leak supports. Cryostats can be independently aligned within a string due to flexible interconnect elements.Beam-based alignment is possible via x-y motion control systems located at the cold mass and/or the cryostat supports.Access to current leads, quads, phase shifters, bpms is possible via access ports in the vacuum vessel/thermal shield when the cryostat string is warm and vented.
SCU 3-Lab Review Meeting, Dec. 16, 2014
Refrigeration system
A cryogenic transfer line connects the refrigerator to the SCU string end boxes.Cryogenic bypasses are used at other warm sections.Static heat load of 2 W/m is a reasonable design goal.
UpstreamString 1
DownstreamString
UpstreamString 2
SurfaceTunnel
RefrigeratorColdbox
HeliumCompressors
Gas Storage
TransferLine
Bypass
SCU 3-Lab Review Meeting, Dec. 16, 2014
Refrigerator example
Some system components as well as buildings and utilities are pre-existing at SLAC.
SCU 3-Lab Review Meeting, Dec. 16, 2014
Summary
Factors affecting the choice of layout strategy include component reliability, maintainability, and cost. The minimal segmentation option can be summarized as follows:– Primary Advantage: Lower capital and operating system
costs are possible due to simpler cryostat geometry, the absence of a separate, external distribution system, and smaller refrigeration requirements.
– Primary Disadvantage: Removal of any individual cryostat requires a room-temperature thermal cycle of the entire undulator string.