SCU Segmented Cryostat Concept M. Leitner, S. Prestemon , D. Arbelaez , S. Myers

SCU Segmented Cryostat ConceptM. Leitner, S. Prestemon, D. Arbelaez, S. Myers

September 2nd, 2014

M. Leitner - SCU Meeting - September 2, 2014 2

Segmented SCU Layout Allows Servicing Individual Undulator Segments While Keeping Whole String ColdOne Cryostat Contains 2 Nominal Two-Meter Undulator Segments

Cryogenic Valves andRemovable Low-Loss Bayonets

Hard X-Ray LineSoft X-Ray Line

CryogenicDistribution

Mass-ProducedCryostats

ReliefCircuits

Quadrupole Concept• Conceptual design of a compact quadropole

– Directly attached to the undulator cold mass– Integrated quadrupole strength of 4 T (LCLS-II quad strength) can be obtained– Independently powered coils can be used for x-field correction

End correctorQuadrupole Magnet

from July 8th SCU meeting [D. Arbelaez, et.al.]

External Fiducialization• Pulsed wire can be placed in the center of the undulator or

quadrupoles• Wire detectors can be fiducialized and used to find the two

ends of the wire• Wire position can be related to external fiducials on the

cryostat based on the cold magnetic measurements

Pulsed Wire Fiducialization

Wire inside vacuum chamber

Fiducialized Detector can be used to find wire location

A second detector will be added to find both ends of the wire


Vertical Alignment with Alignment Quadrupoles

• Use reference quadrupoles at each end of the 3 m structure– Tuning and calibration is based on the line between the magnetic center

of the two quadrupoles– Fiducialization can be performed with a wire measurement and

referenced to fiducials on the outside of the cryostat– Allows for beam based alignment by moving the cryostat to find the

center of the quads with the electron beam

Small Alignment Quadrupole

Full Length Quadrupole


Lb

Conceptual Phase Shifter Layout• Compact phase shifter uses one end corrector from each

undulator and one extra dipole magnet in between• Distance between the undulator cores ~ 13 cm for this layout

(could be reduced if alignment quadrupoles are not necessary)• Joint sections for Nb3Sn undulator are 4 cm long for each core

End corrector End correctorPhase shifter dipole

Alignment Verification Quadrupoles / Bx correction Second Field Integral

with phase shifter

Lb

+k +k

-2k



Example Segmented SCU LayoutUndulator Packing Factor Including Diagnostics Sections = 85%


Two Superconducting Undulator Lines Would Fit Into Existing SLAC Tunnel

Soft X-Ray Line

Hard X-Ray Line


Components Of A Single Undulator Line

Cryogenic Valves andRemovable Low-Loss Bayonets

Existing SLAC Support Posts(For Size Comparison)

CryogenicDistribution

Mass-ProducedCryostats

ReliefCircuits

Current Leads

Vacuum ValvesVacuum PumpsVacuum Gauges

Bellows ForUndulator Removal(Between Cryostats)


Single Undulator Segment ComponentsCryogenic Valves And Removable Bayonets

Allow Removal Of Undulator Segments While Keeping Undulator Line Cold

CryogenicDistribution(High Pressure LHe And GHe Minimize Pipe Diameters)

Cryostat Vacuum Vessel

Relief Circuits Are PipedInto A Distribution Return SystemFor Operation And Cool Down

Current Leads

Vacuum Valve

Vacuum ValveVacuum Pump

Vacuum GaugesBellows

Phase Shifter, Focusing Quad, And BPM Are Inside The Cryostat

Cryogenic Control Valves Are Located In Cryostat To Ease OperationUndulator Alignment Based On

Pulsed Wire Fiducialization


Aluminum Thermal Shield Is Actively Cooled On Bottom And Conduction Cooled On The Sides

(Potential Location For Magnetic Shields)

Single Undulator Segment Components


4.5 K COLDMASS

Single Undulator Segment Components

Undulator Coil Structure Bottom Thermal Shield PlateCryogenic Support Posts

LHe Header

RT Strongback

~50 K SHIELD AND BEAMIPE


Single Undulator Segment ComponentsBottom-Up Design Is Optimized For Mass-Production - Fiberglass Posts Allow Consistent Alignment

Cryogenic Support Posts

Actual Fiberglass Support Post

4.5 K

~50 K

300 K

Room Temperature Strongback

Fixed PostFixed Post

Moveable Posts

Moveable Posts

Linear Precision Bearings


Single Undulator Segment ComponentsPre-Assembled Coldmass Drops Into Vacuum Vessel – Ease Of Assembly, No Major Tooling Required

Connect Beamline Vacuum

Weld Final Cryogenic Connections


Thermal Transitions, Focusing Quadrupole And Cold BPM

Valve

Thermal Transition(Bellows)

Vacuum Chamber

50 K Intercept

Focusing Quad

ColdBPM

Thermal Transition(Bellows)

Valve,Pumping, Gauges, Beamline Bellows

50 K InterceptVacuum ChamberAlignment System


SCU Assembly StepsPrepare Room Temperature Strongback


SCU Assembly StepsPlace Linear Bearings And Pre-Assembled Fiberglass Posts


SCU Assembly StepsPlace Bottom MLI Blankets (Not Shown) And Thermal Shield Bottom Plate With Pre-Welded Cooling Lines


SCU Assembly StepsPlace First, Pre-Fiducialized Undulator Coil Section


SCU Assembly StepsPlace Second, Pre-Fiducialized Undulator Coil Section

Rigid Connection

Small QuadDipole

Phase Shifter

DipoleLarge Quad


SCU Assembly StepsConnect And Align Vacuum Chamber, Connect Thermal Transitions

Vacuum Chamber Alignment Mounts

Vacuum Chamber Alignment Mounts

Thermal Transition

Thermal TransitionAnd BPM


SCU Assembly StepsWeld Pre-Fabricated LHe Header, Wrap With Multi-Layer Insulation


SCU Assembly StepsAssemble Thermal Shield And Wrap With Multi-Layer Insulation


SCU Assembly StepsDrop Coldmass Into Vacuum Vessel, Connect Beamline Vacuum

Beamline VacuumBolted Flange Connection

Beamline VacuumBolted Flange Connection


SCU Assembly StepsConnect Pre-Routed Current Lead Assemblies

Current Feedthroughs


SCU Assembly StepsWeld Final Cryogenic Connections To Bayonet Box

Bayonet Box(Part Of Vacuum Chamber)


SCU Assembly StepsClose Cryostat Vacuum Vessel


SCU Assembly StepsConnect Cryogenic Relief Circuits

Relief ValvesDifferent Circuits For Cooldown and Regular Operation


SCU Assembly StepsConnect Beamline Valves, Vacuum Pumps And Gauges

Interstitial Vacuum Equipment

Interstitial Vacuum Equipment


SCU Assembly StepsPrepare For Checkout And Lifting


SCU Assembly StepsAssemble To Support System


SCU Assembly StepsInstallation And Alignment In Tunnel


SCU Assembly StepsConnection To Cryogenic Distribution Line

Cryogenic Relief Connections

CryogenicsExpansion Joint Box

Shut-Off Valves

Low-Loss Bayonets

Control Valves(Hidden, On Cryostat Side)


Summary

• Segmented cryostat design takes full advantage of LBNL alignment strategy utilizing end quadrupoles

• Cryostat with low-loss fiberglass posts employing bottom-up assembly is optimized for mass-production and superior alignment

• A segmented, superconducting undulator design allows servicing of individual undulator segments while keeping rest of undulator strings cold

• Minimized thermal cycling assures consistent undulator alignment

• High-quality bayonets and cryogenic valves assure low-loss cryogenic operation


Next Steps

• Develop cryostat heat load budget

• Develop cryogenic flow diagram

• Based on flow diagram optimize cryogenic distribution system

SCU Segmented Cryostat Concept M. Leitner, S. Prestemon , D. Arbelaez , S. Myers

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