ILC Main Linac Design Status

ILC Main Linac Design Status
-MPY- Bangalore General layout Cryogenic layout Module layout Segmentation Tunnel sizes

ILC Lutz Lilje DESY -MPY-

Main Linac: Towards an Reference Design Report (RDR)
Since Frascati and the appproval of the BCD several things happened in the main linac layout to get the RDR done Must-link by C. Adolphsen: Main Linac RDR Wiki: Cryomodule & Cryogenics Groups are defining cryomodule length and cryoplant layout First pass generated at Jan CERN meeting, has since been updated RF Group to work with Civil Group to define the size/layout of support tunnel Some detailed analysis is under way – diameter is going down again… Alternate cross section? Magnet group with specifying the linac quad and corrector package Reviewing issues Seperated corrector design Lutz Lilje DESY -MPY-

RDR Linac Definition (Cont)
LET Group has been working resolving beam dynamics related issues at Feb 8-11 CERN meeting Work with Instrumentation Group to define diagnostics List of instruments and issues generated at Jan 17 FNAL meeting Discussing implications of MPS and availability requirements with Himel et al. Lutz Lilje DESY -MPY-

Cryogenics Must-read by T. Peterson: Heat load revisited
Cryogenics is not only the main linac…. Heat load revisited More conservative estimates of static heat leak than in TDR based on TTF measurements (where all module have a warm-cold transition) Higher dynamic load due to higher gradient Keeping the plant sizes below 25 kW total equivalent 4.5 K capacity leads to maximum plant spacing of ~2.3 km Cryo-segmentation every 560 m – warm or cold? Use segments to isolate insulating vacuum sections Not necessarily a warm-cold transition Introduction of a cold-warm transition could be used for shortening regions that are warmed up for repair work Faster cooldown Could be used for Instrumentation and MPS From the beam dynamics standpoint not absolutely needed Main disadvantages are cost contamination issues e.g. need to add fast valves at very short distance from cavity surface increased vulnerability to insulating and beam pipe vacuum failures MPS issue Lutz Lilje DESY -MPY-

Adiabatic Matching Device e+ pre-accelerator ~5GeV
BCD Description -500 GeV Layout- (Slide lifted from “Positron Source Configuration” by KURIKI Masao and John Sheppard, January Cryogenic device description in red added by Tom Peterson) Primary e- source e- DR Target e- Dump Photon Beam Dump e+ Auxiliary e- Source Photon Collimators Adiabatic Matching Device e+ pre-accelerator ~5GeV 150 GeV 100 GeV Helical Undulator In By-Pass Line Photon Target 250 GeV Positron Linac IP Beam Delivery System Up to about 500 MeV via special SRF cavity/magnet modules totaling about 25 m x 20 MV/m Then up to 5 GeV with 21 standard SRF modules 650 MHz SRF, about cavities plus 200 m of CESR-c type SC wigglers, all 3 damping rings SC magnets and crab cavities (no quatities yet) Standard modules (starting at 5 GeV) Standard modules RTML includes SC solenoids plus 61 SRF modules RTML includes SC solenoids plus 61 SRF modules 200 m of SC undulators Up to about 500 MeV via special SRF cavity/magnet modules totaling about 25 m x 20 MV/m Then up to 5 GeV with 21 standard SRF modules

Lengths and Packing Factor (from spreadsheet originated by Chris Adolphsen and revised by Tom Peterson) Lutz Lilje DESY -MPY-

Cryoplant Layout in e- Linac
Tom Peterson For ILC 500, total of ten 25 4 K plants requiring 52 MW of AC power. Lutz Lilje DESY -MPY-

Towards an ILC Cryomodule (4th generation)
International Effort between the three regions Design changes are towards nailing down slot length of components Costing should be straight-forward from TTF (and possibly XFEL) experience Slides from Talks by Don Mitchell, Tom Peterson and Others at Jan CERN Meeting Lutz Lilje DESY -MPY-

ILC Cryomodule Design Considerations
Move quad package to middle of cryomodule to achieve better support and alignment. Shorten cavity-to-cavity interconnect and simplify for ease of fabrication and cost reduction. Overall improved packing factor. Simplify the assembly procedure. MLI redesign to reduce hands-on labor costs. More robust design for shipping. Reliability of tuner motors in cold operation. Revaluate cryogenic pipe sizes partially done for the XFEL already Lutz Lilje DESY -MPY-

Increase diameter beyond X-FEL Review 2-phase pipe Size and
effect of slope Lutz Lilje DESY -MPY-

E.g.: Module pipe sizes increase (T. Peterson – CERN Meeting)
Lutz Lilje DESY -MPY-

Inside an ILC cryomodule
Cavity package Cavity High power RF coupler Tuner Magnet package …(time won‘t permit) Lutz Lilje DESY -MPY-

Cavity with Frequency Tuner
No BCD Tuner, some designs are very close to requirement Generic issue to all designs: motor and piezo reliability Deemed to be feasible, but some R&D needed E.g Bladetuner Issue with cavity’s magnetic shielding Could be also another tuner that does not need inter-cavity space Just watch out for the cryo-lines… Lutz Lilje DESY -MPY-

Existing DESY Interconnect Design
344 Interconnect: Tesla TDR: 283mm Currently 344mm Flange/Bellows Design Specs: • Bolted flange (12 bolts/flange) • Convoluted SS Bellows (10 waves, 54mm free length, ±25mm) -Length of bellows dictated by bolt length, old elastic parameters • Bellows elastic requirements: ±4mm (~1mm thermal + ~3mm tuning) • Aluminum Alloy 5052-H32 Diamond Hex Seal • 7 Ton clamping force, 35 N-m torque/bolt • Mechanical analysis Desy, INFN (Cornelius Martens, Roberto Paulon) Lutz Lilje DESY -MPY-

Proposed Cavity Layout
Flange-to-Flange Cavity Spacing = 1319 mm Lutz Lilje DESY -MPY-

BCD assumes use of XFEL Main Coupler
Graphics from Terry Garvey Lutz Lilje DESY -MPY-

BPM / Quad / Corrector Package
887 77 66 666 78 TDR QUAD and Correctors BPM ILC Preliminary Lutz Lilje DESY -MPY-

Shell Type ILC Dipole Corrector
Vladimir Kashikhin, Fermilab Magnet Parameters Integrated field T-m Center field T Winding ampere-turns 18kA Current A Superconductor NbTi SC diameter mm Outer diameter mm Magnet length ~ 200 mm Flux density and flux lines at max current in both dipole coils Lutz Lilje DESY -MPY-

ACD: Seperate Quad Cryo-section
1530 mm Lutz Lilje DESY -MPY-

ACD: Pros / Cons for a Separate Quad/BPM Cryostat
Allows for a common cryomodule design Flexibility Accommodation of different magnet packages, upgrades, etc. Independent adjustments to the quad/BPM position Handling Allows independent cold testing and measurement of the magnet package Schedule, resources, and fabrication facilities not tied to mainstream cryomodule production Precludes the need for independent quad movers inside the cryomodule (ACD) Cons Design issues Interconnect forces due to bellows could affect quad alignment Vibrations due to interconnect might need crosscheck Cost One extra interconnect required at each quad location Potentially requires more longitudinal space required in the lattice Lutz Lilje DESY -MPY-

Region between Cryomodules
Assume 850 mm Flange-to-Flange length (TTF) 850 mm between flanges, 815 mm ‘free’ space Length partially defined by requirements of cryo tube welding and beam tube assembly (local cleanroom) Includes 270 mm Broadband HOM absorber XFEL design could be used (but likely over-designed) Manual Gate Valves Pump-out Ports (integrated in absorber) Needs to be better defined Lutz Lilje DESY -MPY-

Some critical design issues
ILC specific issues Quad/corrector/BPM package needs more work Implication for the next generation cryomodule (type 4) that is being developed by FNAL/INFN Cavity-to-cavity interconnect design. Magnetic shield re-design. Issues for both ILC and XFEL Tuner reliability, slow and fast. Vibrational analysis, which will be compared to measurements for verification of the model for future design work. Development of module and module component tests. Design of test instrumentation for the module. Verification of cavity positional stability with thermal cycles. Robustness for shipping, analysis of shipping restraints and loads, shipping specifications. Lutz Lilje DESY -MPY-

RF System: RF Unit Solid-state switched modulator with 1:12 step-up transformer and bouncer droop compensator 10 MW 1.3 GHz multi-beam klystron Currently do not have a robust tube design Assume horizontal mounting (could be vertical depending on tunnel height) – no such tube built yet. Waveguide distribution system with three way split to feed 24 cavities – each feed includes isolator and phase shifter / Qext controller. 680 RF units for cold cavities in ILC 500 Modulator, Klystron and three-way splitter in support tunnel, rest in accelerator tunnel. Lutz Lilje DESY -MPY-

Examples of RF three-way split
Leibfritz, FNAL Fukuda, KEK Lutz Lilje DESY -MPY-

TTF Waveguide Distribution

Need more compact design (Each Cavity Fed 350 kW, 1
Need more compact design (Each Cavity Fed 350 kW, 1.5 msec Pulses at 5 Hz) Two of ~ 16,000 Feeds Lutz Lilje DESY -MPY-

RF System Design Work so far on
Understanding interface to LLRF system, which is in the Control’s group domain Compiling list of actuators and signals to be monitored in the linac Working with civil group on rf system layout in the support tunnel Distribution system needs more design work to lower cost Lutz Lilje DESY -MPY-

Example: RF System layout

Example: Implementation using ATCA standard

Civil Facilities: Tunnel Layout
Distance between tunnels based on construction needs, radiation protection is under investigation Water influx Tunnel Sizes Component lists with sizes generated The 4 m diameter support tunnel and 3.2 m diameter beam tunnel in BCD are likely too small Would help to make components narrower – work in progress A lot of work underway on other details Water and power distribution Air supply and temperature regulation Penetration size and access (e.g. crossover) Transportation and stay clear Personnel access and egress Fire Safety Lutz Lilje DESY -MPY-

Tunnel layout: Component Lists

Example: 4.5 m Linac and 5 m Service tunnel

Service tunnel sizes under discussion: 4.5m, 5m and 5.5m

Installation Systems Concept Development
Step Installation Phases & Sequencing

Crossovers between the tunnels

Diagnostics: Under discussion
Aim for BPM resolution of 0.3 micron at full charge and 3 micron at reduced charge (10%) when running with keep-alive source. Want to achieve this bunch-by-bunch with bunch spacing down to 185 ns. Accelerator Physics might be satisfied with less ambitious goals for full charge (~1um) Do not implement HOM readout initially, but to bring signals just outside of the cryomodules where they would be terminated. Use beam coupling to HOM ports to monitor relative bunch intensity and bunch phase relative to rf (use for rf phase control) Optional: Include 6-12 m long warm sections after every 48 cryomodules (560 m) Use for beam line and insulating vacuum isolation. Each would contain a laser wire: with 21 wires, have 7 independent measurements of emittance along each linac. Could contain other instrumentation such as beam halo and dark current monitors. Could contain spoilers for short-train beam abort. Could be used for cryo-segmentation as discussed earlier Penalties (as mentioned before): Cost; MPS issues, contamination Within linacs, measure beam energy and energy spread only for the electron beam in the undulator line. Lutz Lilje DESY -MPY-

Summary Many discussions on-going
Interplay between Area systems and Technical systems is being defined and starts to work Very detailed information becoming available Cryogenics Module layout More work needed Tunnel layout has changed and experts are working e.g. on the component level to further reduce the tunnel size Costing details need more work: E.g. How to handle TESLA TDR or XFEL cost estimates? Is there a ‘common sense‘ to do the costing? Baseline design exists Some of the options need more thorough discussion e.g. cryo segmentation Lutz Lilje DESY -MPY-

Thank you… … to the many colleagues who provided me with transperencies! Lutz Lilje DESY -MPY-

ILC Main Linac Design Status

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