Cavity and Cryomodule R&D Shekhar Mishra Fermilab 3/21/06

WBS for Cavity and Cryomodule

ILC Main Linac Cavity and Cryomodule R&D Goals ILC R&D is focused on addressing the key ILC design and technical, cost reduction and US industrial involvement in ILC. The main thrust of the ILC Cavity and Cryomodule Technology R&D is to establish US technical capabilities in the Superconducting Radio Frequency Cavity and Cryomodule technology. The main goals are Cavity technology development in the US to routinely achieve > 35 MV/m and Q ~0.5-1e10, ILC Cryomodule design, fabrication (cost reduction) Fully tested basic building blocks of the Main Linac (Evaluate the reliabilities issues). LLRF, Instrumentation and Controls development Development of U.S. industrial capability for the fabrication of high performance SCRF cavities and associated infrastructures.

ILC Cavity R&D Baseline Configuration Design (BCD) Cavity (TESLA shape) and Issues Fabrication and processing of Cavities in US 9-cell cavities vertical acceptance tests Fully equipped cavity horizontal tests Reproducibility: Process control studies Progress on Alternate Configuration Design (ACD) Items New shapes 1-cell cavities, multi-cells Large grain (Single grain) Basic R&D on Nb RF superconductivity

Cavity: R&D Material R&D: Fine, Large, Single Crystal Fabrication A number of minor modifications and improvements could be implemented without impact to the basic cavity design. Cavity Preparation Buffer Chemical Processing Cavity Processing (strong R&D needed) Electro-polishing (EP) System High Pressure Rinsing (HPR) Assembly Procedure

Cavity Fabrication Cavity Fabrication Industrial production of the cavity (ACCEL, AES) 8 TESLA Design Cavities ordered 10 ILC Baseline Design Cavities in FY06 Cavity fabrication at Jlab 2 ILC Baseline design and Type-IV 2 LL Cavity Material R&D (Fine Grain, Large Grain, Single Crystal) Cavity fabrication at Cornell Re-Entrant Cavities (70 mm) Re-Entrant Cavities (60 mm) Several single cell for R&D Cavity fabrication at KEK (US-Japan) 4 Cavities of either TESLA or LL design WBS 3.9.2 3.9.2.1 3.9.5 3.9.9 3.9.10

Cavities from ACCEL 3.9.2 Delivery date September 09, 2005, fabrication time 6 month

Cavity Measurements RF measurement of the ACCEL Cavities at Fermilab. 3.9.2 RF measurement of the ACCEL Cavities at Fermilab.

1.3 GHz Cavity Fabrication Status 3.9.2 Advanced Energy Systems (AES) AES is fabricating four 9-cell Tesla cavities with asymmetric end tubes from polycrystalline niobium supplied by Fermilab. Eight proof-of-principle half cells (two long end, two short end and four mid) have been hydroformed and shipped to Fermilab for frequency measurements and CMM profiles of the interior RF surfaces. AES reported that the material exhibited “significant anisotropic behavior” while forming. The CMM data from Inspection confirmed that the half cells are quite elliptical. The TD SRF Materials Group has analyzed the niobium blanks and discussed the issue with Wah Chang. The matter is still under investigation. Two niobium blanks from the same material shipment were heat treated at Fermilab in an attempt to improve the formability of the material. They have been shipped to AES to be hydro-formed into half cells. Progress at AES on the end groups is on schedule.

ILC Cavity R&D at Jlab Milestones [Work package 3.9.5] Several single cell and at least one multi-cell cavity of the LL design made from large grain/single crystal niobium An improved buffered chemical polishing system for producing very smooth rf surfaces on large grain /single crystal material A test cavity for superconducting joint investigation Results from these investigations with the goal to incorporate the most promising design in a super-structure

Progress: Large grain niobium R&D 3.9.5 Several single cell cavities of different shape (TESLA, LL,CEBAF HG) have been fabricated from different material vendors (CBMM ingot”D”, W.C. Heraeus, Ningxia) and have been tested before and after “in situ” baking and post –purification heat treatment. An ILC_LL 7-cell cavity has been manufactured without stiffening rings. Difficulties in tuning were encountered and stiffening rings are presently added to the structure. A 7-cell CEBAF HG cavity was fabricated from CBMM ingot “B” and is being evaluated Large grain niobium for 5 additional single cell cavities has been ordered from W. C. Heraeus (statistics!!) A quotation for large grain niobium from Ningxia for 5 additional single cell cavities has been requested (statistics!)

Results: Large grain niobium evaluation 3.9.5 All cavities were treated by BCP only with subsequent high pressure rinsing All Single cell cavities from different materials were limited by “quench” in the absence of field emission at 30 MV/m < Eacc < 36 MV/m ( “quench fields 128 mT < Hpeak < 160 mT) All cavities showed “Q-slopes”, which disappeared after “in situ” baking at 120C for 12 hrs Best performance achieved with material from Ningxia (China) on Jlab cavity shape In an initial test ( field profile not flat) with the 7-cell ILC_LL cavity a gradient of Eacc~ 20 MV/m was measured limited by availability of rf power ( only ~ 25 W) and FE loading. Retesting planned after stiffening rings are welded.

Results: Large grain niobium R&D 3.9.5

ILC Cavity Fabrication (Jlab MOU with FNAL) 3.9.2.1 Fabricate and test a prototype TESLA cavity from polycrystalline RRR niobium Fabricate 2 modified TESLA/ILC 9-cell cavities from large grain niobium with shorter beam pipe and possibly modified HOM couplers (tests on a single cell with a modified HOM coupler showed improved thermal stability ) Status Half cells for all 3 cavities have been deep drawn All inner cells have been machined for dumbbell welding Flanges (beam line, HOM, FPC, field probe) are in fabrication HOM cans and coupling loops are in fabrication Other parts (He vessel end dish..) are also in fabrication Bottleneck: electron beam welder availability A MOU is in preparation to have JLab fabricate two additional 9-cell Tesla cavities with asymmetric end tubes from polycrystalline niobium. Material is to be supplied by Fermilab.

50 MV/m in Single Cells ! Lower Surface Magnetic Field & Lower Losses 3.9.9 New Shapes Breakthrough 3.9.10 50 MV/m in Single Cells ! Lower Surface Magnetic Field & Lower Losses Re-entrant CornellKEK Need Multi-cells Next Low Loss Jlab KEK Tesla Shape

Proof of Principle Results: Eacc = 47 - 52 MV/m 3.9.9 Proof of Principle Results: Eacc = 47 - 52 MV/m 3.9.10 Fabricated at Cornell /Ichiro

Check Reproducibility of HPR 3.9.9 Check Reproducibility of HPR 3.9.10 Cornell Re-entrant Cavity Work done in Collaboration with KEK

New Reentrant Cavity Shape 3.9.9 New Reentrant Cavity Shape 3.9.10 60 mm aperture similar to LL shape -> 16% lower Hpk/Eacc Work done in Collaboration with KEK

Cornell 9-cell Re-entrant Cavity 3.9.9 Cornell 9-cell Re-entrant Cavity 3.9.10 Production at AES, NY

ILC Cavity Processing 3.9.3 We are using infrastructures at the collaborating laboratories to develop the processing capabilities and parameters in USA to achieve 25 MV/m with BCP and 35 MV/m with EP. These facilities are also being used to train people. Cornell: BCP and HPR Vertical EP Jlab EP Fermilab and ANL (New Facility) BCP 3.9.3.1 3.9.3.2

First ACCEL ILC Cavity at Cornell 3.9.3.1 BCP Complete HPR Complete

Vertical Test of ACCEL Cavity 3.9.3.1 Cornell is ready to vertical test the 9-cell ACCEL cavity. A small leak has developed in dower. It is being fixed. Fermilab is sending engineering staff and technician to participate in the BCP and vertical testing at Cornell.

Goals for EP Development at Jlab 3.9.3.2 Determine the RF performance spread from standard process procedures on a spare 9 cell cavity (S35) without chemistry Document baseline procedures Aim is procedures that are reproducible with little or no field emission Perform HPR, assembly and testing with S35 cavity to analyze procedure effectiveness Record process data in Jlab database Analyze and document results

Goals for EP Development ... 3.9.3.2 Establish EP processing for ILC 9-cell cavities at Jlab Commissioning EP cabinet with Spare DESY 9-cell cavity Investigate standard process procedures to gain a better understanding of current issues (Sulfur precipitation, HF loss during use) Identify and develop relevant process metrics and QA steps Establish and document procedures Aim is uniform reproducible etching with clean surfaces after rinsing Process, test, qualify and prep cavities for FNAL string assembly

Electropolish Development for ILC 3.9.3.2 Jlab EP Cabinet HPR and Assembly Alignment Cage

EP System Alignment Frame and Cathode with ILC Cavity 3.9.3.2

Goals for EP Development ... 3.9.3.2 Supporting efforts for EP development Perform various bench top experiments aimed at answering questions and building knowledge Perform EP processing and testing on 1.3 GHz single cell cavities to support process development and ILC R&D goals Q-disease Surface contamination and removal Effective rinsing Develop better understanding of chemistry EP affects on niobium surface chemistry Develop Thermal model of chemistry

Supporting Efforts – small sample EP tests 3.9.3.2

Status on EP Program at JLab 3.9.3.2 Determine RF performance spread All tooling completed and process steps checked with nine cell cavity RF Test-stand under vacuum and cavity being prepared for assembly Procedures identified Next step: start assembly and testing to develop and document procedures (2-weeks) Establish EP processing at JLab System tested with 9-cell (water) EP cabinet hardware and software ready Next step- perform first EP run (2-3 weeks) Supporting Efforts Bench top experiments underway Started setting up for single cell processing

ILC Surface Processing Facility Development at ANL/FNAL 3.9.3 The Joint ANL/FNAL Superconducting Surface Processing Facility (SCSPF), located at Argonne National Laboratory, is a major chemical processing facility capable of electropolishing and buffered chemical polishing a large quantity and variety of superconducting structures. This Facility is made up of two separate chemical processing rooms, with one room to be operated by FNAL and the other ANL. Adjoining the processing rooms is a shared ante-room that is class-1000 cleanroom certified. Opposing the processing room and adjoining the ante-room are two class-100 cleanrooms, with FNAL operating one room and the other ANL.

ILC Surface Processing Facility Development at ANL/FNAL… 3.9.3 The Facility shares common services and infrastructure. A large ultra-pure water plant and distribution system that feeds all clean rooms and processing rooms. A common 3000 cfm exhaust fume scrubber that ventilates the processing rooms. A large mezzanine used to site electropolishing power supplies and water chillers. The mezzanine also provides space for rack-type storage. Commissioning the SCSPF requires three primary steps. Receive beneficial occupancy following the two major construction efforts (processing room construction and the cleanroom/mezzanine construction). This was finished in Jan 06. We are commissioning the system with water. Receive approval from a safety committee reviewing the general Facility operation and the ANL chemistry room operation. This is 3 months behind schedule. Receive operation approval of the FNAL BCP system. After these three steps are completed, operational readiness clearance (ORC) will be granted by the ANL Physics Division. Once ORC is granted, FNAL will begin buffered chemical polishing 3.9 GHz 3rd Harmonic cavities as part of the FNAL/DESY 3rd Harmonic cryomodule program.

ILC EP Facility Plans 3.9.3 An ILC Electro-polishing facility design is being discussed by the ILC Collaboration. We have held meetings at Snowmass, Fermilab, Frascati to discuss the design issues. An initial plans has been developed for an EP facility to be build at ANL/Fermilab Surface Processing Facility at ANL. This facility should include the knowledge of EP from the ILC Collaboration. This proposal is being discussed by the Technical Board. An EP Facility will be build in FY06-07 at ANL/FNAL Processing Facility.

Cryomodule Design and Fabrication 3.9.4 FNAL In FY05 Fermilab started on converting the DESY/INFN design of the ILC cryomodule (Type-III+). We have formed an ILC Cryomodule working group that is working towards a design of an ILC cryomodule. This design will evolve. The Goal is to design an improved ILC cryomodule (Type-IV) and build one at Fermilab by FY08. High Power testing of the cavities and the fabrication of 1st ILC cryomodule with new design 2008.

Cryomodule Fabrication Plans for an RF Unit test at ILCTA FNAL Cryomodule 3 Cryomodule 1 Cryomodule 2 ILC Length Cavity Purchased By Fermilab (AES/Jlab) Standard Length Cavity Purchased By Fermilab Dressed Cavity Provided By DESY BCP & VT In USA BCP & VT At Cornell Cold Mass By DESY/INFN EP & VT In USA EP & VT At Jlab Dressed New Design and HT At Fermilab Dressed and HT At Fermilab Cryomodule Assembled at Fermilab Cold Mass From Zanon By Fermilab Cold Mass Type-IV From US Company By Fermilab March 07 Mid 08 Dec 07

1st US Assembled Cryomodule: Fermilab, DESY and INFN FNAL DESY will send Fermilab eight 9-Cell 1.3 GHz dressed and horizontally tested cavities. The present schedule for the delivery of these 8 cavities is around end of 2006. DESY will attempt to advance this schedule. DESY and INFN have ordered two cold masses for Type-III cryomodules from Zanon. DESY will send one of these cold masses to Fermilab for the 1st cryomodule assembly at Fermilab. It is expected that this cold mass will be available about Sept.-Oct. 2006. Some parts for the 1.3 GHz cryomodule are not provided by Zanon but rather by INFN. It was agreed that INFN will send these associated parts to Fermilab and provide parts needed for a 3rd cold mass.  INFN-DESY will also send the assembly documentation to Fermilab. Fermilab will work to achieve the earliest possible delivery date for the DESY four cavity 3.9 GHz cryomodule. This is currently expected to be early in  2007.

ILC Cryomodule Design Considerations 3.9.4 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. Possible superconducting joint. Overall improved packing factor. Minimize direct heat load to cavity through MC. Simplify the assembly procedure. MLI redesign to reduce hands-on labor costs. More robust design to survive shipping. Reliability of tuner motors in cold operation. Etc. (we’ve heard many suggestions)

Conceptual Model Development 3.9.4

Change in Cryogenic Distribution 3.9.4 Increase diameter beyond X-FEL Review 2-phase pipe size and effect of slope

T4CM (not the final ILC design) 3.9.4 Minor changes to address major concerns. Magnet alignment and vibration issues. Cryomodule with and without magnet package Define BPM, Steering, and Quad parameters Possible option for separate magnet cryo vessel Reduced cavity length (which tuner design?) Reduced cavity spacing (new interconnect) Need for functional Fast-Tuner Current Cryo3

ILC Cavity Spacing, Dimensions with Blade Tuner 3.9.4 Blade Tuner

Packing factor 3.9.4 Note: Does not include other components installed within the accelerator nor a possible increased magnet package length. Active length = 1036.2 mm x 24 cavities = 24868.6 mm Packing Factor = 24868.6 / 35068 = 0.71 35068mm 1036.2 mm

Applying Component Mode Synthesis (CMS) 3.9.4 Component Mode Synthesis reduces the system matrices to a smaller set of interface degrees of freedom (dof) between substructures (components) and therefore reducing solution runtime 8 Cavities Column Supports Quad/BPM 300 mm Helium Return Pipe Vacuum Vessel Dynamic simulation of the entire Type IV Cryomodule is performed using ANSYS software and applying the CMS method

Cryomodule Design Tools 3.9.4 Excel driven 3-D I-DEAS Model

Free 3-D Visualization with UGS JT2GO 3.9.4

Critical Cryomodule Design Issues 3.9.4 Quad/corrector/BPM package is a major unknown right now and goes into the heart of the module. Tuner details, slow and fast, but especially fast tuner Cavity-to-cavity interconnect design. Vibrational analysis, which will be compared to measurements for verification of the model for future design work. Magnetic shield re-design. Development of module and module component tests. Verification of cavity positional stability with thermal cycles. Design of test instrumentation for the module. Robustness for shipping, analysis of shipping restraints and loads, shipping specifications. Active quad movers(?) A complication

Cavity Dressing and Cryomodule Assembly Facility (CAF) at MP9 FNAL The CAF Facility will be used To dress the cavities for Horizontal Testing Cavity string assembly for the Cryomodule FNAL ILC Infrastructure Funds

CAF Current Status Major Clean Room installation finished FNAL Major Clean Room installation finished Modular inner walls will start by the middle of this 3rd week of March 06 Cavity String Assembly Rail was assembled and aligned during the week of March 6th, 06 Cold Mass Assembly and Vacuum Vessel Assembly Fixtures received at Fermilab. It will be installed in May 06 after the clean rooms construction is completed. Vacuum Vessel Assembly Fixture: Received, currently stored at CDF Cavity String Assembly Fixtures are being currently designed /Americanized from DESY drawings. We plan to install them in May 06 when the clean rooms are operational. CAF Clean Rooms operational: May 06

Cavity and Cryomodule Assembly Fixtures FNAL

Cavity and Cryomodule Assembly Fixtures FNAL

Clean Room at MP9 FNAL

Pictures taken on March 20, 2006 Clean Room at MP9 FNAL Pictures taken on March 20, 2006

1st Cryomodule Assembly Plans FNAL Cavity String Assembly Procedures & Fixtures Learning at DESY (February 20 –March 3, 06) A draft traveler was written during this visit. It is currently being reviewed by Axel Matheisen for comments. Tooling & Fixturing used to assemble the cavity string were identified. Drawing were brought back to Fermilab. Assembly sketches, movies and took a lot of pictures and notes. Cryomodule #6 Assembly Procedures Learning at DESY (May-June 06) CAF Infrastructure ready & operational: May-June 06 Assemble 1st Cryomodule (4 months): Start date depends when we receive the kit from DESY

Cost Study for Cavity and Cryomodule 4.4 Cost Study for Cavity and Cryomodule 4.5 4.10.1 Cost Estimate Sources 1) TESLA cost study and U.S. options cost study 2) XFEL cost information that can be shared 3) LCFOA has proposed a cost study (under evaluation) Tasked to cost a complete RF unit, then Plan for fabrication of 250 RF units, then ( X 3 = 500GeV ILC) Plan for fabrication of 750 RF units Expected duration of study 4-6 months Fermilab is developing a Statement of work to develop a US cost estimate using industrial partners from LCFOA. Fermilab in collaboration with SLAC and Jlab will also undertake an independent cost study for an RF Unit.

Nb Nano chemistry with 3DAP 3.9.7 K. Yoon, D. Seidman NU Variations in oxide layer thickness betw. 0-20 nm (probably because of variations in tip manufacturing process), 10% O in first 20 nm of “bulk”

Magnetic investigation of Nb 3.9.6 P. Lee, A. Gurevich, A. Polyanskii, A. Squitieri, D. Larbalestier – ASC/UW New microscopy, incl. TEM; New MO in parallel and perpendicular field in bi and tri-crystal samples – combined with magnetization; Non uniformity in flux penetration – difference in pinning? Vortices can easily travel in GBs when they are parallel to the boundary!

Plasma Etching for SRF Cavities 3.9.8 L. Vušković, S. Popović, M. Rašković, L. Phillips, AM. Valente S. Radovanov, L. Godet, This work explores plasma etching as an alternative SRF cavity Nb surface preparation process which would be superior in terms of cost, performances, and safety, to the wet chemical process currently in use. Plasma additionally offers a unique opportunity to process cavities wout subsequent exposure to atmosphere allowing the preparation of an oxide free state. Initial results (flat bulk Nb samples) chemically polished plasma-etched The black line represents a distance of 10 mm.

FY07 Plans: Cavities & Cryomodule The FY07 plan of the ART will be the continuation of the plan we are undertaking at present. Cavity Fabrication ILC Design New Shape (LL and RE) Fine, Large and Single Crystal R&D on material, fabrication etc 3.9 GHz deflecting cavity design and fabrication Cavity Processing BCP at Cornell EP at Jlab BCP and EP at FNAL/ANL R&D on surface treatment Design and Fabrication of an Electro polishing Facility FNAL/ANL Cryomodule Design and Fabrication Type III+ Fabrication Type IV Desing US Industrial involvement in Cavity and Cryomodule Design and Fabrication Enhanced university participation in ILC R&D

Summary US-ILC Main Linac: Cavity and Cryomodule R&D program is established to address the key technology issues. Cavity Gradient ILC Cryomodule design and fabrication R&D is focused on the Baseline design of the cavity and cryomodule. We are also working on alternate design for Cavity and material. We are upgrading existing infrastructure at US laboratories to cost effectively advance the R&D program on a ambitious schedule. We are developing infrastructure at Fermilab for cavity processing and testing and fabrication of cryomodule. We are leading the ILC effort in the ILC Cryomodule design. We are working with US industry in fabrication. We are also working with US industry in ILC Cost Study.