RFCC Module and RF Cavity Construction MICE Collaboration Meeting 22 October 20, 2008 Derun Li A. DeMello, M. Green, S. Virostek, M. Zisman Lawrence Berkeley National Laboratory

Progress Summary RFCC module engineering design near completion The coupling coil design and fabrication at ICST of HIT (Wang’s talk) The MICE cavity design is heavily based on the successful MuCool 201-MHz prototype RF cavity and lessons learned Fabrication and post processing Cavity conditioning and operation Engineering design of the cavity is complete CAD model of the cavity, tuners, support and vacuum system Fabrication schemes Vendor qualification: visited potential vendors recently RF cavity final design review at CM-22 (tomorrow) Possible operation at LN temperature? Design accommodates LN operation, but is very challenging RFCC Module and RF Cavity Construction Derun Li - LBNL - October 20, 2008, CM22 at RAL, UK

RF Cavity Summary MICE RF cavity design is based on the successful prototype cavity for the US MuCool program Fabrication of the prototype cavity was successful A slight reduction in cavity diameter to raise the frequency has been specified and analyzed The fabrication techniques used to produce the prototype will be used to fabricate the MICE RF cavities The cavity design was reviewed at CM21 at DL Copper sheets have been ordered and expected to arrive mid-December 2008 A detailed WBS schedule for the design and fabrication of the MICE RF cavities has been developed RFCC Module and RF Cavity Construction Derun Li - LBNL - October 20, 2008, CM22 at RAL, UK

2 RFCC Modules, 8 Cavities SC coupling Coil Curved Be window Cavity Couplers Vacuum Pump 201-MHz cavity Curved Be window RFCC Module and RF Cavity Construction Derun Li - LBNL - October 20, 2008, CM22 at RAL, UK

MICE RF Cavity Design 3-D Microwave Studio RF parameterized model including ports and curved Be windows to simulate frequency, Epeak, etc. Hard to reach the design frequency by spinning technique Frequencies between cavities should be able to achieve within  100 kHz Approaches Modification the prototype spinning form Targeting for higher frequency Fixed tuner to tune cavity close to design frequency (deformation of cavity body) Tuners are in push-in mode  lower frequency RFCC Module and RF Cavity Construction Derun Li - LBNL - October 20, 2008, CM22 at RAL, UK

Cavity Design Parameters Frequency: 201.25 MHz β = 0.87 Shunt impedance (VT2/P): ~ 22 MΩ/m Quality factor (Q0): ~ 53,500 Be window diameter and thickness: 42-cm and 0.38-mm Nominal parameters for MICE and cooling channels in a neutrino factory: 8 MV/m (~16 MV/m) peak accelerating field Peak input RF power: 1 MW (~4.6 MW) per cavity Average power dissipation per cavity: 1 kW (~8.4 kW) Average power dissipation per Be window: 12 watts (~100 watts) RFCC Module and RF Cavity Construction Derun Li - LBNL - October 20, 2008, CM22 at RAL, UK

RF Cavity Assembly RFCC Module and RF Cavity Construction Derun Li - LBNL - October 20, 2008, CM22 at RAL, UK

RF Cavity Fabrication Overview The same fabrication techniques used to make the prototype cavity will be used for the MICE RF cavities Engineering CAD Model of the RF Cavity Cavity half-shells to be formed by metal spinning Precision milling of large parts (1.2 m diameter) Precision turning of mid-sized parts (0.6 m dia.) Precision manufacture of smaller parts CMM measurements throughout the process To limit any annealing and maintain cavity strength, e-beam welding will be used for all cavity welding cavity equator, stiffener rings, nose rings, port annealing and port flanges Cavity inside surfaces are finished by electro-polishing Prototype RF Cavity RFCC Module and RF Cavity Construction Derun Li - LBNL - October 20, 2008, CM22 at RAL, UK

Recent Progress RFCC engineering CAD model refined RF and engineering design of 201-MHz RF cavity complete Integration and interface issues addressed Vendor identification and qualification near complete RFCC Module and RF Cavity Construction Derun Li - LBNL - October 20, 2008, CM22 at RAL, UK

Recent Progress (procurement & fab) The large copper sheets used in the fabrication of the cavity shells have been ordered and will arrive at LBNL in mid-December A series of vendor qualification visits has been conducted Applied Fusion - San Leandro, CA (e-beam welding, machining) Meyer Tool & Mfg., Inc. - Chicago, IL (machining) Sciaky, Inc. - Chicago, IL (e-beam welding) Roark Welding & Engineering - Indianapolis, IN (e-beam welding, machining) ACME Metal Spinning – Minneapolis, MN (cavity shell spinning) Other vendors have been identified Midwest Metal Spinning, Inc. –Bedford, IN (cavity shell spinning) RFCC Module and RF Cavity Construction Derun Li - LBNL - October 20, 2008, CM22 at RAL, UK

Cavity Fabrication Summary The twenty Ø1524 mm copper sheets used in the fabrication of the cavity shells have been purchased and will arrive at LBNL the second or third week of December Quotes from two metal spinning vendors (one local to San Francisco Bay area and the other ACME in Minnesota) have been received A third spinning vendor possibility in Bedford, Indiana has been identified If necessary a process of pre-polishing the copper sheet before spinning will be used to help eliminate scratches on the inside of the spun cavity shell The two spare half shells from the prototype program will be re-spun to the new profile, polished and used for e-beam parameter testing RFCC Module and RF Cavity Construction Derun Li - LBNL - October 20, 2008, CM22 at RAL, UK

Cavity Fabrication Summary (cont’d) Detail drawings of parts needed to fabricate the cavities are nearly complete Three possible e-beam welding vendors have been identified (one local to San Francisco Bay area and the other two in Illinois and Indiana) Request for quote documents will be sent to fabrication and welding shops before the end of 2008 LBNL has the machining equipment necessary to fabricate the complete RF cavity (minus e-beam welding and spinning) and will be considered depending on cost and schedule priorities RFCC Module and RF Cavity Construction Derun Li - LBNL - October 20, 2008, CM22 at RAL, UK

Other Module Components Cavity Suspension Dynamic Tuners RF Coupler Beryllium Window Vacuum System RFCC Module and RF Cavity Construction Derun Li - LBNL - October 20, 2008, CM22 at RAL, UK 13

Other Module Components (cont’d) Beryllium window design is complete; windows are in the process of being ordered (8 per module needed) Design and analysis of the cavity frequency tuners is complete, drawings to be done soon A hexapod cavity suspension system has been incorporated in the design The RF coupler will be based on the SNS design using the off the shelf Toshiba RF window The vacuum system includes an annular feature coupling the inside and the outside of the cavity (further analysis of vacuum rupture scenarios TBD) RFCC Module and RF Cavity Construction Derun Li - LBNL - October 20, 2008, CM22 at RAL, UK

201 MHz Beryllium Windows Each cavity has two Be windows 42-cm diameter and 0.38-mm thick Window is formed at high temperature and later brazed to copper frames Thin TiN coatings on both sides of the window One window curves into the cavity and one curves out Already tested up to 5 MW in 201-MHz cavity at MTA, FNAL 42-cm RFCC Module and RF Cavity Construction Derun Li - LBNL - October 20, 2008, CM22 at RAL, UK

Cavity Tuner Design Features Six tuners spaced evenly around each cavity provide individual frequency adjustment through a feedback loop Layout is offset by 15º from vertical to avoid conflict with cavity ports Tuners touch cavity and apply loads only at the stiffener rings Tuners operate in “push” mode only (i.e. squeezing) RFCC Module and RF Cavity Construction Derun Li - LBNL - October 20, 2008, CM22 at RAL, UK 16

Tuner System Analysis - Deformation ANSYS FEA of one tuner on 1/6 cavity segment Input pressure of 1.38 MPa (200 psi) is applied to actuator piston Deformation at the stiffener ring in the 2 mm range Movement of the arm at the actuator is in the 3 mm range RFCC Module and RF Cavity Construction Derun Li - LBNL - October 20, 2008, CM22 at RAL, UK

Hexapod Strut Arrangement Analysis of a hexapod strut system is complete Each cavity will contain a dedicated set of 6 suspension struts arranged in a hexapod type formation This system spreads the gravity load of the cavity across several struts Example of a hexapod stage RFCC Module and RF Cavity Construction Derun Li - LBNL - October 20, 2008, CM22 at RAL, UK 18

ANSYS FEA Analysis - Stress Maximum stress in the strut suspended cavity, due to gravity alone, is in the 20-30 MPa (2900- 4350 psi) range Yield strength of cavity is in the 275 MPa range RFCC Module and RF Cavity Construction Derun Li - LBNL - October 20, 2008, CM22 at RAL, UK

Vacuum System NEG (non-evaporable getter) pump Cross sectional view of vacuum system A NEG pump has been chosen because it will be unaffected by the large magnetic field A vacuum path between the inside and outside of the cavity eliminates the risk of high pressure differentials and the possible rupture of the thin beryllium window RFCC Module and RF Cavity Construction Derun Li - LBNL - October 20, 2008, CM22 at RAL, UK 20

Vacuum Vessel and Support Summary Engineering 3D CAD model of the vacuum vessel mechanical design is complete Standard machining and manufacturing methods will be used A plan for attaching the coupling coil and the vacuum vessel together has been developed Conceptual design of the support stand is complete (analysis will need to be performed) A method for assembling the cavities into the vacuum vessel has been formulated A conceptual design of the cavity water cooling feedthrough system is finished RFCC Module and RF Cavity Construction Derun Li - LBNL - October 20, 2008, CM22 at RAL, UK

Vacuum Vessel Fabrication Vacuum vessel material must be non-magnetic and strong therefore 304 stainless steel will be used throughout The vacuum vessel will be fabricated by rolling stainless steel sheets into cylinders Two identical vessel halves will be fabricated with all ports and feedthroughs Main 1400mm rolled tube Smaller diameter rolled tube Bellows flange RFCC Module and RF Cavity Construction Derun Li - LBNL - October 20, 2008, CM22 at RAL, UK

Vacuum Vessel and Coupling Coil RFCC Module and RF Cavity Construction Derun Li - LBNL - October 20, 2008, CM22 at RAL, UK

Vacuum Vessel/Coupling Coil Integration LBNL will weld in gussets that fit between the coupling coil and the vacuum vessel Sixteen special gussets are welded between the coupling coil magnet’s cold mass support tubes and the magnet housing The gussets will transfer the magnetic loads between the coupling coil and the vacuum vessel RFCC Module and RF Cavity Construction Derun Li - LBNL - October 20, 2008, CM22 at RAL, UK

RFCC Support Stand RFCC support stand must withstand a longitudinal force of 50 tons transferred from the coupling coil Bolted gussets and cross bracing provide shear strength in the axial direction (analysis will confirm the stand design) RFCC Module and RF Cavity Construction Derun Li - LBNL - October 20, 2008, CM22 at RAL, UK

Liquid Nitrogen Cooling Considerations Suspension of cavities on struts provides low heat leak from cavity to vacuum vessel Beryllium window FEA thermal analysis will need to be performed with new parameters The cavity frequency will be shifted (approximately 600 kHz), therefore tuning system or RF power source modifications will be needed Insulators will need to be added to the RF couplers Coaxial LN feedthrough tubes will be needed to insulate the connection outside of vacuum RFCC Module and RF Cavity Construction Derun Li - LBNL - October 20, 2008, CM22 at RAL, UK

Schedule Overview RFCC design and fabrication project originally expected to be a 3–year project (10/06 to 10/09) Coupling coil effort began in 2006 at ICST (Harbin) Design and fabrication of other RFCC module components was scheduled to begin 10/07 Start was delayed due to lack of availability of qualified manpower Earlier this year, mechanical engineer A. DeMello joined MICE to work on RFCC module design (FTE) Additional manpower required to make up schedule RFCC Module and RF Cavity Construction Derun Li - LBNL - October 20, 2008, CM22 at RAL, UK

Schedule Summary RFCC Module and RF Cavity Construction Derun Li - LBNL - October 20, 2008, CM22 at RAL, UK