Shuichi Noguchi 、 KEK 6-th ILC School, November Superconducting Cavity  Design ( RF, Mechanical, Thermal )  Material  Fabrication Techniques  Surface Treatment  Surface Inspection  Vertical Measurement  Cavity Behavior  Diagnostics Part-1

Shuichi Noguchi 、 KEK 6-th ILC School, November SRF Cavity Peculiarities  Surface Condition is essential, but is usually irregular and contaminated.  No Theory except BCS Surface Resistance.  RF Magnetic Field Limit ?  Many Steps in Production & Clean Works to realize Ideal Surface

Shuichi Noguchi 、 KEK 6-th ILC School, November SRF Cavity Peculiarities PropertyRealityConsequence SuperconductingNeed Helium Thin Wall for better Cooling Nb, Type II Need Magnetic ShieldEven Hext << Hc 1 Multi Layer Structure MaterialNot Uniform, Not IdealGrain Boundary Large Grain ? Contaminated SurfaceIrregularity, Contamination Lattice Orientation Field Enhancement, H & E RF SuperconductivityNot Lossless but Very Low LossResidual Surface Resistance0.3 nΩ/ mgauss Maximum Field Limit Smooth Shape, Less Holes High Impedance 、 HOM Need HOM Dumper StructureMaterial is ExpensiveThin WallMechanical Stability, Coating ProductionDeep Drawing + Machining + EBW Defect Quench Surface Treatment Chemical Treatment + Ultra pure Water Rinsing ContaminationQuench, Field Emission AssemblyClass 10 Clean Room Scatter of Performance PeripheralThermal Insulation in Vacuum Many Critical Components Ceramic Break Others Vacuum Seal

Shuichi Noguchi 、 KEK 6-th ILC School, November Superconducting Cavity Accelerator Users Cryostat Refrigerator High Power RF Low Level RF Input Coupler HOM Coupler Tuner Forming, EBW Surface Treatment Particle Physics Material Science Medical Application Design

Shuichi Noguchi 、 KEK 6-th ILC School, November Design Process Design ParametersInputConstraints Frequency, StructureAccelerating, Deflecting,.... Mode Particle β gap Length Ring / Linac Iris Aperture Operating GradientAccelerator Scale, CW / PulseBeam Power (Coupler) Cooling Power Material Operating TemperatureFrequency, Structure, GradientCooling Power Cavity Unit LengthBeam Current, GradientBeam Power (Coupler) Accelerator ScaleHOM damping Module LengthAccelerator Scale If Pbeam>>Pcavity  Normal

Shuichi Noguchi 、 KEK 6-th ILC School, November  > 0.4  < 0.4 Particlee, ProtonProton, Ion Frequency Ring 0.3~0.5 GHz Linac 0.7~3 GHz Linac 50~300 MHz Beam Current Ring >1 A Linac > 100 mA > 1mA< 1mA Accelerating Elliptical Spoke, Spoke, Half Wave, Quarter Wave DeflectingCrab Cavities FocusingRFQ Structure Examples

Shuichi Noguchi 、 KEK 6-th ILC School, November Accelerating Gap g E E z Space Distribution g

Shuichi Noguchi 、 KEK 6-th ILC School, November Accelerating Gap g g ~  Small  enough g Lower Frequency  -Mode 0-Mode

Shuichi Noguchi 、 KEK 6-th ILC School, November Eacc Acceleration by RF Cavity Frequency Shape Beam RF Resonator, Strong E field on axis Z   - Mode

Shuichi Noguchi 、 KEK 6-th ILC School, November Cavity RF Parameters

Shuichi Noguchi 、 KEK 6-th ILC School, November General RF Design PreferenceCompromise Power EfficiencyHigher R sh R sh of HOM Aperture Acceleration Efficiency Enough Acceleration GapFrequency Cavity Size Multi-Gap/Cell Beam QualityEnough ApertureR sh

Shuichi Noguchi 、 KEK 6-th ILC School, November Q-E Curves （ Performance ） Q0Q0 Quench ? Global Heating Q Switch Field Emission Ideal (Constant Q = Constant R s, T) Quench Multipacting Q Slope H Q-Dieses Eacc

Shuichi Noguchi 、 KEK 6-th ILC School, November RFQ INFN-Legnaro Difficulty High Power Coupler End Flange Contact Frequency Tuning

Shuichi Noguchi 、 KEK 6-th ILC School, November Quarter Wave ( /4) & Split Ring ANL Coaxial Resonator Mechanical Vibration, High Power Coupler

Shuichi Noguchi 、 KEK 6-th ILC School, November Half Beam

Shuichi Noguchi 、 KEK 6-th ILC School, November Half to Spoke By Squeezing the Height

Shuichi Noguchi 、 KEK 6-th ILC School, November Multicell Spoke

Shuichi Noguchi 、 KEK 6-th ILC School, November Two Axis Coupled Cavity Acceleration Beam Coupler Drive Beam

Shuichi Noguchi 、 KEK 6-th ILC School, November Smaller R iris R / Q ; Larger E sp / E acc ; Smaller H sp / E acc ; Smaller Cell Coupling ; Smaller Cleaning ; More Difficult Alignment ; Tight RF Design,  = 1

Shuichi Noguchi 、 KEK 6-th ILC School, November The mechanical design of a cavity follows its RF design: Lorentz Force Detuning Mechanical Resonances Mechanical Design Cavities Lorentz Force Detuning E and H at E acc = 25 MV/m in TESLA inner-cup 50 MV/m 92 kA/m Mechanical Design

Shuichi Noguchi 、 KEK 6-th ILC School, November Surface deformation without and with stiffening ring (courtesy of I. Bonin, FERMI) Mechanical Design Cavities m 3∙10 -5 m No stiffening ring Wall thickness 3mm Stiffening ring at r=54mm Wall thickness 3mm k L = -1 Hz/(MV/m) 2 Essential for the operation of a pulsed accelerator Δf = k L (E acc ) 2 Lorentz Force Deformation - df

Shuichi Noguchi 、 KEK 6-th ILC School, November Lorentz ( Maxwell ) Detuning Ｋ ｊａ ｃｋｅｔ Ｋ tuner Ｋ cavity FZFZ FZFZ ＦｚＦｚ ＦｒＦｒ 42 N 135 N E acc = 35MV/m TTF Saclay-ISTF Slide JackBlade AHz / (MeV/m) (TESLA) BN / (MeV/m) df / dlHz /μm300 KSKS N /μm K jacket N /μm K tuner N /μm Stationary Δf (31.5 MV/m)Hz  f (Compensation) Hz Necessary Tuning Strokeμm

Shuichi Noguchi 、 KEK 6-th ILC School, November Deformation is the Sum of all the Mechanical Modes

Shuichi Noguchi 、 KEK 6-th ILC School, November Two Dominant Mechanical Modes Single –Cell ~ + ~2500Hz~200Hz Need Stiff Cavity Need Stiff Jacket-Tuner System 2-nd order modeFundamental mode F(H 2 ) F(E 2 )

Shuichi Noguchi 、 KEK 6-th ILC School, November /9  mode 204Hz 2/9  mode 376Hz 3/9  mode 548Hz FixFree Longitudinal Modes 9000N by Tuner

Shuichi Noguchi 、 KEK 6-th ILC School, November Transverse Modes 1/9  56Hz 2/9  141Hz 3/9  251Hz

Shuichi Noguchi 、 KEK 6-th ILC School, November Material  High Purity Niobium is almost an unique Choice at the moment. RRR~300 Pb ( Plating ) was used for some Application. Nb 3 Sn (Vapor Deposition + Heat Treatment) NbTiN (Sputtering) High T c Materials are still very difficult.

Shuichi Noguchi 、 KEK 6-th ILC School, November Niobium Sheet Fabrication

Shuichi Noguchi 、 KEK 6-th ILC School, November Niobium Insufficient recrystallization, formability and mechanical properties are effected Fully recrystallized material after appropriate heat treatment (after rolling operation) X. Singer, DESY

Shuichi Noguchi 、 KEK 6-th ILC School, November Large Grain directly from Ingot Lattice Orientation, Slippage at Boundary

Shuichi Noguchi 、 KEK 6-th ILC School, November Property of Nb 2~5kRoom Temperature Density8.57 Lattice StructureB.C.C Melting Temperature 2468 ℃ Conductivity ~ 2x10 9   ・ m Thermal Conductivity 20 ~ 50 W / m ・ k Yield Strength~ 600 MPa~ 40 MPa Tensile Strength~ 900 MPa~ 160 MPa Elongation~ 15%~ 40% Yang Module~ 100 GPa Vickers Hardness~ 500 MPa

Shuichi Noguchi 、 KEK 6-th ILC School, November Niobium Thermal Conductivity  Post-Purification Treatment (G.R.Myneni, Jlab) RRR ; Residual Resistance Ratio Wiedemann-Franz

Shuichi Noguchi 、 KEK 6-th ILC School, November Cooling Efficiency (SRF93’)Temperature Mapping System Quench LimitHeat Flux He-I / He-II 1.8K 4.2K (EPAC96’) 2.17K

Shuichi Noguchi 、 KEK 6-th ILC School, November Cavity Fabrication

Shuichi Noguchi 、 KEK 6-th ILC School, November Cavity (9 Zeller) Endhalbzell- Endrohr- Einheit kurz Endhalbzell- Endrohr- Einheit lang Flansch (Hauptkoppler- Stutzen) Flansch (Endflansch) HOM-Koppler kurze Seite Rippe Anbindung (end-kurz-lang) Endhalbzelle kurz Antennenflansch NW 12 HOM-Koppler DESY End-kurz-lang Formteil F Bordscheibe lange Seite Endhalbzelle lang Flansch (end-kurz-lang) HOM-Koppler lange Seite Flansch (Endflansch) Antennenstutzen lang Endrohr lang Antennenflansch NW 12 Formteil F lang HOM-Koppler DESY End-kurz-lang Hauptkoppler- stutzen Endrohr kurz Cavity (9 cell TESLA / TTF design) End group 1End group 2 Hantel Normalhalb- Zelle Normalhalb- Zelle Stützring Nb-Blech Normalhalelle Nb-Blech Normalhalbzelle Dumb-bell Overview over cavity fabrication

Shuichi Noguchi 、 KEK 6-th ILC School, November Fabrication of STF Baseline Cavities Center-cells (Tokyo Denkai ; RRR~300 Nb) End-groups HOM coupler Magnetic Shield

Shuichi Noguchi 、 KEK 6-th ILC School, November Half Cell Press Forming Iris Thinner Equator Thicker

Shuichi Noguchi 、 KEK 6-th ILC School, November Fabrication

Shuichi Noguchi 、 KEK 6-th ILC School, November Beam Pipe & HOM Coupler Wire cutting of Nb Brock Beam tube HOM Coupler

Shuichi Noguchi 、 KEK 6-th ILC School, November Deepdrawing & Port Forming

Shuichi Noguchi 、 KEK 6-th ILC School, November End Group Ti End Plate End cell & End group

Shuichi Noguchi 、 KEK 6-th ILC School, November Electron Beam Welding (Jlab) DumbbellsStiffening Rings

Shuichi Noguchi 、 KEK 6-th ILC School, November Dumbbells With Stiffener

Shuichi Noguchi 、 KEK 6-th ILC School, November

Shuichi Noguchi 、 KEK 6-th ILC School, November Electron Beam Welding (Jlab)

Shuichi Noguchi 、 KEK 6-th ILC School, November STF Baseline Cavity

Shuichi Noguchi 、 KEK 6-th ILC School, November Other Fabrication Technique  Hydro forming (W.Singer,DESY)Spinning (V.Palmieri,INFN Legnaro)

Shuichi Noguchi 、 KEK 6-th ILC School, November Thin Niobium Films Sputtering