General specifications LHC Crab cavities

1. General specificationsLHC Crab cavities O. Capatina, L. Alberty, K. Brodzinski, R. Calaga, E. Jensen, V. Parma – CERN LHC Crab Cavity Engineering Meeting

2. Overview • Cavity • Tuning • Helium tank • Magnetic shielding LHC Crab Cavity Engineering Meeting

3. SPL beta = 1 cavityassembly Bi-phase helium tube Helium Tank Beam pipe Tuner Cavity Magnetic shielding HOM Coupler RF Power Coupler TTC Meeting

4. Functional specification LHC Crab Cavity Engineering Meeting

5. Cavity • Parameters LHC Crab Cavity Engineering Meeting

6. Cavity • Parameters LHC Crab Cavity Engineering Meeting

7. Cavity • Dimensions R. Calaga, Superconducting Technologies Workshop, Dec. 2012 LHC Crab Cavity Engineering Meeting

8. Cavity • Dimensions • RF design for internal shape at cold • Design for manufacturing by scaling: • Warm (room temperature)/cold shrinkage • Shape modification due to EP, BCP, .. • Deformation due to operation conditions (internal vacuum + external pressure) • … • Integration specification takes into account external dimension (including wall thickness) of the cavity as manufactured, at room temperature LHC Crab Cavity Engineering Meeting

9. Position of 2nd beam pipe: 4-ROD Vittorio Parma, Loren Wright

10. Position of 2nd beam pipe: RF-Dipole Vittorio Parma, Loren Wright

11. Position of 2nd beam pipe: QWR Vittorio Parma, Loren Wright

12. Cavity • Dimensions • Maximum radius external dimension (including wall thickness) at room temperature < 145 mm • Cavities dimensions to be revisited (reduced) LHC Crab Cavity Engineering Meeting

13. Cavity • RF Multipoles R. Calaga, Superconducting Technologies Workshop, Dec. 2012 LHC Crab Cavity Engineering Meeting

14. Tuning • SPS tests • Frequencies at SPS tests to be adjusted with tuner during operation (slow tuning needed only) – set only once (between 400.c and 400.d ~ 10kHz) • Detuning (when cavity not in use) • Range of detuning required: + or - 1.5 kHz ± 200 Hz • Time requirements: fast tuning (fast to be defined in more detail) LHC Crab Cavity Engineering Meeting

15. Tuning • LHC – operating frequency • Detuning (when cavity not in use) • Range of detuning required: + or - 1.5 kHz ± 200 Hz • Time requirements: fast tuning (fast to be defined in more detail) LHC Crab Cavity Engineering Meeting

16. Tuning • Frequency • Bandwidth of 400 Hz () • mm/kHz (cavity specific) => cavity stability and shape adjustment in the order of 10 nm ! • Mech. design compromise between • Rigidity to ensure stability (Lorentz detuning, …) • Flexibility to ensure tunability • Remark: tuner to work in one direction (or compensate for play) LHC Crab Cavity Engineering Meeting

17. Tuning • Process for tuning taking into account • Deformation during manufacturing O(MHz) • Processing (hundreds kHz) • Cold/warm (hundreds kHz) • Operating conditions (< kHz) LHC Crab Cavity Engineering Meeting

18. Helium tank • Temperature • Operating temperature 2 K (saturated superfluid helium) • Heat losses to be evaluated in detail – dimensioning of helium tank, cryo-module and cryo-plant accordingly • Static • Dynamic • ~ 3 W / cavity • But exact and realistic value (especially for SPS tests) – important to estimate and measure LHC Crab Cavity Engineering Meeting

19. Helium tank • Helium tank to be dimensioned correctly to extract maximum heat load • Heat flux in He II depend on bath temp. and channel dimension LHC Crab Cavity Engineering Meeting

20. Helium tank • Helium tank to be dimensioned correctly to extract maximum heat load • If helium cross section expected to extract (order of magnitude) 1 W/cm2 => detailed calculations needed LHC Crab Cavity Engineering Meeting

21. Helium tank • Interfaces • Ideally same helium tank and interfaces for all cavities – not realistic? • Standardization of interfaces for all cavities assemblies - is a very strong requirement • Choice of helium tank material (stainless steel / titanium) – strong impact on transitions: • Beam pipe (suggestion to use SS for flanges) • Cryo-module piping • HOM (and LOM) extraction, Main power coupler, Pick-up LHC Crab Cavity Engineering Meeting

22. Helium tank • Remark:Design (cavity and helium tank) to take into account: • Interfaces for handling and transport • Interfaces for cavity processing • Interfaces for vertical tests at cold • Interfaces for alignment in cryomodule LHC Crab Cavity Engineering Meeting

23. Helium tank • Pressure • Operating helium pressure ~ 20 mbar • Pressure stability: 1 mbar • Design cavities for sensitivity to pressure fluctuation accordingly (200 Hz/mbar would be too large) • Cavity bandwidth 400 Hz => sensitivity to pressure fluctuation should be significantly lower. LHC Crab Cavity Engineering Meeting

24. Helium tank • Pressure • Maximum pressure (transients) • Safety valve set pressure 1.8 bar • Rupture disc 2.2 bar • Pressure equipment • All the cryo-module assembly: cavitie(s), helium tank(s), vacuum vessel – to be treated for the same risk category as the most critical one LHC Crab Cavity Engineering Meeting

25. Helium tank • CERN’s safety policy regarding pressure equipment: • The general requirements for mechanical equipment during its life-cycle are defined by a specific General Safety Regulation; • A General Safety Instruction defines the requirements specific to pressure equipment; • Some general requirements: • A Safety File of the equipment shall be prepared and updated by the Department; • A risk analysis shall be carried out in order to assess critical loading scenarios; • Full traceability shall be ensured from design to commissioning; • The following documentation applies by order of priority: • Internal Specific Safety Instructions • European Union Directives • European Directive 97/23/EC on the ‘Approximation of the laws of the Member States concerning pressure equipment • Harmonised European Standards • EN 13445, EN 13458, (...)

26. Helium tank The application of the European Directive for pressure equipment 97/23/EC: Covers pressure equipment with a maximum allowable pressure greater than 0.5 bar (gauge) Defines the essential safety requirements which allow to comply with the directive & allow free movement within the EU market The equipment is classified into risk categories according to their stored energy and the hazard of the fluid Front page: Directive 97/23/EC For each risk category, modules allow to assess conformity The adoption of European Harmonised Standards ensures conformity with the requirements of the Directive Table for assessment of risk category Higher Risk Categories require the participation of Notified Bodies

27. Helium tank The application of the European Directive for pressure equipment 97/23/EC: • Harmonised European Standards for the design, fabrication and inspection of pressure equipment, which ensure conformity with the Directive 97/23/EC: • EN 13445 – Unfired Pressure Vessels • Part 1: General • Part 2: Materials • Part 3: Design • Part 4: Fabrication • Part 5: Inspection and testing • Other parts: 6, 7, 8 & 9 • EN 13458 - Cryogenic vessels - Static vacuum insulated vessels • Part 1: Fundamental requirements • Part 2: Design, Fabrication, Inspection and Testing • Part 3: Operational requirements

28. Helium tank • Pressure equipment • Remark: All the cryo-module assembly: cavitie(s), helium tank(s), vacuum vessel – to be treated for the same risk category as the most critical one • Could be treated at CERN as special equipment: not necessity of the CE marking but same quality requirements • For 1.8 bar pressure relieve valve => design for 1.8*1.43 = 2.6 bar for cavity ext pressure, helium tank internal pressure LHC Crab Cavity Engineering Meeting

29. Helium tank • Pressure equipment – example of safety file LHC Crab Cavity Engineering Meeting

30. Helium tank • Pressure equipment – example of some manufacturing requirements for a category I equipment • Materials • All materials have to be supplied with a certification of type 3.1 according to EN 10204:2004 (compliance with the order and indication of test results attested by the manufacturer) • Materials covered by Harmonised European Standards automatically do comply with the requirements of PED • Remarks: • Niobium and Titanium not covered by the Harmonised European Standards • In the frame of special equipment it can be accepted on the basis of the risk analysis and of proven behavior at operating temperature LHC Crab Cavity Engineering Meeting

31. Helium tank • Pressure equipment – example of some manufacturing requirements for a category I equipment • Every weld shall be identified on manufacturing drawings and linked to an appropriate weld procedure: • Welding procedure specification (WPS) / Brazing procedure specification (BPS); • Welding procedure qualification record (WPQR)/ Brazing procedure approval record (BPAR); • Welding operators qualification /Brazer approval; • Radiographic inspection of 25% of the total circumferential seams and 100% of the total longitudinal seams. • ... LHC Crab Cavity Engineering Meeting

32. Magnetic shielding • Static magnetic field shielding required • The field to be below 1 µT at the outer surface of the cavity • Numerical simulations to determine the material thickness and specification, as well as geometry • Recommended to evaluate the effect inside and outside the helium vessel (compatible with cavity compactness requirements) LHC Crab Cavity Engineering Meeting