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General specifications LHC Crab cavities. O. Capatina, L. Alberty , K. Brodzinski , R . Calaga , E. Jensen, V . Parma – CERN. Overview. Cavity Tuning Helium tank Magnetic shielding. SPL beta = 1 cavity assembly. Bi-phase helium tube. Helium Tank. Beam pipe. T uner. Cavity. - PowerPoint PPT Presentation
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General specificationsLHC Crab cavities
O. Capatina, L. Alberty, K. Brodzinski, R. Calaga,
E. Jensen, V. Parma – CERN
LHC Crab Cavity Engineering MeetingOC, 13/December/2012 1
• Cavity
• Tuning
• Helium tank
• Magnetic shielding
Overview
OC, 13/December/2012 LHC Crab Cavity Engineering Meeting 2
RF Power Coupler
Cavity
Helium Tank
Tuner
HOM Coupler
Bi-phase helium tube
Magnetic shielding
Beam pipe
TTC Meeting 3OC, VP, 7/November/2012
SPL beta = 1 cavityassembly
Functional specification
OC, 13/December/2012 LHC Crab Cavity Engineering Meeting 4
• Parameters
Cavity
OC, 13/December/2012 LHC Crab Cavity Engineering Meeting 5
Parameter Units Value
Frequency MHz See next page
Cavity b 1
Design gradient MV 3.3 (pushed=5.0)
R/Q W >300
Q0 >1 x 1010
Qext 1 x 106
• Parameters
Cavity
OC, 13/December/2012 LHC Crab Cavity Engineering Meeting 6
Parameter Units LHC SPS
Beam Energy GeV 7,000 55 120 270
Frequency MHz 400.79 400.b 400.c 400.c
• Dimensions
Cavity
OC, 13/December/2012 LHC Crab Cavity Engineering Meeting 7
R. Calaga, Superconducting Technologies Workshop, Dec. 2012
• 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
Cavity
OC, 13/December/2012 LHC Crab Cavity Engineering Meeting 8
Position of 2nd beam pipe: 4-ROD
Vittorio Parma, Loren Wright
Position of 2nd beam pipe: RF-Dipole
Vittorio Parma, Loren Wright
Position of 2nd beam pipe: QWR
Vittorio Parma, Loren Wright
• Dimensions
• Maximum radius external dimension (including wall thickness) at room temperature < 145 mm
• Cavities dimensions to be revisited (reduced)
Cavity
OC, 13/December/2012 LHC Crab Cavity Engineering Meeting 12
• RF Multipoles
Cavity
OC, 13/December/2012 LHC Crab Cavity Engineering Meeting 13
R. Calaga, Superconducting Technologies Workshop, Dec. 2012
• 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)
Tuning
OC, 13/December/2012 LHC Crab Cavity Engineering Meeting 14
Parameter Units LHC SPS
Frequency MHz 400.79 400.b 400.c 400.d
Bandwidth Hz 400 400 400 400
• 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)
Tuning
OC, 13/December/2012 LHC Crab Cavity Engineering Meeting 15
Parameter Units LHC SPS
Frequency MHz 400.a 400.b 400.c 400.d
Bandwidth Hz 400 400 400 400
• 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)
Tuning
OC, 13/December/2012 LHC Crab Cavity Engineering Meeting 16
• Process for tuning taking into account• Deformation during manufacturing O(MHz)• Processing (hundreds kHz)• Cold/warm (hundreds kHz)• Operating conditions (< kHz)
Tuning
OC, 13/December/2012 LHC Crab Cavity Engineering Meeting 17
• 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
Helium tank
OC, 13/December/2012 LHC Crab Cavity Engineering Meeting 18
• Helium tank to be dimensioned correctly to extract maximum heat load • Heat flux in He II depend on bath temp. and
channel dimension
Helium tank
OC, 13/December/2012 LHC Crab Cavity Engineering Meeting 19
• 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
Helium tank
OC, 13/December/2012 LHC Crab Cavity Engineering Meeting 20
• 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
Helium tank
OC, 13/December/2012 LHC Crab Cavity Engineering Meeting 21
• 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
Helium tank
OC, 13/December/2012 LHC Crab Cavity Engineering Meeting 22
• 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.
Helium tank
OC, 13/December/2012 LHC Crab Cavity Engineering Meeting 23
• 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
Helium tank
OC, 13/December/2012 LHC Crab Cavity Engineering Meeting 24
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, (...)
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
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
Front page: Directive 97/23/EC
Higher Risk Categories require the participation of Notified Bodies
Helium tank
The application of the European Directive for pressure equipment 97/23/EC:
o 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 VesselsPart 1: GeneralPart 2: MaterialsPart 3: DesignPart 4: FabricationPart 5: Inspection and testingOther parts: 6, 7, 8 & 9
EN 13458 - Cryogenic vessels - Static vacuum insulated vesselsPart 1: Fundamental requirementsPart 2: Design, Fabrication, Inspection and TestingPart 3: Operational requirements
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
Helium tank
OC, 13/December/2012 LHC Crab Cavity Engineering Meeting 28
• Pressure equipment – example of safety file
Helium tank
OC, 13/December/2012 LHC Crab Cavity Engineering Meeting 29
Helium tank
OC, 13/December/2012 LHC Crab Cavity Engineering Meeting 30
• 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
• 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.
• ...
Helium tank
OC, 13/December/2012 LHC Crab Cavity Engineering Meeting 31
• 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)
Magnetic shielding
OC, 13/December/2012 LHC Crab Cavity Engineering Meeting 32