fnal crab cavities dec2012 oc

7/28/2019 FNAL Crab Cavities Dec2012 OC

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General specifications

LHC Crab cavities

O. Capatina, L. Alberty, K. Brodzinski, R.Calaga,

E. Jensen, V. Parma CERN

LHC Crab Cavity Engineering MeetingOC, 13/December/2012 1


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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 cavity

assembly


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Functional specification

OC, 13/December/2012 LHC Crab Cavity Engineering Meeting 4


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Parameters

Cavity


Parameter Units Value

Frequency MHz See next page

Cavity b 1Design gradient MV 3.3 (pushed=5.0)

R/Q W >300

Q0 >1 x 1010

Qext 1 x 106


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Parameters

Cavity


Parameter Units LHC SPS

Beam Energy GeV 7,000 55 120 270

Frequency MHz 400.79 400.b 400.c 400.c


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Dimensions

Cavity


R. Calaga, Superconducting Technologies Workshop, Dec. 2012


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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



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Position of 2nd beam pipe: 4-ROD

Vittorio Parma, Loren Wright


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Position of 2nd beam pipe: RF-Dipole



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Position of 2nd beam pipe: QWR



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Dimensions

Maximum radius external dimension

(including wall thickness) at room

temperature < 145 mm

Cavities dimensions to be revisited (reduced)

Cavity



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RF Multipoles

Cavity


R. Calaga, Superconducting Technologies Workshop, Dec. 2012


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SPS tests

Frequencies at SPS tests to be adjusted with tunerduring 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



Frequency MHz 400.79 400.b 400.c 400.d

Bandwidth Hz 400 400 400 400


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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 definedin more detail)

Tuning



Frequency MHz 400.a 400.b 400.c 400.d

Bandwidth Hz 400 400 400 400


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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



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Process for tuning taking into account

Deformation during manufacturing O(MHz)

Processing (hundreds kHz)

Cold/warm (hundreds kHz)

Operating conditions (< kHz)

Tuning



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Temperature

Operating temperature 2 K(saturated superfluid helium)

Heat losses to be evaluated in detail

dimensioning of helium tank, cryo-module andcryo-plant accordingly

Static

Dynamic

~ 3 W / cavity

But exact and realistic value (especially for SPS

tests) important to estimate and measure

Helium tank



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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



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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



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Interfaces

Ideally same helium tank and interfaces for all cavitiesnot 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



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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



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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



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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), vacuumvessel to be treated for the same risk

category as the most critical one

Helium tank



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CERNs 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


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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

H li k


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The application of the European Directive for pressure equipment 97/23/EC:

o Harmonised European Standards for the design, fabrication and inspection of pressureequipment, 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

Helium tank

H li t k


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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


H li t k


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Pressure equipment example of safety file

Helium tank


H li t k


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Helium tank


Pressure equipmentexample of some manufacturingrequirements 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 HarmonisedEuropean 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

H li t k


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Pressure equipment example of somemanufacturing 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) / Brazingprocedure 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


M ti hi ldi


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Static magnetic field shielding required

The field to be below 1 T at the outer

surface of the cavity

Numerical simulations to determine the

material thickness and specification, aswell as geometry

Recommended to evaluate the effect

inside and outside the helium vessel(compatible with cavity compactness

requirements)

Magnetic shielding


fnal crab cavities dec2012 oc

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