STATUS OF THE PREPARATION OF THE ELLIPTICAL CAVITY … · Cavity preparation for test • The cavity frequency at room temperature should be 702.8 MHz in order to have 704.4 MHz at

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STATUS OF THE PREPARATION OF THE ELLIPTICAL CAVITY SYSTEM FOR THE

STATUS OF THE PREPARATION OF THE ELLIPTICAL CAVITY SYSTEM FOR THE

N Panzeri S Barbanotti A Bosotti P PieriniN Panzeri S Barbanotti A Bosotti P Pierini

ELLIPTICAL CAVITY SYSTEM FOR THE EUROTRANS CRYOMODULE

ELLIPTICAL CAVITY SYSTEM FOR THE EUROTRANS CRYOMODULE

N. Panzeri, S. Barbanotti, A. Bosotti, P. PieriniN. Panzeri, S. Barbanotti, A. Bosotti, P. Pierini

Sezione di MilanoSezione di MilanoSezione di MilanoLASASezione di MilanoLASA

Outline

• TRASCO cavity– Experimental tests

Requirements for the external components

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– Requirements for the external components

• Helium tank and tuner system– Design

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– Reliability

• Preparation for horizontal tests

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Author: Nicola Panzeri --- INFN Milano - LASA 2

The TRASCO cavitiesks

hop

2 cavities TRASCO β=0.47 for proton (90 a 200 MeV)

Test #1 limited by strong field emission Z501 Z502 - before conditioning Z502 - after conditioning Design Value

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1010

Q0Successfully tested up to 17 MV/m (design requirement 8 5 MV/m)

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109

start of electron emissionmultipacting barriers

(design requirement 8.5 MV/m)

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0 2 4 6 8 10 12 14 16 18 20Eacc [MV/m]

Cavity requirements

-1000

0

Δν

Z502 Test #1 Z502 Test #2 Z502 Test #3 Z501 Test #1 Z501 Test #2 Z501 Test #3

cavext

accLL KK

EFzfKK

+∂∂

+=∞

∞2

3000

-2000 KL = -31

KL = -24

KL = -47

KL = -20

KL = -32

Δν[Hz]

During the tests the Lorentz force detuning (LFD) coefficient was derived: the values obtained were larger than expected and

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p 0 20 40 60 80 100 120 140 160 180 200

-3000KL = -35

E2acc [(MV/m)2]

with a relevant spread

This is mainly due to the uncertainty of the external constraints applied to the

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30

-20

-10

0

MV

/m)2 ]

Semianalytical modelJLABSaclay

the external constraints applied to the cavities during the tests

Big sensitivity of the cavity to thet l t i t tiff

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60

-50

-40

-30K

L [H

z/(Mexternal constraint stiffness

We should operate here:

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-601.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06

K ext [N/mm]

p|KL|<10 Hz/(MV/m)2 ⇒ Kext > 9 kN/mm

Tuner and helium tank design

• Tuner and HT have been designed with this goal in mind:– Fulfill the cavity requirements in terms of external stiffness and tuning range– Reliable

Si l ( bl d ti )– Simple (assembly and preparation)– As cheap as possible

• Our starting point from the experience in TTF

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• Our starting point from the experience in TTF– The HT is simpler than the HT in TTF– Assembly easier

- 8

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- 10

- 9

8

L– The tuner has the same

components as the TTF bladetuner already tested

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- 12

- 11

LK Actual experimental stiffness including leverage (TTF)

tuner already tested

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15 20 30

ktunerAkN€€€€€€€€€€€€€mmE

Tuner and helium tank designThe tuner consists of three mainThe tuner consists of three main

components:– the rings-blades assembly, made of titanium; – the leverage mechanism, in stainless steel 316L e e e age ec a s , s a ess s ee 3 6

and brass MS58, that drives the rings-blade assembly movements;

– the piezo actuator part, that provides the fast tuning action necessary for compensation under

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• Design by Finite Element Method:

tuning action necessary for compensation under pulsed operation.

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– Rings and mechanism considered separately– Stiffness in different boundary conditions

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Tuner design: stiffness

Finite element results:• central ring free (without leverage): KT = 2.4 kN/mm• central ring with leverage (working condition): KT = 52.3 kN/mm

• Compliance of the motor and of the bearings was notconsidered

• Lacks and slack joints can not be included consistently inth FE l i

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the FE analysis

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It seems convenient to use as reference for thewhole tuner stiffness the value which has beenmeasured experimentally (25 kN/mm) on the proven

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H TTF tuner.

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Tuner design: tuning range

TTF bl d tTTF blade tunerSlow tuning action

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k

maximum elongation of approximately 1 3 h d i

Fast tuning action

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H 1.3 mm that corresponds to a cavity stretching of 1.2 mm (≅400 kHz)

2 piezo elements, stroke depends on their length.For L = 40 mm we expect more than 2 f di l t ( 700 H )

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2μm of displacement (> 700 Hz)

Tuner reliability• The components of the blade tuner (motor, ball bearings, harmonic drive) are continuously tested in

TTF• Used also for the Saclay tuner, we can get all the experience of the last 10 years.• 4 TTF blade tuner installed on superstructure were tested at Desy• We have 2 TTF blade tuner and 2 HPPA blade tuner ready for test

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Tuner reliability

TTF Cavity Tuner Life Time Tests at 2K (courtesy R. Lange)

Results of 3 performed tuner long term(lifetime) tests Status:May-1998 R. Lange –MKS-After 23 000 000 motorsteps warm up and cool downSystem Nr. 1 90 000 000 motor-steps

==>Tests performed without problemsInspection:No damages on the system

System Nr. 2 50 000 000 motor-steps

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==>Test stopped because uneven run (fr, Video)Inspection:Slight damages on the motor ball bearings

System Nr. 3 70 000 000 Motor-Steps==>Test stopped because blocked drive(fr, Video)

Inspection:Strong damages on the motor ball bearingsStrong damages on the wave generator

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Summary: After these long term tests we knew, the motor ball bearingsare the weakest parts of the tuner!

But:Assuming the linac will be cooled down and warmed up 2/year, we can do the following life time estimation:

-Tuning to 2K-resonance(ca.340 kHz) 450 000 motor-steps

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H -Fine tuning at 2K (total) 300 000 motor-steps-Tuning to 300K-position(ca.340kHz) 450 000 motor-steps

==>Amount for 1 cold/warm cycle 1 200 000 motor-steps==>Amount for 1 year 2 400 000 motor-steps==>Expectation life time 20 years 48 000 000 motor-steps

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Tuner and helium tank constructionStatus of tuner and HTStatus of tuner and HT

construction• Construction finishedConstruction finished• Delivery in time• Assembled in our lab for test at RT

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Dressed cavity

Part Axial stiffness c (μm/kN) k (kN/mm) Helium tank KH 1.17 856 End dishes KW 63.4 15.7

Bellow KB 3205 0.312 Blade tuner K 40 0 25 0

From the mechanical point of view, the dressed cavity can be described as a spring

Blade tuner KT 40.0 25.0 Piezo PIC255 KP 4.176 2x105 system

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1/K t = 1/KH + 1/KT + 1/KW + 1/(2KP) → K t = 9 2 > 9 kN/mm

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1/Kext 1/KH + 1/KT + 1/KW + 1/(2KP) → Kext 9.2 > 9 kN/mm

The external stiffness satisfies the cavity requirement

Cavity preparation for test• The cavity frequency at room temperature should be

702.8 MHz in order to have 704.4 MHz at cold• Cavity stretched from 699.9 to 702.1 Mhz• Field flatness not so bad: final stretching and field

fl t dj t t ft th h t t t t iflatness adjustment after the heat treatment in a vacuum furnace at CERN

• Leak rate test performed after the cavity tuning. No leaks observed.

• The cavity will be shipped in the next days to CERN

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• The cavity will be shipped in the next days to CERN• A chemical treatment is foreseen at Saclay after the last

tuning

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Conclusions

Conclusions/Scheduling• The tuner and helium tank have been designed to fulfill the cavity

requirements in term of stiffness and tuning range;R li bilit b d t t f d th TTF bl d t hi h h th• Reliability based on test performed on the TTF blade tuner, which share the same design

• The tuner and helium tank are ready• Low power test foreseen beginning 2008 after cavity preparation and

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• Low power test foreseen beginning 2008, after cavity preparation and assembly in the HT

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Documents

STATUS OF THE PREPARATION OF THE ELLIPTICAL CAVITY … · Cavity preparation for test • The cavity frequency at room temperature should be 702.8 MHz in order to have 704.4 MHz at