Superconducting RF cavities activities for the MAX project · Pre -conditioning (1 kW) of the couplers Power ramped-up to 880 W in 24 h Automatic procedure and control program validated

Superconducting RF cavities activities for

the MAX project

OECD-NEA TCADS-2 Workshop

Nantes, 22 May 2013

Marouan El Yakoubi, CNRS / IPNO

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TCADS-2 Workshop, Nantes

EL Yakoubi M. TCADS-2 Workshop, Nantes May 22, 2013

Contents

• 352 MHz spoke Cryomodule design

• 700 MHz test area

• 700 MHz Power couplers

• 700 MHz Power couplers conditioning setup

• Conclusions & Roadmap

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MYRRHA / XT-ADS Accelerator Scheme

Βg = 0.47 section of the Linac5 cell cavity Freq = 704.4 MHzNominal accelerating voltage Eacc(Βg ) = 8.5 MV/m

IntroductionTCADS-2 Workshop, Nantes



4

F 1200

Connection to

Valves Box

Warm Stop Valve

Cavity Train Put on adjustable Posts

One Thermal

Shield (40K/80K)

Coupler Barometric

Compensation

Supporting Frame

Sliding Blocks 2 Beta 0.37, 352 MHz Spoke Cavities

Op. Temperatures : 2 K, 5/10 K, 40/80 K

352 MHz Cryomodule overviewH. Saugnac (IPNO)



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Electro Magnetic Optimization : CST

Mechanical Optimization : ANSYS.

Mechanical/EM coupled Simulations :

ANSYS

Detailed Drawings OK

Cavity Wall: Nb RRR>250 (thck. 3 mm)

Helium Vessel Ti Grade 2 (thck. 3 mm)

Epk

Bpk

352 MHz Spoke Cavity Beta 0,37

Optimized Parameters Optimized Parameters

Eacc normal operation;

Eacc fault tolerance

6,2

8,2 MV/m

Lacc=optimal beta x c x f [m] 0,315

Epk/Eacc 4,29 Tuning Sensitivity [kHz/mm] 156

Bpk/Eacc [mT/MV/m] 7,32 Sensitivity to Pressure

[Hz/mbar]

7,6 < SP< 14

G [Ohm] 109 Lorentz Force Factor

[Hz/(MV/m)2]

-6 < KL< -5,28

r/Q [Ohm] 217 Approximated Bandwidth 150 Hz

Qo @ 2K for Rres=20 nΩ 5,2.109 b optimal 0.37

H. Saugnac (IPNO)



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The CTS (CEA ‘Soleil’ Type) for The MAX Spoke cavities is the Same as the one Designed for the ESS Spoke Cavities.

PiezoActuators

Stepping Motor

Cold Tuning SystemH. Saugnac (IPNO)

Cavity elongation along its Axis

Coarse Range (Stepping Motor) ~ 150 KHZ @2K Limited by Max Stress

Fine Range (Piezo) > 300 Hz

Stiffness > 100 KN/mm



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A Power Coupler 352MHz, 20 kW CW (designed), 50 W. WARM WINDOW

Was manufactured, in the framework of Eurotrans and successfully tested at 8 kW (amplifier limitation) CW on a 350 MHz, beta 0.15 Spoke cavity in a Cryomodule configuration.

Basis for design

2 CF16 ports for vacuum measurements.

1 port for electron emission measurement pick up

1 water cooling loop for the window

Plain Copper Antenna

CF 63 on cavity

Thermal interception at 70 K (~15 W solid conduction) and ~ 10 K (~3 W solid conduction)

The Design (SNS Type) will be kept as it for MAX

Power coupler

H. Saugnac (IPNO)


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RF Source 80 kW CW

160 kW DC Power Supply + IOT

700 MHz Cryomodule

• Cavity & tuning system

• Power Coupler

• RF source 80 kW CW

• Cryogenic Valves Box

700 MHz area

Cavity 5-cells β=0.47 700MHz Cryomodule

Power coupler



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Cavity (5 cells)

Cavity coupling port

Outer conductor (Lhe-cooled @4.5K)

Inner conductor / Antenna (water – cooled)

Doorknob: Transition coaxial (power coupler) to rectangular waveguide (towards the IOT)

Vacuum

Air

Ceramic (97% alumina ) disc window (water-cooled)

Power coupler main view

Power couplers

(I)

(II)

(III)



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Power Couplers

Heat exchanger received, vacuum tests revealed no leak.

•2 prototypes of window + antenna were brazed & delivered.

•1 ceramic disc have TiNdeposit (20 nm)

1 ceramic disc without deposit.

2 Power Couplers manufactured by SCT SocietyAnd checked at IPN Orsay in May 2009



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17th to 21st Spet.2012 : the IOT has beensuccessfully re-tested with its RF circulator in fullreflection until 80 kW. The current of the circulatorcoil had been tuned to enable fast RF power increase(J. Lesrel )

The DC power supply can now be control througha Labview program via Ethernet (C. Joly )

RF power supply

25th sept. 2012 : The coupler conditioning bench wasassembled to the IOT

Conditioning started in October 2012 (E. Rampnoux)



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Power Couplers conditioning setupPower coupler conditioning : Experimental setup

Conditioning cavity



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Pre -conditioning (1 kW) of the couplers

Power ramped-up to 880 W in 24 h

Automatic procedure and control programvalidated.

RF

po

we

r (W

)

Time

Cin

Cout

E. Rampnoux & S. Berthelot

IN OUT

Cavity


No multipacting detected during the lowpower test

Vacuum leak rate remained at: 1.210-8

mbar.l.s-1


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Couplers conditioning

RF power conditioning couplers in CW operation mode @ 30 kW.

1,80E-08

3,80E-08

5,80E-08

7,80E-08

9,80E-08

1,18E-07

1,38E-07

1,58E-07

1,78E-07

0

5

10

15

20

25

30

35

00: 00: 00 00: 50: 03 1: 40: 05 2: 30: 08 3: 20: 10 4: 10: 13 5: 00: 16 5: 50: 18

Pre

ssu

re (

mb

ar.

l.s-1

)

RF

Po

we

r (k

W)

Time (hh:mm:ss)

RF Power

Vacuum Pressure

• RF power reaches 30 kW in 6 hours

• No safety system at fault

• Degradation of vacuum level from 17 kW.



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Couplers conditioning

RF power conditioning couplers in CW operation mode @ 42 kW.

high vacuum level: Input coupler ceramic broken !

Hypothesis :• TiN deposit have weakened the ceramic

window.• Heat stress• Coupler conditioning with CW mode is not suitable

Ongoing :•Analysis under progress to understand what happened.• Modification of the conditioning procedure: operating in pulsed mode, which is the safe state-of-the-art.•New coupler TOSHIBA was prepared.

1,00E-08

1,00E-07

1,00E-06

1,00E-05

1,00E-04

1,00E-03

1,00E-02

1,00E-01

1,00E+00

0,00E+00

5,00E+03

1,00E+04

1,50E+04

2,00E+04

2,50E+04

3,00E+04

3,50E+04

4,00E+04

4,50E+04

0:00:300:01:000:01:310:02:010:02:310:03:010:03:320:04:020:04:32

Ps3

Vide Cin

Vide Cout

November 8, 2012



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New TOSHIBA coupler

end of the antenna

Power Coupler manufactured by TOSHIBA Society

Mechanical constructions were achieved at IPNO (D. Grolet) .

Electron beam welding was carried out by SAFEL society.

outer envelope

TOSHIBA coupler is ready and qualified

TOSHIBA window

Internal antenna




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Goal: Improve the surface condition of the antennaReduce scratch marks on the antenna.

• Electro-polishing bath: Phosphoric acid + alcohol (propanol)

• Voltage Generator (10 V / 30 A)

. Eliminating a thickness

of 200 μm matter

. Appearance close to the

mirrorBefore After

Coupler electro-polishing @ LPSC

• Y. Gomez Martinez, P. De Lamberterie, T. Cabanel (LPSC)• R. Martret (IPNO)

Materiel

Results



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Gate = 20 µs rise time = 1nsPk = 64 kW

Test with low pulse frequency= 1 Hz (J. Lesrel)

• To prevent the temperature of the RF power supply diodes exceed 30°C

• No disjunction of the power supply 40 kV

IOT output Power meter

Current security 3.9A (not to exceed)

Pulsed test IOT

Chanel 2 = I HV

(4A/10V)

Chanel 1 = U HV(40kV/10V)

We can work in Pulsed Wave if the rate is low

Tests sent to Brucker company for validation


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Conclusion & Roadmap The Spoke Cryomodule design is in progress.

A new power coupler was prepared in short time.

The IOT was tested successfully pulsed mode.

Re-assembling the conditioning bench with the IOT is under progress .

The power coupler conditioning will restart very soon and we plan a 2 weeks period for the

test.

A clean room session is foreseen for the end of June 2013: for the power coupler assembly.

The Module preparation & wave guide installation will start soon.

First INTEGRATED high power test @ CRYOGENIC TEMPERATURE: Summer 2013.

Goal before end 2013: reliability-oriented experiment with Digital LLRF + Cold tuningsystem + ADEX smart control to validate the fast fault recovery procedure.



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I’ Would to Thank you very much for your attention



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Conditioning @ 18 kW

A first travelling wave (CW) conditioning at 18 kW was foreseen.

1,00E-08

1,00E-07

1,00E-06

1,00E-05

1,00E-04

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

00:00:0000:00:0000:00:0000:00:0000:00:0000:00:0000:00:00Temps (h:mm;ss)

Ps3

Vide Cin



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Gate =1,8 ms with rise time = 100 µs



MAX meeting, Louvain

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Documents

Superconducting RF cavities activities for the MAX project · Pre -conditioning (1 kW) of the couplers Power ramped-up to 880 W in 24 h Automatic procedure and control program validated