superconducting accelerating cryo-module tests at desy international workshop on linear colliders...

Superconducting AcceleratingCryo-Module Tests at DESY

International Workshop on Linear Colliders 2010 (ECFA-CLIC-ILC Joint Meeting)

Denis Kostin, MHF-SL, DESY. 21.10.2010

2

Denis Kostin, MHF-SL, DESY. International Workshop on Linear Colliders 2010 (ECFA-CLIC-ILC Joint Meeting) 21.10.2010

Superconducting Accelerating Cryo-Module Tests at DESY

Overview

Module Test Stand CMTB

Module Test Procedure

Module Test Results

Summary

3



Cryo Module Test Bench

4



70K shield

Cavity type TESLANumber of cavities 8Cavity length 1.038 mOperating frequency 1.3 GHzR/Q 1036 ΩAccelerating Gradient 20..35 MV/mQuality factor 1010

Qext (input coupler) 3×106

Operating temperature 2 K

LHe cooling 2K / 31mbarHERA cryoplant is used

12m

4K shield

input coupler

2 phase LHe pipe

He gas return pipe

Module / Cryogenics

5



SRF module

10 MW klystron (MBK)

WG switchcirculator

modulator

coupler 1 coupler 8

CMTB RF System

6



CMTB LLRF System

7



Two gamma detectors are placed near the beam line on both ends of the module (by the end-caps).

Gamma detector "GUN"Gamma detector "DUMP"

module

Module Gamma Radiation Measurement

8



Module

Coupler

Common pumping line

Ion Getter PumpTi Sublimation Pump

Beam line

TSP/IGP connected in parallel and IGP used as a vacuum gauge.

Module Vacuum System

9



3 times e- (charged particles)

light in coupler vacuum

light in wave guide (air side)

temperature cold ceramic

temperature warm ceramic

vacuum coupler

vacuum cavity

bias voltage

cryogenic OK

low level R

F gate on klystron

all thresholds are hardware set

Coupler Technical Interlock

10



1. RF Cables Calibration. TDR cables check Dir.Couplers / Circulators: get calibration data. Calibrate RF power measurement cables with attenuators

at 1.3 GHz ( P for/ref att. 93 dB, P trans/HOM 40 dB ) Calibrate RF power measurement cables with attenuators

at 1…4 GHz ( optional ) Make RF calibration summary table

2. Technical Interlock / Sensors. Check the sensors (e-, Light, Spark, Temp.) Set the hardware interlock thresholds Check the interlock

3. RF source / Waveguides / LLRF. Klystron / LLRF check on the load WGs visual check System check / RF leak check at low power (1 kW pro coupler)

4. Warm Input RF Couplers Conditioning ( all / 1234 + 5678 ). Run the standard conditioning program:

20, 50, 100, 200, 400 s pulse lengths up to 1MW (min. 700kW), 800, 1300 s pulse lengths up to 600 kW, 2 Hz rep.rate. (If the klystron gives not enough of RF power divide the system into the successive tests in such a way that each coupler will be conditioned up to 1MW.)

Module Test Procedure (1)

11



5. Cooldown to 2K. 6. Cavities Spectra measurements.

Measure the fundamental mode spectra Measure the cavities HOMs spectra and Qload Calibrate the cold RF cables at 2K

7. Cavities Tuners Test. Test the cavities step-motor frequency tuners Tune the cavities to the 1.3GHz using the Network Analyzer

8. Couplers Qload measurement. Measure the Qload vs antennae positions,

check Qload.MIN and Qload.MAX using the Network Analyzer Set Qload = 3106 for each coupler

9. Cavities On Resonance. Cavities fine-tuning to the 1.3GHz using LLRF system Qload, Kt calibration ( Eacc=kt(Ptrans)

1/2 )


12



10. Cold Input RF Couplers and Cavities Conditioning. Find the cavities/couplers limits at 2 Hz rep.rate Run the standard cavity/coupler conditioning program:

20, 50, 100, 200 s pulse lengths up to 1MW (min. 700kW), 300, 400 s up to 330 kW, 500 s + 100, 200, 400, 800 s flat top pulse up to 250 kW, 2 Hz rep.rate. Eacc.MAX = 25 MV/m. Cavities HPP test is part of the conditioning (automatic), if the cavities limits are lower, run up to the min.cavity limit.

11. Module Performance Measurement. Module Eacc.MAX measurement at 2 Hz rep.rate Module accelerating gradient measurement at 10 Hz rep.rate

with cryo losses (Qo) and radiation measurements Radiation / Dark Current measurements, if needed. WG power redistribution possibilities check in case of

too different cavities limits (Eacc.MAX > 5 MV/m) 12. Single Cavities Measurements.

Detune all cavities except the one under test Flat-top pulse measurements at 10 Hz rep.rate

with cryo losses (Qo) and radiation measurements Investigate the cavities limits at 10 Hz rep.rate

13. Cryo system performance test (if needed).


13



mVPk

eL

PQQ

R

E

transt

Qtf

cavity

forloadsh

ACCload

fill

,

14 0

evaluated error margins for accelerating gradients in this test are about 10..16%.

RF Power Calibration

Rsh/Q=1030, Lcavity=1.035m, Qload=3106, f0=1.3GHz, Pfor5kW,tfill=1300s (for calibration, 500s for flat-top)

raterept

PP

PQR

LEQ

pulse

cryoloss

loss

acc

.

;2

0

HOMtransext

ext

accext

PPP

PQR

LEQ

,

;2

flat-top RF power pulse

Cavities gradients for the 1.3 ms rectangular pulse

RF Calibration / Test

14



M6-12

56

M6-34

78

M7-12

56

M7-34

78

M5-34

78

M5-12

56 M8 M3**

PXFE

L1

PXFE

L3

0102030405060708090

100110120130140150

module

MTS

cou

pler

s te

st: RF

pow

er r

ise

time

[hr]

pulse length:1300s 800 s 400 s 200 s 100 s 50 s 20 s

PMAX=700kW

IGP vacuum pressure IL limit set to 10-6 mbar

TS

P s

atu

rate

d

TS

P s

atu

rate

d

C1

wa

rm p

art

lig

ht

RF Couplers Conditioning Time

15



1 - AC129 2 - AC123 3 - AC125 4 - Z143 5 - Z103 6 - Z93 7 - Z100 8 - AC1130

5

10

15

20

25

30

35

40

FLASH 30MV/m XFEL goal

13.07.2009

EA

CC [

MV

/m]

cavity

Cavity tests: Vertical ( CW ) Horizontal (10Hz) CMTB M8 (10Hz) CMTB (10Hz)

very

long

CW

cond

ition

ing

Cavities gradient limits

1 - AC129 2 - AC123 3 - AC125 4 - Z143 5 - Z103 6 - Z93 7 - Z100 8 - AC1130

5

10

15

20

25

30

35

40

Cavities Field Emission

13.07.2009

EA

CC [

MV

/m]

Module PXFEL1 MTS: FE start

X > 10-2 mGy/min

max.gradient

cavity

1 - AC129 2 - AC123 3 - AC125 4 - Z143 5 - Z103 6 - Z93 7 - Z100 8 - AC11310-5

10-4

10-3

10-2

10-1

H

M

MM

V

V

V

cavity 8 tested in horizontal cryostat before module assembly (H)

cavities 1..4 tested in vertical cryostat before module assembly (V)

13.07.2009

Xra

ys [

mG

y/m

in]

X-raysmax

:

V/H/M test MTS.Gun MTS.Dump

single cavities radiation at Eacc.max

cavity

cavities 5,6,7 were in the module 8 at the same positions (M)

V

Module Test Results: PXFEL1 (1)

16



10 15 20 25 300

2

4

6

8

dyn

am

ic (

RF

) lo

sse

s P

cryo

[W]

<Eacc

> [MV/m]

10 Hz

10 15 20 25 30109

1010

Q0

<Eacc

> [MV/m]

10 15 20 25 3010-5

10-4

10-3

10-2

10-110 Hz

X-r

ays

[mG

y/m

in]

<Eacc

> [MV/m]

XGun

XDump

Flat-top pulse 500+800μs operation at 10 Hz


17



measured (CMTB) XFEL specification

RF power, kW 120 230 200

4K losses, W 0.1 0.26 0.5

70K losses, W 2.5 3.75 6.0

RF power coupler dynamic losses

18 19 20 21 22 23 24 25 26 27 28 2910-5

10-4

10-3

10-2

10-1

Module PXFEL1 all cavities tuned

CMTB, 10Hz MTS.Gun MTS.Dump

X-r

ays

[m

Gy/

min

]

<EACC

> [MV/m]

Module Field Emission vs Accelerating GradientModule Test Results: PXFEL1 (3)

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1 - Z141 2 - AC150 3 - Z133 4 - Z139 5 - AC122 6 - AC121 7 - AC128 8 - AC1150

5

10

15

20

25

30

35


XFEL goal

04.05.2010

EA

CC [

MV

/m]

cavity

Cavity tests: Vertical ( CW ) Horizontal(10Hz) CMTB (10Hz)

MP

1 - Z141 2 - AC150 3 - Z133 4 - Z139 5 - AC122 6 - AC121 7 - AC128 8 - AC1150

5

10

15

20

25

30

35

Cavities Field Emission

04.05.2010

EA

CC [

MV

/m]


X > 10-2 mGy/min

max.gradient

cavity

1 - Z141 2 - AC150 3 - Z133 4 - Z139 5 - AC122 6 - AC121 7 - AC128 8 - AC11510-5

10-4

10-3

10-2

10-1 04.05.2010

Xra

ys [

mG

y/m

in]

X-raysmax

:

Vert. test MTS.Gun MTS.Dump


cavity


19



15 16 17 18 19 20 21 22 23 24 25 26109

1010

cav.

3 de

tune

d

Q0

<Eacc

> [MV/m]

cav.

3 de

tune

d

15 16 17 18 19 20 21 22 23 24 25 2610-5

10-4

10-3

10-2

10-1cav.3 detuned

cav.3 detuned

10 Hz

X-r

ays

[mG

y/m

in]

<Eacc

> [MV/m]

XGun

XDump

15 16 17 18 19 20 21 22 23 24 25 2601234567

cav.

3 d

etu

ned

cav.3 detuned

dyna

mic

(R

F)

loss

es P

cryo

[W]

<Eacc

> [MV/m]

10 Hz


20



1 - Z135 2 - AC124 3 - Z88 4 - Z134 5 - Z101 6 - AC127 7 - Z140 8 - Z970

5

10

15

20

25

30

35


XFEL goal

13.09.2010

EA

CC [

MV

/m]

cavity

Cavity tests: Vertical ( CW ) Horizontal(10Hz) CMTB (10Hz)

MP

FE

FE

1 - Z135 2 - AC124 3 - Z88 4 - Z134 5 - Z101 6 - AC127 7 - Z140 8 - Z970

5

10

15

20

25

30

35Cavities Field Emission

13.09.2010

EA

CC [

MV

/m]


X > 10-2 mGy/min max.gradient

cavity

1 - Z135 2 - AC124 3 - Z88 4 - Z134 5 - Z101 6 - AC127 7 - Z140 8 - Z9710-5

10-4

10-3

10-2

10-113.09.2010

Xra

ys [

mG

y/m

in]

X-raysmax

:

Vert. test MTS.Gun MTS.Dump


cavity


21



14 15 16 17 18 19 20 21 22 23 24 25109

1010

cav.

3,6

,7 d

etu

ne

d

Q0

<Eacc

> [MV/m]

cav.

3,6

de

tun

ed

14 15 16 17 18 19 20 21 22 23 24 2510-6

10-5

10-4

10-3

10-2

10-1

cav.

3,6

,7 d

etu

ne

d

cav.3,6 detuned

10 Hz

X-r

ays

[mG

y/m

in]

<Eacc

> [MV/m]

XGun

XDump

14 15 16 17 18 19 20 21 22 23 24 250

1

2

3

4

cav.

3,6

,7 d

etu

ne

d

cav.3,6 detuned

dyna

mic

(R

F)

loss

es P

cryo

[W]

<Eacc

> [MV/m]

10 Hz


22



Summary

The Cryo Module Test Bench ( CMTB ) was built at DESY to test the accelerating SRF modules and cavities independently from the FLASH operation. CMTB allows the high and low power RF tests, as well as cryogenic tests to be conducted on one SRF module. 9 SRF modules ( including one 3.9 GHz module ) tested until now at CMTB.

7 superconducting accelerating modules are used now in the FLASH LINAC at DESY. 3 modules were tested at FLASH and 4 modules were tested at CMTB facility.

First three XFEL prototype modules PXFEL1,2,3 were assembled in team-work with XFEL Cold Linac Partners ( IHEP / Beijing, CEA-IRFU / Saclay, IN2P3-LAL / Orsay, INFN / Milano, CIEMAT / Madrid, DESY ) and tested at module test stand CMTB at DESY.

Modules tested with equal cavity RF power distribution as well as single cavities with only one cavity on resonance at time. The cavities were tested with the flat-top RF pulse with 0.5 ms rise time and 0.8 ms flat-top. The own quality factors Q0 measurements were done using the cryogenic losses measurement on the CMTB, modules radiation measurements done as well on the both ends of the module ( gun / dump side ).

In PXFEL1 cavities gradients from 27 to 36 MV/m are reached, module operation with average gradient of 30 MV/m using tailored RF power distribution is possible. PXFEL1 is used in FLASH (ACC7).

Modules PXFEL2 and 3 suffered from some cavities degradation: one cavity in PXFEL2 and two in PXFEL3 did not reach 20 MV/m.

superconducting accelerating cryo-module tests at desy international workshop on linear colliders...

Documents

thesuccessive tests

rf cables calibration

cold rf cables

rf power measurement

warm input rf couplers

desymodule test procedure

rf source waveguides

cavities tuners