denis kostin, desy meeting. desy, november 9 , 2004 · denis kostin, desy mac meeting.desy,...

MAC Meeting. DESY, November 9th, 2004Denis Kostin, DESY


«VUV-FEL LINAC Accelerating Modules«VUV-FEL LINAC RF Power Couplers«VUV-FEL LINAC Cavities«Conclusion


ACC1 ACC2 ACC3 ACC4 ACC5RF-GUNBC2 BC3


CylindricalCylindricalTTF IIIMar. 20025ACC5Plane, WGCylindricalTTF IIJul. 20014ACC4Plane, WGCylindricalTTF IIFeb. 20033*ACC3

PlanarConical/Cyl.FNAL/TTF IIMar. 20001*ACC2Planar/CylConical/Cyl.FNAL/TTF IIIJan. 20042*ACC1

warm windowcold windowcoupler typeassembledmoduleposition

Five accelerating modules were installed into the TTF tunnel as a part of the VUV FEL LinacEach module has 8 superconducting cavities and RF power input couplers


TTF III Coupler


bias voltage, suppressing multipactingisolated inner conductor6 W70 K heat load

sufficient for safe operation and monitoring

diagnostic

0.5 W4 K heat load0.06 W2 K heat load

• safe operation• clean cavity assembly for high Eacc

two windows, TiN coated

pulsed: 500 µsec risetime,800 µsec flat top with beam

operation

1.3 GHzfrequency

adjustable( 106 - 107 )

fixed( 3*106 )

adjustable( 106 - 107 )

Coupling (Qext)

1.9 kW3.2 kW / 6.4 kW

3.2 kWAverage power

10 Hz5 Hz10 HzRepetition rate

150 kW250 kW / 500 kW

250 kWPeak power + control margin

XFELTESLA 9cell / upgradeTTF


FNAL coupler


module 70K shield 4K shield

cavitycold windowwarm window


À Total of 40 RF power couplers connected to the superconducting cavities in the VUV FEL linac, eight in a module.

À All couplers in the VUV FEL linac could be processed and operated up to the cavity performance limits.

À The parallel processing of 8 respectively 16 couplers at the modules is slower than that at the test stands or in the horizontal cryostat.

À RF power couplers were tested up to 1 MW of pulsed power at 1.3 ms pulse length 2 Hz at the test stand.

À RF power couplers operated ~270000 hours*coupler.À Last coupler design TTF III has simplified assembly as well as

better performance, conditioning time is shorter.À TTF III couplers are tested together with cavities at gradients of 35

MV/m (600 kW) 5 Hz without degradation of cavity or coupler.


[ ]mVPk

eL

PQQ

R

E

transt

Qtf

cavity

forloadsh

ACCload

fill

,

14 0

×=

=

−×=

−π

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

RF Power Calibration

Rsh/Q=1030Ω, Lcavity=1.035m, Qload=3×106, f0=1.3GHz, Pfor≈5kW,tfill=1300µs (for calibration, 500µs for flat-top (FT))


EP cavity

1 - Z54 2 - Z51 3 - D42 4 - D37 5 - AC72 6 - C47 7 - Z53 8 - AC690

5

10

15

20

25

30

35

FEMod

ule

2 3 .04 .2004

M o d u le 2*

EA

CC [M

V/m

]

Cavity

Cryostat tests: Vertical Horizontal Module (5Hz)

3dB att.

3dB WG power attenuator put before cavity 7 to lower the fieldemission and to use cavities 5,6 and 8 with higher gradients


1 - S31 2 - C44 3 - C46 4 - S36 5 - D2 6 - A18 7 - D1 8 - A170

5

10

15

20

25

30

35

Mod

ule

5 .11 .2002

M o d u le 1*

EA

CC [M

V/m

]

Cavity

Cryostat tests: Vertical Horizontal Module

2dB att.3dB att.1dB att.

WG power attenuators are installed before cavities 1, 2 and 6 to use other cavities with higher gradients


1 - D41 2 - S32 3 - S29 4 - S30 5 - AC58 6 - D40 7 - S28 8 - Z500

5

10

15

20

25

30

35

Mod

ule

BD, F

E

cav.

tune

r

M o d u le 3*

0 1 .10 .2004

EA

CC [M

V/m

]

Cavity

Cavity tests: Vertical (CW) Horizontal (10Hz) Module 3 (10Hz) Module 3* (5Hz)

During Module 3 disassembly couplers antennae touched cavity surface. Cavity 4: cavity tuner problem. Cavity 7: 6dB WG power attenuator installed.

6dB att.


1 - C48 2 - S34 3 - AC57 4 - AC56 5 - AC55 6 - AC59 7 - Z52 8 - AC640

5

10

15

20

25

30

35

Mod

ule

BD

BD

BDBD

M o d u le 4

0 1 .10 .2004

EA

CC [M

V/m

]

Cavity

Cavity tests: Vertical (CW) Horizontal (10Hz) Module 4 (1Hz) Module 4 (5Hz)


1 - AC62 2 - AC61 3 - AC65 4 - AC66 5 - AC79 6 - AC77 7 - AC63 8 - AC600

5

10

15

20

25

30

35

BDdark current src

M o d u le 5

0 1 .10 .2004

EA

CC [M

V/m

]

Cavity

Cavity tests: Vertical (CW) Horizontal (10Hz) Module 5 (1Hz) Module 5 (5Hz)

Cavity 6 is a source of a dark current of 200 nA (peak) at 25 MV/m. Radiation level measured at 1 m distance from module 5 dump side: 18 µSv/min.


1* 2* 3* 4 50

5

10

15

20

25E

AC

C [M

V/m

]

TESLA500 specs.

ModuleACC2 ACC1 ACC3 ACC4 ACC5


0

10 15 20 25 30

109

1010

Q0(E

A C C) @ 5 H z

M o d u le 1* M o d u le 3* M o d u le 4 M o d u le 5

QO

EA C C

[ M V / m ]

ACC2ACC3ACC4ACC5


1,0E+09

1,0E+10

1,0E+11

0 5 10 15 20 25 30 35 40Eacc [MV/m]

Q0

Low power testHigh power pulsed test 1HzHigh power pulsed test 5Hz

Accelerator RF test

Cavity AC72 1011

109

1010

Ú Same performance with beam as in previous low and high power tests without beam

Ú Very low cryogenic losses as in high power testsÚ Standard X-ray radiation measurement indicates no radiation

up to 35 MV/m


« All couplers in the VUV FEL linac could be processed and operated up to the cavity performance limits.

« The last two modules, 4 and 5, fulfill the TESLA500 specifications.

« ACC5 / module 5, tested at the repetition rate of 5 Hz was operating atthe accelerating gradient of 25.5 MV/m , 500 + 800 µs full length flat-toppulse and quality factor of 1×1010.

« ACC5: cavity 6 is a source of a dark current of 200 nA (peak) at 25 MV/m.

« ACC1: cavity 7 is a source of a dark current, up to 10 mGy/min measured on axis.

« All modules have functioned continuously during certain periods of time.

« The beam operation started with all modules.

« Cavity 5 (AC72, EP) tested in Module 2* / ACC1 reached 35 MV/m,confirmed with beam.

denis kostin, desy meeting. desy, november 9 , 2004 · denis kostin, desy mac meeting.desy,...

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