ILC Tech Meeting, March 29ILC Tech Meeting, March 29thth20072007

Cold quadrupole vibration measurements on Module 6 during the 10th/11th thermal cycles

at CMTB

Ramila Amirikas, Alessandro Bertolini, Wilhelm Bialowons, Markus

KubczigkDESY

ILC Tech Meeting, March 29ILC Tech Meeting, March 29thth20072007

Some views of the CMTB at Bldg.70Some views of the CMTB at Bldg.70

Feedbox

Feedbox to feedcap connection

Cryomodule (quad side) to endcap connections

ILC Tech Meeting, March 29ILC Tech Meeting, March 29thth20072007

The experimentThe experiment

Two new seismic sensors (one vertical+one horizontal geophone) were installed aboard the Module 6 quadrupole for the 10/11th thermal cycles, from February 19st to March 8th.

ILC Tech Meeting, March 28ILC Tech Meeting, March 28thth20072007

The experiment - The experiment - GoalsGoals

Test geophone behaviour at 4 K inside a fully operating cryomodule

• on-board seismic sensor with adequate noise level down to below 1 Hz potentially available for quad and cavities.

• behaviour unknown, never been tested by the manufacturer in these extreme conditions, the company recommends use of the device down to -40°C, only one cryogenic application cited in literature.

• the very robust and mature (~30 years) design was encouraging and the test has been successful.

Quadrupole vibration measurements at 4 K

• chance to give a first quantitative (from 1 Hz) evaluation of the impact of cryogenic plant and high gradient RF on the quadrupole vibration level, not possible so far because of the lack of sensitivity of cooled piezo accelerometers below ~10 Hz

The experiment – The experiment – SetupSetup

ILC Tech Meeting, March 29ILC Tech Meeting, March 29thth20072007

Cold/warm Geophone

20 m cable20 m cable

preampreampp

InversInverse filtere filter

l

l

Qi

Qi

1221

0220

Test amplifierTest amplifier

24 bit Güralp digitizer

200 S/s200 S/s

Inverse filteInverse filtering ring provides equalization provides equalization of the geophone of the geophone response down to 0.35 response down to 0.35 HzHz

LaptopData loggingSpectral analysis (FFT, PSD, Coherence,RMS,Transfer function,etc.)

Vessel top vertical sensor (horizontal

transverse companion not visible)

Ground vertical sensor (horizontal

transverse companion not

visible)

Some definitions

Quadrupole vibrations – Quadrupole vibrations – Cryomodule Cryomodule warm I warm I

ILC Tech Meeting, March 29ILC Tech Meeting, March 29thth20072007

General features General features of the spectraof the spectraTypical DESY site Typical DESY site spectrum at low spectrum at low frequencies. frequencies. Technical noise Technical noise dominating > 20 Hz; dominating > 20 Hz; strongest peak from strongest peak from the insulation the insulation vacuum pump at 48 vacuum pump at 48 HzHz. Module vertical . Module vertical resonance at resonance at 27 Hz27 Hz; ; quad vs top transfer quad vs top transfer function almost flat function almost flat below 40 Hz.below 40 Hz.

Values @ 1 Hz:Ground 76 nmTop 90 nmQuad 103 nm

*2 hrs data measured at the end of the 10th thermal cycle*2 hrs data measured at the end of the 10th thermal cycle

Quadrupole vibrations – Quadrupole vibrations – Cryomodule Cryomodule warm IIwarm II

ILC Tech Meeting, March 29ILC Tech Meeting, March 29thth20072007

Coupling between axesCoupling between axesCoupling with the Coupling with the 18 Hz18 Hz horizontal longitudinal mode at both quad and top positions. Coupling with the horizontal longitudinal mode at both quad and top positions. Coupling with the 11 Hz11 Hz horizontal transverse rocking mode on quad (due to the off-axis location). horizontal transverse rocking mode on quad (due to the off-axis location).

Quadrupole vibrations – Quadrupole vibrations – Cryomodule Cryomodule warm IIIwarm III

ILC Tech Meeting, March 29ILC Tech Meeting, March 29thth20072007

RMS analysisRMS analysis

In the low frequency In the low frequency band the quadrupole band the quadrupole motion tracks the motion tracks the ground vibration ground vibration level. level. Slight amplitude Slight amplitude differences are differences are related mainly to the related mainly to the mechanical transfer mechanical transfer function of the function of the module on its module on its support system. support system. Non perfect Non perfect equalization of the equalization of the sensor response sensor response can can also affectalso affect the the accuracy. Low accuracy. Low frequency quad RMS frequency quad RMS overestimated overestimated (~10%) because of (~10%) because of the low resonant the low resonant frequency (4.14 Hz) frequency (4.14 Hz) of this geophone at of this geophone at room temperature.room temperature.

Quadrupole vibrations – Quadrupole vibrations – Reaching the cold steady state – no Reaching the cold steady state – no RF - IRF - I

ILC Tech Meeting, March 29ILC Tech Meeting, March 29thth20072007

RMS analysisRMS analysis

Ground motion Ground motion tracking confirmed at tracking confirmed at low frequencies, with low frequencies, with ~10% quad/gnd and ~10% quad/gnd and top/gnd rms ratios. top/gnd rms ratios. No difference with No difference with warm operation.warm operation.The The refrigeration refrigeration system doesn’t affect system doesn’t affect the quadrupole the quadrupole vertical stability at vertical stability at low frequency (f<30 low frequency (f<30 Hz).Hz).Large vibrations due Large vibrations due to the build up of a to the build up of a strong peak above strong peak above 30Hz. The peak 30Hz. The peak shows slow shows slow frequency changes frequency changes from 30.1Hz up to from 30.1Hz up to 32Hz. The amplitude 32Hz. The amplitude can vary from 200 can vary from 200 nm up to > 1 µm. nm up to > 1 µm. Not a mechanical Not a mechanical resonance of the resonance of the cryomodule; not cryomodule; not visible at all in the visible at all in the quad vs top transfer quad vs top transfer function.function.

Steady stateSteady state

Quadrupole vibrations – Quadrupole vibrations – Reaching the cold steady state – no Reaching the cold steady state – no RF - IIRF - II

ILC Tech Meeting, March 29ILC Tech Meeting, March 29thth20072007

08 March 08 March in steady statein steady stateQuad LHe inlet flow: 8.2 g/secQuad LHe inlet flow: 8.2 g/secQuad LHe inlet valve: 20%Quad LHe inlet valve: 20%Cavity Cavity 2K Inlet valve: 56%2K Inlet valve: 56%Cavity 2K Cavity 2K He flow: 5 g/secHe flow: 5 g/secCavity 2K He reservoir level:43%Cavity 2K He reservoir level:43%

CommentsCommentsPeak frequency ~ 32Hz in this case. The integrated RMS Peak frequency ~ 32Hz in this case. The integrated RMS @1 Hz values are 78 nm (ground), 206 nm (vessel top), @1 Hz values are 78 nm (ground), 206 nm (vessel top), 260 nm (quad). The peak is also visible in the ground 260 nm (quad). The peak is also visible in the ground spectrum.spectrum.

Quadrupole vibrations – Quadrupole vibrations – Cold operation with LLRF and RF High Cold operation with LLRF and RF High gradientgradient

ILC Tech Meeting, March 29ILC Tech Meeting, March 29thth20072007

Note:Note:EMI from the klystron modulator at 10 Hz and harmonics; reduced by a factor ~10 with better digitizer and battery operation.EMI from the klystron modulator at 10 Hz and harmonics; reduced by a factor ~10 with better digitizer and battery operation.

20 February 20 February High gradient steady High gradient steady statestateQuad LHe inlet flow: 5.5 g/secQuad LHe inlet flow: 5.5 g/secQuad LHe inlet valve: 100%Quad LHe inlet valve: 100%Cavity Cavity 2K Inlet valve: 50%2K Inlet valve: 50%Cavity 2K Cavity 2K He flow: 4.5 g/secHe flow: 4.5 g/secCavity 2K He reservoir level:43%Cavity 2K He reservoir level:43%

2233 February February Low gradient steady Low gradient steady statestateQuad LHe inlet flow: 5.5 g/secQuad LHe inlet flow: 5.5 g/secQuad LHe inlet valve: 100%Quad LHe inlet valve: 100%Cavity Cavity 2K Inlet valve: 35%2K Inlet valve: 35%Cavity 2K Cavity 2K He flow: 3.8 g/secHe flow: 3.8 g/secCavity 2K He reservoir level:43%Cavity 2K He reservoir level:43%

Quadrupole vibrations – Quadrupole vibrations – RF high gradient – RF high gradient – 2K/1.8K/1.6K2K/1.8K/1.6K

ILC Tech Meeting, March 29ILC Tech Meeting, March 29thth20072007

RMS analysisRMS analysis

Ground motion Ground motion tracking confirmed at tracking confirmed at low frequencies. low frequencies. Usual large vibration Usual large vibration amplitude at high amplitude at high frequency. frequency. The The high high gradient RF gradient RF operation doesn’t operation doesn’t affect the quadrupole affect the quadrupole stability.stability. High frequency High frequency vibrations stopped vibrations stopped during the refilling of during the refilling of the cavity reservoir the cavity reservoir at 9:12AM. The quad-at 9:12AM. The quad-LHe inlet valve is LHe inlet valve is closed in that case. closed in that case. Suspects on the 4.5K Suspects on the 4.5K circuit are confirmed.circuit are confirmed.

Quadrupole vibrations – Quadrupole vibrations – RF high gradient – RF high gradient – 2K/1.8K/1.6K2K/1.8K/1.6K

ILC Tech Meeting, March 29ILC Tech Meeting, March 29thth20072007

Correlations?Correlations?

The high frequency The high frequency RMS level seem RMS level seem correlated to correlated to changes in the LHe changes in the LHe level in the Feedbox level in the Feedbox Heat exchanger.Heat exchanger.

ILC Tech Meeting, March 29ILC Tech Meeting, March 29hh20072007

Summary of the resultsSummary of the results

Geophone test at 4.5K

• classic 4.5 Hz industrial geophone can operate at 4K without any loss of sensitivity

• in-situ high accuracy calibration procedure demonstrated

Quadrupole vibration measurements at 4.5K

• low frequency (1-100 Hz) quadrupole vertical stability is not affected by high gradient RF operation

• quadrupole vertical stability is not affected by the refrigeration system at frequencies up to 30 Hz; results not conclusive at higher frequency because of the presently not completely understood mechanical behaviour of the CMTB 4.5K circuit.

• need to continue investigation on Module 7 at CMTB (for better understanding) and on Module 6 in different conditions (in operation in the FLASH linac for example).

• Module 8 will operate at 2K…

ILC Tech Meeting, March 29ILC Tech Meeting, March 29hh20072007

NextNext

Module 7 at CMTB:

Two cold geophones+the existing two piezo accelerometers already installed aboard the quadrupole. Complementary geophones on top of the vessel and on the ground. Continuous data acquisition for the whole test (only one thermal cycle). Two or more DOOCS acquisition channels should be available for the beginning of the run. Cool down starting end next week.

Geophone pair mounted in front of the Geophone pair mounted in front of the Module 7 quadrupole; new stiffer holder will Module 7 quadrupole; new stiffer holder will be installed this afternoonbe installed this afternoon

Module 6 in FLASH linac:

Geophones will stay on Module 6 and Module 7 permanently. MKS asked for more sensors to also equip ACC4 and ACC5. Data acquisition with sufficient number of channels must be produced. Cool down of the FLASH linac is scheduled for the end of July.

Thanks to:

Rolf Lange, Kay Jensch, Wolfgang Maschmann, Peter Smirnov, Oliver Paschold, Helmut Remde