April 27th, 2006April 27th, 2006Paola Puppo – INFN RomaPaola Puppo – INFN Roma

ILIASILIAS

Cryogenic payloads and cooling systems Cryogenic payloads and cooling systems (towards a third generation interferometer)(towards a third generation interferometer)

part II:part II: the Vibration Free the Vibration Free Cryostat and the Cryogenic Mini-Cryostat and the Cryogenic Mini-PayloadPayload

Paola PuppoPaola PuppoI.N.F.N. Sezione di Roma I.N.F.N. Sezione di Roma

April 27th, 2006April 27th, 2006Paola Puppo – INFN RomaPaola Puppo – INFN Roma

ILIASILIAS

Refrigeration system study:

The Vibration Free Cryostat (V.F.C.) Thermal behavior; Cryogenic Instrumentation for the monitor and control

displacement sensor (low frequency) cryogenic accelerometers (high frequency)

Results on the vibration control

Cryogenic small scale payload made of silicon:

• Assembly test

April 27th, 2006April 27th, 2006Paola Puppo – INFN RomaPaola Puppo – INFN Roma

ILIASILIAS

Refrigeration system studyRefrigeration system study::

The cryogenic facility: Vibration Free The cryogenic facility: Vibration Free Cryostat (Cryostat (V.F.C.V.F.C.))

April 27th, 2006April 27th, 2006Paola Puppo – INFN RomaPaola Puppo – INFN Roma

ILIASILIAS

The Vibration Free Cryostat: principle schemeThe Vibration Free Cryostat: principle scheme

V.F.C.

Spring

Active vibrational Active vibrational isolation system for isolation system for the heat linkthe heat link

Shorter heat linkShorter heat link Refrigerating power Refrigerating power

preservedpreserved

It is necessary to It is necessary to monitor the vibration monitor the vibration at low temperature at low temperature and to act on the and to act on the refrigerator:refrigerator:

Accelerometers Accelerometers and position and position sensing devices;sensing devices;

Actuators;Actuators;

April 27th, 2006April 27th, 2006Paola Puppo – INFN RomaPaola Puppo – INFN Roma

ILIASILIAS

Sumitomo cryocoolerSumitomo cryocooler

Cooling capacity1st stage 10W/20W @ 45 K (50/60 Hz)

2nd stage 0.5W/0.5W @ 4.2 K (50/60 Hz)

Lowest temperature < 3 K

April 27th, 2006April 27th, 2006Paola Puppo – INFN RomaPaola Puppo – INFN Roma

ILIASILIAS

Vibration Free Cryostat:Vibration Free Cryostat:

April 27th, 2006April 27th, 2006Paola Puppo – INFN RomaPaola Puppo – INFN Roma

ILIASILIAS

1

2

3

4

The jelly fish thermal contact

The special bellow

The piezo actuator

Vibration Free Cryostat: detailsVibration Free Cryostat: details

April 27th, 2006April 27th, 2006Paola Puppo – INFN RomaPaola Puppo – INFN Roma

ILIASILIAS

Current statusCurrent status

Thermal behavior of the system (FEM and data);

Mechanical noise characterization completed;

PT Refrigeration system : set up of the vibration compensation system;

Mechanical transfer function measurements;

Control of the pulse tube induced vibrations;

April 27th, 2006April 27th, 2006Paola Puppo – INFN RomaPaola Puppo – INFN Roma

ILIASILIAS

Thermal FEM simulationThermal FEM simulation

Cold Stage 1

Cold Stage 2

April 27th, 2006April 27th, 2006Paola Puppo – INFN RomaPaola Puppo – INFN Roma

ILIASILIAS

ResultsResultsThe results are used to evaluate the thermalpowers extracted at the cold stages points.

April 27th, 2006April 27th, 2006Paola Puppo – INFN RomaPaola Puppo – INFN Roma

ILIASILIAS

Noise characterization:Noise characterization:

Low Frequency noiseLow Frequency noise

High Frequency noiseHigh Frequency noise

Results:• Two orders of magnitude gained at frequencies grater than 100 Hz

10-10

10-9

10-8

10-7

10-6

10-5

0,0001

0,001

0 5 10 15 20 25

m/ sqrt(Hz) cold head m/ sqrt(Hz) Vacuum Chamber

Hz

10-16

10-14

10-12

10-10

10-8

10-6

0,0001

0 1000 2000 3000 4000 5000 6000 7000

m/ sqrt(Hz) Vacuum Chamberm/ sqrt(Hz) Head

Hz

Setup:•1 Accelerometer placed on the cold head•1 Accelerometer on the top of the vacuum chamber

April 27th, 2006April 27th, 2006Paola Puppo – INFN RomaPaola Puppo – INFN Roma

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Position sensor : the optical fiber Position sensor : the optical fiber bundlebundleMeasurement set-upMeasurement set-up

Material: optran silica for broad temperature rangeProtection: PVC or s.s.Laser source : 638 nm (red)Target: polished surface

Target

Laser

Photodiode

April 27th, 2006April 27th, 2006Paola Puppo – INFN RomaPaola Puppo – INFN Roma

ILIASILIAS

Vertical Noise Vertical Noise measurementsmeasurements

10-8

10-7

10-6

10-5

0.0001

0 2 4 6 8 10 12

Dftt(m/sqrt(Hz))

Hz

The optical sensor is sensitive in the low frequency range and it is used as the readout ofthe control system.

April 27th, 2006April 27th, 2006Paola Puppo – INFN RomaPaola Puppo – INFN Roma

ILIASILIAS

Vertical Tranfer Vertical Tranfer function function

MeasurementsMeasurements

Exciting source: piezo actuators

Sensor: optical sensor onthe II stage

April 27th, 2006April 27th, 2006Paola Puppo – INFN RomaPaola Puppo – INFN Roma

ILIASILIAS

Preliminary results of VFC (no payload in the inner chamber):• Cooling down OK;• Vertical control monitoring the cold head OK (position sensing);• Study of all the mechanical couplings inside the VFC.

INFN-Roma

,

-120

-110

-100

-90

-80

-70

-60

-50

-40

0 1 2 3 4 5

Mag open-loopMag closed-loop (10 Hz bandwidth)

dB

f [Hz]

DAC noise plateau + no-roll-off filter effect

Preliminary results of VFC (no payload in the inner chamber):• Cooling down OK;• Vertical control monitoring the cold head OK (position sensing);• Study of all the mechanical couplings inside the VFC.

April 27th, 2006April 27th, 2006Paola Puppo – INFN RomaPaola Puppo – INFN Roma

ILIASILIAS

• Outer tank mode excitedby the control system and visible on the cold head residual motion when the control loop is closed;

• Such a coupling can be removed by modifying the mechanical set up both of the optical readout and of theouter tank;

April 27th, 2006April 27th, 2006Paola Puppo – INFN RomaPaola Puppo – INFN Roma

ILIASILIAS

Cryogenic reduced scale silicon payloadCryogenic reduced scale silicon payload

April 27th, 2006April 27th, 2006Paola Puppo – INFN RomaPaola Puppo – INFN Roma

ILIASILIAS

Mini payload made Mini payload made of silicon:of silicon: 1/3.5 1/3.5

scaledscaled

Si

Si

Copper insert in the silicon marionetta suspension point

April 27th, 2006April 27th, 2006Paola Puppo – INFN RomaPaola Puppo – INFN Roma

ILIASILIAS

1. Silicon mirror2. Copper reaction mass of the

mirror3. Silicon marionetta with shaped

copper insert to optimizethe thermal contact with

suspensions, and steel arms4. Reaction mass for marionetta

2

2

4

4

3

Cryogenic Payload, scaled to 1/3 a Virgo payload

1

April 27th, 2006April 27th, 2006Paola Puppo – INFN RomaPaola Puppo – INFN Roma

ILIASILIAS

Assembly test:Assembly test:thermal links on aluminum thermal links on aluminum

samples of marionetta and mirrorsamples of marionetta and mirror

April 27th, 2006April 27th, 2006Paola Puppo – INFN RomaPaola Puppo – INFN Roma

ILIASILIAS

1. Mirror assembly2. Marionetta assembly in its reaction mass3. Connection of the thermal links

1

2

3

April 27th, 2006April 27th, 2006Paola Puppo – INFN RomaPaola Puppo – INFN Roma

ILIASILIAS

4.Mirror reaction mass assembly

5.Coils assembly4

5

April 27th, 2006April 27th, 2006Paola Puppo – INFN RomaPaola Puppo – INFN Roma

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6.The minipayload ready to be suspended on the vacuum chamber flange.

April 27th, 2006April 27th, 2006Paola Puppo – INFN RomaPaola Puppo – INFN Roma

ILIASILIAS

Mirror

ReactionMass

Marionettaarms

Marionetta

Reaction Mass for Marionetta Ansys simulationAnsys simulation

April 27th, 2006April 27th, 2006Paola Puppo – INFN RomaPaola Puppo – INFN Roma

ILIASILIAS

ConclusionsConclusions• Cancellation of the extra-noise vibration associated to the cooling system:

•vertical noise measured•transfer function measured•active control performed•thermal study performed

• Minipayload: first assembly test of the payload with aluminum mirror and marionetta. •Next step: to insert the assembled system in the VFC cryostat to cool it down and study the mechanical behavior.