Advanced ligo design and simulation t ools
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 Advanced LIGO Design and Simulation T ools. Lisa Barsotti (MIT). GWDAW 2010, Kyoto. Historical Context. 1 st generation. 1 st generation +. 2 nd generation . 2 nd generation +. 3 rd generation . Historical Context. 1 st generation. 1 st generation +. 2 nd generation .

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Advanced ligo design and simulation t ools

 Advanced LIGO Design and Simulation Tools

Lisa Barsotti (MIT)

GWDAW 2010, Kyoto


Historical context

Historical Context

1st generation

1st generation +

2nd generation

2nd generation +

3rd generation


Historical context1

Historical Context

1st generation

1st generation +

2nd generation

2nd generation +

3rd generation

4th generation !!


Outline

Outline

  • Design Process

  • Questions we asked ourselves

  • Some of the answers we found by means of simulations

  • Thoughts on simulation tools

  • Conclusions


Naive design process

(Naive) Design Process

  • Parametric Instabilities

  • Gas Damping Noise

Simulations can’t help you anymore….


Aligo design

aLIGO Design

  • Fundamental Noises:

    • SEISMIC NOISE

    • THERMAL NOISE

    • SHOT NOISE

  • Arm cavities: 4 km

  • Max Power: 125W

GWINC (Matlab)


Can we control our ifo

Can we control our IFO?

  • New opticalconfiguration:

    • Signal Recycling

    • Stable cavities

  • High Power

  • More (coupled) DOFs

  • Noise performance down to 10 Hz

  • New suspensions and actuators


Can we control our ifo1

Can we control our IFO?

  • Arm cavities: 4km

  • Max Power: 125W

  • Arm Finesse: 450

  • ITM T: 1.4%, PRM T:3%, SRM T=20%

  • Schnupp asymmetry: 5cm

  • Modulation Frequencies: 9 & 45 MHz

  • Recycling cavities: 57m

  • Length sensing and control scheme (LSC):

    • Modulation Frequencies

    • Error signals

    • Control loops (Looptickle, now Lentickle)

OPTICKLE


Can we align our ifo

kpend

kpend

kopt

Can we align our IFO?

  • High Power: radiation pressure effects

  • Stable cavities are good, but:

    • alignment signals smaller

    • more mirrors to control

Physics Letters A 354 (2006) 167–172


Can we align our ifo1

Can we align our IFO?

  • Optickle model of angular DOFs (PICKLE)

  • Complete Matlabmodel of the aLIGO suspension + seismic isolation system performance


Are the control noises compatible with the design sensitivity

Are the control noises compatible with the design sensitivity?

OPTICKLE


How do we deal with thermal effects

How do we deal with thermal effects?

Stationary Interferometer Simulation

  • Mode matching stability vs input power: optimal Gouy phases

  • Compromise with alignment sensing

ROCs (m):

Rprm = -11.45

Rpr2 = -4.516

Rpr3 = 36.00

Rsrm = -5.250

Rsr2 = -6.455

Rsr3 = 36.00

vGouyPRC = 24.803

vGouySRC = 20.342

Beam Sizes (mm):

PRM 2.3

PR2 6.1

PR3 54

SRM 1.9

SR2 8.23

SR3 54

Arain, Mueller


Can we robustly lock our ifo

Can we robustly lock our IFO?

  • Yes, but extra hardware is needed

ALS (green beams)

End2End (C++)

Hierarchical Control of the Quadruple Suspension (SIMULINK)

John, Bram (ANU)

Work on Hierarchical Control on the Quad Prototype at MIT

The 40m will experimentally study lock acquisition for aLIGO this year


Do we know our main actuator

Do we know our main actuator?

5mm GAP between the Test Masses and the ESDs:

Gas Damping Noise (Rai)

COMSOL

(John Miller)

MONTECARLO

(Matt Evans)

Electro-Static Drive (ESD)


Questions not answered yet

Questions not answered (yet)

  • Locking signals vs static mirror misalignments (asked by Hartmut 2 years ago): FINESSE can do it…lazy simulator

  • Model for OMC alignment

  • Full signal chain with electronic noise, ADC/ DAC, whitening filters, saturations, etc..

  • Add your own


Some thoughts on simulation tools

Some Thoughts on Simulation Tools

  • It can be hard to find answers, but it is also hard to ask the right questions

  • Which questions are the right ones is not obvious

  • You might already know the answer. You might be able to write it on an envelope, but you might be wrong…that’s why good simulation tools are needed! 


Conclusions

Conclusions

  • aLIGO design phase is ending..we are actually building it!

  • Massive use of simulation in the design process

  • Hard to find optimal solutions: trade offs

  • Models will be useful to understand the as built IFO as well….keep simulations handy!


Sidles sigg instabilities

kpend

kpend

kopt

Sidles-Sigg Instabilities

c1

Physics Letters A 354 (2006) 167–172

HARD

x2

x1

Torque induced by radiation pressure

c2

c1

c2

x1

x2

SOFT

  • Modification of the pendulum resonance frequencies:


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