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# Cavity Control Influence on Damping - PowerPoint PPT Presentation

Cavity Control Influence on Damping. - Case 1: All cavity control on Pendulum 2. *. Pendulum 1. Pendulum 2. * Top to top mass transfer function. longitudinal. u 1 ,2. u 2,2. u 1 ,3. u 2,3. What you would expect – the quad is just hanging free.

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## PowerPoint Slideshow about ' Cavity Control Influence on Damping' - birch

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Presentation Transcript

- Case 1: All cavity control on Pendulum 2

*

Pendulum 1

Pendulum 2

* Top to top mass transfer function

longitudinal

u1,2

u2,2

u1,3

u2,3

• What you would expect – the quad is just hanging free.

• Note: both pendulums are identical in this simulation.

u1,4

u2,4

Control Law

0

1

G1200774

- Case 2: All cavity control on Pendulum 1

Pendulum 1

Pendulum 2

*

* Top to top mass transfer function

longitudinal

u1,2

u2,2

u1,3

u2,3

• The top mass of pendulum 1 behaves like the UIM, PUM, and test mass are clamped to gnd.

• This happens when the ugfs of the UIM, PUM, and test mass loops are above the quad’s resonant frequencies.

u1,4

u2,4

Control Law

1

0

G1200774

- Case 3: Cavity control split evenly between both pendulums

Pendulum 1

Pendulum 2

*

* Top to top mass transfer function

longitudinal

u1,2

u2,2

u1,3

u2,3

• The top mass response is now an average of the previous two cases -> 5 resonances to damp.

• Control up to the PUM, rather than the UIM, would yield 6 resonances.

• aLIGO will likely behave like this.

u1,4

u2,4

Control Law

0.5

0.5

G1200774