Type-C (TAMA) suspension

Type-C suspension is a relatively small double pendulum with intermediate mass passively damped by eddy current damping.
Some of the type-C suspensions which are used in KAGRA were once used for TAMA300, originally designed by K. Arai in 1990s.
So type-C suspension is sometimes called as TAMA-type suspension.

Type-C can be roughly divided into 2 types.
PO (Pick-off) type suspends the mirror with the thickness of about 3cm.
TM (test mass) type suspends the mirror with the thickness of about 6cm.
Main differences are in the intermediate mass and frame design.


In 2017, 5 type-C suspensions were installed in iKAGRA.
In the final iKAGRA configuration, 7 mirrors were suspended and 6 of them were Type-C.

Mode Cleaner suspensions

The thickness of the mode cleaner mirrors are about 3cm.
(In TAMA, thickness of the MCe mirror was about 6cm; it means that its suspension was TM type. )
So the suspensions for the MC mirrors are PO-type.
Following the suggestion by K. Arai,
*Design change for new suspensions(by K. Arai)
main frames have been redesigned by H. Ishizaki.

Mode cleaner suspensions will be used for long term even after the iKAGRA.
Nakano-san installed MC_i, MC_e, and MC_o. The thickness of the MC mirrors are about 3cm. This type of the is called as PO(pick-off).

Temporarily used suspensions

As ETMX and ETMY, TM type mirrors were used. Work log about 2 iKAGRA ETMs is here. The last one is coming from CLIO, the size of the BS mirror was 4cm in thickness and 15cm in diameter.



KAGRA/Subgroups/VIS/Type-C (last edited 2020-04-30 12:05:11 by KousekiMiyo)