KAGRA/Subgroups/VIS/Type-C

Type-C (TAMA) suspension

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

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. Three were PO(pick-off) type; MC_i, MC_e, MC_o with the mirror thickness of about 3cm, and the others were TM(test mass) or RM type; ETMX, ETMY with the mirror thickness of about 6cm. The last one is coming from CLIO, the size of the BS mirror was 4cm in thickness and 15cm in diameter.
Work log about 2 iKAGRA ETMs is here.
ETM Transfer function
long term drift

Two suspensions used at the X/Y ends, are used as IMMT1 and IMMT2 for bKAGRA.
Memo by Yamamoto-san
IMMT Preparation