Gravitational Wave Group
Sapphier Test Mass Cooling using Spphire Fiber
Motivation
The only heat path to cool the sapphire test mass is suspension fibers.
We investigated that sapphire fibers could be good heat paths, because of
its drastic decrease of specific heat around 20[K].
In addition to this, we also investigated the thermal equilibrium between
cooling and heating due to power absorption in the test mass.
Experimental setup
Result
The temperature of sapphire test mass was successfully cooled at 4 [K]
,using two wrapping sapphier fibers. The sapphier fibers proved to be a good
heat path.The equilibrium temperature was 25 [K], which was low enough to
decrease the thermal noise of a interferometer. The thermal distribution was
less than 0.8 [K] in the test mass.