Currently, the Japanese gravitational wave laser interferometer KAGRA is under construction in the Kamioka mine. As one main feature, it will employ sapphire mirrors operated at a temperature of 20 K to reduce the impact from thermal noise. To reduce seismic noise, the mirrors will also be suspended from multi-stage pendulums. Thus the heat load deposited in the mirrors by absorption of the circulating laser light as well as heat load from thermal radiation will need to be extracted through the last suspension stage. This stage will consist of four thin sapphire fibers with larger heads necessary to connect the fibers to both the mirror and the upper stage. In this paper, we discuss heat conductivity measurements on different fiber candidates. While all fibers had a diameter of 1.6 mm, different surface treatments and approaches to attach the heads were analyzed. Our measurements show that fibers fulfilling the basic KAGRA heat conductivity requirement of κ 5000 W m-1 K -1 at 20 K are technologically feasible. © 2014 IOP Publishing Ltd.

Evaluation of heat extraction through sapphire fibers for the GW observatory KAGRA / Khalaidovski, A.; Hofmann, G.; Chen, D.; Komma, J.; Schwarz, C.; Tokoku, C.; Kimura, N.; Suzuki, T.; Scheie, A. O.; Majorana, E.; Nawrodt, R.; Yamamoto, K.. - In: CLASSICAL AND QUANTUM GRAVITY. - ISSN 0264-9381. - 31:10(2014), p. 105004. [10.1088/0264-9381/31/10/105004]

Evaluation of heat extraction through sapphire fibers for the GW observatory KAGRA

Schwarz C.;Kimura N.;Suzuki T.;Majorana E.;
2014

Abstract

Currently, the Japanese gravitational wave laser interferometer KAGRA is under construction in the Kamioka mine. As one main feature, it will employ sapphire mirrors operated at a temperature of 20 K to reduce the impact from thermal noise. To reduce seismic noise, the mirrors will also be suspended from multi-stage pendulums. Thus the heat load deposited in the mirrors by absorption of the circulating laser light as well as heat load from thermal radiation will need to be extracted through the last suspension stage. This stage will consist of four thin sapphire fibers with larger heads necessary to connect the fibers to both the mirror and the upper stage. In this paper, we discuss heat conductivity measurements on different fiber candidates. While all fibers had a diameter of 1.6 mm, different surface treatments and approaches to attach the heads were analyzed. Our measurements show that fibers fulfilling the basic KAGRA heat conductivity requirement of κ 5000 W m-1 K -1 at 20 K are technologically feasible. © 2014 IOP Publishing Ltd.
2014
cryogenic laser interferometer; gravitational wave observatories; gravitational waves; sapphire thermal conductivity
01 Pubblicazione su rivista::01a Articolo in rivista
Evaluation of heat extraction through sapphire fibers for the GW observatory KAGRA / Khalaidovski, A.; Hofmann, G.; Chen, D.; Komma, J.; Schwarz, C.; Tokoku, C.; Kimura, N.; Suzuki, T.; Scheie, A. O.; Majorana, E.; Nawrodt, R.; Yamamoto, K.. - In: CLASSICAL AND QUANTUM GRAVITY. - ISSN 0264-9381. - 31:10(2014), p. 105004. [10.1088/0264-9381/31/10/105004]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1408642
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