Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evaluation of heat extraction through sapphire fibers for the GW
  observatory KAGRA   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 20K 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 1.6mm, different surface treatments and approaches to
attach the heads were analyzed. Our measurements show that fibers fulfilling
the basic KAGRA heat conductivity requirement of $\kappa\geq $5000W/m/K at 20K
are technologically feasible.

9
The categories of this paper are: nlin
8
The categories of this paper are: hep-ex
35
The categories of this paper are: mtrl-th
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs
34
The categories of this paper are: chem-ph
32
The categories of this paper are: atom-ph
20
The categories of this paper are: acc-phys
21
The categories of this paper are: adap-org
25
The categories of this paper are: patt-sol
15
The categories of this paper are: nucl-ex
29
The categories of this paper are: funct-an
33
The categories of this paper are: plasm-ph
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas
36
The categories of this paper are: cmp-lg