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@PHDTHESIS{Kuhlbusch:1020812,
author = {Kuhlbusch, Tim Johannes},
othercontributors = {Stahl, Achim and Hebbeker, Thomas},
title = {{C}ryogenic sensing and actuation techniques for the
{E}instein {T}elescope},
school = {RWTH Aachen University},
type = {Dissertation},
address = {Aachen},
publisher = {RWTH Aachen University},
reportid = {RWTH-2025-09249},
pages = {1 Online-Ressource : Illustrationen},
year = {2025},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University; Dissertation, RWTH Aachen University, 2025},
abstract = {Improving the sensitivity of gravitational wave detectors
is essential to increase the observable fraction of our
universe and to enable new observation possibilities. The
low frequency region below 10 Hz is essential for many
science cases like multi-messenger astronomy. Therefore,
future gravitational wave detectors like the Einstein
Telescope will require cryogenic mirrors and cryogenic
suspension systems to decrease thermal noise. Many
components of the mirror suspension systems must be improved
to work across the temperature range from 10 to 300 K.
Commercial availability of components specified for these
low temperatures is scarce. This work explores the
challenges of selecting components and evaluates possible
solutions. Optical displacement sensors are required to
monitor the movement of the suspension system, characterize
mechanical properties, and derive feedback signals for the
control systems. LEDs are used in many sensors of the
current generation of gravitational wave detectors. They
were successfully operated at cryogenic temperatures as part
of this work but have limitations regarding efficiency,
optical beam quality, and noise. Another option is to use
optical fibers and collimators to make light from stabilized
light sources accessible in the cryogenic environment.
Photodiodes are the most common solution for reading out
optical sensors. The challenges in selecting appropriate
photodiodes are outlined in this thesis, and the selection
of a photodiode for 1550nm is discussed. Presented
measurements were used to select the optical components for
sensors of a cryogenic suspension prototype developed in the
E-TEST project. To control the movement of the suspension
structures and steer the optical components, feedback forces
must be applied. Voice-coil actuators are employed in all
current detectors. Cryogenic temperatures add new
requirements for these actuators, such as compatibility with
cryogenic temperatures and low waste heat. Superconductors
are a promising option to eliminate resistive heating in
actuator coils, as the cryogenic temperatures required for
superconductivity are already present. A process for
additive manufacturing of the superconductor yttrium barium
copper oxide in a powder bed fusion process and the
characterization of produced samples are outlined.
Additionally, techniques for noise prediction and mitigation
in interferometric detectors are discussed and evaluated on
a bench-top Michelson interferometer.},
cin = {133510 / 130000},
ddc = {540},
cid = {$I:(DE-82)133510_20140620$ / $I:(DE-82)130000_20140620$},
pnm = {EMR113 - E-Test (EMR113) / OPSF736 - Additive manufacturing
of superconductors for gravitational wave research
(EXS-SF-OPSF736) / Exploratory Research Space: Seed Fund (2)
als Anschubfinanzierung zur Erforschung neuer
interdisziplinärer Ideen (EXS-SF) / Excellence Strategy
(EXS)},
pid = {G:(EFRE)EMR113 / G:(DE-82)EXS-SF-OPSF736 / G:(DE-82)EXS-SF
/ G:(DE-82)EXS},
typ = {PUB:(DE-HGF)11},
doi = {10.18154/RWTH-2025-09249},
url = {https://publications.rwth-aachen.de/record/1020812},
}
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