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Acoustic detection in superconducting magnets for performance characterization and diagnostics
Quench diagnostics in superconducting accelerator magnets is essential for
understanding performance limitations and improving magnet design.
Applicability of the conventional quench diagnostics methods such as voltage
taps or quench antennas is limited for long magnets or complex winding
geometries, and alternative approaches are desirable. Here, we discuss acoustic
sensing technique for detecting mechanical vibrations in superconducting
magnets. Using LARP high-field Nb3Sn quadrupole HQ01 [1], we show how acoustic
data is connected with voltage instabilities measured simultaneously in the
magnet windings during provoked extractions and current ramps to quench.
Instrumentation and data analysis techniques for acoustic sensing are reviewed.Comment: 5 pages, Contribution to WAMSDO 2013: Workshop on Accelerator Magnet,
Superconductor, Design and Optimization; 15 - 16 Jan 2013, CERN, Geneva,
Switzerlan
Applications of Acoustic Wave Devices for Sensing in Liquid Environments
Acoustic wave devices such as thickness shear mode (TSM) resonators and shear horizontal surface acoustic wave (SH-SAW) devices can be utilized for characterizing physical properties of liquids and for chemical sensor applications. Basic device configurations are reviewed and the relationships between experimental observables (frequency shifts and attenuation) and physical properties of liquids are presented. Examples of physical property (density and viscosity) determination and also of chemical sensing are presented for a variety of liquid phase applications. Applications of TSMs and polymer-coated guided SH-SAWs for chemical sensing and uncoated SH-SAWs for “electronic tongue” applications are also discussed
Turbofan aft duct suppressor study. Contractor's data report of mode probe signal data
Acoustic modal distributions were measured in a fan test model having an annular exhaust duct for comparison with theoretically predicted acoustic suppression values. This report contains the amplitude and phase data of the acoustic signals sensed by the transducers of the two mode probes employed in the measurement. Each mode probe consisted of an array of 12 transducers sensing the acoustic field at three axial positions and four radial positions
Sensing Small Changes in a Wave Chaotic Scattering System
Classical analogs of the quantum mechanical concepts of the Loschmidt Echo
and quantum fidelity are developed with the goal of detecting small
perturbations in a closed wave chaotic region. Sensing techniques that employ a
one-recording-channel time-reversal-mirror, which in turn relies on time
reversal invariance and spatial reciprocity of the classical wave equation, are
introduced. In analogy with quantum fidelity, we employ Scattering Fidelity
techniques which work by comparing response signals of the scattering region,
by means of cross correlation and mutual information of signals. The
performance of the sensing techniques is compared for various perturbations
induced experimentally in an acoustic resonant cavity. The acoustic signals are
parametrically processed to mitigate the effect of dissipation and to vary the
spatial diversity of the sensing schemes. In addition to static boundary
condition perturbations at specified locations, perturbations to the medium of
wave propagation are shown to be detectable, opening up various real world
sensing applications in which a false negative cannot be tolerated.Comment: 14 pages, 11 figures, as published on J. Appl. Phy
Optical fiber interferometer for the study of ultrasonic waves in composite materials
The possibility of acoustic emission detection in composites using embedded optical fibers as sensing elements was investigated. Optical fiber interferometry, fiber acoustic sensitivity, fiber interferometer calibration, and acoustic emission detection are reported. Adhesive bond layer dynamical properties using ultrasonic interface waves, the design and construction of an ultrasonic transducer with a two dimensional Gaussian pressure profile, and the development of an optical differential technique for the measurement of surface acoustic wave particle displacements and propagation direction are also examined
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Sonar behaviour in non-terrestrial ocean exploration
A goal for a future Europan payload is to determine the extent of the postulated sea, aspects of acoustic remote sensing are discussed with a view to operating a sonar in such an subsurface ocean
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