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  • 1
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2021
    In:  The Journal of the Acoustical Society of America Vol. 150, No. 4_Supplement ( 2021-10-01), p. A95-A95
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 150, No. 4_Supplement ( 2021-10-01), p. A95-A95
    Abstract: High Temperature Superconducting (HTS) tapes are needed for high field magnets in high-energy physics and nuclear fusion. However, quench events, in which the superconductor loses its superconductivity, can cause significant and costly damage to the device if allowed to propagate. Consequently, rapid quench detection methods are crucial. Existing methods such as voltage taps can be less effective in HTS applications, as the normal zone propagation velocities of HTS devices are slow, drastically increasing quench detection time (Iwasa, Cryogenics, 2003). We propose an alternative method that utilizes a linear array of MEMS microphones embedded in the cryogenic coolant channel (Takayasu, IEEE Transactions on Applied Superconductivity, 2019). The system requires amplifiers and acoustic sensors capable of operation at cryogenic temperatures as low as 4.2 K, although operation at 20 K may be sufficient. We report on cryogenic testing of the Vesper microphone preamplifier ASIC, as well as opamp based preamplifiers using the OPA838, LT1464, AD8591, and AD8057 ICs. The amplifiers are being used with the Vesper VM4 MEMS microphone to achieve acoustic measurements in gaseous helium at temperatures as low as 8 K. A charge amp scheme using the AD8591 achieved the best results to date. [Support from DOE STTR DE-SC0019905.]
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2021
    detail.hit.zdb_id: 1461063-2
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  • 2
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2023
    In:  The Journal of the Acoustical Society of America Vol. 153, No. 3_supplement ( 2023-03-01), p. A107-A107
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 153, No. 3_supplement ( 2023-03-01), p. A107-A107
    Abstract: An acoustic array is proposed as a quench detection method in superconducting magnets. A quench occurs when the current density in the superconductor exceeds a critical value, resulting in a loss of superconductivity and rapid local heating. This event is destructive and must be rapidly detected. It is thought that the quench may act as an acoustic source (Takayasu, 2019), which could be detected and localized by a microphone array inserted into the cryogenic coolant. A main advantage of this method is that acoustics propagate 1000 times faster than the normal zone propagation velocity in HTS conductors, providing for fast detection times. To demonstrate this concept, we first characterized the performance of a piezoelectric MEMS microphone and several potential preamplifiers under cryogenic conditions. An acoustic sense node was then constructed that operates down to 10 K. A cryogenic probe incorporating the MEMS array was used to study a quench event in a segment of a 2 mm wide REBCO tape. Quench experiments were carried out in a 7.6 cm diameter, 111 cm tall cryostat in Helium gas at 20 to 50 K. The MEMS array clearly detects a quench induced failure. Other observed acoustic features of unknown origin will be described.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2023
    detail.hit.zdb_id: 1461063-2
    Location Call Number Limitation Availability
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  • 3
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2020
    In:  The Journal of the Acoustical Society of America Vol. 148, No. 4_Supplement ( 2020-10-01), p. 2640-2640
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 148, No. 4_Supplement ( 2020-10-01), p. 2640-2640
    Abstract: High Temperature Superconducting (HTS) tapes such as Rare Earth Barium Copper Oxide (REBCO) are an attractive option for high field magnets operated in cryogenic fluids. However, quench events can occur in which the conductor locally loses its superconducting properties. It is critical to rapidly detect and respond to such an event. Conventional quench detection methods using voltage taps are difficult in HTS devices, since the normal zone propagation velocities are 2–3 orders of magnitude lower in HTS compared to low temperature superconductors (Iwasa, Cryogenics, 2003). We propose an alternative in which a linear array of MEMS microphones is distributed down the central cooling channel of a cable in-conduit conductor. The array can detect the acoustic signature caused by a quench event which propagates in the cooling fluid. The proposed method differs from Acoustic Emission (AE) detection, which uses sensors mounted on the magnet surface to detect structural vibration (Tsukamoto, Appl. Phys. Lett., 1981). In order to implement the system, MEMS microphones and preamplifiers must operate in cryogenic fluids. We report on characterization of commercial MEMS microphones in cryogenic gaseous helium between 0.5 and 1.5 bar down to 20 K, and in liquid nitrogen at 1 bar and 77 K.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2020
    detail.hit.zdb_id: 1461063-2
    Location Call Number Limitation Availability
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