HTS SQUID system with Joule-Thomson cryocooler for eddy current nondestructive evaluation of aircraft structures

Hohmann, R.; Krause, Hans‐Joachim; Soltner, H.; Zhang, H.; Copetti, Christian; Bousack, Herbert; Braginski, A. I.; Faley, M.I.

doi:10.1109/77.621886

Cited by 28 publications

(14 citation statements)

References 10 publications

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“…The recent success in suppression ofthe motion-induced SQUID noise [7], in combination with other advantages like high linearity and high dynamic range, make HTS SQUID very attractive sensors for eddy current NDE applications. Future work will include the improvement of the system regarding reliability and handling and its application for testing of aircraft structures.…”

Section: Discussionmentioning

confidence: 99%

“…The increase during movement may originate from sensor vibrations, from the motion of flux lines in the superconducting YBCO films, or from eddy currents generated in the copper by power line and other low-frequency fields. Recent work [7] with a new integration scheme, using a sapphire cold finger for planar rf gradiometers [14] operated with a Joule-Thomson cryocooler, demonstrates clearly that even during movement, the sensitivity ofthe SQUID is only weakly impaired. This leaves the last explanation as the most probable.…”

Section: Discussionmentioning

confidence: 99%

“…Machine coolers may lead to problems for SQUID operation due to electromagnetic interference by the compressor or moving parts in the cold end, vibrations which indirectly lead to EMI due to tilting ofthe SQUID in the geomagnetic field, or due to instability ofthe temperature. Allthese influences may have a negative effect on SQUID performance [5,6] and have tobe dealt with [7]. This paperwill focus on the performance of dc and rf SQUIDs, operated with a portable cryostat, and its application to NDE.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Mobile HTS SQUID System for Eddy Current Testing of Aircraft

Krause

Hohmann

Soltner

et al. 1997

Review of Progress in Quantitative Nondestructive Evaluation

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Mobile HTS SQUID System for Eddy Current Testing of Aircraft

Krause

Hohmann

Soltner

et al. 1997

Review of Progress in Quantitative Nondestructive Evaluation

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“…To reduce the influence of environmental magnetic noise, HTS (high temperature superconductor) SQUID gradiometers cooled by cryocoolers were developed and have been used for eddy-current NDE (nondestructive evaluation) and MCG (magnetocardiography) measurements [2], [4].…”

Section: Introductionmentioning

confidence: 99%

Electronic Axial HTS dc SQUID Gradiometer Cooled by Pulse-Tube Cooler

Yoshizawa

Nakamura

et al. 2005

IEEE Trans. Appl. Supercond.

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“…We have previously reported that Pulse-Tube refrigerators and Joule-Thomson refrigerators can be used for cooling of high-T, SQUIDs [6], [7]. So far, the field sensitivity of the SQUIDs integrated with the coolers has been limited rather by the intrinsic noise of the SQUIDs or the electronics.…”

Section: Introductionmentioning

confidence: 99%

Comparison of low noise cooling performance of a Joule-Thomson cooler and a pulse-tube cooler using a HT SQUID

Hohmann

Lienerth

Zhang

et al. 1999

IEEE Trans. Appl. Supercond.

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Due to their intrinsic low mechanical vibration level both, Joule-Thomson refrigerator and Pulse-Tube refrigerator are promising candidates for low noise cooling of high-Tc SQUIDs. We report here on a test comparing the performance of a commercial Joule-Thomson cooler and a single stage Pulse-Tube cooler used to operate one and the same HT rf SQUID under comparable conditions in shielded environment. In order to reduce vibrations the cold stages of both cooler systems were connected by flexible plastic lines of several meters length with their compressors. Operated in a liquid nitrogen cryostat, the white field noise of the SQUID was 40jT,/&z at frequencies above 30 Hz. A slightly higher white noise (about 6OfT/&z) was observed for operation with either of the two coolers. This is probably due to the vicinity of superinsulation to the SQUID. The Joule-Thomson cooler produced a somewhat higher low frequency excess noise below 30 Hz and some characteristic noise bands at intermediate frequencies (ca. 100 Hz -500 Hz). The Pulse-Tube cooler led to a spectrum of lines at multiples of the pulse frequency (4.6 Hz). Both effects could be attributed (using cross correlation measurements) to residual mechanical vibrations of the cold heads of both coolers.

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HTS SQUID system with Joule-Thomson cryocooler for eddy current nondestructive evaluation of aircraft structures

Cited by 28 publications

References 10 publications

Mobile HTS SQUID System for Eddy Current Testing of Aircraft

Mobile HTS SQUID System for Eddy Current Testing of Aircraft

Electronic Axial HTS dc SQUID Gradiometer Cooled by Pulse-Tube Cooler

Comparison of low noise cooling performance of a Joule-Thomson cooler and a pulse-tube cooler using a HT SQUID

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