Mobile HTS SQUID System for Eddy Current Testing of Aircraft

In Non-Destructive Evaluation (NDE), eddy current techniques are commonly used for the detection of hidden material defects in metallic structures. Conventionally, one works with an excitation coil generating a field at a distinct frequency. The eddy currents are deviated by materials flaws and the resulting distorted field is sensed by a secondary coil. Because of the law of induction, this technique has its limitations in the low frequency range. This leads to a decrease of the Probability of flaw Detection (POD) in larger depths

Pulse-Tube-Kuehler Abschlussbericht

Arising from the increased international interest shown since approximately 1960 in the development of a low-maintenance method of sensor refrigeration, especially for Pulse-Tube-Refrigerators, research has been taken up on our part concerning the feasibility and efficiency of such systems. In co-ordination with and in addition to other research being conducted in Karlsruhe, Jena und Giessen, our efforts have been especially directed at researching and developing a small, mobile and cost-effective refrigerator (1.5 W at 70 K). The theoretical research undertaken was aimed at achieving a fundamental understanding of the function of the Pulse-Tube-Refrigerator-System and at arriving at an optimal geometrical and functional design. The theoretical effort was therefore mainly directed at capturing the basic function and design of an optimal structure based on a differential view of the gas passage-pressure relationship. According to the research carried out on the main criteria of the relationship between gas movement and change of pressure, relatively favourable conditions can be built by overlapping a direct wave and a harmonic wave with the double frequency. The gas passage and the march of pressure occur in such a manner that the minimum pressure prevails in the mean position of the gas, whereby the pressure increases with a shift from the mean position. The experiments were always carried out with parallel wired pipes of a small diameter so that the wall coupling was very strong. Thus, heat conduction for a symmetrical arrangement was not detected. The research carried out offers a good base for continuing with the concept of developing small mobile pulse-tube-refrigerators. (orig.)SIGLEAvailable from TIB Hannover: F95B2493+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Kryo-Gasumwaelzsystem: Auslegung und Optimierung des Gasumwaelzsystems fuer stoerarme Kuehlung von HTSL-SQUID-Sensoren Abschlussbericht

Zur stoerarmen Kuehlung von HTSL-SQUID-Sensoren werden mehrere Kuehlmoeglichkeiten hinsichtlich ihrer kurzfristigen Realisierung ueberprueft. Als praktikable Loesung wird ein kombiniertes Kuehlverfahren getestet, bestehend aus Split-Stirling-Kaeltemaschine und einem geschlossenen Stickstoffkreislauf mit Verfluessiger, Siphonleitung und Verdampfer. Mit dem experimentell erprobten Kuehlsystem ist die stoerarme SQUID-Kuehlung moeglich. Fuer die Anwendung ist eine Optimierung mit dem SQUID-Messsystem und eine konstruktive Bearbeitung erforderlich. (orig.)Several cooling methods for HTSC-SQUID-sensors, having low electrical and mechanical disturbances are checked concerning their short time realizability. A combination of a Split-Stirling-Refrigerator and a miniaturized thermosiphon is tested as a practicable cooling system. Lt. allows SQUID-cooling in a laboratory with the required parameters. For the wide application the cooling system and the SQUID-system have to be adjusted, including reworking of the construction data. (orig.)Available from TIB Hannover: D.Dt.F. QN1(6,3) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman

Zerstoerungsfreie Pruefung an Flugzeugteilen mittels SQUID. Teilvorhaben: Kuehltechnik Abschlussbericht

Several kinds of cooling possibilities have been investigated for SQUID measuring techniques to be used in non-destructive evaluation. Considered from the view point of a sufficiently good functionality/cost-ratio a new developed mobile, position independent liquid nitrogen cryostat made of glass fiber reinforced epoxy resin was chosen. This cryostat is manufactured at ILK Dresden in small amount series for research purposes. During the tests of the measuring system for non-destructive evaluation of aircraft elements done in the laboratories of Research Centre, Juelich and University of Giessen as well as in the demonstration tests in the aircraft maintenance halls of Hamburg airport and Frankfurt/Main airport the cryostat has proven to be suitable for this application. (orig.)SIGLEAvailable from TIB Hannover: RR 4453(99-238)+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung (BMBF), Bonn (Germany)DEGerman

Mobile SQUID-Messsysteme fuer die Flugzeuginspektion. Teilvorhaben: Mobile Kuehltechnik Abschlussbericht

Today SQUID measuring systems are used for the non-destructive material test, for measurement of biomagnetic fields (heart, brine) and for geological explorations. Up to now the used systems were cooled exclusively by LN_2 cryostats made from glas fibre reinforced epoxy resins. A closed cooling system with Stirling cooler, LN_2 pump for circulation and nitrogen as refrigerant is investigated for coming serial use. The practical useability was proved in the research lab of FZ-Juelich GmbH. The SQUID sensor can be cooled reliably and undisturbedly through a non-limited duration by this cooling system. Other applications like magnetic and contactless bearings with HTSC materials are prepared. (orig.)SQUID-Messsysteme werden gegenwaertig fuer die zerstoerungsfreie Werkstoffpruefung, fuer Messungen biomagnetischer Felder (Herz, Hirn) und geologische Erkundungen eingesetzt. Bisher werden eingesetzte Systeme ausschliesslich mit LN_2-Kryostaten aus glasfaserverstaerkten Epoxidharzwerkstoffen gekuehlt. Fuer kuenftige Serienanwendungen wird ein Geschlossenes Kuehlsystem mit Stirlingkuehler als Kaeltequelle, Stickstoff als Kaeltemittel und Fluessigstickstoffpumpe zur Umwaelzung untersucht. Die praktische Anwendbarkeit wurde im Forschungslabor der FZ Juelich GmbH nachgewiesen. Mit dem Kuehlsystem kann unbegrenzte Zeit der SQUID-Sensor zuverlaessig und stoerungsfrei gekuehlt werden. Andere Anwendungen, wie z.B. magnetische beruehrungslose Lager mit HTSL-Materialien, sind in Vorbereitung. (orig.)SIGLEAvailable from TIB Hannover: F02B1720 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung, Berlin (Germany)DEGerman

Stoerarmes HTSL-SQUID-Kuehlsystem Abschlussbericht

In the context of the research project, work was done for HTSL-SQUID on (1) the development of a thermo-siphon cooler (low fault and continuously working) and (2) the development of a latent storage cooler (low fault and discontinuously working). Two development versions of the latent storage cooler were followed up, the development of a spherical latent storage cooler and the development of an annular vessel latent storage cooler. A further precondition for the construction of the cooler was the use of split Stirling refrigerators as units producing the cold. The experimental sample was built up with refrigerators which could produce a nominal cooling output of 1.2 W at 80 K. Two samples of the thermo-siphon cooler were built, tested and improved. The second sample was developed further as a demonstration model, introduced at meetings and prepared for testing the cooling of HTSL-SQUIDs. The thermo-siphon cooler can be designed for cooling output up to about 2 W at 80 K and can be used controlled for a temperature range of 90 K to 66 K. (orig./MM)Im Rahmen des Forschungsvorhabens wurde fuer HTSL-SQUID's an der (1) Entwicklung eines Thermosiphon-Kuehlers (stoerarm und kontinuierlich arbeitend) und (2) Entwicklung eines Latentspeicher-Kuehlers (stoerfrei und diskontinuierlich arbeitend) gearbeitet. Bei dem Latentspeicher-Kuehler wurden zwei Entwicklungsversionen verfolgt, und zwar Entwicklung eines Kugel-Latentspeicher-Kuehlers und Entwicklung eines Ringgefaess-Latentspeicher-Kuehlers. Eine weitere Praemisse zum Aufbau der Kuehler war der Einsatz von Split-Stirling-Kaeltemaschinen als kaelteerzeugende Baugruppe. Die Versuchsmuster wurden mit Kaeltemaschinen aufgebaut, die eine Nennkuehlleistung von 1,2 W bei 80 K erzeugen konnten. Der Thermosiphon-Kuehler wurde in zwei Musterexemplaren aufgebaut, erprobt und verbessert. Das Zweitmuster wurde als Demonstrator weiterentwickelt, zu Fachtagungen vorgestellt und zur Testung der Kuehlung von HTSL-SQUIDs bereitgestellt. Der Thermosiphon-Kuehler kann fuer Kuehlobjektleistungen bis etwa 2 W bei 80 K ausgelegt werden und ist fuer einen Temperaturbereich zwischen 90 K und 66 K geregelt einsetzbar. (orig./MM)Available from TIB Hannover: F97B1207+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Geophysikalisches RMS-Verfahren mit HTc-SQUID. Teilvorhaben: Kryostate mit hoher magnetischer Transparenz fuer das geophysikalische RMS-Verfahren mit HT_c-SQUID Abschlussbericht

SIGLEAvailable from TIB Hannover: F00B1376+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Mobile HTS SQUID System for Eddy Current Testing of Aircraft

In Non-Destructive Evaluation (NDE), eddy current techniques are commonly used for the detection of hidden material defects in metallic structures. Conventionally, one works with an excitation coil generating a field at a distinct frequency. The eddy currents are deviated by materials flaws and the resulting distorted field is sensed by a secondary coil. Because of the law of induction, this technique has its limitations in the low frequency range. This leads to a decrease of the Probability of flaw Detection (POD) in larger depths.</p