EP0941482A2 - Device for coupling an rf-squid to a super conducting tank circuit - Google PatentsDevice for coupling an rf-squid to a super conducting tank circuit
- Publication number
- EP0941482A2 EP0941482A2 EP19970951807 EP97951807A EP0941482A2 EP 0941482 A2 EP0941482 A2 EP 0941482A2 EP 19970951807 EP19970951807 EP 19970951807 EP 97951807 A EP97951807 A EP 97951807A EP 0941482 A2 EP0941482 A2 EP 0941482A2
- Grant status
- Patent type
- Prior art keywords
- arrangement according
- tank circuit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/035—Measuring direction or magnitude of magnetic fields or magnetic flux using superconductive devices
- G01R33/0358—SQUIDS coupling the flux to the SQUID
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S505/00—Superconductor technology: apparatus, material, process
- Y10S505/825—Apparatus per se, device per se, or process of making or operating same
- Y10S505/842—Measuring and testing
- Y10S505/846—Magnetometer using superconductive quantum interference device, i.e. squid
Arrangement for coupling an rf-SQUID to a superconducting oscillating tank circuit
The present invention relates to an arrangement for coupling an rf-SQUID to a superconducting oscillating tank circuit and to a base plate in which the tank circuit and the rf-SQUID form a coplanar structure and the tank circuit has a slot.
Various proposals have been pursued so far, to couple rf SQUID magnetometers to superconductive tank oscillating circuits.
One possibility is to use a λ- resonator to which an rf-SQUID is electrically coupled and the same time as a river pickup loop works. Such a SQUID magnetometer may have a tank frequency of 3 GHz.
The use of a λ resonator is problematic because it shows only a low quality of some 100th This is in view of the already reached with the λ / 2 resonators grades of several 1000 a fairly small size. In addition, also results in the fact that a hard-to-calculate parameters by the galvanic coupling, namely, the high-frequency current distribution must be taken into account to considerable problems. The Hochfrequenzstro distribution represents a not easy to be calculated or experimentally to be controlled size. The SQUID layout is therefore difficult to optimize.
Another possibility is to produce planar LC resonant circuits of YBaCuO thin films with high frequency and high quality. This LC resonant circuits are operated in a flip-chip arrangement with the rf-SQUID in washer- SQUID structure. The thereby occurring parasitical capacities between the LC circuit and the rf-SQUID reduce the quality factor of the LC resonant circuit and make the current distribution in the combined resonant LC circuit - / washer-SQUID structure complicated.
In the as yet unpublished application 196 11 900.6, the Applicant has described the aforementioned arrangement. This solves the problem of parasitic capacitances. As before, however, there is the problem that due to the facts before that the coplanar arranged rf-SQUID and tank circuit can not be arranged with the base plate in one plane and the ground plane also represents a potential source of noise, the use of an rf-SQUID may limit -Magnetometers.
The object of the present invention is therefore to provide an arrangement which eliminates during coupling an rf-SQUID magnetometer to a superconducting oscillating circuit, the above problems.
The object is achieved according to claim 1, characterized in that the base plate is designed as outer loop co-planar to the rf-SQUID and the tank circuit and comprises a slot, and that the tank circuit includes an inner loop in which the slit is formed and the orientation of the slots of the inner loop and the outer loop to each other, the resonance frequency f r is determined.
The arrangement according to the invention relates to the possibility of an advantageous optimal coupling an rf-SQUID to a tank circuit and a base plate which does not have the aforementioned disadvantages. With the fully integrated arrangement of rf-SQUID, tank circuit and the base plate and the training or orientation of the slots in the rf-SQUID and in the base plate according to claim 1, the tank frequency can be adjusted geo- metrieabhängig in a simple manner and thus provides a significant advantage z. As in building a multichannel SQUID system for medical applications. In addition, a conditional through the base plate, noise can be suppressed.
In addition, the fully integrated arrangement permits simple estimation of coupling between the rf-SQUID and the tank circuit.
According to claim 2 it is advantageous that an adjustment of the slots to each other, a change in resonant frequency caused F__ 300 <Mhz.
Another advantage according to claim 3 is that a defined superconducting short circuit between the rf-SQUID and the tank circuit is incorporated. The Resonanzfreque- unz of the resonant circuit takes namely with decreasing dimension. Above a cutoff frequency of 1 GHz but the required SQUID electronics is very complex and expensive. By the defined superconducting short-circuit the resonant frequency is significantly reduced, so that a very simple possibility is to obtain by simple geometry change discrete frequency ranges within a span of 600 MHz, and with very small dimensions still resonant frequencies to 500 MHz. These discrete frequencies are a necessary condition for the realization of a multi-channel SQUID-HTS system.
Further advantages of the present invention are obtained by the features of the claims 4 to 12th
According to claim 13 it is advantageous that a flux transformer is integrated into the arrangement in order to increase the magnetic field sensitivity of an rf-SQUID further.
A further advantage of claim 14 is that the flux transformer comprising an input coil, which is short-circuited. This takes place a decoupling of two current forms ex istieren in such an arrangement. The two current forms differ in their high and low frequencies. By decoupling disappear parasitic contributions of the high frequency current that occur at the intersections of the flux transformer. In the decoupled state flows through the crossings only low-frequency current.
According to claim 15 it is of particular advantage if the short circuit ER at a certain position of the capacitor follows.
A further advantage of claim 16 is that the field direction of the insert loop opposite to the field direction of the coupling coil is. Thus the SQUID signal is amplified in this geometry.
Embodiments of the present invention will be described in more detail below with reference to the drawings. Show it:
Figure la is a schematic view of a first geometry of a SQUID magnetometer with a base plate designed as a coplanar loop according to the first embodiment of the present invention.
Fig. Lb shows a schematic view of a second geometry of a SQUID magnetometer with a base plate designed as a coplanar loop according to the first embodiment of the present invention;
Figure lc is a schematic view of a third geometry of a SQUID magnetometer with a base plate designed as a coplanar loop according to the first embodiment of the present invention.
Figure 2 is a diagram of a test measurement with a geometry according to Figure la..; Fig. 3a shows a schematic view of a SQUID magnetometer without built-in short circuit;
Figure 3b is a schematic view of a SQUID magnetometer according to a second embodiment of the present invention incorporating a short-circuit and with a first geometry.
3c is a schematic view of a SQUID magnetometer according to a second embodiment of the present invention incorporating a short-circuit and with a second geometry.
Fig. 3d is a schematic view of a SQUID magnetometer according to a second embodiment with built-in short-circuit and with a third geometry;
4a and 4b show a schematic representation of an rf-SQUID with a planar tank circuit and a base plate.
Fig. 5 is a plate-schematic plan view of an rf-SQUID and a tank circuit without coplanar ground;
Fig. 6 is a schematic plan view of a single-layer flux transformer with a base plate designed as a coplanar loop according vorlieg- of the invention;
Fig. 7 is a schematic view of a single-layer flux transformer with a loop formed as a coplanar base plate and a multi-layer flux transformer according to the present
Invention; Figure 8 is a schematic view of a single-layer flux transformer with a loop formed as a coplanar base plate and a multi-layer flux transformer with a short circuit according to the present invention.
Fig. 9 is a schematic plan view of a SQUID gradiometer or two-hole SQUID.
In Fig. 4a and 4b are respectively a tank circuit 1 and an rf-SQUID magnetometer 2 with Planarschwingkreisen and λ / 2 or λ resonators are shown, which are coupled to a base plate 10 made of metal or superconductor material. This has the consequence that the tank circuit 1 with an integrated SQUID 2 and the base plate 10 can not be arranged in one plane. 10 In addition, the base plate is a possible source of noise that may restrict the use of an rf-SQUID magnetometer. 2 In Fig. 5, a tank circuit 1 is shown with a coplanar arranged rf-SQUID magnetometer 2 without base plate 10.
In Fig. La to lc shows an inventive arrangement in a first embodiment is schematically shown, in which the base plate 10 is formed as a coplanar arrangement in the form of an outer loop 10a. Thereby, the tank circuit 1, the SQUID 2 and the base plate can be disposed in a plane 10 degrees.
In Figure la, lb and lc have a different geometry of a SQUID magnetometer 2 is shown in each case which is present with a coplanar arrangement of an inner loop la of the tank circuit 1 and the äußerern loop 10a of the base plate 10 as a rf resonant circuit. The SQUID geometry in figure 4a, 4b is added an additional outer superconducting loop 10a. This loop 10a is provided with a slot 11 the coplanar resonant circuit. The area A in Figure la, lb, lc can be used as washer- be designed multiloop or current injection-SQUID structure. It is also possible to use this area as a flux concentrator or flux transformer to combine the coplanar resonant circuit with a washer-SQUID magnetometer in flip-chip geometry.
A major advantage of this coplanar oscillating circuits 10a is the geometry-dependent resonance frequency of the oscillating circuit. The only difference in the geometries in Figures la to lc is the orientation of the slot 11 in the outer loop to the slot 4 in the inner loop la. In Fig. La are both slots 4, 11 aligned over each other, the difference in orientation is 0 degrees or 360 degrees. The resonant frequency is at f e. = 850 MHz. 550, the resonance frequency changes to the orientation of 180 degrees (Fig. Lc), so takes on f 1 = _ MHz. At 90 degrees (Fig. Lb), the resonance frequency f _ I = 650 MHz. This results in a very simple way to achieve discrete frequency ranges within a range of 300 MHz to the geometry by simply changing. These discrete frequency sequences Squid system is a necessary condition for the realization of a multi-channel HTS.
Through the simple change in the geometry of the coplanar oscillating circuit 10a, a frequency change of the Tankfre- is achieved frequency of the rf-SQUID. 2 This is a significant advantage over the prior art especially with regard to the development of a multichannel SQUID system, for example, medical applications.
In Fig. 2 Test measurements using this layout are shown, which at a resonant frequency of the tank circuit of 850 MHz, a quality of about 5000 and a white noise of
* ~ 5 have shown Φ O / VHZ 1.85 10th
Figures 3b to 3d show the geometry of a coplanar resonant circuit according to a second embodiment of the present invention with a defined superconducting short circuit 5. In Fig. 3a of the Resonanzschwing- is circular without this short-circuit 5 shown. The frequency in Fig. 3a is f 0 = l, l GHz at a quality Q> 5000. In Fig. 3b to 3d defined superconducting shorts 5 are fitted. These shorts 5 are at 180 degrees (Fig. 3b), 90 degrees (Fig. 3c) and 360 degrees (Fig. 3d) attached. The changes of the resonant frequency in Fig. 3b to 3d the short circuits 5 with respect to the resonant frequency without short circuit is significant. In Fig. 3b, the resonant frequency is f 1 = 920 MHz, in Fig. 3c, the resonant frequency is f 2 = 803MHz and in Fig. 3d, the resonance frequency f 3 = is 620 MHz. The quality is still better than Q> 5000 for all manufactured resonant circuits. Since the quality determines the coupling between the SQUID and the resonant circuit is still not affected by the presented improve the SQUID function.
This results in the very simple Möglichhkeit to achieve discrete frequency ranges within a range of 600 Mhz to the geometry by simply changing. Even with substrate dimensions of lO lOmm β 2 can be realized by the invention, resonance frequencies up to 500 MHz.
Fig. 6 shows schematically a further embodiment of an assembly according to the invention, in which the base plate 10 is formed as a coplanar arrangement in the form of an outer loop 10a and the tank circuit 1 and the base plate are arranged in a plane 10. Within the tank circuit 1, a flux transformer having an enclosure loop 3.1 is arranged. A SQUID gradiometer 2 or two-hole SQUID (Fig. 9) is inserted such that the Josephson junction is positioned at the point of contact of the two Washerflachen. This SQUID 2 is applied in flip-chip arrangement on the flux transformer.
In Fig. 7 is inside the tank circuit 1, a
Flux transformer is provided, which comprises a multi-layer Einkop- pelspule 3.2. The multilayer coupling coil 3.2 also has a crossover. 6
Due to the fact that present in the present arrangement, a high-frequency and low-frequency current waveform and the high frequency current affects parasitically to the intersections 6 of the flux transformer and degrades at a tank frequency of about 900 MHz, the quality of the resonant circuit is at a position A (Fig. 8) provided at a con- capacitor 7 shorts decouple the two current waveforms, so that via the crossings 6 in the decoupled state flow only low-frequency currents. The shorts are normally conducting high frequency metal shorts. The second superconducting loop 10a is used for high-frequency coupling between the SQUID 2 and flux transformer. Here affects the high frequency current and ensures the coupling between the SQUID 2 and tank circuit 1. The fact that the field direction of the deposits loop 3.1, and the multi-layer coil are 3.2 to accurately set corresponds, the SQUID signal is amplified in this geometry.
Priority Applications (7)
|Application Number||Priority Date||Filing Date||Title|
|DE1996220718 DE29620718U1 (en)||1996-03-26||1996-11-28||Arrangement for coupling an rf-SQUID magnetometer to a superconducting oscillating tank circuit|
|DE1997117801 DE19717801C2 (en)||1996-11-28||1997-04-26||Arrangement for coupling an rf-SQUID to a superconducting oscillating tank circuit|
|DE1997215860 DE29715860U1 (en)||1996-11-28||1997-09-04||Arrangement for coupling an rf-SQUID to a superconducting oscillating tank circuit|
|PCT/DE1997/002760 WO1998023969A3 (en)||1996-11-28||1997-11-26||DEVICE FOR COUPLING AN rf-SQUID TO A SUPER CONDUCTING TANK CIRCUIT|
|Publication Number||Publication Date|
|EP0941482A2 true true EP0941482A2 (en)||1999-09-15|
Family Applications (1)
|Application Number||Title||Priority Date||Filing Date|
|EP19970951807 Withdrawn EP0941482A2 (en)||1996-03-26||1997-11-26||Device for coupling an rf-squid to a super conducting tank circuit|
Country Status (4)
|US (1)||US6300760B1 (en)|
|EP (1)||EP0941482A2 (en)|
|JP (1)||JP2001504589A (en)|
|WO (1)||WO1998023969A3 (en)|
Families Citing this family (8)
|Publication number||Priority date||Publication date||Assignee||Title|
|JP4820481B2 (en) *||2000-09-13||2011-11-24||エスアイアイ・ナノテクノロジー株式会社||SQUID|
|JP2002243817A (en) *||2001-02-21||2002-08-28||Hitachi Ltd||Detection coil-integrated gradiometer and magnetic field measuring instrument|
|US6894584B2 (en) *||2002-08-12||2005-05-17||Isco International, Inc.||Thin film resonators|
|WO2007008646A3 (en)||2005-07-12||2008-02-28||Massachusetts Inst Technology||Wireless non-radiative energy transfer|
|US7825543B2 (en)||2005-07-12||2010-11-02||Massachusetts Institute Of Technology||Wireless energy transfer|
|US8179133B1 (en)||2008-08-18||2012-05-15||Hypres, Inc.||High linearity superconducting radio frequency magnetic field detector|
|US8362651B2 (en)||2008-10-01||2013-01-29||Massachusetts Institute Of Technology||Efficient near-field wireless energy transfer using adiabatic system variations|
|DE102009025716A1 (en)||2009-06-20||2010-12-30||Forschungszentrum Jülich GmbH||Meter, electrical resistance elements and measurement system for measuring time-varying magnetic fields or field gradients|
Family Cites Families (1)
|Publication number||Priority date||Publication date||Assignee||Title|
|DE4003524A1 (en) *||1990-02-06||1991-08-08||Forschungszentrum Juelich Gmbh||Circuit with superconducting quanta interference detectors or SQUIDs|
Non-Patent Citations (1)
|See references of WO9823969A2 *|
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|17P||Request for examination filed||
Effective date: 19990408
|17Q||First examination report||
Effective date: 20000328
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Owner name: FORSCHUNGSZENTRUM JUELICH GMBH
Free format text: DEVICE FOR COUPLING AN RF-SQUID TO A SUPER CONDUCTING TANK CIRCUIT
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Effective date: 20041123