Quantum flux coupling optimization structure of low-temperature current comparator

Abstract

The application discloses a low-temperature current comparator quantum flux coupling optimization structure, and is applied to the technical field of measurement testing instruments. The low-temperature current comparator quantum flux coupling optimization structure comprises a detection coil assembly, a superconducting proportional coil and a superconducting quantum interference device. The detection coil assembly comprises a ring-shaped framework and a superconducting detection coil. The ring-shaped framework has coaxially nested outer and inner layers. The outer layer is made of high-conductivity material, and the inner layer is made of high-permeability material. The outer periphery of the outer layer is provided with a spiral groove. The superconducting detection coil is wound in the spiral groove. The ring-shaped framework is arranged at the inner center position of the superconducting proportional coil. The superconducting detection coil leads out a tap to the input coil of the superconducting quantum interference device. The application suppresses high-frequency interference through eddy current shielding and flux aggregation effect, changes the traditional surface winding inductance coupling mechanism into a directional magnetic circuit coupling mechanism based on a high-permeability magnetic core, improves coupling efficiency, and improves the current resolution of the low-temperature current comparator.

Description

Technical Field

[0001] This invention relates to the field of metrology and testing instrument technology, and more specifically to an optimized quantum flux coupling structure for a low-temperature current comparator. Background Technology

[0002] The Cryogenic Current Comparator (CCC) utilizes the Meissner effect of superconducting materials at low temperatures to create a near-ideal zero-flux shielding environment. It also employs a superconducting quantum interference device (QFID) with extreme flux sensitivity as the flux detection unit, achieving proportional accuracy down to the E-11 order of magnitude in current proportionality measurements. This makes it the closest to theoretically perfect current proportionalizer to date. The resistance bridge system and current amplifier built upon the CCC are also currently the highest-specification resistance and current transfer devices internationally, and are the preferred choice for quantized resistance and current transfer by various national metrology institutes.

[0003] However, traditional detection coil coupling methods are limited by multiple conduction paths and assembly processes, inevitably introducing coupling losses. Simultaneously, the presence of high-frequency interference prevents further increases in the comparison turns ratio, causing the CCC's limiting current resolution to fall short of the ideal fA level, thus restricting the CCC's transmission performance in quantum current and resistance references. Therefore, how to provide an optimized quantum flux coupling structure for low-temperature current comparators is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] In view of this, the present invention provides a quantum flux coupling optimization structure for a low-temperature current comparator. By designing a high conductivity-high permeability double-layer composite skeleton, an eddy current screen filter is constructed to solve the high-frequency interference problem in the low-temperature current comparator system. Furthermore, the inductive coupling mechanism of the surface winding in the traditional detection coil is optimized into a magnetic core magnetic circuit aggregation mechanism to overcome the influence of weak inductive coupling of mirror current and coupling factor loss, so as to fully utilize the application performance of CCC in the field of weak current measurement.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A quantum flux coupling optimization structure for a low-temperature current comparator includes a detection coil assembly, a superconducting proportional coil, and a superconducting quantum interference device (QFID). The detection coil assembly includes a ring frame and a superconducting detection coil. The ring frame has a coaxially nested outer layer and an inner layer. The outer circumferential surface of the outer layer is provided with a helical groove. The superconducting detection coil is wound in the helical groove. The ring frame is located at the internal center of the superconducting proportional coil. A tap from the superconducting detection coil is led out to the input coil of the superconducting quantum interference device.

[0006] Optionally, the outer layer is made of a highly conductive material, and the inner layer is made of a highly magnetically permeable material. The highly conductive material is selected from at least one of copper, aluminum, and silver; the highly magnetically permeable material is selected from at least one of permalloy, silicon steel, and amorphous alloy.

[0007] Optionally, the number of turns of the spiral groove is determined based on the matching principle between the input coil inductance of the superconducting quantum interference device and the effective inductance of the superconducting proportional coil: ; In the formula, The turns ratio of the detection coil after inductor matching. The inductance of the input coil of the superconducting quantum interference device is... is the effective inductance of the superconducting proportional coil.

[0008] Optionally, the core wire of the superconducting detection coil is made of niobium or niobium-titanium alloy.

[0009] Optionally, the superconducting proportional coil and the annular frame are fixed by a bracket, and the superconducting proportional coil and the annular frame are insulated from each other.

[0010] Optionally, the bracket is made of a highly insulating material, which includes at least one of ceramic, polytetrafluoroethylene, polyetheretherketone, and epoxy resin.

[0011] Optionally, the superconducting detection coil and the superconducting quantum interference device are connected by a superconducting connection, and there is no normal resistance in the connection path.

[0012] As can be seen from the above technical solutions, compared with the prior art, the present invention provides a quantum flux coupling optimized structure for a low-temperature current comparator, which has the following beneficial effects: The present invention solves the problem of high-frequency interference in the low-temperature current comparator system by designing a high conductivity-high permeability double-layer composite skeleton and constructing an eddy current screen filter. It optimizes the surface winding inductive coupling mechanism in the traditional detection coil into a magnetic core magnetic circuit aggregation mechanism, overcomes the influence of weak inductive coupling of mirror current and coupling factor loss, and can give full play to the application performance of CCC in the field of weak current measurement. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of the assembly of the quantum flux coupling optimization structure of the present invention; Figure 2 This is a schematic diagram of the high conductivity-high magnetic permeability composite double-layer ring skeleton of the present invention. In the figure: 1-ring skeleton, 11-outer layer, 12-inner layer, 13-spiral groove, 2-superconducting proportional coil, 3-superconducting detection coil, 4-support. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] This invention discloses an optimized quantum flux coupling structure for a low-temperature current comparator, such as... Figure 1 and Figure 2 As shown, the device includes a detection coil assembly, a superconducting proportional coil 2, and a superconducting quantum interference device (QFID). The detection coil assembly includes a ring frame 1 and a superconducting detection coil 3. The ring frame 1 has a coaxially nested outer layer 11 and an inner layer 12. The outer circumferential surface of the outer layer 11 is provided with a spiral groove 13. The superconducting detection coil 3 is wound in the spiral groove 13. The ring frame 1 is located at the internal center of the superconducting proportional coil 2. The superconducting detection coil 3 has a tap led out to the input coil of the superconducting quantum interference device.

[0017] Furthermore, the outer layer 11 is made of a highly conductive material, and the inner layer 12 is made of a highly magnetically permeable material. The highly conductive material is selected from at least one of copper, aluminum, and silver; the highly magnetically permeable material is selected from at least one of permalloy, silicon steel, and amorphous alloy. In this embodiment, the highly conductive material is brass, and the highly magnetically permeable material is silicon steel.

[0018] The outer layer 11 is a highly conductive layer that forms an eddy current screen filter to solve the problem of high-frequency interference in the cryogenic current comparator system; the inner layer 12 is a highly magnetic permeable layer that effectively aggregates and confines the magnetic field lines of the superconducting coil within the skeleton domain, overcoming the weak coupling effect of traditional mirror current and the influence of coupling factor loss on conduction efficiency, thereby achieving high-sensitivity coupling to weak quantum magnetic flux signals.

[0019] Furthermore, the number of turns of the spiral groove 13 is determined based on the matching principle between the inductance of the input coil of the superconducting quantum interference device and the effective inductance of the superconducting proportional coil 2: ; In the formula, The turns ratio of the detection coil after inductor matching. The inductance of the input coil of the superconducting quantum interference device. This is the effective inductance of the superconducting proportional coil 2.

[0020] In this embodiment of the invention, the inductance of the input coil of the superconducting quantum interference device is 1.8 μH, and the effective inductance of the superconducting proportional coil 2 is 10 nH. According to the inductance matching calculation, the optimal number of turns of the detection coil is N≈13.4. In this embodiment, it should be set to 13 turns. According to the lead wire size used in the superconducting detection coil 3 in the cryogenic current comparator, the depth and width of the spiral groove 13 are determined. In this embodiment, the outer diameter of the outer layer 11 of the annular skeleton 1 is 12 mm, the inner diameter is 8 mm, the height is 15 mm, and the number of turns is 13. Based on this, an M12×1 metric thread is selected.

[0021] Furthermore, the core wire of the superconducting detection coil 3 is made of either niobium or niobium-titanium alloy.

[0022] Furthermore, the superconducting proportional coil 2 and the annular frame 1 are fixed by the bracket 4, and the superconducting proportional coil 2 and the annular frame 1 are insulated from each other. In this embodiment, raw rubber tape can be used to achieve the insulation.

[0023] Furthermore, the support 4 is made of a highly insulating material, which includes at least one of ceramic, polytetrafluoroethylene, polyetheretherketone, and epoxy resin. In this embodiment, PEEK or alumina ceramic is selected.

[0024] Furthermore, the superconducting detection coil 3 and the superconducting quantum interference device are connected by a superconducting connection, and there is no normal resistance in the connection path.

[0025] In this embodiment of the invention, the outer diameter, inner diameter, and height parameters of the annular frame 1 are determined based on the design dimensions of the superconducting proportional coil 2. The design dimensions of the superconducting proportional coil 2 include the inner diameter, outer diameter, and height of the coil, specifically: outer diameter 32 mm, inner diameter 18 mm, and height 17 mm. The outer diameter of the composite annular frame 1 is smaller than the inner diameter of the superconducting proportional coil 2, and the height is smaller than the height of the superconducting proportional coil 2. Specifically, the outer diameter of the outer layer 11 is 12 mm, the inner diameter is 8 mm, and the height is 15 mm; the outer diameter of the inner layer 12 is 7.9 mm, the inner diameter is 5 mm, and the height is 15 mm.

[0026] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0027] Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A quantum flux coupling optimized structure for a low-temperature current comparator, characterized in that, The device includes a detection coil assembly, a superconducting proportional coil (2), and a superconducting quantum interference device. The detection coil assembly includes a ring frame (1) and a superconducting detection coil (3). The ring frame (1) has a coaxially nested outer layer (11) and an inner layer (12). The outer circumferential surface of the outer layer (11) is provided with a spiral groove (13). The superconducting detection coil (3) is wound in the spiral groove (13). The ring frame (1) is located at the internal center of the superconducting proportional coil (2). The superconducting detection coil (3) has a tap led out to the input coil of the superconducting quantum interference device.

2. The quantum flux coupling optimization structure for a low-temperature current comparator according to claim 1, characterized in that, The outer layer (11) is made of a highly conductive material, and the inner layer (12) is made of a highly magnetic material. The highly conductive material is selected from at least one of copper, aluminum, and silver; the highly magnetic material is selected from at least one of permalloy, silicon steel, and amorphous alloy.

3. The optimized quantum flux coupling structure for a low-temperature current comparator according to claim 1, characterized in that, The number of turns of the spiral groove (13) is determined based on the matching principle between the input coil inductance of the superconducting quantum interference device and the effective inductance of the superconducting proportional coil (2): ； In the formula, The turns ratio of the detection coil after inductor matching. The inductance of the input coil of the superconducting quantum interference device is... The effective inductance of the superconducting proportional coil (2) is given.

4. The quantum flux coupling optimization structure for a low-temperature current comparator according to claim 1, characterized in that, The core wire of the superconducting detection coil (3) is made of either niobium or niobium-titanium alloy.

5. The quantum flux coupling optimization structure for a low-temperature current comparator according to claim 1, characterized in that, The superconducting proportional coil (2) and the annular frame (1) are fixed by a bracket (4), and the superconducting proportional coil (2) and the annular frame (1) are insulated from each other.

6. The quantum flux coupling optimization structure for a low-temperature current comparator according to claim 5, characterized in that, The support (4) is made of a highly insulating material, which includes at least one of ceramic, polytetrafluoroethylene, polyetheretherketone, and epoxy resin.

7. The quantum flux coupling optimization structure for a low-temperature current comparator according to claim 1, characterized in that, The superconducting detection coil (3) and the superconducting quantum interference device are connected by a superconducting connection, and there is no normal resistance in the connection path.

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