Ion irradiation method for improving performance of copper-based superconducting strip

Abstract

The invention provides an ion irradiation method for improving the performance of a copper-based superconducting strip, and belongs to the technical field of ion irradiation. The ion irradiation method comprises the following steps: carrying out ion irradiation on the copper-based superconducting tape by adopting an ion beam under a vacuum condition; the ion beam comprises a light ion beam or a heavy ion beam. By accurately controlling the energy, dosage and current intensity of the ion beam, effective modification of the copper-based superconducting strip is realized, the current-carrying performance of the 2G-HTS strip under high temperature and high field is remarkably improved, and the critical current density Jc is improved by 2.1-5 times. In addition, modification can be carried out according to the specific requirements of the copper-based superconducting strip, and then the consistency and stability of the modification effect are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of ion irradiation technology, and in particular relates to an ion irradiation method for improving the performance of a copper-based superconducting tape. Background Art

[0002] With the rapid development of superconducting technology, the second generation of high temperature superconducting tape (2G-HTS) has unique properties, such as high critical transition temperature (T c ), upper critical field (H c2 ), critical current density (J c ), low AC loss, good thermodynamic and magnetic stability, and shows great application potential in the fields of electricity, transportation, and medical treatment.

[0003] However, under extreme environments, its performance stability and reliability have become bottlenecks restricting its further development. Although traditional material modification methods (such as introducing secondary phase doping) have certain effects, it is difficult to meet the current carrying performance (heavy ion critical current density J) of 2G-HTS tapes under high temperature (>30K) and high field (>3T) environments. c The increase is about 1.1 to 1.5 times, and the light ion is 1.1 to 1.2 times). Summary of the invention

[0004] In view of this, the object of the present invention is to provide an ion irradiation method for improving the performance of copper-based superconducting tapes. The ion irradiation method provided by the present invention can significantly improve the current carrying performance of 2G-HTS tapes under high temperature and high field.

[0005] In order to achieve the above object, the present invention provides the following scheme:

[0006] The present invention provides an ion irradiation method for improving the performance of a copper-based superconducting tape, comprising the following steps:

[0007] Under vacuum conditions, an ion beam is used to irradiate a copper-based superconducting tape; the ion beam includes a light ion beam or a heavy ion beam; and the ion irradiation current intensity is 1 to 10 μA;

[0008] The energy of the light ion beam is 270 keV and the dose is 0.1×10 16 ~1×10 16 irons / cm 2 ;

[0009] The energy of the heavy ion beam is 45-200 MeV, and the dose is 0.01×10 12 ~1×10 12 irons / cm 2 .

[0010] Preferably, the light ion beam comprises a proton beam; and the heavy ion beam comprises a Xe ion beam.

[0011] Preferably, the vacuum degree of the vacuum condition is 1×10 -3 Torr.

[0012] Preferably, the ion irradiation injection rate is 5×10 9 irons / (cm 2 ·s).

[0013] Preferably, the energy of the heavy ion beam is 45 MeV, 65 MeV, 85 MeV, 100 MeV, 150 MeV or 200 MeV, and the dose is 2×10 10 , 5×10 10 , 2×10 11 , 4×10 11 , 5×10 11 or 1×10 12 irons / cm 2 .

[0014] Preferably, the copper-based superconducting tape is located at the center of the ion irradiation spot; the size of the ion irradiation spot is 2 cm×2 cm.

[0015] Preferably, when a plurality of copper-based superconducting tapes are subjected to ion irradiation at the same time, the distance between adjacent copper-based superconducting tapes is 1 mm; and the width of a single copper-based superconducting tape is 4 mm.

[0016] Preferably, the copper-based superconducting tape comprises a 2G-HTS tape.

[0017] Preferably, the superconducting layer of the 2G-HTS tape is a doped or undoped EuBa2Cu3O7 layer; when the superconducting layer is a doped EuBa2Cu3O7 layer, the secondary phase dopant includes BaHfO3.

[0018] Preferably, the EuBa2Cu3O7 layer is a single-layer, double-layer or triple-layer structure, with a single-layer thickness of 1 μm, a double-layer thickness of 2 μm, and a triple-layer thickness of 3 μm.

[0019] The present invention provides an ion irradiation method for improving the performance of a copper-based superconducting tape, comprising the following steps: ion irradiating the copper-based superconducting tape with an ion beam; the ion beam comprises a light ion beam or a heavy ion beam; the ion irradiation current is 1 to 10 μA; the energy of the light ion beam is 270 keV, and the dose is 0.1×10 16 ~1×10 16 irons / cm 2The energy of the heavy ion beam is 45-200 MeV, and the dose is 0.01×10 12 ~1×10 12 irons / cm 2 .

[0020] The present invention achieves effective modification of copper-based superconducting tapes by precisely controlling the energy, dosage and current intensity of the ion beam, and significantly improves the current carrying performance of 2G-HTS tapes under high temperature and high field. The results of the embodiment show that the critical current density J c Increased by 2.1 to 5 times.

[0021] The present invention monitors the ion beam parameters and the strip response in real time, and adjusts the irradiation parameters in time to ensure the modification effect (J c The stability and consistency of the value) can be seen from the stable change of flow intensity over time during the test.

[0022] The present invention can avoid burning of the copper-based superconducting tape due to high current intensity by controlling the current intensity to be as low as possible (1-10 μA).

[0023] In addition, due to the complex composition structure and large surface area of ​​2G-HTS tape, the loss energy of irradiated ions in the tape is large, resulting in uneven defect density distribution introduced by the ion beam, thereby affecting its current carrying performance. The present invention controls the spot size to 2cm×2cm, so that the spot can cover at least one cut sample (maximum 4mm×4mm) while satisfying its uniformity (uniform distribution of ion beam on the surface of the tape), and can avoid the problem of non-uniformity caused by ion irradiation, thereby avoiding affecting the current carrying performance of 2G-HTS tape. The present invention ensures uniform distribution and efficient irradiation of the ion beam on the surface of the tape by optimizing the fixed position of the tape and the spacing between the tapes (the tape width is 4mm, which is at the center of the spot; the distance between the tapes is 1mm) and the current intensity of the ion beam.

[0024] The ion irradiation method provided by the present invention is not only applicable to the modification of 2G-HTS tapes, but can also be extended to the modification of other types of superconducting materials and superconducting tapes with complex structures, and therefore has strong adaptability and flexibility.

[0025] The ion irradiation method provided by the present invention not only brings technical competitive advantages to material modification, but also provides favorable support for the wide application of high-temperature superconducting tapes, and promotes the further development of superconducting technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0027] Figure 1 The strip material before and after Xe ion irradiation in Example 1 (double layer + 6% BaHfO3 (BHO for short) doping, superconducting layer thickness of about 2 μm) c Data with external magnetic field H at 77K, different irradiation energies and doses;

[0028] Figure 2 The strip material before and after Xe ion irradiation in Example 2 (three layers + 10% BHO doping, superconducting layer thickness of about 3 μm) c Data with external magnetic field H at 77K, different irradiation energies and doses;

[0029] Figure 3 For example, 3270keV protons [dose 1×10 15 irons / cm 2 ] Strip before and after irradiation (three layers + 10% BHO doping, film thickness about 3μm)J c Variation results of external magnetic field H at different temperatures. DETAILED DESCRIPTION

[0030] The present invention provides an ion irradiation method for improving the performance of a copper-based superconducting tape, comprising the following steps:

[0031] Under vacuum conditions, an ion beam is used to perform ion irradiation on a copper-based superconducting tape; the ion beam includes a light ion beam or a heavy ion beam.

[0032] Unless otherwise specified, the materials and equipment used in the present invention are commercially available products.

[0033] In the present invention, the vacuum degree of the vacuum condition is preferably 1×10 -3 In the present invention, the light ion beam preferably comprises a proton beam; and the heavy ion beam preferably comprises a Xe ion beam.

[0034] In the present invention, the copper-based superconducting tape preferably includes a 2G-HTS tape; the 2G-HTS tape preferably consists of a Hastelloy alloy, a buffer layer, a superconducting layer and a protective layer stacked in sequence; the superconducting layer of the 2G-HTS tape is preferably a doped or undoped EuBa2Cu3O7 layer, and the EuBa2Cu3O7 layer is preferably a single-layer, double-layer or triple-layer structure, the single-layer thickness is preferably 1 μm, the double-layer thickness is preferably 2 μm, and the triple-layer thickness is preferably 3 μm; when the superconducting layer is a doped EuBa2Cu3O7 layer, the secondary phase dopant preferably includes BaHfO3.

[0035] In the present invention, the superconducting layer preferably includes a doped BaHfO3 superconducting layer or an undoped BaHfO3 superconducting layer. In the present invention, the molar concentration of BaHfO3 in the doped BaHfO3 superconducting layer is preferably >0% and ≤10%, and in the embodiment of the present invention, it can be 3.5%, 4.5%, 5%, 6% or 10%.

[0036] In the present invention, the protective layer is preferably an Ag layer, and the thickness of the Ag layer is preferably 0.38 μm.

[0037] In the present invention, when a plurality of copper-based superconducting tapes are subjected to ion irradiation at the same time, the distance between adjacent copper-based superconducting tapes is preferably 1 mm, and the width of a single copper-based superconducting tape is preferably 4 mm.

[0038] In the present invention, the current intensity of the ion irradiation is 1-10 μA, and in the embodiments of the present invention, it can be 1 μA, 4 μA, 6 μA, 8 μA or 10 μA. The present invention can avoid burning the copper-based superconducting tape due to high current intensity by controlling the current intensity as low as possible (1-10 μA).

[0039] In the present invention, the spot size of the ion irradiation is preferably 2 cm×2 cm. The temperature of the ion irradiation is preferably room temperature. In the present invention, the copper-based superconducting tape is preferably located at the center of the spot of ion irradiation; the distance between the copper-based superconducting tapes is 1 mm.

[0040] The present invention controls the spot size to 2cm×2cm, so that the spot can cover at least one cut sample (maximum 4mm×4mm) while satisfying its uniformity (uniform distribution of ion beam on the surface of the strip), and can avoid the problem of non-uniformity caused by ion irradiation, thereby avoiding affecting the current carrying performance of 2G-HTS strips. The present invention ensures uniform distribution and efficient irradiation of ion beams on the surface of the strips by optimizing the fixed position of the strips and the spacing between the strips (the strip width is 4mm, which is at the center of the spot; the distance between the strips is 1mm) and the current intensity of the ion beam.

[0041] In the present invention, the dose of the light ion beam is 0.1×10 16 ~1×10 16 irons / cm 2 In the embodiment of the present invention, it can be 1×10 16 irons / cm 2 or 1×10 15 irons / cm 2 .

[0042] In the present invention, the energy of the heavy ion beam is 45 to 200 MeV. In an embodiment of the present invention, it can be 45 MeV, 65 MeV, 85 MeV, 100 MeV, 150 MeV or 200 MeV.

[0043] In the present invention, the dose of the heavy ion beam is 0.01×10 12 ~1×10 12 irons / cm 2 In the embodiment of the present invention, it can be 2×10 10 , 5×10 10 , 2×10 11 , 4×10 11 , 5×10 11 or 1×10 12 irons / cm 2 .

[0044] In the present invention, the irradiation injection rate of the ion irradiation is preferably 5×10 9 irons / (cm 2 ·s). The ion irradiation time in the present invention can be calculated by dividing the ion irradiation dose by the irradiation injection rate.

[0045] The present invention achieves effective modification of copper-based superconducting tapes by precisely controlling the energy, dosage and current intensity of the ion beam, significantly improving the current carrying performance of 2G-HTS tapes under high temperature and high field, that is, the critical current density J c Increased by 2.1 to 5 times.

[0046] The present invention monitors the ion beam parameters and the strip response in real time, and adjusts the irradiation parameters in time to ensure the modification effect (J c The stability and consistency of the value) can be seen from the stable change of the flux intensity over time during the test. For example, if the strip is found to be shiny during the irradiation process, it means that the irradiation causes the strip to overheat and may damage the strip. At this time, it is necessary to reduce the irradiation energy or stop the irradiation.

[0047] In order to further illustrate the present invention, an ion irradiation method for improving the performance of a copper-based superconducting tape provided by the present invention is described in detail below in conjunction with the accompanying drawings and embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0048] Example 1

[0049] The method of ion irradiation of copper-based superconducting tape using heavy ion beam Xe ions is as follows:

[0050] 1. Preparation stage: Select 2G-HTS strips that meet the experimental requirements and reserve ion irradiation equipment in good condition.

[0051] Materials and equipment preparation: First, select the 2G-HTS tape to be irradiated: double layer + 6% BaHfO3 (BHO for short), superconducting layer thickness of about 2μm, to ensure that its superconducting performance meets the experimental requirements. At the same time, make an appointment for the corresponding ion irradiation equipment, and clarify the operating status of the equipment to ensure that it can operate stably during the experiment. Among them, proton and Xe ion irradiation require tandem accelerators with different energies, and the specific irradiation energy depends on the demand.

[0052] Xe ion irradiation utilizes the medium energy irradiation terminal (No. 128) equipment in the heavy ion accelerator device of the Institute of Modern Physics [which can provide the required irradiation energy of 50MeV~200MeV].

[0053] Environmental preparation: Ensure that the experimental environment meets the requirements of temperature, vacuum degree, etc., and take appropriate isolation measures to avoid external interference.

[0054] Specifically, the experimental environment temperature is room temperature; the cavity containing the sample is maintained by a mechanical pump and pumped to 10 -3 Torr;

[0055] Isolation measures are to wear protective clothing and avoid entering the separate room containing irradiation equipment as much as possible during irradiation operation.

[0056] The environment has a significant impact on the experiment. If the vacuum level cannot be lowered, it will be difficult for the ion beam to evenly illuminate the sample surface, and the energy of the ion beam (irradiation energy) will be lost to a great extent. In addition, heavy ion Xe ion irradiation may radiate other particles (such as gamma rays) and affect the human body, so isolation measures are necessary.

[0057] Safety preparation: Wear protective equipment and check the safety performance of the equipment to ensure the safety of the experiment.

[0058] 2. Parameter setting: Parameter setting is one of the key steps in ion irradiation modification experiments.

[0059] Ion beam type and energy selection: Select the appropriate ion beam type (Xe ions) and its energy according to the strip requirements. Specifically, the energies are 100MeV, 150MeV or 200MeV.

[0060] Flux and irradiation injection setting: Consider the ion beam energy, type and strip characteristics comprehensively, and set a reasonable flux and irradiation injection. By adjusting the flux and irradiation injection, the uniformity and consistency of the ion beam on the strip surface can be controlled. The specific flux is 10μA, and the irradiation injection (dose) rate is 5×10 9 irons / (cm 2 ·s)

[0061] Set the temperature during ion irradiation: room temperature (maintained at a constant temperature by water cooling);

[0062] Set the spot size: 2cm×2cm.

[0063] 3. Irradiation treatment: Irradiation treatment is the core step of the irradiation modification experiment.

[0064] Strip placement: Place the prepared 2G-HTS strip into the irradiation chamber of the ion irradiation equipment, and ensure that the relative position between the strip and the ion beam is fixed (the strip width is 4mm, in the center of the spot; the distance between the strips is 1mm). At the same time, check the fixation of the strip to avoid movement or deformation during irradiation.

[0065] Ion beam start: Start the ion source according to the preset parameters.

[0066] Irradiation process monitoring: During the irradiation process, the parameters of the ion beam and the response of the strip need to be monitored in real time.

[0067] Inspection after irradiation: After the irradiation treatment is completed, the integrity and surface condition of the strip need to be checked.

[0068] Performance test before and after irradiation Compare the performance data before and after irradiation to evaluate the modification effect.

[0069] Example 2

[0070] The method of ion irradiation of copper-based superconducting tape using heavy ion beam Xe ions is as follows:

[0071] The steps are the same as those in Example 1, with the only difference being that the instrument is a medium-energy irradiation terminal (name: leaf terminal) device in the heavy ion accelerator device of the Institute of Modern Physics [which can provide the required irradiation energy of 45MeV to 90MeV].

[0072] 2G-HTS tape: The superconducting layer consists of three layers (the thickness of the superconducting layer is about 3 μm) + 10% BHO doping.

[0073] The parameter settings are: 45MeV~85MeVXe ions, dose 2×10 10 ~4×10 11 irons / cm 2 ; Spot size 2cm×2cm; Set the temperature during ion irradiation: room temperature (kept at a constant temperature by water cooling).

[0074] Example 3

[0075] The method of ion irradiation of copper-based superconducting tape using a single light ion beam proton is as follows:

[0076] The steps are the same as those in Example 1, except that the proton irradiation utilizes a 320keV low-energy ion device in the heavy ion accelerator of the Institute of Modern Physics, Chinese Academy of Sciences.

[0077] 2G-HTS tape: The superconducting layer is EuBa2Cu3O7, the superconducting layer is three layers + 10% BHO doping, and the superconducting layer film thickness is about 3μm.

[0078] The parameter settings are: 270keV protons, dose 1×10 15 irons / cm 2 , the current intensity is 10μA; the spot size is 2cm×2cm; the temperature during ion irradiation is set to room temperature (kept at a constant temperature by water cooling).

[0079] Performance Testing

[0080] The performance of the 2G-HTS tapes irradiated by ion beams in Examples 1 to 3 was tested using a PPMS instrument.

[0081] Figure 1 The ribbon (double layer + 6% BHO doping) before and after Xe ion irradiation in Example 1 c Data with external magnetic field H at 77K (liquid nitrogen temperature) and different irradiation energies. Among them, pristine means no irradiation;

[0082] from Figure 1 It can be seen that for the double-layer +6% BHO doped ribbon irradiated with Xe ions [doses include 5×10 10 and 2×10 11 irons / cm 2 Two doses], in low field [here refers to the external magnetic field H < 2T], such as 150MeV irradiation at H = 0T, the J of the unirradiated sample (pristine) can be reduced to c Increased by 4.7 times, while at high field J c The improvement is more obvious. This is a very high value among other heavy ion irradiation effects.

[0083] Figure 2 The ribbon (three layers + 10% BHO doping) before and after Xe ion irradiation in Example 2 c Data of different irradiation energies at 77K with external field, where J c The fold changes at H=5T are shown in Table 1.

[0084] Table 1J c Change factor at H = 5T

[0085] Energy-dose <![CDATA[J after irradiation c Magnification factor at H = 5T]]> 65MeV-2e10 2.1 65MeV-5e10 2.6 65MeV-2e11 3.2 65MeV-4e11 3.9 85MeV-5e10 1.9 85MeV-2e11 2.1

[0086] From Table 1, we can see that for J before and after irradiation c The change factor is 65MeV irradiation energy [dose is 4×10 11 irons / cm 2 ] provides a relatively optimal reference value. The corresponding J c It increased nearly four times under the external field H=5T, which is still significantly greater than the average value of other heavy ion irradiation effects.

[0087] In conclusion, Xe ion irradiation effectively improves the current-carrying performance of the strip, especially the performance under high temperature and high field, which is of great significance for practical engineering applications.

[0088] Figure 3 For example, 3270keV protons [dose 1×10 15 irons / cm 2 ] Strip before and after irradiation (three layers + 10% BHO doping)J c The results of the change of external magnetic field H at different temperatures. Among them, pristine means no irradiation; Irradiation means irradiation.

[0089] from Figure 3 It can be seen that the irradiation effect of protons at low temperature is more significant than that at high temperature. For example, J before and after irradiation under 4.2K self-field (H=0) c The difference between before and after irradiation gradually disappears as the temperature rises. This is because proton irradiation introduces point defects or clusters generated by collision cascades. At low temperatures, their size is similar to the coherence length of the superconductor, which can effectively pin the magnetic flux, causing Jc to increase slightly. As the temperature rises, the coherence length increases, and the pinning ability of the point defects weakens. At this time, proton irradiation has a negative effect on Jc. c The impact is not significant.

[0090] In contrast, Xe ion irradiation introduces columnar defects, which can effectively pin the magnetic flux lines along the direction of the columnar defects. In addition, entanglement will occur between adjacent magnetic flux lines, which makes it more sensitive to J cThe improvement of Xe ion on J of samples with different film thickness and doping is more significant than that of proton irradiation. c All of them have different degrees of improvement, while proton irradiation only improves the J of some samples at low temperature. c A certain effect is produced, which is closely related to the intrinsic pinning mode.

[0091] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. An ion irradiation method for improving the performance of copper-based superconducting tape, characterized in that: The following steps are involved: Under vacuum conditions, an ion beam is used to irradiate a copper-based superconducting tape; the ion beam includes a light ion beam or a heavy ion beam; and the ion irradiation current intensity is 1 to 10 μA; The energy of the light ion beam is 270 keV and the dose is 0.1×10 16 ~1×10 16 irons / cm 2 ; The energy of the heavy ion beam is 45-200 MeV, and the dose is 0.01×10 12 ~1×10 12 irons / cm 2 .

2. The ion irradiation method according to claim 1, characterized in that: The light ion beam includes a proton beam; the heavy ion beam includes a Xe ion beam.

3. The ion irradiation method according to claim 1 or 2, characterized in that: The vacuum degree of the vacuum condition is 1×10 -3 Torr.

4. The ion irradiation method according to claim 1 or 2, characterized in that: The ion irradiation rate is 5×10 9 irons / (cm 2 ·s).

5. The ion irradiation method according to claim 1 or 2, characterized in that: The energy of the heavy ion beam is 45 MeV, 65 MeV, 85 MeV, 100 MeV, 150 MeV or 200 MeV, and the dose is 2×10 10 , 5×10 10 , 2×10 11 , 4×10 11 , 5×10 11 or 1×10 12 irons / cm 2 .

6. The ion irradiation method according to claim 1 or 2, characterized in that: The copper-based superconducting tape is located at the center of the ion irradiation spot; the size of the ion irradiation spot is 2 cm×2 cm.

7. The ion irradiation method according to claim 1 or 2, characterized in that: When multiple copper-based superconducting tapes are irradiated with ions at the same time, the distance between adjacent copper-based superconducting tapes is 1 mm; the width of a single copper-based superconducting tape is 4 mm.

8. The ion irradiation method according to claim 1 or 2, characterized in that: The copper-based superconducting tape comprises a 2G-HTS tape.

9. The ion irradiation method according to claim 8, characterized in that: The superconducting layer of the 2G-HTS tape is a doped or undoped EuBa2Cu3O7 layer; when the superconducting layer is a doped EuBa2Cu3O7 layer, the secondary phase dopant includes BaHfO3.

10. The ion irradiation method according to claim 9, characterized in that: The EuBa2Cu3O7 layer is a single-layer, double-layer or triple-layer structure, with a single-layer thickness of 1 μm, a double-layer thickness of 2 μm, and a triple-layer thickness of 3 μm.

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