Levitation Forces, Relaxation and Magnetic Stiffness of Melt-Quenched YBa2Cu3Ox

Moon, Francis C.; Chang, P.-Z.; Hojaji, H.; Barkatt, Aaron; Thorpe, A. N.

doi:10.1143/jjap.29.1257

Cited by 59 publications

(16 citation statements)

References 8 publications

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“…However, reports on this dynamic behavior are very few. 24,44 On the other hand, no models so far have taken this relaxation behavior of the magnetic levitation force into account. This is quite surprising considering the operating temperature of the levitation system between a HTS and a PM, which is normally at the relatively high temperature of 77 K, where the relaxation rate is usually quite high.…”

Section: Force Creepmentioning

confidence: 99%

Calculation of the hysteretic force between a superconductor and a magnet

Qin

Liu

et al. 2002

Phys. Rev. B

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The magnetic levitation forces exerted on a high-temperature superconducting ͑HTS͒ disk by a cylindrical permanent magnet ͑PM͒ are calculated from first principles for superconductors with finite thickness. The current j( ,z) and field B( ,z) profiles in the HTS in the nonuniform magnetic field generated by the PM are derived. The levitation force depends nonlinearly on the critical current density j c and on the thickness of the HTS. The flux creep is described by a current-voltage law E( j)ϭE c ( j/ j c ) n , from which we show that the levitation force depends on the speed at which the PM approaches or recedes from the HTS, which accounts for the experimentally observed force creep phenomenon. The stiffness of the system is derived by calculating minor force loops. The numerical results reproduce many of the features observed in experiments.

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Section: Force Creepmentioning

confidence: 99%

Calculation of the hysteretic force between a superconductor and a magnet

Qin

Liu

et al. 2002

Phys. Rev. B

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“…As a result, the COF is calculated as 10 -1~1 0 -2 order value. Compared to the prior researches, this result means that flux creep, which is an inherent phenomenon in HTS, is generated in the higher magnetic field and decreases the levitation force [7]. Also, the large flux trap is occurred between the HTS and the bearing magnet and it is another factor of the drag torque.…”

Section: Experiments and Resultsmentioning

confidence: 78%

Micro generator using flywheel energy storage system with high-temperature superconductor bearing

Lee

Kim

et al. 2007

2007 IEEE 20th International Conference on Micro Electro Mechanical Systems (MEMS)

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This paper presents the design and fabrication of the micro generator using flywheel energy storage system with High-Temperature Superconductor bearing. The micro generator is characterized by the three-phase axial flux permanent magnets. The planar stator is fabricated with 5-lines, 100 μm-width, and 50 μmheight for low eddy current loss and high current density. The flywheel rotates up to 51,000 rpm (3.4[kHz] × 60 [sec] / 4 [pairs of poles]) and stores the rotational kinetic energy of 337 J. The flywheel can rotate freely during 3 hr 20 min without input voltage and the coefficient of friction is calculated as 0.001~0.002. At maximum speed, the no-load threephase electric output of the micro generator is 802mV rms.

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“…There are many similar configurations of the PM-HTS oscillating systems, which have been studied by other authors [37][38][39][40][41]. We mention here three the most sensitive ones.…”

Section: Resonance Oscillation Techniquementioning

confidence: 89%

Magnetic Flux Dynamics in HTS Bulks with Levitation Techniques

et al. 2002

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The discovery of high-temperature superconductors (HTS) has led to understanding that, in order to explain and utilize the phenomenon, completely new physical approaches should be introduced at all scales: microscopic, mesoscopic, macroscopic. Leaving first two scales beyond the scope of the present paper, we focus in the upper limit of the last scale, the study of the magnetic flux dynamics in HTS bulks-the dynamics of the 'compact vortex structures'. A new direction in the experimental superconducting physics, the investigation of HTS bulks with levitation techniques, which has been elaborated during last years to effectively explore the subject, as well as the new fundamental and applied results obtained there from are overviewed here.Відкриття високотемпературних надпровідників (ВТНП) призвело до розуміння то-го, що задля пояснення та використання цього явища на всіх рівнях: мікроскопічно-му, мезоскопічному та макроскопічному, має бути створено принципово нові фізичні підходи. Полишаючи перші два рівні поза увагою даної роботи, ми детально розгля-даємо верхню границю останнього -дослідження динаміки магнітного потоку в масивних ВТНП, динаміки «компактових вихорових структур». Дана робота -це огляд нового напрямку експериментальної фізики надпровідників -дослідження масивних ВТНП левітаційними методами -що його було вироблено останнім часом для вивчення зазначеної проблеми, а також тих нових фундаментальних та практич-них результатів, що було тут отримано.Открытие высокотемпературных сверхпроводников (ВТСП) привело к пониманию того, что для объяснения и использования этого явления необходимо создание принципиально новых физических подходов на всех уровнях: микроскопическом, мезоскопическом, макроскопическом. Оставляя первые два уровня за рамками данной работы, мы сфокусировали внимание на верхнем пределе последнего -исследовании динамики магнитного потока в массивных ВТСП, динамики «ком-пактных вихревых структур». Данная работа -это обзор нового направления экс-периментальной физики сверхпроводников, которое было выработано за послед- Fiz. Met. 2002, т. 3, сс. 357-386 Оттиски доступны непосредственно от издателя Фотокопирование разрешено только в соответствии с лицензией 2002 ИМФ (Институт металлофизики им. Г. В. Курдюмова НАН Украины) Напечатано в Украине. 358A. A. Kordyuk, V. V. Nemoshkalenko , A. I. Plyushchay, and R. V. Viznichenko ние годы, а также тех новых фундаментальных и прикладных результатов, которые были здесь получены.

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Levitation Forces, Relaxation and Magnetic Stiffness of Melt-Quenched YBa₂Cu₃O_x

Cited by 59 publications

References 8 publications

Calculation of the hysteretic force between a superconductor and a magnet

Calculation of the hysteretic force between a superconductor and a magnet

Micro generator using flywheel energy storage system with high-temperature superconductor bearing

Magnetic Flux Dynamics in HTS Bulks with Levitation Techniques

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