ДИНАМИКА ТЕРМОМАГНИТНЫХ НЕУСТОЙЧИВОСТЕЙ В СВЕРХПРОВОДЯЩИХ СОЕДИНЕНИЯХ И СПЛАВАХ
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| Title |
ДИНАМИКА ТЕРМОМАГНИТНЫХ НЕУСТОЙЧИВОСТЕЙ В СВЕРХПРОВОДЯЩИХ СОЕДИНЕНИЯХ И СПЛАВАХ
THE DYNAMICS OF THERMOMAGNETIC INSTABILITIES IN SUPERCONDUCTING COMPOUNDS AND ALLOYS |
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| Creator |
Русаков, Владимир Федорович
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| Subject |
термомагнитная лавина
экранирующие токи сверхпроводники superconductors screening currents thermomagnetic avalanche |
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| Description |
В работе представлены результаты анализа экспериментального исследования формы профиля индукции магнитного поля в сверхпроводящем образце в режиме экранирования и захвата магнитного поля. Предложена модель распределения экранирующих токов, позволяющая объяснить наблюдаемые значения индукции магнитного поля в образце. Объяснено как превышение индукции магнитного поля в образце в процессе вхождения лавины (парамагнитное состояние), так и более низкое значение индукции магнитного поля в образце по отношению к внешнему магнитному полю, в процессе лавинного выхода потока (диамагнитное состояние).
Thermomagnetic avalanches that occur in hard type-II superconductors and lead to a sudden failure of the critical state are a major factor limiting the use of such materials in conditions of high-density electric currents and high magnetic field strengths. Niobium-titanium alloys, yttrium-barium and mercury ceramics, and other superconducting materials are widely used for obtaining magnetic fields of high intensity and conductors with high current densities for different applications. The central question in the search of prevention of catastrophic events in the materials due to thermomagnetic instabilities is to understand the mechanisms of their origin and determining the conditioning driving forces in their development. The results of the analysis of the experimental study of the profile shape of the magnetic field induction in a superconducting sample in the mode of screening and the trapping of the magnetic field is presented in the paper. A model of the distribution of the screening currents allowing explanation the observed values of the magnetic field in the sample is proposed. It is shown that in the regime of the external magnetic field shielding in the course of the avalanche entering on the edge of the region occupied by an avalanche currents having a direction opposite to the screening currents are flowing. These currents create a magnetic field, which coincides with the direction of the external magnetic field. As a result of the superposition of these fields, the field in the region occupied by avalanche exceeds the external magnetic field (paramagnetic state). In the magnetic flux trapping mode with a decrease of the external magnetic field avalanche flux leaving the sample is possible. In this case the currents flowing on the boundary of the region of the avalanche process create a field whose direction is opposite to the field in the sample. This leads to the fact that the magnetic field in the region of the avalanche is less than external magnetic field (diamagnetic state). The above model satisfactorily explains the experimentally observed phenomena, both the excess of the magnetic field in the sample in the process of the thermomagnetic avalanche entering, and lower, compared to the external magnetic field, magnetic induction in a superconductor in the course of magnetic flux avalanche leaving the sample. |
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| Date |
2013-04-13T12:55:33Z
2013-04-13T12:55:33Z 2013 |
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| Type |
Article
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| Identifier |
2074-6652
УДК 538.95+945 http://ea.donntu.edu.ua/handle/123456789/18463 |
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| Relation |
Наукові праці ДонНТУ;Серія: Хімія і хімічна технологія, 2013. - Вип.2(21). - С.72-76
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| Publisher |
Донецк, ДонНТУ
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