Abstract

The screw dynamo is a critical phenomenon—a self-excitation that occurs only when the magnetic Reynolds number (Rm) reaches some threshold value. Temporal magnetic field growth is shown to occur at Rm slightly smaller than this critical value. The appearance of temporal growth is also limited from below by the second critical value of Rm. If, however, a seed magnetic field is present permanently, and not just at the initial time of evolution, temporal subcritical magnetic field growth gives rise to a stationary magnetic configuration. This stationary magnetic field turns out to be particularly strong if the seed field in the form of a traveling wave coincides in phase velocity with the magnetic field that emerges in the presence of a self-excitation. The possibilities for detecting such a resonance in the subcritical regime of operation of an experimental setup based on the screw dynamo are considered.

中文翻译：

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螺丝发电机的瞬态状态

摘要

螺旋发电机是一种严重的现象-仅在雷诺磁数（Rm）达到某个阈值时才会发生自激。瞬时磁场的增长在Rm处出现，比该临界值稍小。时间增长的出现也受到Rm的第二临界值的限制。但是，如果种子磁场永久存在，而不仅仅是在演化的初始时间存在，那么亚临界磁场的瞬时生长会产生固定的磁场。如果以行波形式的种子场与在自激存在时出现的磁场的相速度一致，则该固定磁场特别强。