论文标题
电磁辐射和振荡磁偶极子的自动扭矩
Electromagnetic radiation and the self torque of an oscillating magnetic dipole
论文作者
论文摘要
一个均匀电荷的半径$ r $，质量$ m $的球形外壳和总电荷$ Q $，在固定轴周围具有振荡性角速度$ω（t）$，是磁性偶极子的型号，可在固定的振动频率$ω$ω$ω$ω$ω$ω$上辐射电磁场的磁极偶极子。经典电动力学的Maxwell-Lorentz方程的精确解决方案产生了在球形外壳上作用的辐射电阻的自我刺激，这是$ R $，$ Q $和$ω$的函数。借助壳的牛顿运动方程式，我们将其角速度$ω（t）$与外部施加的扭矩联系起来，然后继续检查磁偶极子对在给定时间瞬间应用的冲动扭矩的响应，例如，$ t = 0 $。只要在球形壳的运动动力方程中使用，偶极子的脉冲响应被发现是因果降低到极小的$ r $（即$ r \至0 $）的极小值。
A uniformly-charged spherical shell of radius $R$, mass $m$, and total electrical charge $q$, having an oscillatory angular velocity $Ω(t)$ around a fixed axis, is a model for a magnetic dipole that radiates an electromagnetic field into its surrounding free space at a fixed oscillation frequency $ω$. An exact solution of the Maxwell-Lorentz equations of classical electrodynamics yields the self-torque of radiation resistance acting on the spherical shell as a function of $R$, $q$, and $ω$. Invoking the Newtonian equation of motion for the shell, we relate its angular velocity $Ω(t)$ to an externally applied torque, and proceed to examine the response of the magnetic dipole to an impulsive torque applied at a given instant of time, say, $t=0$. The impulse response of the dipole is found to be causal down to extremely small values of $R$ (i.e., as $R \to 0$) so long as the exact expression of the self-torque is used in the dynamical equation of motion of the spherical shell.
