TY - GEN

T1 - Electromagnetic radiation and the self torque of an oscillating magnetic dipole

AU - Mansuripur, Masud

AU - Jakobsen, Per K.

N1 - Funding Information:
Acknowledgement. The authors express their gratitude to Vladimir Hnizdo for generously sharing with us his extensive knowledge of the electrodynamics of charged particles. This work has been supported in part by the AFOSR grant FA9550-19-1-0032.

PY - 2020

Y1 - 2020

N2 - 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 → 0) so long as the exact expression of the self-torque is used in the dynamical equation of motion of the spherical shell.

AB - 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 → 0) so long as the exact expression of the self-torque is used in the dynamical equation of motion of the spherical shell.

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U2 - 10.1117/12.2569137

DO - 10.1117/12.2569137

M3 - Conference contribution

AN - SCOPUS:85092005540

T3 - Proceedings of SPIE - The International Society for Optical Engineering

BT - Plasmonics

A2 - Tsai, Din Ping

A2 - Tanaka, Takuo

PB - SPIE

T2 - Plasmonics: Design, Materials, Fabrication, Characterization, and Applications XVIII 2020

Y2 - 24 August 2020 through 4 September 2020

ER -