Radiative noise in circuits with inductance: Poynting vector, radiation emitted by the solenoid and stability of the spectrum

摘要

We clarify the relationship between the microscopic current fluctuations and the macroscopic concept of radiation resistance R-rad. The fluctuations are generated by absorptions and emissions of radiation within the solenoid coils. which exchange energy with the surrounding vacuum. This fact is explained by a detailed calculation of the Poynting vector generated by the solenoid of a simple RLC circuit without batteries. Our study also includes the Nyquist current fluctuations. associated with the ohmic resistance R-ohmic of the circuit. We show that the average value of the Poynting vector is zero, in any direction and at any frequency of the electromagnetic spectrum, provided that total resistance R of the circuit is R-rad + R-ohmic. Consequently, as is expected physically, the vacuum radiation pattern is stable and no radiation energy can be detected above the zero-point and thermal background. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 8]