Experimental Investigation of the Dynamic Effects of Time-Varying Plasma
on Low-Frequency Electromagnetic Wave Propagation
Abstract
In this paper, we reveal the dynamic effects of time-varying plasma on
low-frequency (LF) electromagnetic (EM) wave propagation. The
time-varying attenuation, time-varying phase shift, and power spectrum
of the LF EM waves are presented. By using the frequency division
multiplexing method, LF EM waves at the four discrete frequencies
simultaneously penetrate through a shared time-varying plasma in one
shock tube experiment. The experimental results indicate that the
time-varying attenuation and phase shift of the LF EM wave are
determined by the time-varying behavior of the plasma, and they are
positively related to the electron density and frequency of the LF EM
waves. The theoretical results are well consistent with the experimental
results. Moreover, in the frequency domain, the time-varying plasma
causes spectrum expansion of the LF EM waves. These results help us
deeply understand the propagation process of LF EM waves in time-varying
plasma and design LF communication systems.