Excitation of electromagnetic waves by a pulsed ring electric current in a magnetoplasma containing a cylindrical density duct

Pulsed radiation from a ring electric current placed coaxially in a cylindrical enhanced-density duct surrounded by a uniform cold magnetoplasma is studied. An expression for the radiated energy is derived and its distribution over the spatial and frequency spectra of the excited waves is analyzed. Numerical results referring to the case where the frequency spectrum of the current is concentrated in the whistler range are discussed. It is found that in the resonant part of the whistler range, the slightly leaky modes guided by the duct give the main contribution to the radiated energy. It is shown that the presence of a cylindrical duct with enhanced plasma density can lead to a significant increase in the energy radiated from a pulsed ring current compared with the case where the same source is immersed in the surrounding uniform magnetoplasma modeled upon the Earth´s ionosphere.