Broadband instability of the whistler band in a magnetized plasma density depletion with a parallel current

Broadband electromagnetic instability has been detected in a current-carrying depletion of the density of a magnetized laboratory plasma formed by an electrode with a high positive potential. Intense noise with a continuous frequency spectrum is excited in the whistler band below the electron gyrofrequency. This instability is current-driven because noise exists only when an electric current flows in the plasma; noise disappears when the current is interrupted. Broadband signals observed in the laboratory are close in some properties to electromagnetic noise detected in natural density depletions of the high-latitude ionosphere and magnetosphere of the Earth.