Generation of “spiky” potential structures associated with multiharmonic electrostatic ion-cyclotron waves

The production of coherent, “spiky” electrostatic potential structures, similar to the spiky electric-field structures that have been observed in the Earth’s auroral region, is investigated in a magnetized Q machine plasma. These structures are associated with coherent multiharmonic electrostatic ion-cyclotron EIC waves in a current-free plasma having a localized region of ion flow shear ion flow parallel to B with a gradient in the direction transverse to B . A multiharmonic EIC spectrum is detected in the region of ion flow shear when broadband electrostatic white noise is applied to the plasma column from an antenna. The time series of the potential fluctuations exhibit spiky structures with repetition rates near the ion-cyclotron frequency. Spiky structures can arise from linear combinations of phase-locked multiharmonic EIC waves when the amplitudes of the harmonic components are comparable to that of the fundamental EIC mode. © 2006 American Institute of Physics. DOI: 10.1063/1.2148919