Excitation of progressing dust ionization waves on PK-4 facility

Abstract

We report observation of the dust ionization waves (DIWs) excited by an external oscillating electric field on the Plasma Kristall-4 facilityunder microgravity conditions. It is shown that at the smallest excitation amplitude, the waves are linear, and the dispersion relation can bededuced from the experimental data. The microparticle oscillations are represented as a superposition of two longitudinal waves propagatingin the opposite directions. In the investigated range of excitation frequency, the wavenumber is not directly proportional to the frequency,and the phase velocity is almost proportional to the frequency. We propose an interpretation of DIW assuming that the microparticle effecton the recombination rate rather than the microparticle subsystem compressibility is responsible for the wave propagation. The calculatedphase velocity of DIW is compatible with the experimental one.