Measurement of the speed of sound by observation of the Mach cones in a complex plasma under microgravity conditions

作者：Zhukhovitskii D I^*; Fortov V E; Molotkov V I; Lipaev A M; Naumkin V N; Thomas H M; Ivlev A V; Schwabe M; Morfill G E

来源：Physics of Plasmas, 2015, 22(2): 023701.

DOI：10.1063/1.4907221

We report the first observation of the Mach cones excited by a larger microparticle (projectile) moving through a cloud of smaller microparticles (dust) in a complex plasma with neon as a buffer gas under microgravity conditions. A collective motion of the dust particles occurs as propagation of the contact discontinuity. The corresponding speed of sound was measured by a special method of the Mach cone visualization. The measurement results are incompatible with the theory of ion acoustic waves. The estimate for the pressure in a strongly coupled Coulomb system and a scaling law for the complex plasma make it possible to derive an evaluation for the speed of sound, which is in a reasonable agreement with the experiments in complex plasmas.

• 出版日期2015-2