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

D. I. Zhukhovitskii; V. E. Fortov; V. I. Molotkov; A. M. Lipaev; V. N. Naumkin; H. M. Thomas; A. V. Ivlev; M. Schwabe; G. E. Morfill

doi:10.1063/1.4907221

arXiv · 1411.7641

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

D. I. Zhukhovitskii·V. E. Fortov·V. I. Molotkov·A. M. Lipaev·V. N. Naumkin·H. M. Thomas·A. V. Ivlev·M. Schwabe·G. E. Morfill

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Abstract

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.

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D. I. Zhukhovitskii, V. E. Fortov, V. I. Molotkov, A. M. Lipaev, V. N. Naumkin, H. M. Thomas, A. V. Ivlev, M. Schwabe, G. E. Morfill. 2015-06-13. Measurement of the speed of sound by observation of the Mach cones in a complex plasma under microgravity conditions. https://doi.org/10.1063/1.4907221

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