Phonon spectrum in a plasma crystal.
The Fourier spectra of longitudinal and transverse waves corresponding to random particle motion were measured in a two-dimensional plasma crystal. The crystal was composed of negatively charged microspheres immersed in a plasma at a low gas pressure. The phonons were found to obey a dispersion relation that assumes a Yukawa interparticle potential. The crystal was in a nonthermal equilibrium, nevertheless phonon energies were almost equally distributed with respect to wave number over the entire first Brillouin zone.
Nunomura
S
S
Department of Physics and Astronomy, The University of Iowa, Iowa City, Iowa 52242, USA.
Goree
J
J
Hu
S
S
Wang
X
X
Bhattacharjee
A
A
Avinash
K
K