41 research outputs found
Constructing KMS states from infinite-dimensional spectral triples
We construct KMS-states from -summable semifinite spectral
triples and show that in several important examples the construction coincides
with well-known direct constructions of KMS-states for naturally defined flows.
Under further summability assumptions the constructed KMS-state can be computed
in terms of Dixmier traces. For closed manifolds, we recover the ordinary
Lebesgue integral. For Cuntz-Pimsner algebras with their gauge flow, the
construction produces KMS-states from traces on the coefficient algebra and
recovers the Laca-Neshveyev correspondence. For a discrete group acting on its
Stone-\v{C}ech boundary, we recover the Patterson-Sullivan measures on the
Stone-\v{C}ech boundary for a flow defined from the Radon-Nikodym cocycle.Comment: 66 page
Three-dimensional structure of a string-fluid complex plasma
Three-dimensional structure of complex (dusty) plasmas was investigated under
long-term microgravity conditions in the International-Space-Station-based
Plasmakristall-4 facility. The microparticle suspensions were confined in a
polarity-switched dc discharge. The experimental results were compared to the
results of the molecular dynamics simulations with the interparticle
interaction potential represented as a superposition of isotropic Yukawa and
anisotropic quadrupole terms. Both simulated and experimental data exhibited
qualitatively similar structural features indicating the bulk liquid-like order
with the inclusion of solid-like strings aligned with the axial electric field.
Individual strings were identified and their size spectrum was calculated. The
decay rate of the size spectrum was found to decrease with the enhancement of
string-like structural features
Slowing of acoustic waves in electrorheological and string-fluid complex plasmas
The PK-4 laboratory consists of a direct current plasma tube into which microparticles are injected, forming a complex plasma. The microparticles acquire many electrons from the ambient plasma and are thus highly charged and interact with each other. If ion streams are present, wakes form downstream of the microparticles, which lead to an attractive term in the potential between the microparticles, triggering the appearance of microparticle strings and modifying the complex plasma into an electrorheological form. Here we report on a set of experiments on compressional waves in such a string fluid in the PK-4 laboratory during a parabolic flight and on board the International Space Station. We find a slowing of acoustic waves and hypothesize that the additional attractive interaction term leads to slower wave speeds than in complex plasmas with purely repulsive potentials. We test this hypothesis with simulations, and compare with theory