Post on 13-Jan-2016
Complex Plasmas as a Model for Complex Plasmas as a Model for
the Quark-Gluon-Plasma Liquidthe Quark-Gluon-Plasma Liquid
Markus H. Thoma*
Max-Planck-Institute for Extraterrestrial Physics
1. Strongly Coupled Plasmas
2. Complex Plasmas
3. Applications to the Quark-Gluon Plasma
* Supported by DLR (BMBF)
1.1. Strongly Coupled PlasmasStrongly Coupled Plasmas
Plasma = ionized gas, 99% of visible matter in Universe
Plasmas generated by high temperatures, electric fields, or radiation
Classifications:1. Non-relativistic – relativistic plasmas (pair plasmas, QGP)2. Classical – quantum plasmas (white dwarfs, QGP)3. Ideal – strongly coupled plasmas (complex plasmas, QGP)
Coulomb coupling parameter
Td
Q2
Q: charge of plasma particlesd: inter particle distanceT: plasma temperature
Ideal plasmas: most plasmas:
Strongly coupled plasmas:
Examples: ion component in white dwarfs, high-density plasmas at GSI
Non-perturbative description, e.g., molecular dynamics
One-component plasma, pure Coulomb interaction (repulsive):
> 172 Coulomb crystal
Debye screening Yukawa systems
Additional parameter: d/D
Drer
QrV /)(
Liquid phase:
Purely repulsive interactionno gas-liquid transition,only supercritical fluid
2. Complex Plasmas2. Complex Plasmas
Dusty or complex plasmas = multi component plasmas containingions, electrons, neutral gas, and microparticles, e.g., dust
Example: low temperature neon plasma in a dc- or rf discharge
Injection of microparticles with diameter 1 – 10 m
High electron mobility microparticlescollect electrons on surface largenegative charge: Q = 103 – 105 e
Inter particle distance about 200 m
plasma crystal (predicted 1986, discovered 1994 at MPE)
Observation: illumination by laser sheet and recorded by CCD camera
Melting of plasma crystal by pressure reductionless neutral gas friction temperature increase decrease of Coulomb coupling parameter Q2/(dT)
Quantitive analysis of equation of state and determination of : pair correlation function
)(1
)( ji
N
ji
rrrN
rg
Crystal: long range order sharp peaks at the nearest neighbors, next to nearest neighbors and so on
Liquid: short range order (incompressibility) only one clear peak corresponding to inter particle distance plus one ortwo broad and small peaks
Gas: no order no clear peaks
Gravity has strong influence on microparticles microgravity experiments
Applications of complex plasmas:
1. Model system for phase transitions, crystallization, dynamical behavior of liquids and plasmas on the microscopic level
2. Astrophysics: comets, interstellar plasmas, star and planet formation, planetary rings, …
3. Technology: plasma coating and etching, e.g. microchip production, problem: dust contamination
3. Applications to the Quark-Gluon 3. Applications to the Quark-Gluon PlasmaPlasma
Td
C S2Estimate of interaction parameter
C = 4/3 (quarks), C = 3 (gluons)200MeV S = 0.3 - 0.5 d = 0.5 fmUltrarelativistic plasma: magnetic interaction as important as electric
1.5 – 6 QGP Liquid?
RHIC data (hydrodynamical descriptionwith small viscosity, fast thermalization) indicate QGP Liquid
Attractive and repulsive interaction gas-liquid transition at a temperatureof a few hundred MeV
Static structure function (Fourier transform of pair correlation function) experimental and theoretical analysis of liquids
Hard Thermal Loop approximation (T >> Tc):
rmDfD
D
f Der
m
n
TNrggTm
mp
p
n
TNpS
23
22
23
2)(,
2)(
interacting gas
QCD lattice simulations QGP liquid?
Strongly coupled plasmas cross section enhancement
Reason: Coulomb radius, rC = Q2/E, larger than Debye screening lengthD = 1/mD modification of Coulomb scattering theory enhancement of ion-microparticle interaction (ion drag force)
QGP: rC /D = 1 – 5 parton cross section enhancement by factor 2 – 9small mean free path (corresponding to small viscostity and fastthermalization. Additional cross section enhancement by non-linear and non-perturbativeeffects
Implication: enhancement of collisional
energy loss, suppression of radiative energy loss byLPM effect (formation time) jet quenching
,E
dx
dE
coll
Conclusions Conclusions
• Strongly coupled plasmas are of increasing importance in fundamental research as well as technology
• QGP and complex plasmas are important examples of strongly coupled plasmas
• QGP is the most challenging strongly coupled plasma
• Complex plasmas can easily be studied and used as a model for the QGP (phase transitions, correlation functions, cross sections, …)
• RHIC and ISS provide very important information on strongly coupled plasmas