Complex plasmas consist of microscopic particles in a plasma environment where the charged particles form a strongly-coupled many-particle system. Complex plasmas provide a wide and interdisciplinary research field that enables new insights into fundamental physical properties of matter on the kinetic level of individual particles, including e.g.:

  • Statistical physics, nonlinear dynamics and phase transitions
  • Active matter
  • Planetary physics and dust transport and mitigation
  • Particles as diagnostics in plasmas

The complex plasma research in COMPACT will advance applications in industrial plasma processing, e.g. etching, plasma coating, safety of fusion devices, or planetary exploration.

Interesting problems to be tackled in COMPACT are:

Statistical physics

  • Equation of State (EOS): Determine the relation between thermodynamic quantities, such as temperature T, volume V or pressure p, describing the state of complex plasma matter; thermodynamics of systems in which Newton’s third law is “broken”

  • Deviations from an ideal gas, e.g. influence of non-negligible occupied volume of the dust particles

  • Transport properties as a response to perturbations, e.g. thermal conductivity, viscosity and diffusion

  • Non-equilibrium thermodynamics: coupling of the thermodynamic properties of the dust particles to the non-equilibrium environment of the plasma particles (electrons and ions)

  • Fluctuation theorem, e.g. explore the probability of small dust systems to lose energy relative to the probability to gain energy

Phase transitions

  • Solid-liquid phase transitions: fully resolved atomistic dynamics with complex plasmas to study the elementary processes governing crystallization; homogeneous and heterogeneous crystallization processes

  • Supercooled liquids: kinetics of slow relaxation processes

  • Glass transitions: quenching of liquids below their melting point by cooling or compression in a manner that prevents crystallization

Nonlinear dynamics

  • Turbulence: study of active turbulence through internal instabilities; determination of energy cascades

  • Nonlinear waves: driven large-amplitude waves; influence of agglomeration, size distributions and strong-coupling effects; shock waves; rogue waves

Active and non-spherical particles

  • Structure and order in systems of non-spherical particles: phase diagram of ellipsoidal or dumbbell-shaped particles; emergence of orientational order and liquid crystal phases

  • Statistical physics of diatomic colloidal matter: EOS of ellipsoidal or dumbbell-shaped particles; influence of rotational degree of freedom

  • Mode dynamics in systems of non-spherical particles: visco-elastic properties; rheology of non-spherical particle systems

  • Active particle systems: statistical properties of active particles; structure of dust systems with active particles

  • Rheology and collective behavior of active particle systems; rheology, turbulence and sound waves in dust systems with active particles; giant number fluctuations; emergence of cooperative/collective behavior

Planetary physics

  • Aerosol coagulation: validation of coagulation rate constant models

  • Contact charging events upon collision: particle drifts in plasma-free environments

Particles as diagnostics in plasmas

  • Particles as floating probes: charging and potentials; UV charging; afterglow plasmas

  • Particles as force sensors; wave dispersions; electric field forces

  • Electron depletion effects: correlation with the electric characteristics of the plasma