Prof. Dr. Dietmar Block

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Dietmar Block

Prof. Dr. Dietmar Block

Institute for Experimental and Applied Physics
Experimental Plasma Physics
Kiel University
Leibnizstraße 15, R. LS15-67
24118 Kiel
Tel.: +49 (0) 431 880 3862
Fax: +49 (0) 431 880 3809

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Research Interest


I have worked on several topics of plasma physics so far. A special focus has always been on the development of advanced diagnostics to study structure formation and transport processes. This starts with impedance probes for absolute electron density measurements in the lower ionosphere, continued with spatio-temporally resolved measurements of drift wave turbulence and techniques to control and suppress turbulence and transport and has concentrated in the last years on laser manipulation of complex plasmas. Digital holography, optical tweezers, and advanced Mie scattering diagnostics are tools which are currently used in my group to investigate structure and dynamics of finite plasma crystals and binary mixtures. Please find below a short description of each research area and some related/recent publications. Thank you for your interest in my research!


Complex Plasmas - a laboratory for strong correlations

Complex plasmas are plasmas which besides electrons and ions contain highly charged micro-particles. The charging is a result of the electron and ion currents to the particle surface. As a consequence of the high charge the particles arrange in regular patterns and can form so called plasma crystals. Thus, these complex plasmas are a strongly coupled system, i.e. the thermal energy of the particles is much less than their interaction energy. My group performs experiments and MD-simulations in the field of complex plasmas since 2002. Some of my personal research highlights as well as current research topic are listed below. The papers listed right below are tutorials I have contributed to and which might help to get an overview.
 

 

Binary Mixtures

In the frame work of the DFG-Project BL555-3, we investigate the special properties of binary mixtures in complex plasmas. So far, complex plasma studies concentrated on monodisperse micro-particles which turned out to be an excellent model system for strong coupling. Systems with two different particle species (i.e. with different charge) are called binary mixtures. In complex plasmas all experiments so far show that the two particle species instantaneously demix. Our recent experiments however show that it is possible to create binary mixtures. This opens unique opportunities to study structural and dynamical phenomena in strongly coupled systems. Normal modes, waves, phase transitions, transport processes and heat conduction are just a few examples which can be addressed for the first time in binary mixture experiments. Therefore, this project aims at a systematic characterization of the structural and dynamical properties of binary mixtures in complex plasmas.

  • Frank Wieben and Dietmar Block, Photophoretic force measurement on microparticles in binary complex plasmas, Physics of Plasmas 25, 123705 (2018); https://doi.org/10.1063/1.5078561

  • Frank Wieben, Jan Schablinski, and Dietmar Block, Generation of two-dimensional binary mixtures in complex plasmas, Physics of Plasmas 24, 033707 (2017); https://doi.org/10.1063/1.4977989


 

Diagnostics

We have worked on a number of diagnostic tools for complex plasma research:

  • digital holography
  • laser heating
  • optical tweezer
  • angular and polarization resolved Mie scattering

 

F. Wieben, J. Schablinski, and D. Block,  Modification of microparticles due to intense laser manipulation.  Physics of Plasmas 26, 033701 (2019) https://aip.scitation.org/doi/10.1063/1.5090452

 

Finite systems

One speciality of complex plasmas is that it is possible to study small bounded systems of a few particles only. Further these systems can be studied with 1D, 2D, and 3D geometry. In the frame work of the SFB TR24 Fundamentals of Complex Plasmas  we have studied in close collaboration together with the group of Prof Melzer and Prof Bonitz finite 3D systems, the so called Yukawa balls. We were able to understand their fundamental construction principle als well as to study their dynamical and even thermodynamical properties. 
 

  • Structure  (shells, parabolic density profile, meta stable configurations)
  • Dynamics (Normal modes, shear stability)
  • Thermodynamics (phase transitions, melting point)