Plasma Dynamics and Diagnostics

Plasma turbulence, waves in plasmas, magnetic confinement, experiments at the torsatron TJ-K and at the large tokamak ASDEX, laboratory plasmas, fusion research

Main fields of research

Research topics are related to questions of high-temperature fusion plasmas and to fundamental problems of laboratory plasmas.

Experiments and computer simulations are carried out to study energy and particle transport in fusion plasmas. Objective is an improved understanding of transport losses in toroidally confined plasmas which are caused by plasma turbulence. Turbulent transport is the key parameter determining the economy of a fusion power plant.

Electromagnetic waves are a versatile tool used for plasma heating and diagnostics. In experiment and simulation the physical properties of wave propagation, mode conversion and absorption are investigated in magnetised and unmagnetised plasmas.

Experiments are carried out on the torsatron TJ-K and at the large tokamak ASDEX Upgrade of MPI für Plasmaphysik (IPP) in Garching. Furthermore, the linear plasma device FLIPS is used for the study of fundamental plasma properties. The activities comprise design and construction of diagnostics, to plan and carry out experimental campaigns and to apply modern data analyses techniques to the data.

The experimental work is accompanied by computer simulations. At IPF the 3-dimensional code IPF-FD3D has been developed which treats electromagnetic waves in a plasma. A PIC-Code is used for the interpretation of plasma waves and the plasma sheath, and the plasma-turbulence code GEM3 developed at IPP is used for comparison with turbulence measurements.

Join us
We offer Bacherlor-, Master- and  Doctoral Theses on current topics in plasma research. An impression of previous key topics can be gained by looking at selected projects. Alternatively, visit our stellarator experiment "TJ-K" in the laboratory. Are you interested? Contact us.

Publications

  1. 2024

    1. A. Köhn-Seemann, “Tutorial: Microwave Plasma Interactions.” Culham, UK, Jan. 2024. [Online]. Available: https://ukaeaevents.com/uk-microwaves-in-beams-and-plasmas/
    2. A. Köhn-Seemann et al., “EBW Experiments on the TJ-K Stellarator.” Culham, UK, Jan. 2024. [Online]. Available: https://ukaeaevents.com/uk-microwaves-in-beams-and-plasmas/
  2. 2023

    1. L. A. Holland, A. Köhn-Seemann, and R. G. L. Vann, “Parametric dependence of microwave beam broadening by plasma density turbulence,” Nuclear Fusion, May 2023, doi: 10.1088/1741-4326/acc25e.
    2. M. W. Brookman et al., “Broadening of microwave heating beams in the DIII-D tokamak by edge turbulence,” Nuclear Fusion, vol. 63, no. 4, Art. no. 4, Mar. 2023, doi: 10.1088/1741-4326/acbb8e.
    3. A. J. Coelho et al., “Validation of GBS plasma turbulence simulation of the TJ-K stellarator,” Plasma Phys. Control. Fusion, vol. 65, no. 8, Art. no. 8, 2023, doi: 10.1088/1361-6587/ace4f3.
    4. N. Müller, P. Manz, and M. Ramisch, “Nondiffusive particle transport in the stellarator experiment TJ-K,” Phys. Plasmas, vol. 30, no. 9, Art. no. 9, 2023, doi: 10.1063/5.0156125.
    5. N. Dumérat, M. Ramisch, B. Schmid, and G. E. M. Tovar, “Investigation of the coupling between zonal flow activity and multi-scale turbulent phenomena at the stellarator TJ-K,” in Proc. of the 49th EPS Conference on Plasma Physics, in Proc. of the 49th EPS Conference on Plasma Physics, vol. 47, Fr\_MCF65. Bordeaux, France, Jul. 2023.
    6. C. Vagkidis et al., “Full-wave investigation of microwave propagation through plasma density inhomogeneities,” in Proc. of the 49th EPS Conference on Plasma Physics, in Proc. of the 49th EPS Conference on Plasma Physics, vol. 47, Fr-LTPD2. Bordeaux, France, Jul. 2023.
    7. A. Köhn-Seemann, B. E. Eliasson, S. J. Freethy, L. A. Holland, and R. G. L. Vann, “Benchmarking full-wave codes for studying the O-SX mode conversion in MAST Upgrade,” in EPJ Web of Conferences, in EPJ Web of Conferences, vol. 277. 2023, p. 01010. doi: 10.1051/epjconf/202327701010.
    8. T. Wilson et al., “Electron Bernstein Wave (EBW) Current Drive Profiles and Efficiency for STEP,” in EPJ Web of Conferences, E. Poli, Y. Liu, and V. Udintsev, Eds., in EPJ Web of Conferences, vol. 277. 2023, p. 01011. doi: 10.1051/epjconf/202327701011.
    9. S. Freethy et al., “Microwave Current Drive for STEP and MAST Upgrade,” in EPJ Web of Conferences, E. Poli, Y. Liu, and V. Udintsev, Eds., in EPJ Web of Conferences, vol. 277. 2023, p. 04001. doi: 10.1051/epjconf/202327704001.
    10. E. Devlaminck, “A deep learning approach to the inverse microwave scattering problem for plasma tomography,” Master thesis, 2023.
    11. E. Villalobos Granados, “Investigation of the suprathermal electron population in the TJ-K stellarator using a pulse height analyzer,” Master thesis, 2023.
    12. I. Gediz, “Precise measurement and modelling of radiative transfer in TJ-K,” Master thesis, 2023.
    13. J. Joshi-Thompson, “A Neural network for the analysis of Langmuir probe characteristics,” Master thesis, 2023.
    14. C. Vagkidis et al., “A machine learning approach to the inverse scattering problem,” Nov. 2023. [Online]. Available: https://conferences.iaea.org/event/335/contributions/28992/contribution.pdf
    15. A. J. Coelho et al., “Global Flux-Driven Simulations of Plasma Turbulence in the Boundary of Stellarators,” Denver, Colorado, USA, Oct. 2023.
    16. A. Köhn-Seemann, “Aktuelles Aus Der Fusionsforschung,” Online, Oct. 2023.
    17. M. Henderson et al., “The Concept Design Of The STEP Heating And Current Drive System,” London, UK, Oct. 2023.
    18. S. J. Freethy et al., “The STEP Microwave Heating and Current Drive System,” London, UK, Oct. 2023.
    19. R. Sarkis, M. Ramisch, B. Schmid, and G. Tover, “Impact of density and potential coupling on turbulent particle and momentum  transport in TJ-K plasmas,” Aug. 2023. [Online]. Available: https://indico.fusenet.eu/event/47/
    20. M. Henderson et al., “Option-Engineering Assessment of the STEP Heating and Current Drive System,” Oxford, UK, Jul. 2023.
    21. A. Köhn-Seemann, B. E. Eliasson, S. J. Freethy, L. A. Holland, and R. G. L. Vann, “Numerical studies of coupling to electron Bernstein waves in MAST Upgrade,” Jul. 2023. [Online]. Available: https://epsplasma2023.eu
    22. A. Köhn-Seemann, “Fusionsforschung: Eine Einführung,” Online, Jun. 2023.
    23. A. Köhn-Seemann, “Fusionsforschung – Die Sonne Auf Die Erde Holen,” Stuttgart, Germany, May 2023.
    24. A. Köhn-Seemann, B. E. Eliasson, S. J. Freethy, L. A. Holland, and R. G. L. Vann, “Simulations of the O-SX mode conversion in MAST Upgrade,” Mar. 2023. [Online]. Available: https://www.dpg-verhandlungen.de/year/2023/conference/smuk/part/p/session/6/contribution/5
    25. I. Gediz and A. Köhn-Seemann, “Measurement and Modeling of radiation losses in the stellarator TJ-K,” Dresden, Germany, Mar. 2023. [Online]. Available: https://www.dpg-verhandlungen.de/year/2023/conference/smuk/part/p/session/12/contribution/28
    26. E. Devlaminck, C. Vagkidis, M. Ramisch, and A. Köhn-Seemann, “Applying machine learning to the inverse scattering problem for experimental plasma profiles,” Dresden, Germany, Mar. 2023. [Online]. Available: https://www.dpg-verhandlungen.de/year/2023/conference/smuk/part/p/session/11/contribution/3
    27. N. Dumérat and M. Ramisch, “Causal coupling between small-scale fluctuations and zonal flows at the stellarator TJ-K,” Dresden, Germany, Mar. 2023. [Online]. Available: https://www.dpg-verhandlungen.de/year/2023/conference/smuk/part/p/session/12/contribution/26
    28. E. Villalobos Granados and A. Köhn-Seemann, “Study of fast electrons population in the TJ-K stellarator,” Dresden, Germany, Mar. 2023. [Online]. Available: https://www.dpg-verhandlungen.de/year/2023/conference/smuk/part/p/session/11/contribution/28
    29. C. Vagkidis et al., “Novel microwave interferometry approach for spatial plasma profile measurements,” Dresden, Germany, Mar. 2023. [Online]. Available: https://www.dpg-verhandlungen.de/year/2023/conference/smuk/part/p/session/11/contribution/1
    30. J. Joshi-Thompson and M. Ramisch, “Neural Networks for the analysis of Langmuir probe characteristics,” Dresden, Germany, Mar. 2023. [Online]. Available: https://www.dpg-verhandlungen.de/year/2023/conference/smuk/part/p/session/11/contribution/22
    31. A. Köhn-Seemann, “Fusionsforschung,” Waiblingen, Germany, Mar. 2023.
    32. R. Sarkis and M. Ramisch, “Interplay of turbulent density and momentum transport in TJ-K plasmas,” Dresden, Germany, Mar. 2023. [Online]. Available: https://www.dpg-verhandlungen.de/year/2023/conference/smuk/part/p/session/12/contribution/19
    33. A. Köhn-Seemann, “Physik Im Beruf: Beispiel Plasmaphysik & Kernfusion in Der Forschung,” Online, Feb. 2023.
    34. A. Köhn-Seemann, B. E. Eliasson, S. J. Freethy, L. A. Holland, and R. G. L. Vann, “Simulation of the O-X mode conversion in MAST Upgrade,” Feb. 2023.
    35. A. Köhn-Seemann, B. E. Eliasson, S. J. Freethy, L. A. Holland, and R. G. L. Vann, “Numerical studies of coupling to electron Bernstein waves in MAST Upgrade,” 2023.
  3. 2022

    1. A. Köhn-Seemann et al., “Plasma electron acceleration in a non-resonant microwave heating scheme below the electron cyclotron frequency,” New Journal of Physics, Jun. 2022, doi: 10.1088/1367-2630/ac747a.
    2. N. Müller, “Non-locality of particle transport in the stellarator TJ-K,” Bachelor thesis, 2022.
    3. H. Beeck, “Investigation into the spatial distribution of intermittency at the stellarator TJ-K,” Master thesis, 2022.
    4. N. Dumérat, B. Schmid, and M. Ramisch, “Causality analysis between turbulent phenomena across the separatrix at the TJ-K stellarator,” 2022. [Online]. Available: https://www.dpg-verhandlungen.de/year/2022/conference/mainz/part/p/session/19/contribution/27
    5. N. Dumérat, B. Schmid, and M. Ramisch, “Causality analysis of turbulent structures in the stellarator TJ-K,” 2022. [Online]. Available: https://www.epsplasma2022.eu/
    6. C. Vagkidis et al., “Obtaining Line-Integrated Density and Spatial Profile of a Cylindrical Shaped Plasma from Interferometry,” 2022. [Online]. Available: https://indico.fusenet.eu/event/35/
    7. N. Dumérat, B. Schmid, and M. Ramisch, “Causal link between turbulent structures at the stellarator TJ-K,” 2022. [Online]. Available: https://indico.fusenet.eu/event/35/
  4. 2021

    1. T. Ullmann, B. Schmid, P. Manz, G. E. M. Tovar, and M. Ramisch, “Turbulent energy transfer into zonal flows from the weak to the strong flow shear regime in the stellarator TJ-K,” Physics of Plasmas, vol. 28, no. 5, Art. no. 5, May 2021, doi: 10.1063/5.0039959.
    2. Y. Lin, “Identifying the Characteristics of Weak and Strong Turbulence in TJ-K plasmas,” Master thesis, 2021.
    3. T. Ullmann, “The Influence of Flow Shear on Drift-Wave Interactions in the Stellarator TJ-K,” Universität Stuttgart, 2021.
    4. M. Peret et al., “A model of interchange turbulent transport across separatrix with sheared flows,” 2021.
    5. B. Schmid, “Zonal Flow Physics and Diagnostic Development as Trigger of New Physics in the TJ-K Stellarator,” 2021.
  5. 2020

    1. T. Ullmann, B. Schmid, P. Manz, B. van Milligen, G. E. M. Tovar, and M. Ramisch, “Experimental observation of resonance manifold shrinking under zonal flow shear,” Physical Review E, vol. 102, no. 6, Art. no. 6, Dec. 2020, doi: 10.1103/physreve.102.063201.
    2. S. Garland, P. Manz, and M. Ramisch, “The influence of magnetic field curvature on intermittency in drift-wave turbulence in the stellarator TJ-K,” Physics of Plasmas, vol. 27, no. 5, Art. no. 5, May 2020, doi: 10.1063/5.0004963.
    3. T. Ullmann, B. Schmid, P. Manz, and M. Ramisch, “The Shrinking of the Resonant Manifold under Flow Shear,” 2020.
    4. T. Ullmann, B. Schmid, P. Manz, and M. Ramisch, “The Influence of Shear Flows on Nonlinear Interaction in Plasma Turbulence,” 2020.
    5. T. Ullmann, S. Schmid, P. Manz, B. van Milligen, and M. Ramisch, “The Effect of Resonance Manifold Shrinking under Zonal Flow Shear at the TJ-K Experiment,” 2020. [Online]. Available: http://aappsdpp.org/DPP2020/listPI.html
  6. 2019

    1. T. Ullmann, P. Manz, B. Schmid, and M. Ramisch, “Shrinking of resonant manifold under flow shear at the stellarator TJ-K,” 46th EPS Conference on Plasma Physics, EPS 2019, 2019.
  7. 2018

    1. P. Manz et al., “Magnetic configuration effects on the Reynolds stress in the plasma edge,” Physics of Plasmas, vol. 25, no. 7, Art. no. 7, Jul. 2018, doi: 10.1063/1.5037511.
    2. A. Köhn et al., “Microwave beam broadening due to turbulent plasma density fluctuations within the limit of the Born approximation and beyond,” Plasma Physics and Controlled Fusion, Apr. 2018, doi: 10.1088/1361-6587/aac000.
    3. A. Snicker et al., “The effect of density fluctuations on electron cyclotron beam broadening and implications for ITER,” Nuclear Fusion, vol. 58, no. 1, Art. no. 1, 2018, doi: 10.1088/1741-4326/aa8d07.
  8. 2017

    1. S. Garland, K. Reuther, M. Ramisch, and P. Manz, “The collisionality dependence of intermittency level in drift-wave turbulence in the stellarator TJ-K,” Physics of Plasmas, vol. 24, no. 11, Art. no. 11, Nov. 2017, doi: 10.1063/1.4991609.
    2. A. Snicker et al., “Interaction of the electron density fluctuations with electron cyclotron waves from the equatorial launcher in ITER,” Plasma Physics and Controlled Fusion, vol. 60, no. 1, Art. no. 1, Nov. 2017, doi: 10.1088/1361-6587/aa8f1a.
    3. B. Schmid, P. Manz, M. Ramisch, and U. Stroth, “Spatio-temporal structure of turbulent Reynolds stress zonal flow drive in 3D magnetic configuration,” New Journal of Physics, vol. 19, no. 5, Art. no. 5, May 2017, doi: 10.1088/1367-2630/aa67af.
    4. B. Schmid, P. Manz, M. Ramisch, and U. Stroth, “Collisional Scaling of the Energy Transfer in Drift-Wave Zonal Flow Turbulence,” Physical Review Letters, vol. 118, no. 5, Art. no. 5, Jan. 2017, doi: 10.1103/physrevlett.118.055001.
    5. P. Manz et al., “Magnetic configuration effects on the radial electric field and the Reynolds stress in the plasma edge,” 44th EPS Conference on Plasma Physics, EPS 2017, 2017.
    6. X. Yang et al., “Simulations of High Harmonic Fast Wave Heating on the C-2U Advanced Beam-Driven Field-Reversed Configuration Device,” EPJ Web of Conferences, vol. 157, p. 03065, 2017, doi: 10.1051/epjconf/201715703065.
    7. G. Sichardt, L. Bock, E. Holzhauer, A. Kohn, M. Ramisch, and T. Hirth, “Electron cyclotron emission measurements at the optically thin plasmas of the stellarator TJ-K,” 44th EPS Conference on Plasma Physics, EPS 2017, 2017.
  9. 2016

    1. C. Hidalgo, J. Talmadge, and M. Ramisch, “Advancing the understanding of plasma transport in mid-size stellarators,” Plasma Physics and Controlled Fusion, vol. 59, no. 1, Art. no. 1, Nov. 2016, doi: 10.1088/0741-3335/59/1/014051.
    2. G. Fuchert, G. Birkenmeier, M. Ramisch, and U. Stroth, “Characterization of the blob generation region and blobby transport in a stellarator,” Plasma Physics and Controlled Fusion, vol. 58, no. 5, Art. no. 5, Apr. 2016, doi: 10.1088/0741-3335/58/5/054005.
    3. S. Garland, G. Fuchert, M. Ramisch, and T. Hirth, “The structure and poloidal dynamics of blob filaments in TJ-K,” Plasma Physics and Controlled Fusion, vol. 58, no. 4, Art. no. 4, Mar. 2016, doi: 10.1088/0741-3335/58/4/044012.
    4. S. Garland, G. Fuchert, M. Ramisch, and T. Hirth, “The effect of magnetic field geometry on filamentary plasma structures in TJ-K,” 43rd European Physical Society Conference on Plasma Physics, EPS 2016, 2016.
  10. 2015

    1. B. Schmid, P. Manz, M. Ramisch, and U. Stroth, “Investigation of the energy transfer to zonal flows at the stellarator TJ-K,” 42nd European Physical Society Conference on Plasma Physics, EPS 2015, 2015.
    2. S. Garland, M. Ramisch, and T. Hirth, “Effect of magnetic field geometry on blob structure and dynamics in TJ-K,” 42nd European Physical Society Conference on Plasma Physics, EPS 2015, 2015.
  11. 2014

    1. G. Fuchert et al., “Blob properties in L- and H-mode from gas-puff imaging in ASDEX upgrade,” Plasma Physics and Controlled Fusion, vol. 56, no. 12, Art. no. 12, Oct. 2014, doi: 10.1088/0741-3335/56/12/125001.
    2. B. Nold et al., “Turbulent transport across shear layers in magnetically confined plasmas,” Physics of Plasmas, vol. 21, no. 10, Art. no. 10, Oct. 2014, doi: 10.1063/1.4897312.
    3. P. Simon et al., “Scaling and transport analyses based on an international edge turbulence database,” Plasma Physics and Controlled Fusion, vol. 56, no. 9, Art. no. 9, Jul. 2014, doi: 10.1088/0741-3335/56/9/095015.
    4. B. Ph. van Milligen, G. Birkenmeier, M. Ramisch, T. Estrada, C. Hidalgo, and A. Alonso, “Causality detection and turbulence in fusion plasmas,” Nuclear Fusion, vol. 54, no. 2, Art. no. 2, Feb. 2014, doi: 10.1088/0029-5515/54/2/023011.
  12. 2013

    1. G. Fuchert, G. Birkenmeier, B. Nold, M. Ramisch, and U. Stroth, “The influence of plasma edge dynamics on blob properties in the stellarator TJ-K,” Plasma Physics and Controlled Fusion, vol. 55, no. 12, Art. no. 12, Oct. 2013, doi: 10.1088/0741-3335/55/12/125002.
    2. G. Birkenmeier, M. Ramisch, B. Schmid, and U. Stroth, “Experimental Evidence of Turbulent Transport Regulation by Zonal Flows,” Physical Review Letters, vol. 110, no. 14, Art. no. 14, Apr. 2013, doi: 10.1103/physrevlett.110.145004.
    3. J. Adámek et al., “Application of the Ball-Pen Probe in Two Low-Temperature Mag-netised Plasma Devices and in Torsatron TJ-K,” Contributions to Plasma Physics, vol. 53, no. 1, Art. no. 1, Jan. 2013, doi: 10.1002/ctpp.201310007.
  13. 2012

    1. G. Birkenmeier, M. Ramisch, G. Fuchert, A. Köhn, B. Nold, and U. Stroth, “Spatial structure of drift-wave turbulence and transport in a stellarator,” Plasma Physics and Controlled Fusion, vol. 55, no. 1, Art. no. 1, Nov. 2012, doi: 10.1088/0741-3335/55/1/015003.
    2. P. Manz, G. Birkenmeier, M. Ramisch, and U. Stroth, “A link between nonlinear self-organization and dissipation in drift-wave turbulence,” Physics of Plasmas, vol. 19, no. 8, Art. no. 8, Aug. 2012, doi: 10.1063/1.4748143.
    3. B. Nold et al., “Influence of temperature fluctuations on plasma turbulence investigations with Langmuir probes,” New Journal of Physics, vol. 14, no. 6, Art. no. 6, Jun. 2012, doi: 10.1088/1367-2630/14/6/063022.
    4. G. Fuchert, B. Bätz, G. Birkenmeier, M. Ramisch, and U. Stroth, “Influence of plasma edge dynamics on blob properties,” 39th EPS Conference on Plasma Physics 2012, EPS 2012 and the 16th International Congress on Plasma Physics, vol. 3, pp. 1999–2002, 2012.
  14. 2008

    1. A. Kohn, H. Hohnle, E. Holzhauer, W. Kasparek, M. Ramisch, and U. Stroth, “ECRH of overdense plasmas in TJ-K,” AIP Conference Proceedings, vol. 993, no. 1, Art. no. 1, 2008.

Mirko Ramisch

Dr.

Head of Plasma Dynamics and Diagnostics / Library officer

This image shows Alf Köhn-Seemann

Alf Köhn-Seemann

Dr.

Lecturer, Principal Investigator, Plasma Dynamics and Diagnostics

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