Seminar by Hyeon K. PARK – UNIST Fusion Plasma Laboratory (South Korea)

A seminar given by

Dr. Hyeon K. Park

professor at the Departement of Physics of UNIST (South Korea) and director of UNIST Fusion Plasma Laboratory

titled:

History, Science and Perspective of Fusion Energy Development

will take place on
Friday, January 27th at 10:30
in the salle du Conseil – service 322 of the PIIM laboratory (Campus St. Jerome)

Abstract: Long history of fusion plasma research is briefly reviewed and relevant lessons will be emphasized. Following the lessons, common factor of a variety of the claimed improved confinement regimes in the magnetic fusion plasma (e.g. L-, H-, VH-, Super-H-, I-, Supershot-, High_beta_P-, RS-, ERS-, FIRE-mode, etc.) is suggested. In addition, study of MHD instabilities by a new 2-D visualization tool (Electron Cyclotron Emission Imaging system) demonstrated the physics of MHDs that we understand and what we do not understand. Based on accumulated empirical knowledge of the toroidal fusion plasmas such as scaling laws for the confinement time and triple products for the fusion power, a comprehensive and effective path for the ignition is suggested along with the perspective of ITER and size limit of a possible compact magnetic confinement device for ignition will be discussed.

Bio: Hyeon K. Park is professor at the Department of Physics at UNIST (Ulsan National Institute of Science & Technology) and director of the UNIST Fusion plasma Laboratory. Find more information here.

Seminar by Junji YUHARA – School of Engineering, Nagoya University (Japan)

A seminar given by

Dr. Junji Yuhara,

professor at the School of Engineering, Nagoya University (Japan)

titled:

Fabrication and characterization of two-dimensional materials on solid surface

will take place on
Tuesday, November 8th at 15:30
in the salle du Conseil – service 322 of the PIIM laboratory (Campus St. Jerome)

Abstract: In my research activities, I have been studying the following topics using variety of techniques such as LEED, AES, STM, LEIS, RBS, PES, and ARUPS; (a) binary metal adsorbates on Si(111) surface, (b) two dimensional alloy on metal surfaces, (c) intermetallic compound and metal oxide quasicrystals, (d) oxide surface and metal-oxide thin films on metal surfaces, (e) single crystal stainless steel surface, and (f) group 14 post-graphene materials. I will review some of these topics in this seminar.

  • It has been studied for a decade that binary metal adsorbates on Si(111) surface induce a unique superstructure that is different from single metal adsorbate. In the case of lead and tin, they form a variety of superstructures, like √7×√3, √3×√3, and 2√7×3 structures, although lead and tin are immiscible in bulk [1]. For the immiscible binary adsorbates of silver and copper on Si(111), Cu atoms behave a dissolution and segregation depending on the surface [2].
  • To fabricate two-dimensional (2D) alloy, the substrate has to be static and inert against adsorbates. The 2D alloy is an overlayer monolayer film and should be incommensurate to the substrate. I succeeded in fabricating Pb-Sn 2D ordered 2D alloy and Pb-Bi solid solution 2D alloy for the first time using Rh(111) surface [3].
  • I demonstrated to identify the Al surface segregation on an Al-Co-Ni and Al-Co-Cu decagonal quasicrystal surfaces and determine the atomic arrangement [4]. Recently, oxide quasicrystal on Pt(111) has been prepared and structural properties are examined [5].
  • The synthesis and characterization of post-graphene materials have been intensively studied with the aim of utilizing novel 2D properties. Most studies adopted molecular beam epitaxy as a synthesis method of 2D materials grown on clean crystalline surfaces. In my study, I will focus on the epitaxial growth of germanene, stanene, and plumbene on surface alloy and alloy surface by segregation and deposition methods[6].

References

[1] J. Yuhara et al, Surf. Sci., 482/485, 1374 (2001); J. Yuhara et al, Mat. Sci. and Eng. 96, 145 (2002); J. Yuhara et al, Nucl. Instr. and Meth. B 199, 422 (2003).

[2] J. Yuhara et al, Surf. Sci. 326, 133 (1995); J. Yuhara et al, Appl. Surf. Sci. 104/105, 163 (1996).

[3] J. Yuhara et al, Phys. Rev. B 67, 195407 (2003); J. Yuhara et al, J. of Appl. Phys. 110, 074314 (2011).

[4] J. Yuhara et al, Phys. Rev. B 70, 24203 (2004); R. Zenkyu et al, Phys. Rev. B 86, 115422 (2012).

[5] J. Yuhara et al, Phys. Rev. Mater. 4, 103402 (2020); Li et al, Appl. Surf. Sci. 561, 150099 (2021).

[6] J. Yuhara et al, ACS Nano 12, 11632 (2018); J. Yuhara et al, 2D Materials 5, 025002 (2018); J. Yuhara et al, Adv. Mater. 31, 1901017 (2019); J. Yuhara and G. Le Lay, Jpn. J. Appl. Phys. 59, SN0801 (2020); T. Ogikubo et al, Adv. Mater. Inter. 7, 1902132 (2020); W. Pang et al, Appl. Surf. Sci. 517, 146224 (2020); J. Yuhara et al, Appl. Surf. Sci. 550, 149236 (2021); J. Yuhara et al, Phys. Rev. Mater. 5, 053403 (2021); J. Yuhara et al, 2D Mater. 8, 045039 (2021); S. Mizuno et al, Appl. Phys. Express 14, 125501 (2021).

Bio: Junji Yuhara is currently associate professor at Department of Energy Science and Engineering at the Nagoya University. In 1995, he obtained a PhD in engineering at the Nagoya University, performing his research at Department of Crystalline Materials Science. He was visiting researcher in the USA, Austria and Singapore. His research focuses in the synthesis and characterization of 2D materials.

Mini-workshop on Complex dynamics of plasmas

A mini-workshop titled:

Complex dynamics of plasmas

organized by prof. Y. Elskens (PIIM laboratory, Aix-Marseille Université, CNRS) in the frame of CAPES/COFECUB project

will take place on
Monday, November 7th
from 13:30 to 17:20
in the salle du Conseil – service 322 of the PIIM laboratory (Campus St. Jerome) or by Zoom

Workshop program:

  • 13:30 – 14:10 (30′ talk+10′ Questions/Answers), Nicolas Dubuit (PIIM laboratory, Aix-Marseille Université, CNRS) – “Statistics of transport in the vicinity of lagrangian coherent structures”
  • 14:10 – 15:00 (40′ talk+10′ QA), Ricardo Viana (Univ. São Paulo and Univ. Fed. Paraná, Curitiba) –Fractal escape basins in open chaotic systems”
  • 15:00 – 15:20, Coffee break
  • 15:20 – 16:00 (30′ talk+10′ QA), Matteo Faganello (PIIM laboratory, Aix-Marseille Université, CNRS) – “Kelvin-Helmholtz instability and induced magnetic reconnection at the Earth’s magnetopause”
  • 16:00 – 16:40 (30′ talk+10′ QA), Leonardo Osorio (Univ. São Paulo and Aix-Marseille Univ.) – “Shearless edge transport barriers in L-H transition
  • 16:40 – 17:20 (30′ talk+10′ QA), Dominique Escande (PIIM laboratory, Aix-Marseille Université, CNRS) – Description of magnetic field lines without arcanes”

Abstracts:

    1. Nicola Dubuit – Statistics of transport in the vicinity of lagrangian coherent structures: Transport properties of magnetic fluctuations, in particular the role of Lagrangian Coherent Structures, are investigated from a statistical point of view in a sheared magnetic field. It is shown that field lines escape a tube (jet) over a finite length which is independent of tube size. However this escape length is not uniform in a chaotic sea, and in particular is minimum (indicating maximal transport) in the vicinity of Lagrangian Coherent Structures. Combined with the fact that LCS are not fixed but vary, both in time and with the velocities of particles, this could reduce their effectiveness as transport barriers in cases where other transport processes exist.
    2. Ricardo Viana Fractal escape basins in open chaotic systemsThe dynamics of chaotic orbits in non-integrable Hamiltonian systems is mostly determined by the fractal character of the homoclinic tangles. In open systems, the escape basin is the set of initial conditions (in phase space) leading to trajectories exiting the domain of interest through a given region. The escape basin boundary is a fractal curve, which leads to final-state uncertainty, a phenomenon that can be quantified using different techniques. In this talk I will describe some of them, in open Hamiltonian models of systems of interest in plasma physics.
    3. Matteo FaganelloKelvin-Helmholtz instability and induced magnetic reconnection at the Earth’s magnetopause: A 3D two-fluid simulation, using plasma parameters as measured by MMS on 8 September 2015, shows the nonlinear development of the Kelvin–Helmholtz instability at the Earth’s magnetopause. It shows extremely rich dynamics, including the development of a complex magnetic topology, vortex merging and secondary instabilities. Vortex induced and mid-latitude magnetic reconnection coexist and produce an asymmetric distribution of magnetic reconnection events. Off-equator reconnection exhibits a predominance of events in the Southern Hemisphere during the early nonlinear phase, as observed by satellites at the dayside magnetopause. The late nonlinear phase shows the development of vortex pairing for all latitudes while secondary Kelvin–Helmholtz instability develops only in the Northern Hemisphere, leading to an enhancement of the occurrence of off-equator reconnection there.
      Since vortices move tailward while evolving, this suggests that reconnection events in the Northern Hemisphere should dominate at the nightside magnetopause.
    4. Leonardo OsorioShearless edge transport barriers in L-H transition: Shearless transport barriers (STBs) have been extensively studied in several dynamical non-twist systems to control the chaotic transport. Those barriers are associated through the extrema of the rotation number profile and, because of that, they exhibit a strong resistance to perturbations. For magnetized plasmas, ExB drift wave transport models have shown that, on using non-monotonic plasma profiles, STBs can appear to prevent the particle flux. So, considering a tokamak with a large aspect ratio, R>>a, and on using an ExB wave transport model, we study the chaotic transport at the plasma edge when typical radial electric field profiles in LH-transition are taken. We show that, by doing this, STBs appear at the plasma edge and, as the depth of the well-like radial electric field increases, they become more resistant to perturbations, impeding almost any flux to the vessel chamber. In a sense, we show through a description of invariant shearless curves a L-H transition behaviour.
    5. Dominique EscandeDescription of magnetic field lines without arcanes: The action principles for magnetic field lines and for Hamiltonian mechanics are analogous. The first one can be deduced in a pedestrian way from first principles. It makes practical calculations simpler and safer, with an intuitive background. In particular, it is shown that the width of a magnetic island is proportional to the square root of the magnetic flux through a ribbon whose edges are the field lines related to the O and X point of the island. There is some beauty in the approach, which may provide a new pedagogical and intuitive introduction to Hamiltonian mechanics.
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Seminar by Anne Lafosse – Paris-Saclay University, ISMO laboratory (France)

A seminar given by

Dr. Anne Lafosse, professor at the Paris-Saclay University, ISMO laboratory, Saclay (France)

titled:

Quantifying the unavoidable contribution of electron – supported molecular film interactions – Nanolithography and astrophysics

will take place on
Tuesday, October 18th at 14:30
in the salle du Conseil – service 322 of the PIIM laboratory (Campus St. Jerome)

Abstract: What do chemical enrichment of the interstellar medium and nanolithography processes have in common? Electron-induced processes within molecular films deposited, respectively, on interstellar dust grains and on substrates to be functionalized. The interaction of high-energy radiations (X-ray, ions, electrons) with a condensed medium leads to the formation of low-energy (<20 eV) secondary electron bursts. These electrons created within the irradiated medium contribute efficiently to its chemical modification. In all application contexts (astrochemistry, radiation damage, nanolithography), one of the important issues is to quantify the efficiency of the induced processes, in terms of yields, but also of effective cross sections and required doses.
The approach proposed by the “electron-solids” group is to study directly the effects of electron irradiation on interfaces deposited on substrates by combining: (i) quantitative mass analysis of neutrals desorbing during irradiation (ESD) and (ii) analysis of the deposits before and after irradiation by temperature programmed désorption (TPD) and vibrational spectroscopy HREELS (High Resolution Electron Energy Loss Spectroscopy).
Two systems will be discussed and the derived quantitative markers presented:
– the decomposition under electron irradiation of a film of a halogenated unsaturated compound potentially of interest in the development of EUV lithographic resists,
– the non-thermal desorption from molecular ice of methanol CH3OH, with an interpretation linked to XESD (X-ray induced electron-stimulated desorption) processes.

Bio : Anne Lafosse is full professor at the University of Paris-Saclay. She performs her research in the laboratory ISMO (Institut des Sciences Moléculaire d’Orsay). She is the team leader of the Surface chemistry & slow electrons team.

Seminar by Haruhisa Nakano – National Institute for Fusion Science (Japan)

A seminar given by

Dr. Haruhisa Nakano, Associate professor at the National Institute for Fusion Science, Gifu (Japan)

titled:

Neutral Beam Injection at the stellarator LHD (Large Helical Device)

will take place on
Monday, October 10th at 14:00
in the salle du Conseil – service 322 of the PIIM laboratory (Campus St. Jerome)

Abstract: Improvement of deuterium injection power in the negative-ion-based NBIs (n-NBIs, Neutral Beam Injectors) for the Large Helical Device (LHD) are reported. Co-extracted electron current at acceleration of deuterium negative ions (D ions) limits the injection power. The electron current is reduced by decreasing the extraction gap, and the injected D current evaluated from the injection power increased from 46 to 55 A. Greater electron reduction was achieved by installing a structure named an ‘electron fence’ (EF), with which D beam power was successfully improved from 2.0 MW to 3.0 MW. The injection power in three configurations − without EF, with EF of 5 mm and 7 mm distance from the plasma grid (PG) surface − have been compared in both cases of hydrogen and deuterium operations, and it was found that the configuration with the EF of 5 mm distance was the best to satisfy the performance for both of hydrogen and deuterium injections. Although the co-extracted electron current is reduced in the negative ion sources applied for JT-60SA and ITER by utilizing the PG filter, it is possible to achieve more effective electron reduction by combining the PG filter and the EF.

 

Seminar by Justin Little – University of Washington (USA)

A seminar given by

Dr. Justin Little, Professor at the University of Washington, Seattle (USA)

titled:

Mode Transitions in Low-Temperature Aerospace Plasmas

will take place on
Wednesday, September 14th at 14:30
in the salle du Conseil – service 322 of the PIIM laboratory (Campus St. Jerome)

Abstract: Laboratory plasmas can experience abrupt transitions between operating modes during which either the plasma structure or dynamics undergo a sudden change. Nonlinear in nature, these mode transitions typically result from the existence of multiple stable plasma states. When developing new plasma sources, transitions between states generally occur in mysterious and oftentimes unexpected ways. Unpredictable mode transitions are particularly problematic to the design of new plasma-based aerospace technologies, such as electric propulsion systems. Detailed models of mode transition physics and scaling are critical to ensuring new systems behave as expected within their desired operating range. In this talk I will present experimental and theoretical research into the nature of mode transitions for two emerging technologies. The first technology is the helicon plasma thruster, an electrodeless propulsion concept that relies on radiofrequency plasma heating and acceleration through a magnetic nozzle. The second technology, the plasma magnetoshell, is an aerocapture concept that utilizes magnetized plasma to generate drag on a spacecraft upon entry into a planetary atmosphere. I will finish by highlighting the potential for new data science techniques to make significant advances in the discovery and analysis of plasma mode transitions.

Bio: Prof. Little is an Assistant Professor in the William E. Boeing Department of Aeronautics & Astronautics at the University of Washington. He received a BS in Physics and Aerospace engineering from the University of California, Irvine, and a PhD in Mechanical & Aerospace Engineering from Princeton University. Prof. Little’s research focuses on understanding how low-temperature plasma physics influence the performance and design of emerging electric propulsion technologies. His research methods emphasize a close relationship between reduced-order theoretical modeling and innovative experiment design to explore the fundamental scaling of dominant physics. He is a National Defense Science and Engineering Graduate Fellow and a recipient of the AFOSR Young Investigator Program award. https://www.aa.washington.edu/facultyfinder/justin-little

 

Seminar by Chijin Xiao – University of Saskatchewan

A seminar given by

Dr. Chijin Xiao
Professor at the University of Saskatchewan (Canada)
titled

Plasma-Wall Interaction Related Research at the University of Saskatchewan

will take place on
Thursday, June 16th at 14:30
in the salle du Conseil – service 322 of the PIIM laboratory (Campus St. Jerome)

Abstract : The envisaged power load on the plasma-facing components, particularly on the diverters, in the future tokamaks, such as in ITER, will well exceed 1 MW/m2. High power load will not only damage the plasma-facing components (PFCs), but also generate tritium-containing dusts. For compact spherical tokamaks with high magnetic field, the power load is even higher. Study of plasma-wall interaction (PWI) is important not only for choosing suitable first-wall materials, but also for understanding transport of the dust particles produced by PWI. At the University of Saskatchewan, compact torus (CT), a high-density and high-speed plasmoid confined by its own magnetic field, and dense plasma focus (DPF), an excellent plasma source for producing high flux and high-energy ion beams in our case, are used as plasma sources to study PWI on various substrate samples. A dust dispenser has been designed and characterized to introduce dust particles to the STOR-M tokamak discharge or to be incorporated in CTs for injecting dust-containing CTs to the core of the STOR-M discharges.  This talk will present the features of the plasma sources used, some experimental results for PWI studies, and the plans for studies of dust dynamics in the STOR-M tokamak.

Bio: Chijin obtained his B.Sc. and M.Sc. degrees from the University of Science and Technology of China, Hefei and the Doctor of Natural Science degree from the Ruhr-University Bochum, Germany, all specializing in Plasma Physics. He joined the Plasma Physics Laboratory at the University of Saskatchewan, first as a Postdoctoral Fellow and then as a Research Associate before joining the faculty of the Department of Physics and Engineering Physics at the University of Saskatchewan. Dr Xiao is currently a tenured full professor at the University of Saskatchewan. Dr. Xiao’s research interests have been in plasma physics and engineering for fusion research and industrial applications, particularly in plasma production and diagnostics. Over his career, Dr. Xiao has worked on a variety of plasma devices including the STOR-M tokamak, compact torus injectors, dense plasma focus, RF and microwave plasma devices. Dr. Xiao has trained many HQPs including Ph.D. and M.Sc. students, PDFs and a research engineer. Dr Xiao is currently the principal investigator for the STOR-M tokamak. He authored and co-authored over 130 journal papers.

We will be glad to welcome the speaker with a coffee and pastries at 14:00.

Seminar by Laurent Lamy – LESIA, OBSPM, Paris & LAM, Marseille

A seminar led by

Dr. Laurent Lamy, Assistant astronomer at LESIA at the Paris Observatory

entitled :

Studying the magnetospheres of the solar system and beyond using radio observations:
From in situ space exploration to the Square Kilometer Array (SKA).

will be held Tuesday, May 31 at 10:30 a.m. in the Board Room – Department 322 of the PIIM laboratory (St. Jerome Campus)

Abstract: The magnetospheres of the planets of the solar system are the seat of intense electromagnetic auroral radiation, observed in various spectral ranges, and in particular in low frequency radio (long wavelengths). Several decades of in situ (from Viking/Voyager to Cassini/Juno) and ground-based (such as the Nançay Decametric Network) radio observations of these objects have allowed us to understand the diagnosis that these observations bring for the study and characterization of planetary magnetospheres. They also revealed a common non-thermal emission mechanism, the electron Maser Cyclotron instability, which allows to amplify very efficiently circularly polarized radio waves from electrons accelerated to kinetic energies of a few keV in plasma sparse and strongly magnetized regions. The advent of giant radio telescopes (such as LOFAR, NenuFAR and soon SKA) promises to considerably enlarge the number of detected magnetospheres, with already a few tens of cases of radio emissions from stars, brown dwarfs and possible exoplanets identified.

 

Bio : Laurent Lamy is an assistant astronomer at the Laboratoire d’Etudes Spatiales et d’Instrumentation en Astrophysique (LESIA) of Paris Observatory, seconded to the Laboratoire d’Astrophysique de Marseille (LAM). He is a specialist in the comparative study of space plasmas, planetary magnetospheres and auroral processes. He is scientifically involved in various space radio instruments (Cassini, Juno, JUICE) and ground-based instruments (Nançay telescopes, NenuFAR, Réseau décamétrique, LOFAR, SKA).

The seminar will be preceded by a welcome breakfast at 10:00 am.

Seminar by Lorenzo Giustolisi – University of Catania

A seminar given by
Lorenzo Giustolisi
Catania Astrophysical Observatory – University of Catania (Italy) 
titled
Polarisation in Spectral line profiles calculations with Magnetic Stellar Atmosphere conditions
will take place on Tuesday, May 3rd at 14:00 in the salle du Conseil – service 322 of the PIIM laboratory (Campus St. Jerome) (or by Zoom)

Abstract: Spectropolarimetry is a well-established technique to infer magnetic fields in observative astrophysics. In particular, Full Stokes spectropolarimetry is the only way to obtain full information on magnetic field geometries by means of polarised light in spectra. In this optics, a new method for modelling full Stokes parameters with Zeeman-Stark effect is in development and aims to reproduce line profiles in plasma conditions similar to those found in stellar atmospheres. This may also have direct applications to Magnetic White Dwarfs (MWDs), whose spectra until now have been taken only in Stokes I and Stokes V (few cases). Future observations may be combined with simulations to retrieve magnetic geometries from H Balmer lines. 

Bio: Bsc and Msc Degrees in Physics with Astrophysics curriculum at University of Catania. Master Thesis with title « Zeeman non-Doppler imaging of HD24712 » on application of Spectropolarimetry to magnetic field measurements in Chemically peculiar (CP) Ap stars.Currently PhD student in Physics XXXVI cycle at University of Catania working on typical observative astrophysical techniques applied to plasma physics and line shape calculations of plasmas of astrophysical interest.

We will be glad to welcome you all with coffee and pastries at 13:30.

Seminar by Matheus Lazarotto – University of São Paulo, Brasil

AbstractSpatial diffusion of particles in periodic potential models has provided a good framework for studying the role of chaos in global properties of classical systems. A bidimensional “soft” billiard, which is a classical dynamics derived from an optical lattice hamiltonian system, is used to study diffusion transitions under variation of the control parameters. Sudden transitions between normal and ballistic regimes are found and characterized by inspection of topological changes in phase-space. Transitions correlated with increases in global stability area are shown to occur for energy levels where local maxima points become accessible, deviating trajectories approaching them. These instabilities promote a slowing down of the dynamics and an island myriad bifurcation phenomenon (fig 1-B), along with the suppression of long flights within the lattice. Other diffusion regime variations occurring within small intervals of control parameters are shown to be related to the emergence of a set of orbits with long flights, thus altering the total average displacement for long integration times but without global changes in phase-space.
 
Short bioMatheus Lazarotto is a PhD student at University of São Paulo (Brazil). He is currently visiting PIIM laboratory (Turbulence Plasma team) for 6 months in the framework of the CAPES/COFECUB program. With a bachelor background in physics and a master’s in molecular dynamics, he currently works with dynamical hamiltonian systems and chaos, particularly with low-dimensional chaotic models in lattice potentials and wave-particle interaction.
 
Health conditions permitting, the talk will be preceded by a welcome breakfast at 10:15.