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TP4
PROF. YURI LITVINENKO
Prof. Dr. Yuri Litvinenko from the University of Waikato, New Zealand, has been a guest at TP4/FOR1048 since 11.2.2013 and will give a talk on "A Numerical Study of Diffusive Cosmic-Ray Transport with Adiabatic Focusing" on Thursday, 14.02.2013, starting at 11.00 in NB 7/67. Interested parties are welcome to attend!
ABSTRACT: Focused particle transport in a nonuniform large-scale magnetic field is investigated numerically in the case of isotropic pitch-angle scattering. Evolving particle density profiles and distribution moments are computed from solutions of a system of stochastic differential equivalent to the original Fokker-Planck equation for the particle distribution. Conflicting analytical predictions for the transport coefficients in the diffusion limit, independently calculated by Beeck & Wibberenz and Shalchi, are compared with the numerical results. The reasons for the discrepancies among the analytical and numerical treatments, as well as the general limitations of the diffusion model, are discussed. The telegraph equation, derived in a higher-order expansion of the particle distribution function is shown to describe the particle transport much more accurately than the diffusion model, especially ahead of a moving density pulse.
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EP2
VICTOR AMARY
From February the 4th to March the 31th Master-Student Victor Amary from the Groupe de Recherches sur l'Energétique des Milieux Ionisés (GREMI) of the Université d'Orléans has successfully completed his internship at the Institute of Application Oriented Plasma Physics (EP2).
In the course of his stay he participated in working in the Project A1 of the DFG Research Unit FOR1123 around Phd-Student Daniel Schröder and Dr. Schulz-von der Gathen. He focusses his investigations on diverse further developments concerning the Micro-Plasma Jet (µ-APPJ). By the variation of the material and the widths of the electrodes, he managed to ignite the µ-APPJ with an argon feed gas flow combined with the spectroscopic characterisation of this new operation mode of the jet device.
Victor Amary is now continuing his Master Studies at the Ruhr-Universität Bochum in course of the Erasmus Programme. The team of Project A1thanks Mr. Amary for his successful participation and wishes him all the best for his future career.
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H.E.S.S. MEETING 2013
From April 22-26, 2013, the Chair of Theoretical Space and Astrophysics will host the Spring Meeting of the H.E.S.S. Collaboration. It has been held at the RUB Event Center.
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28.01.2013 - STEFAN SPIEKERMEIER AT BILKENT UNIVERSITY IN ANKARA
From January 13th till 27th, 2013 Stefan Spiekermeier visited the Group of Prof. Ömer Ilday at Bilkent University, Ankara, Turkey. Dr. Marc Böke, his supervisor, visited as well from January 22nd till 24th, 2013.
His group developed the fiber-laser-system that is used for laser assisted plasma breakdown and phase resolved absorption spectroscopy at RUB. During the stay, a new temperature stabilized oscillator for the laser has been tested. Further improvements for the laser have been discussed. Aside from that, an attempt to ignite a plasma inside a hollow-core-PCF-fiber has been made.
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21.01.2013 - DR. ILIJA STEFANOVIĆ AT KHARKIV NATIONAL UNIVERSITY IN UKRAINE
Dr. Ilija Stefanović visited the Kharkiv National University. From January 21st to February the 1st, 2013 Dr. Ilija Stefanović visited Prof. Igor Denysenko from Department of Physics and Technology of Kharkiv National University, Ukraine, and gave the lecture on «Diagnostics and Modeling of RF Plasmas with Nanoparticles». He visited low temperature plasma laboratories and got acquainted with application oriented research on the Department, especially with bipolar ion source. Beside of that, he was invited to Ukrainian National Institute for Physics and Technology, where he gave a lecture with the title «Stability and Similarity Laws of DC Microdischarges». The Ukrainian colleagues presented him their newest results of their different activities, including the basic research on two stelerators and application oriented, low temperature plasma reactors. Dr. Stefanović's travel to Kharkiv has been supported by Alexander von Humboldt-Stiftung in the frame of institutional partnership between Institut für Experimentalphysik II and Department of Physics and Technology, V. N. Karazin Kharkiv National University.
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TP1
PROF. DR. GERMASCHEWSKI & PROF. DR. TOBIAS SCHÄFER
On Monday, January 14, 2013, Prof. Dr. Germaschewski (2:15 p.m.) and Prof. Dr. Tobias Schäfer (3:00 p.m.) will give talks in room NB 7/165. Prof. Germaschewski from the Department of Physics / Space Science Center at the University of New Hampshire, Durham, USA will talk about "Exploiting the power of heterogeneous computing for kinetic simulations of plasmas", Prof. Schäfer from the Department of Mathematics at CUNY, USA will talk about "Geometric minimum action method for stochastic Burger's equation". The lectures will take place in the framework of FOR 1048 "Instabilities, Turbulence and Transport in Cosmic Magnetic Fields". Interested persons are welcome to attend.
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EP2
PROF. DIEDERIK DEPLA
Prof. Diederik Depla from the Department of Solid State Sciences at Ghent University (Belgium) will visit the Institute of Experimencal Physics next week. You are all cordially invited to attend to his short seminar about "Magnetron sputter deposition, the role of the ions" on Tuesday January 15th, 2013, NB5/158, at 10:00 (s.t.).
Abstract: Ions play an prominent role during reactive magnetron sputtering. Their influence can be quite explicit as for example when a substrate bias is applied during thin film growth. However, ions can also play a more hidden role. This paper aims to give an overview of the different processes in which ions play a key role.
The first, and most obvious during magnetron sputtering, is of course the sputter process as such. Although it seems straightforward to describe this, fundamental issues as the angular emission profile, compound sputter yield hampers a quantitative description of the deposition profile, and therefore the deposition rate at the substrate [1].
A similar question exists about the role of ions during the sustaining mechanism of the magnetron discharges. In recent years, substantial progress has been in the understanding of the behaviour of the electron emission yield when oxidizing the target [2]. As the latter behaviour also influences the emission of negative oxygen ions, a good understanding is needed because high energetic negative oxygen ions affect in an important way the growth of the thin film. A few examples of this behaviour will be given [3].
As the ions bombard the target, they also become implanted. For inert gas atoms, their influence is minor. However, reactive ion implantation is an important pathway in the poisoning mechanism during reactive magnetron sputtering [4]. The paper will discuss the latest trends in the modelling of this process.
Finally, ions can be used as a tool to influence the thin film growth. As they are charged species, their energy can easily be influenced by biasing the substrate. Moreover, they can also be guided towards the substrate. This approach becomes even more interesting when most of the metal species are ionized as in HIPIMS plasmas. However, when studying thin film growth, one must realize that not only the ions are important, and other species play also their role. This will be discussed in the context of the characterisation of the different particle fluxes from the plasma towards the substrate [5].
[1] Deposition of thin films by sputtering cold isostatically pressed powder targets: A case study. F. Boydens, W. Leroy, R. Persoons, D. Depla. Phys. Status Solidi A, 209: (2012), 524-530
The correlation between target surface morphology and sputter deposition rate, F. Boydens, W.P. Leroy, R. Persoons, D. Depla, paper accepted in J. Phys. D : Appl.Phys.
[2] Magnetron sputter deposition: Linking discharge voltage with target properties, D. Depla, S. Mahieu, R. De Gryse, Thin Solid Films 517 (2009) 2825–2839
[3] Modeling the flux of high energy negative ions during reactive magnetron sputtering, S. Mahieu, W. P. Leroy, K. Van Aeken, and D. Depla, J. Appl. Phys. 106 (2009) 093302
[4] Rotating cylindrical magnetron sputtering: Simulation of the reactive process, D. Depla, X. Y. Li,S. Mahieu,K. Van Aeken,W. P. Leroy, J. Haemers, R. De Gryse, A. Bogaerts, J. Appl. Phys. 107 (2010) 0113307
[5] Sputter deposited transition metal nitrides as back electrode for CIGS solar cells, S. Mahieu, W.P. Leroy, K. Van Aeken, M. Wolter, J. Colaux, S. Lucas, G. Abadias, P. Matthys, D. Depla, Solar Energy 85 (2011) 538–544
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TET
PROF. MIKHAIL BENILOV
On January 7, 2013, Prof. Mikhail Benilov from Universidade da Madeira will give a talk on "Multiple steady-state solutions in the theory of DC glow and arc discharges and simulation of cathode spots". Place and time: ID 04/401 at 12:00. All interested parties are cordially invited.
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GROSSE AUSZEICHNUNG FÜR PROF. PADMA KANT SHUKLA
Prof. Dr. Dr. h.c. Padma Kant Shukla (International Chair der Ruhr-Universität) wird mit dem „Hind Rattan“-Preis ausgezeichnet, zu Deutsch „Juwel Indiens“. Der indische Premierminister Dr. Manmohan Singh vergibt den Preis zusammen mit der NRI Welfare Society of India jährlich an etwa 30 Mitglieder der weltweiten indischen Diaspora, d.h. im Ausland lebende Inder (NRIs) oder Personen mit indischem Ursprung. Die Auszeichnung würdigt den außergewöhnlichen Beitrag und die Verdienste von Prof. Shukla in seinem Arbeitsbereich, die Indien in der Welt sichtbar machen. Die Preisverleihung wird auf dem „32nd International Congress of NRI's“ vom 24. bis 28. Januar in Neu-Delhi stattfinden, an dem regelmäßig internationale Botschafter und bedeutende Mitglieder der indischen Regierung teilnehmen.
"Die RUB war meine Bestimmung"
Padma Kant Shukla wurde 1950 in Tulapur (Indien) geborgen und zog nach Europa, als er 21 Jahre alt war. „Die Ruhr-Universität war meine Bestimmung“, sagt der Physiker. „Hier habe ich all meine wissenschaftliche Arbeit gemacht.“ Er forscht an einer Schnittstelle zwischen Astrophysik, Plasmaphysik und Physik der kondensierten Materie und hat seine Ergebnisse in zahlreichen Artikeln in hochkarätigen wissenschaftlichen Zeitschriften publiziert, u.a. Nature und Physical Review Letters. „Als ich hörte, dass ich den Hind Rattan-Preis bekomme, hat mich das sehr bewegt. Niemals hätte ich mir das erträumt“, so der heute 62-jährige RUB-Forscher.
Internationale Beziehungen
Padma Kant Shukla wird auf dem NRI-Kongress die Interessen Deutschlands und der Ruhr-Universität vertreten. Er ist seit 1993 deutscher Staatsbürger und hat seit 2010 den International Chair der RUB inne. Als „Botschafter“ forciert er die grenz- und fachüberschreitende Vernetzung der Universität, um die Wertschätzung der RUB im Ausland weiter zu erhöhen. Padma Kant Shukla ist ein hoch dekorierter Wissenschaftler mit exzellenten internationalen Kontakten. In den vergangenen Jahren hat er zahlreiche Auszeichnungen und Ehrungen für seine Verdienste erhalten. Besonders herausragend ist zum einen die Nicholson-Medaille, die er im Jahr 2005 als erster Westeuropäer überhaupt bekam. Zum anderen wurde Shukla im Herbst 2006 als erster deutscher Staatsbürger in die Physikklasse der Königlich Schwedischen Akademie der Wissenschaften berufen, der nur wenige ausgewählte Wissenschaftler aus aller Welt angehören. Als Mitglied der Akademie nominiert er Physikerinnen und Physiker für den Nobelpreis und berät das Nobelpreis-Komitee.
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Orléans
07.12.2012 - JUDITH GOLDA & DR. VOLKER SCHULZ-VON DER GATHEN AM GREMI IN ORLÉANS
Master-Studentin Judith Golda und Dr. Volker Schulz-von der Gathen besuchten Remi Dussarts Groupe de Recherches sur l'Energétique des Milieux Ionisés (GREMI) an der Université d'Orléans.
Judith Golda ist vom 19. November bis zum 14. Dezember am GREMI, Volker Schulz-von der Gathen vom 7. bis zum 12. Dezember.
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Atlanta
06.12.2012 - HENDRIK BAHRE AM GEORGIA INSTITUTE OF TECHNOLOGY
Vom 19.11.12 bis 14.12.12 besuchte Hendrik Bahre für vier Wochen Dr. Samuel Grahams Forschergruppe "Electronics Manufacturing and Reliability Laboratory" am Georgia Institute of Technology in Atlanta, Georgia (USA). Im Vordergrund der Kollaboration stand dabei das Abscheiden ultradünner, hochdichter Gasbarriereschichten mittels Atomlagenabscheidung (ALD) und physikalisch verbesserter chemischer Gasphasenabscheidung (PECVD).