Institutskolloquium des IPP 2017

Data from the German electricity system for the years 2010, 2012, 2013, and 2015 are used and scaled up to a 100% supply by intermittent renewable energy sources (iRES). In the average, 330 GW wind and PV power are required to meet a 100% target. A back-up system is necessary with the power of 89% of peak load. Surplus electricity accrues at high power levels. Curtailing surplus power to a large extent is found to be uneconomic. Demand-side-management will suffer from the strong day-to-day variation of available surplus energy. A day storage is ineffective because of the day-night correlation of surplus power during winter. A seasonal storage loses its character when transformation losses are considered because it can contribute only after periods with excessive surplus production. The capacities to be installed stress the difficulty to base heat supply and mobility also on iRES generated electricity in the future. As the German energy transition replaces one CO2-free electricity supply system by another one no major reduction in CO2 emission can be expected till the last nuclear reactor will be switched off. The German GHG emission targets for 2020 and beyond may be in jeopardy. [mehr]

Towards the origin of stuff – 60 years research with neutrons at Garching

In 1957 after a construction time of only one year the first neutron source for Germany has been taken into operation on the potato fields outside of Garching. It was the crystallization point of what is today one of the largest research campus in Europe. In 2005 its successor, the Neutron Research Source Heinz Maier-Leibnitz (FRMII) opened for routine operation. Today it attracts yearly about 1000 scientists for from all over the world to do experiments with neutrons. “Do something new!” was the motto of Heinz Maier-Leibnitz, doyen of research with neutrons in Europe, to achieve in international competition scientific excellence. And in Garching new things have been undertaken: guiding thermal neutrons by optics, concepts for high resolution inelastic scattering, concepts for detecting mesoscopic structures by neutrons, precise cross sections for the interaction of thermal neutrons with matter, ultra-cold neutrons, hadron therapy of cancer by fast neutrons … Today FRM II stands for research with neutrons spanning from material sciences with strong feed-back to industrial needs over life sciences towards tackling fundamental questions like the origin of the universe. After a brief historical review the talk will present examples of actual and future cutting edge research at FRM II. [mehr]

Automatisches Fahren – Wie? Wo? Wann? Überhaupt?

Die Historie des automatischen Fahrens zeigt, dass schon seit fast 30 Jahren immer wieder prototypisch automatische fahrende Fahrzeuge aufgebaut und demonstriert wurden. Dies waren in der Regel eine Demonstration des machbaren, häufig jedoch weit von einer Serienanwendung entfernt. Aktuelle Forschungsprojekte zeigen, dass die Entwicklung in den letzten Jahren rasch vorangeschritten ist. Somit erwarten derzeit viele die Einführung des automatischen Fahrens in den nächsten Jahren. Viele Probleme, die immer noch vorhanden sind, werden ausgeblendet. Prof. Lienkamp zeigt auf, ob und wie die Probleme gelöst werden können und welche Funktionen danach noch realistisch umsetzbar sind. Die Auswirkungen auf die Zulieferer werden diskutiert. [mehr]

Dense and Direct Methods for Image-based 3D Reconstruction

The reconstruction of the 3D world from images is among the central challenges in computer vision. Starting in the 2000s,researchers have pioneered algorithms which can reconstruct camera motion and sparse feature-points in real-time. In my talk, I will introduce spatially dense methods for camera tracking and 3D reconstruction which do not require feature point estimation, which exploit all available input data and which recover dense or semi-dense geometry rather than sparse point clouds. Applications include 3D photography, 3D television, and autonomous vehicles. [mehr]

Laser Wakefield Accelerator-Driven Light Sources

Plasma wakes, excited by short high-power laser pulses or short bunches of relativistic charged particles passing through the plasma, give rise to strong longitudinal electric fields which can be employed to accelerate electrons. The accelerating gradients achieved in a plasma wakefield can exceed those of accelerating structures typically used in state-of-the-art particle accelerators by three to four orders of magnitude. Since the scale of accelerator-driven research facilities drives their construction and operation cost on the one hand and limits their range of applications on the other, it appears extremely attractive to utilize plasma-wakefield accelerating techniques in future: one may dream of X-ray free electron lasers fitting into university laboratories and hospitals or of TeV electron-positron colliders less than one kilometer long instead of requiring a 50 to 100 kilometer long tunnel passing beneath the Lake Geneva. Therefore, since the first experimental demonstration of the acceleration of plasma background electrons in the so-called wave-breaking regime of laser wakefield acceleration in 2004 a steadily increasing R&D effort in laser, plasma and accelerator physics has been devoted to this topic.In my talk I will give a - non-exhaustive - review of the current status of laser wakefield electron accelerators and introduce the particular challenges one is facing if one intends to combine laser wakefield and "conventional" accelerator techniques in order to realize synchrotron light sources or even free electron lasers. I will present our ideas on how to possibly cope with some of these challenges. [mehr]

Near-Earth space as a laboratory: a key to the plasma universe

The massive campaign of space exploration carried out in the past century has revealed that the vast majority of ordinary matter in the Universe is in the plasma state. The hot dilute plasma between galaxies and galaxy clusters dominates baryonic matter and can also be found within galaxies, for example in the interstellar medium, outer atmospheres and stellar winds of stars, and coronas of accretion disks. Astrophysical plasmas are generally turbulent, and dissipation of turbulent fluctuations leads to continuous plasma heating and acceleration of charged particles. The basic plasma processes of heating and energization in turbulent magnetized plasmas are of fundamental importance for the comprehension of the evolution of the Universe. This is one of the main motivations of the Turbulence Heating ObserveR (THOR) proposal, a candidate for the next M4 space mission by the European Space Agency (ESA). THOR is a fundamental plasma physics mission, which uses near-Earth space as its laboratory and which has been designed to directly address the ESA Cosmic Vision theme "How does the Solar System work?", by studying the basic processes occurring "From the Sun to the edge of the Solar System". The scientific focus of the THOR project has not only attracted large support for the mission from the laboratory, solar and astrophysical plasma communities, but it has also already initiated many synergetic studies between them. To achieve its scientific goal, THOR will make in situ measurements with unprecedented resolution in specific regions in near-Earth space: the pristine solar wind, the Earth’s bow shock and interplanetary shocks, and the compressed solar wind regions downstream of shocks. These regions are selected because of their different turbulence properties, and reflect similar astrophysical environments. Here, we present the science of the THOR mission and we discuss implications ofTHOR observations for space, astrophysical and laboratory turbulent plasmas. Moreover, we will present the activities of the Numerical Simulation Support Team, that provides scientific support to the design phase of the THOR satellite. [mehr]

A Theory of Rational Belief: Logic, Probability Theory, and Neural Networks

In recent years, the application of formal methods has become increasingly important in philosophy. In my talk I will present a recent instance of that development: a new theory of rational belief which involves methods from logic, probability theory, and the theory of artificial neural networks. The theory might lay the foundations for future methods by which probabilistic data and the dynamics of neural networks can be interpreted rationally with the help of qualitative terms and logical rules. [mehr]

Energie Offshore Speichern

Das Projekt umfasst Entwicklung und Erprobung eines neuartigen Pumpspeicherkonzeptes zur Speicherung großer Mengen elektrischer Energie offshore. Das Konzept des Meeres-Pumpspeicherkraftwerk nutzt das Meer selbst als oberes Speicherreservoir. Das untere Speicherbecken wird durch einen Hohlkörper auf dem Meeresgrund gebildet, der im Pumpbetrieb mit Ladestrom leer gepumpt wird und im Entladebetrieb über eine Turbine zum Generatorantrieb wieder mit Wasser gefüllt wird. [mehr]

MHD instabilities and their control

Magneto-hydrodynamic instabilities, that can develop in tokamak plasma, strongly limit the range of possible plasma parameters. During tokamak operation, these instabilities should be avoided, stabilized, or controlled to ensure stable plasma behavior. Depending on the instability nature and drive, different actuators and actions are required for its stabilization. In this talk, we discuss physics and control of few main MHD instabilities: sawteeth, neoclassical tearing modes, and resistive wall modes. [mehr]

The Enigma of Solar Energy: From Gravity over Radioactivity to Nuclear Processes

It took about a century until the riddle of the origin of the Sun's energy was solved. The first theory based on energy conservation was suggested in the 1840s, to be transformed into the successful Helmholtz-Kelvin contraction theory a few decades later. This theory held the position as a standard theory for about 40 years, but was eventually challenged by theories based on radioactive decay. However, the Sun is not a radioactive machine and only in the late 1930s, after the emergence of nuclear physics, did a satisfactory explanation arrive with Bethe's celebrated theory of stellar energy production. The talk reviews the development in a historical perspective. [mehr]
The Universe features a rather strange composition, with unknown dark matter and dark energy components dominating today's energy density. Early numerical simulations have played a pivotal role in demonstrating that this unexpected cosmological model gives rise to a remarkably successful theory for structure formation. Nowadays, hydrodynamical simulations have become our most important theoretical tool to study non-linear multi-scale dynamics in the baryonic sector, allowing us to follow how hydrogen and helium gases condense out in galaxies, form stars, and populate the predicted dark matter structures. However, we still struggle to understand the regulation of star formation, which appears rather inefficient on a global scale, defying simple theoretical expectations. In this talk, I will review some of the current results of galaxy formation simulations and discuss how they help us to identify and constrain the physics shaping galaxies and clusters of galaxies. In particular, I will discuss calculations that track an additional cosmic ray component and follow the amplification of magnetic fields during galaxy formation. [mehr]

Jim Knopf and the physics of Michael Ende

The story of Jim Knopf und his friend Lukas, the engine driver, is probably the master piece of the book author Michael Ende. The thrilling story on magnetic mountains, mermaids, dragons, pirates und flying railway locomotives is embedded into a plethora of phenomena from practically all fields of physics, all charmingly distorted to be attractive for children. We will have a fresh look at the adventures of the two friends, connecting them to fields of modern physics, like quantum physics, particle physics, and cosmology. [mehr]

Towards quantitative turbulence predictions with gyrokinetics

On the way to a better understanding and prediction of plasma turbulence, gyrokinetics is nowadays considered the best compromise between realism and efficiency in plasma theory. Although highly optimized for magnetically confined plasmas, corresponding applications still require massively parallelized codes which are able to exploit present-day supercomputers. The remarkable evolution of such tools from rather qualitative to more and more quantitatively reliable predictions over the last decade is exemplified with the gyrokinetic code GENE ( -- an IPP born software package. Particular focus will be placed on the multi-scale nature of plasma turbulence -- both in its relation to macroscopic (machine-size) scales as well as its characteristic manifestations on ion- and electron-gyroradius scales. Verification studies as well as state-of-the-art comparisons with fluctuation measurements involving so-called synthetic diagnostics will be highlighted. Finally, an outlook is given on how these tools are actually integrated in reactor design and where future efforts need to be focused. [mehr]

Properties and design of quasi-axisymmetric stellarators

The possibility of magnetic confinement devices that have the same neoclassical transport properties as axisymmetric tokamaks was realised by Nührenberg and co-workers three decades ago. In quasi-axisymmetric stellarators, the magnetic strength is independent of the toroidal (Boozer) angle, the particle orbits are similar to those in a tokamak, and the drift kinetic equation is the same. In such devices, the particle orbits are thus well confined and the bootstrap current can contribute substantially to the rotational transform of the magnetic field. However, some of the rotational transform comes from external coils and the plasma is thus confined even in the absence of a toroidal plasma current. This opens the possibility for a device that is maximally similar to a tokamak but can operate in steady state, hopefully without disruptions.In this talk, I will review the theoretical background and describe the first steps that have been undertaken in Greifswald to design a new such device. [mehr]
Enabling steady-state operation of a tokamak fusion reactor, i.e. with a pulse length that is not constrained by physics but only by maintenance needs, requires all plasma current to be driven non-inductively. Neutral beam injection (NBI) promises very high current drive efficiency. Recent quantitative analysis of the composition of the plasma current in highly non-inductive discharges in ASDEX Upgrade indicated that the various non-inductive contributions are predicted with good accuracy by the established models. This result reinforces confidence that the current drive predictions for DEMO and power plant scenarios that are based on the same physics models yield realistic results. On the other hand, designing an NBI beamline for a steady-state tokamak reactor presents technological challenges that go far beyond those of the ITER beamline. Energetic efficiency of the entire current drive system, which is no major concern for an experimental reactor, is of paramount importance for the economic viability of a power plant. Presently, the efficiency of NNBI beamlines is mainly limited by neutralisation efficiency, and new, experimentally not yet proven, neutralizer concepts are needed. The neutraliser is also the key component that largely determines the design parameters of most other beamline components. Conceptual system studies that explore a wide variety of technological options are therefore urgently needed, and IPP’s NBI group is getting actively involved within EUROfusion’s work package heating and current drive. The beam transport modelling tools developed to this end are also applied profitably to the study of poorly understood beam transport phenomena in the ASDEX Upgrade beamlines and the planning of future upgrades of the system that could increase NBI’s operational space. [mehr]
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