Institut für Theoretische Physik
Start / Aktuell
Oktober  2014
Mi
22.10.2014
Auditorium MPS
MPI für Sonnensystemforschung
14:00
S3-Seminar

Farhad Shakeri
IMPRS

Solar VUV variability of the quit Sun



Kontakt: Sonja Schuh
Mi
22.10.2014
Auditorium MPS
MPI für Sonnensystemforschung
14:40
S3-Seminar

Adam Pluta
IMPRS

Empirical data analysis and modeling for extrem geomagnetic storm correlating earth directed coronal mass ejection dynamics obtained through non-multipoint observations



Kontakt: Sonja Schuh
Mi
22.10.2014
Auditorium MPS
MPI für Sonnensystemforschung
15:20
S3-Seminar

Rakesh Yadav
IMPRS

Modelling starspots using computer simulations



Kontakt: Sonja Schuh
Do
23.10.2014
MPS-Auditorium
MPI für Sonnensystemforschung
14:00
MPS-Seminar

Lei Ni
Yunnan Observatories, Kunming, China und Universität Potsdam

Fast magnetic reconnection in the solar chromosphere mediated by the
plasmoid instability



Kontakt: Hardi Peter
Do
23.10.2014
Hörsaal 3
Fakultät für Physik
16:00
Joint Physics Seminar

Prof. Stephen M. Goodnick
School of Electrical Computer and Energy Engineering, Arizona State University, USA

Nanotechnology and Advanced Concept Photovoltaics

Nanostructured solar cells have multiple approaches by which they can improve photovoltaic performance: (1) New physical approaches in order to reach thermodynamic limits of energy conversion; (2) Circumvent material limitations through bandgap engineered systems; and (3) Provide new routes for low-cost fabrica-tion by self-assembly or design of new materials. Here we focus on pathways to high efficiency solar cells and energy conversion using various approaches employing nanostructured materials. In particular, we will discuss some of the challenges of modeling advanced solar cell structures where semi-classical continuum models for electronic transport break down. We first discuss approaches for improving the efficiency of crystalline Si solar cells to exceed the Shockley-Queisser limit through Si heterojunctions, carrier selective contacts, hot carrier effects, and multi-exciton generation. Hot carrier solar cells are another approach to high efficiency, where phononic bandgap materials are being investigated to reduce energy loss. Here we discuss modeling of the hot carrier dynamics in relation to hot carrier collection and efficiency. We then discuss improvements in multijunction solar cells through quantum well devices, which allow the effective bandgap to be tuned while maintaining latticed matched materials. Finally we discuss hybrid multijunction photovoltaics coupled with concentrating solar thermal in order to improve the system efficiency above either that of the photovoltaic or CSP system by itself.

Kontakt: Dr. Robert Maaß
Do
23.10.2014
Hörsaal 3, A.00.105
4. Physik
16:00
Hausseminar

Prof. Stephen M. Goodnick
School of Electrical Computer and Energy Engineering, Arizona State University, USA

Nanotechnology and Advanced Concept Photovoltaics

Nanostructured solar cells have multiple approaches by which they can improve photovoltaic performance: (1) New physical approaches in order to reach thermodynamic limits of energy conversion; (2) Circumvent material limitations through bandgap engineered systems; and (3) Provide new routes for low-cost fabrication by self-assembly or design of new materials. Here we focus on pathways to high efficiency solar cells and energy conversion using various approaches employing nanostructured materials. In particular, we will discuss some of the challenges of modeling advanced solar cell structures where semi-classical continuum models for electronic transport break down. We first discuss approaches for improving the efficiency of crystalline Si solar cells to exceed the Shockley-Queisser limit through Si heterojunctions, carrier selective contacts, hot carrier effects, and multi-exciton generation. Hot carrier solar cells are another approach to high efficiency, where phononic bandgap materials are being investigated to reduce energy loss. Here we discuss modeling of the hot carrier dynamics in relation to hot carrier collection and efficiency. We then discuss improvements in multijunction solar cells through quantum well devices, which allow the effective bandgap to be tuned while maintaining latticed matched materials. Finally we discuss hybrid multijunction photovoltaics coupled with concentrating solar thermal in order to improve the system efficiency above either that of the photovoltaic or CSP system by itself.

Kontakt: R. Maaß
Fr
24.10.2014
MPS
MPI für Sonnensystemforschung
13:30
Rosetta-Seminar

Hermann Böhnhardt, Reinhard Roll
MPS

Update on Philae landing sequence and planned science



Fr
24.10.2014
Seminarraum 11, C3.101
SFB 1073
14:15
SFB Seminar

Prof. Dr. Ivo Feußner
Göttingen Zentrum für molekulare Biowissenschaften, Albrecht-von-Haller-Institut

From the oceans to the fields - Producing wax esters in plants

Industrial chemicals derive currently mainly from fossil oil-based raw materials. The availability of fossil oil however is declining. Plant oils provide functionally equivalent and renewable alternatives for these raw materials. Replacement of fossil oil used in the chemical industry with renewable plant oils and ensuring that growing demand for food oils is also met, will require a trebling of global plant oil production. This will rely on application of plant biotechnology to (i) tailor plant oils to have high purity of a single molecule, (ii) introduce unusual molecules that have specialty end-use functionalities and (iii) increase plant oil production not only by increasing oil content in seeds of current oil crops, but more importantly conversion of other high biomass crops into oil accumulating crops. Wax esters are normally minor constituents of plant oils exhibiting desirable properties for lubrication. Natural sources have traditionally been whales. Additionally some plants, bacteria and insects produce wax esters. Currently there is no biological source available for long chain length monounsaturated wax esters which are most suited for industrial applications. Therefore, we are exploring enzymatic activities from bacteria, insects and plants for the desired properties. Suitable enzymes are then analyzed for their suitability and additional requirements enabling the production of wax esters in oil crops. In order to minimize the risk of inadvertent mixing with seeds for food purposes and to prevent genes for industrial oil qualities from crossing into oil crops intended for food, we are not using any food crop in our genetic modifications. We use two oil crops as production platforms, Camelina sativa and Crambe abyssinica for producing wax esters as feed stocks for the chemical industry.

Mo
27.10.2014
MPS Cygnus + Draco
MPI für Sonnensystemforschung
11:00
Solar-Seminar

Thierry Dudok de Wit

The solar butterfly diagram: from a low-dimensional model to new proxies of solar activity (T. Dudok de Wit)



Mo
27.10.2014
MPS - Aquila + Bootes
MPI für Sonnensystemforschung
14:00
MPS-Seminar

Avijeet Prasad
IIA, Bangalore, India

Separable solutions of force-free spheres and applications to solar active regions



Kontakt: Hardi Peter
Di
28.10.2014
MPS - Aquila + Bootes
MPI für Sonnensystemforschung
11:00
Solar-Seminar

Johann Hirzberger
MPS

The PHI instrument on Solar Orbiter



Di
28.10.2014
MPS Cygnus + Draco
MPI für Sonnensystemforschung
11:00
Planetary-Seminar

Wojciech J. Markiewicz
MPS

Morphology, dynamics and physical properties of the Venus upper clouds from imaging with Venus Monitoring Camera on Venus Express

The Venus Monitoring Camera (VMC) on Venus Express (VEX) spacecraft has been observing the upper cloud layer since April 2006. To date more than three hundred thousand images have been acquired. VEX has a highly elliptical orbit allowing for global as well as close up views with resolution down to 200 meter per pixel. The VMC is a CCD camera with four channels in the UV, visible and near IR, with centre wavelengths at 365, 513, 965 and 1010 nanometers respectively. The VMC UV wavelength corresponds to the spectral feature of a, so far unidentified, absorber. In particular this subset of the VMC data shows great variety of morphologies. On global scales these include equatorial belts, bright polar bands and polar caps. The observed small scale features change their appearance from mottled clouds and convective cells at low latitudes to streaky patterns at middle and high latitudes. Time sequences of global views have been used extensively to track clouds and hence to obtain wind speed vectors. 90 orbits were processed manually resulting in 50000 wind speed vectors. With a correlation algorithm we have to date obtained more than 400000 vectors. Many of the morphological features we see in UV channel are also visible in other wavelengths. As the VEX spacecraft comes closer to the planet we no longer monitor cloud motion and rather quickly fly over them. During this pericentre passage it is possible to make dayside mosaics of the clouds as well as night side mosaics of the surface. The pericentre passage allows for the highest resolution images. Some of the most interesting ones are found in the equatorial convective region. The scales of the cells go down to few tens of kilometers and are significantly smaller than observed previously. This may have implications for the thickness of the convective zone itself and hence provide clues for understanding the difficult problem of vertical transport of energy and momentum. In near polar regions, usually above 50º latitude, we see many waves. These are most likely gravity waves and are visible in all four VMC channels. By modeling phase dependence of brightness in the VMC data in all channels we can infer the physical properties of the upper clouds as well as the haze which in most cases lies above the clouds. In the seminar I will also discuss observations and analysis of the glory on the top of the clouds. These data are the first observations of a full glory outside of the Earth environment.

Kontakt: Urs Mall

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Last modified: Mon Mar 5 10:17:50 CET 2012