At the Institute for Applied Physics (FB Physik, TU Darmstadt), a position is open in the research unit „Relativistic laser-plasma interactions'' and available now for a:
Research Assistant (all genders) – 65 %
The position has a limited duration of three years from the start date.
The research topic is the control of laser-plasma instabilities (LPI) in experiment and simulation. LPI appear during the interaction of a highly energetic laser pulse with matter. Because LPIs can be detrimental to laser-plasma interaction, their control and prediction is important for many applications. Here, in the context of this project, the influence of the plasma and laser parameters on the onset of LPI should be studied experimentally with the goal to develop LPI control methods. The PHELIX facility at GSI Helmholtzzentrum für Schwerionenforschunng GmbH will play a central role in the experimental part of the work, with an emphasis on tests with the newly-developed laser frontend that delivers incoherent broadband laser pulses. The experimental results will be illustrated with 2-to-3 dimensional particle-in-cell simulations, using the EPOCH simulation code.
Your tasks:
The tasks of the candidate include the design and planning of the experiment and its realization. A first experiment in planned for 2024 at PHELIX. Other experiments in an international context are also envisioned. In addition, the analysis of the experimental data and the comparison with simulation should be part of the project.
In addition, an active participation of the candidate to teaching activities is expected.
Your profile:
- A successfully completed university degree (Master/Diplom) in physics is required.
- In addition, a knowledge and preliminary experience in laser and plasma physics is required.
- A direct experience in the field of high-intensity lasers will be particularly appreciated.
- The candidate should be proficient with one of the following scientific programming languages: Matlab or Python, in order to perform the analysis of data produced by simulation and experiment.
- We expect an interest for interdisciplinary work to foster the collaboration with colleagues from connected topics.
Opportunity for further qualification (doctoral dissertation) is given. The fulfillment of the duties likewise enables the scientific qualifications of the candidate.
The Technische Universität Darmstadt intends to increase the number of female employees and encourages female candidates to apply. In case of equal qualifications applicants with a degree of disability of at least 50 or equal will be given preference. Wages and salaries are according to the collective agreements on salary scales, which apply to the Technische Universität Darmstadt (TV-TU Darmstadt).
Applications should be sent electronically as a PDF file with the usual documents, quoting the identification number, to: vincent.bagnoud@physik.tu-darmstadt.de.
Bachelor or Master Thesis
To better understand the interaction of an intense laser beam with matter it is necessary to know the parameters of the laser system. In particular, this this includes a measurement of the temporal laser pulse profile. The method of "Frequency Resolved Optical Gating" (FROG) has proven itself as a possible way for such characterizations, which is able to reconstruct both the temporal envelope of the pulse and the corresponding temporal phase from a measured "FROG trace". After the measurement, the temporal pulse shape can be optimized with the aid of an "Acousto-Optic Programmable Dispersive Filter" (AOPDF). The aim of the first part of this work is therefore to plan a FROG, set it up at the PHELIX system and use it to measure and optimize the temporal laser pulse.
These measurements are complicated by beam aberrations and the coupling between spatio-temporal effects, which typically occur in large laser systems. Therefore, the aim of the second part of this work is to consider and potentially optimise precisely such effects in the existing reconstruction algorithm.
Tasks B.Sc.:
- Planning and design of the FROG system
- Calibration of the system
- Commissioning and testing on at PHELIX system.
- Optimisation of the laser pulse in a control loop with an AOPDF (Acousto-Opti Porgrammable Dispersive Filter)
Additional Tasks M.Sc:
- Extension of the existing reconstruction algorithm under consideration of spatial-spectral effects
- Test of the new algorithm with controlled spatial-spectral effects and comparison with the expected behavior
- Investigation the effect of beam aberrations on pulse measurement and pulse reconstruction
Useful prior knowledge: Knowledge in the field of optics and non-linear effects, programming skills (LabVIEW, MATLAB or Python are of advantage)
If you are interested in this work please send a mail to:
v.bagnoud(at)gsi.de und j.hornung(at)gsi.de
Masterarbeit
Motivation:
Flawless beam quality is required for the generation of ultra-intense laser pulses. However, optical defects or incorrect alignment can quickly introduce errors in the beam that cannot be corrected retrospectively - reliable measurement methods are therefore essential!
The measurement of frequency-dependent beam errors, so-called "chromatic aberrations", is still very time-consuming today. This project aims to change this: Here, established techniques for wavefront measurement and spectral imaging are to be combined to design a compact and robust "plug-and-play" measuring device for the first time.
Task description:
- Sensor characterization in the laboratory
- Programming of live image evaluations (LabVIEW)
- Design, simulation and construction of an optical test bench
- Laboratory work on the Apollon Laser System in France
Objectives:
- Calibration of a multispectral camera
- Construction of a spectral wavefront sensor
- Test of the sensor on the Apollon Laser System
Prerequisites:
- Bachelor thesis with reference to optics
- Experience in programming
- Attendance of the lecture "Spectroscopy"
- Fluent in English
Literature:
- QWLSI wavefront measurement: www.researchgate.net/publication/221725185
- Multispectral wavefront measurement: doi.org/10.1364/OE.26.033387
