Fakultät für Physik




Hands-on laser plasma accelerators – Projects

Project 1: 1D gridless plasma simulation code (Students and T. Ostermayr)

Overview The central part of this project is to follow mathematics and concepts laid out in Popov’s
PhD thesis and papers to write an efficient (c++) program for 1D simulation of a hot spherical
plasma consisting of electrons, protons and more ion species.


  • Write the code
  • reproduce key-results of Popov verification of the code.
  • Write documentation of the code and the verification results
  • study interesting, new questions that arise accessible by spherically expanding plasmas using your code, e.g.
  • optimization of the initial density distribution or component-composition of a sphere with respect to the formation of a Coulomb-shock density-front
  • non-isotropic initial particle temperature.
  • Summarize results in form of an at least 4 page document.

Project 2: Phase-retrieval from focal spot measurements (Students and J.

Overview: Recording the focal spot of a laser is a standard routine which precedes any experiment with
high power laser pulses. Imperfections lead to losses in peak intensity and can in most cases
be attributed to non-flat phase fronts before the final focusing optics, which could be
corrected based on the estimated phase map. This work aims to establish and test a phase
retrieval algorithm solely based on the measurement of two (or more) intensity profiles
close to the focal spot.


  • Familiarize with the concept of beam propagation, Kirchhoff Diffraction integrals, Fraunhofer and Fresnel approximation and the relevant numerical tool light pipes
  • Calculate the intensity distribution of a round beam with arbitrary phase in focus and 100 μm outside of focus in both directions
  • Develop a retrieval to invert the above problem
  • Apply the routine to experimental data (offered from our group)
  • Summarize results in form of an at least 4 page document.

Project 3: Evaluation of proton-radiographic images (Students and T.

Overview: In this project you will evaluate experimental data recorded at the Texas Petawatt laser. The CR39 detector records single ions behind the imaged object. The evaluation is based on microscope-images of the detector and requires efficient recognition of each proton-track.


  • Use Fiji (ImageJ) or other software packages to get location and size-information of each proton on the microscope image
  • Produce images by translating this information into a histogram
  • Verify your algorithm
  • Prepare your code to run on a computer-cluster (no front-end, more than one microscope input image).
  • Summarize results in form of an at least 4 page document.

Project 4: Evaluating LIONo-acoustic data with a simulated US-array (Students
and S. Lehrack)

Overview: Ionoacoustics offers a way to directly measure range of mono-energetic ion-bunches in
water. So far, single element detectors were used to retrieve pressure signals. To develop
ourselves towards sophisticated methods, one approach is the use of multi-element
transducers, i.e. PZT-Arrays, to enhance the reconstruction e.g. by triangulation. The Matlab
toolbox k-Wave offers a PDE-solver to simulate the pressure wave evaluation from any kind
of energy input and any kind of detectors, with build-in features to emulate clinical
This project requires at least a basic understanding of Matlab, its features and workflow as
well as the use of a bash-shell, meaning data handling, remote access and script editing in
Linux. Proper Manuals and online-resources will be provided.


  • From previous examples and scripts, get familiar with k-Wave, generate simple, artificial energy inputs and recover the data correctly
  • “realistic” energy input will be provided, e.g. known Dose distributions for conventional accelerators, even LION-data
  • Evaluate different reconstruction procedures and compare them. This should end up in a proposal for an experiment including a US-probe or similar.
  • Summarize results in form of an at least 4-page document
  • Document the workflow and produce a generic MasterScript for future work.

Project 5: Evaluation of spectrometer-data for charged particles (Students
and F. Lindner)

Overview: Many laser plasma acceleration experiments use magnetic spectrometers to infer energy
distributions of generated charged particle beams. Critical steps in the data evaluation are
the physical modelling of the spectrometer and the proper matching between model and
experiment (tracking). Based upon this and taking into consideration noise, background and
detector quantum efficiency, the recorded raw data are processed into ion kinetic energydistributions.
The increasing repetition rates in laser plasma experiments presents additional
challenges on the speed of the data analysis.
This project aims to produce an efficient, easy to use and fast evaluation routine, starting
from the particle tracking up to the calculation of the ion numbers per energy.


  • Write a charged particle tracker for static electric and magnetic fields
  • Write a code that allows to retrieve differential energy distributions from raw data based on your tracking
  • Take into consideration the detector noise, background and quantum efficiency
  • Summarize results in form of an at least 4 page document.

Project 6: First steps towards polychromatic proton CT (Students, F.
Englbrecht, T. Ostermayr)

Overview: Laser-driven ion accelerators are inherently polychromatic, i.e. multi-energetic. This can be
used as an advantage in imaging applications, where a known input-spectrum of protons and
the spectrum measured behind an object can be used to retrieve quasi-three dimensional
information about the object without involving rotation of either the beam or the object. In
this project, first steps will be taken to elucidate possibilities of this approach and to retrieve
3D information from simulated data of known objects.


  • Get familiar with the basic concepts of proton stopping in matter and consider problems thereof for imaging applications
  • Get familiar with our concept to retrieve information from recorded images
  • Write a code to implement one possible information retrieval
  • Use your code with known simulated objects
  • Summarize results in form of an at least 4 page document.