Funded Projects 2018

Influence of Nitration of SRF grade Niobium on Kapitza Resistance and Thermal Conductivity

Copyright: Dr. Marc Wenskat

Dr. Marc Wenskat (UHH)

Project Partners: Guilherme Dalla Lana Semione, Christopher Bate

Superconducting radio-frequency (SRF) cavities are the workhorse for modern accelerators, whether for the European Spallation Source, the European XFEL or LCLSII and the cavity production for the European XFEL set standards. But in recent years, new treatments have emerged. In particular the LCLSII cavity production is based on a treatment which mechanisms remain mysterious. These so called “nitrogen doped” cavities have a lower surface resistance RS by a factor 2-3 in the operational range for a continuous wave machine, which drastically reduces operational costs, but the maximum accelerating field was also reduced by about 30%. Another improvement is the “nitrogen infusion” process, which reduces Rs but maintains the accelerating field. This process is difficult to control and not all relevant process parameters are yet identified. None of the new treatments are understood in terms of surface processes or relation to cavity performance. We want to investigate our new hypotheses to explain the reduced accelerating field for nitrogen-doped cavities. In parallel we will test a theory for the origin of the reduced Rs. If the hypothesis is found to be correct, the limitation of doped cavities can be overcome. But even more important, a new insight in the relation of surface properties and cavity performance would be achieved.

Probing unknown iron uptake mechanisms in the human malaria parasite Plasmodium falciparum using a structural systems biology approach

Copyright: Prof. Dr. Tim-Wolf Gilberger

Prof. Dr. Tim - Wolf Gilberger (UHH/CSSB)

Project Partners: Dr. Strauß (EMBL), Dr. Christian Löw (EMBL)

Iron is a key element for life on Earth due to its broad function as biocatalyst and flexible redox chemistry. However, its low bioavailability limits life in many environments and cells need to acquire iron against a concentration gradient using efficient iron uptake systems.
The human malaria parasite Plasmodium falciparum – responsible for 400,000 deaths per year – depends on iron from the blood to proliferate. Nutritional immunity reactions that limit the availability of iron and other trace metal nutrients to parasites are a major part of the human defense against infections. Hence, iron levels are tightly controlled and low concentrations of free iron control the proliferation of P. falciparum. Indeed, adding iron binding agents has cytocidal effects on the parasite.
Surprisingly, despite its great potential as antimalarial drug target, the molecular mechanisms of iron acquisition in P. falciparum from its host are insufficiently studied and our understanding remains elusive. This is exacerbated by the fact that up to 50% of the genes encoded in the genome of P. falciparum remain unknown due to its unique evolutionary history from a free-living photosynthetic organism to an obligate parasite.
We will address this knowledge gap using an integrative approach by combining continuous cell culturing of Plasmodium falciparum with transcriptome and proteome profiling to identify iron-responsive gene and protein networks and characterize unknown proteins using biochemistry and X-ray crystallography.

Pulse-post compression in gas-filled multi-pass cells

Copyright: Dr. Christoph Heyl

Dr. Christoph Heyl (FS-LA)

Project Partners:
Prof. Markus Drescher (Group leader); (UHH),
Dr. Tino Lang (Team leader within FS-LA); (DESY; FS-LA)
Dr. Cord Arnold (University Lecturer), Lund University, Sweden

Ultrashort laser pulses, nowadays employed for a variety of applications ranging from material processing to gravitational wave detection, can undergo nonlinear interactions if sufficiently high intensities are reached.
Such nonlinear interactions do not only form the basis of modern laser technology, but have also led to the emergence of completely new research fields such as attosecond science. They found applications within modern surgery and might enable lightning control. Via nonlinear light matter interactions, light can control light. Laser light at the nominal wavelength can be transformed into a beautiful white light supercontinuum, covering the entire visible spectral regime and extending far beyond its frontiers.
The precise control of nonlinear light-matter interaction is possible for example in guiding structures such as optical fibers, which guide laser light over long distances. As a striking alternative, researchers have only very recently designed an optical resonator-like system, which provides completely new degrees of freedom for controlling nonlinear light matter interactions by replacing the guiding optical fiber with a simple mirror arrangement. The idea is simple but remarkably effective: instead of letting a light pulse pass a nonlinear medium once, we can now bundle the laser beams and send them again and again through the same medium while altering their properties in-between. This way, we foresee that new regimes for laser intensity, wavelength and pulse-duration can be reached. The scientific objective of this project is the investigation of novel methods to control nonlinear light-matter interaction in multi-pass cell arrangements. Using gases as nonlinear media, we explore the power-scalability of this scheme and its potential to reach new spectral regimes.