The Swiss Plasma Center seeks PhD students throughout the year and encourages candidates to apply at any time. PhD projects are discussed with the prospective thesis supervisor at SPC during the application phase, and can be tuned to the candidate’s interest. A non-exhaustive list of possible projects can be found below.
If you need more information on any proposal, send an e-mail to the corresponding contact person.
If you want to apply, please follow the procedure indicated on this page.
Thank you.
Experimental physics on the TCV tokamak
Experimental physics in the Basic Physics Plasma group
Experimental physics at the BioPlasmas Lab
Open positions in experimental physics on the TCV tokamak
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Motional-Stark spectroscopy for current distribution determination in the plasma core
Contact person: Dr. Dmytry Mykytchuk, Dr. MER Stefano Coda
Information on the current distribution of the current flowing, mostly toroidally, within the tokamak core is important in understanding the governing physics of impacting plasma instabilities and in seeking their mitigation. This information is also crucial to reliable plasma equilibrium reconstruction, particularly in scenarios where the current distribution is significantly changed by the electron cyclotron and/or neutral beam heating systems, both of which are exploited on TCV.
To obtain the current profile spectroscopically, a beam of fast, illuminating, neutral particles is injected into the plasma core. The polarization of emission resulting from these beam particles interacting with the plasma can be used to reveal the magnetic field direction at the emitting plasma location. The photon polarization is set by the direction of the electric field in the rest frame of a beam particle crossing the magnetic field, E=VxB (the effect of this electric field on the atomic energy levels is called Motional-Stark effect). A new spectroscopic system has been recently installed on TCV to measure the emission intensity distribution as a function of wavelength for Dα emission. The magnetic field is obtained by regressing the measured Dα intensity distribution to a model that considers both Motional-Stark and Zeeman effects, with the magnetic field as a variable. The current distribution is then obtained using Ampere’s law from the field measured at multiple radii across the core.
The PhD student will be expected to take responsibility for the remaining technical developments, namely: i) commissioning and calibration of the new spectroscopic system using dedicated discharge discharge scenarios operated on TCV, ii) development of the analysis workflow to regress measurements upon atomic model for Motional-Stark effect, iii) measurement of the current distribution in plasma scenarios with non-inductive current drive, iv) study of the plasma equilibrium reconstruction by the LIUQE code when constrained by these measurements of the core magnetic field. Points iii and iv will evolve into the more physics-based part of the thesis, which will be built around plasma regimes in which the details of the current profile play a key role: the so-called advanced scenario with flat or even hollow current profiles, featuring increased core confinement, is a very likely candidate – but more options will be available within the constantly shifting experimental program of TCV.
- Study of Electron Cyclotron Emission (ECE) on TCV Tokamak
Contact person: Prof. Ambrogio Fasoli ; Dr. Laurie Porte
Electron Cyclotron Emission (ECE) is ubiquitous in magnetically confined plasma. It is generated by the acceleration of free electrons immersed in a magnetic field and, in the right conditions, can be used to determine the electron temperature of the plasma with high spatial and temporal resolution. By changing the line of sight, or in the presence of strong microwave heating, the frequency spectrum of ECE provides information on the electron energy distribution. This information provides information on the generation and the dynamics of ‘runaway’ electrons in tokamaks that are of sufficient energy to damage the vacuum vessel and are to be avoided. It also is important in the characterisation of electron cyclotron current drive efficiency which is a key parameter for future steady state tokamak designs. Now, by making very highly resolved measurements of the ECE spectrum and by making estimates of the statistical properties of the measured signal it is possible to infer the spatial distribution and spectral content of electron turbulence. This measurement is key in the understanding of energy and heat transport in tokamaks; a subject that is a dynamic area of tokamak research. TCV is equipped with a suite of heterodyne radiometers that permit detailed study of ECE on TCV. Making use of the numerous lines of sight available, measurements can be made of electron temperature, electron turbulence and of the dynamics of the electron energy distribution function in various plasma regimes. A PhD dissertation is proposed where the candidate is expected to contribute to the operation of the whole suite of ECE diagnostic systems on TCV. At the same time the candidate will be expected to develop new and robust means of calibration of the systems and to develop data analysis tools. The candidate will be free to contribute original work in collaboration with the TCV team, in any or all fields of research. This may include extensive modelling of ECE emission and its relation to non-thermal electron energy distributions or, indeed, the use of machine learning and Bayesian techniques for optimising diagnostic data analysis. The candidate may prefer more technical challenges like, for example but not limited to, implementing real-time control of filters and polarisers.
- Predicting operational space for QCE regime in TCV and JT-60SA
Contact person: Dr. Benoît Labit
The Quasi-Continuous Exhaust regime is a promising ELM free scenario, established on TCV (and AUG and JET) and extensively investigated in past years under various experimental conditions. The Candidate will start with the analysis of the collected data (pedestal stability, divertor footprint, confinement, …). In view of a possible extrapolation to a reactor, the operating space for this regime must be understood. Our current understanding about the physical mechanism which prevent a deleterious ELM crash is the existence of increased transport at the foot of the pedestal. The role of plasma fuelling setting the plasma density at the separatrix and the role of plasma shaping will be investigated with ideal or resistive MHD numerical codes like HELENA, CASTOR and potentially JOREK, the ultimate goal being to develop a predictive framework for QCE regime for TCV. Finally, based on a staged ladder approach, the framework will be extended to JT-60SA, the new largest worldwide tokamak which will start its operation in the next 5 years. Being able to predict the existence of the QCE regime for JT-60SA and demonstrate it in the future will certainly give more confidence on its attractiveness for a DEMO reactor.
- The Separatrix Operational Space (SepOS) for TCV plasmas
The goal of the thesis is to develop the SepOS for TCV. The Candidate will analyze and combine TCV data coming from several diagnostics to derive the scaling laws for scale lengths and to derive the parameters characterizing the different turbulence regimes.
The different limits in the TCV SepOS will be compared with the scalings derived from two-fluid, three-dimensional, flux-driven, global, electromagnetic turbulence simulations carried out with the GBS code.
Finally, a specific SepOS for plasmas featuring a negative triangularity, for which edge transport is reduced, will be developed.
- Divertor simulations towards a plasma exhaust solution for a reactor
Contact: Dr MER Holger Reimerdes
Power exhaust remains a major challenge in the development of fusion energy. The TCV boundary programme seeks to optimise current divertor solutions and explore alternative geometries. TCV is, therefore, starting a new divertor upgrade to investigate the tightly-baffled long-legged divertor (TBLLD). The objective of this PhD project is to support the development and exploitation of this upgrade using divertor models of different levels of complexity, but with a focus on the SOLPS-ITER code. SOLPS-ITER is a code package that simulates plasma, impurities and neutrals in the divertor and the plasma edge and was used to design the ITER divertor. In a first phase a proof-of-concept TBLLD will be tested in TCV in 2025/26. The exploitation of this TBLLD will be supported by divertor modelling. The comparison of predictions with measurements will guide refinements of the models. In a second phase the TBLLD will be integrated in a core-boundary solution (e.g. a negative triangularity plasma with tightly baffled divertors). The experience gained in the first phase will allow the candidate to use the same divertor modelling to prepare the second phase. In parallel, the models will be employed to evaluate the potential of the TBLLD concept for a fusion reactor, such as DEMO.
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Gyrokinetic simulations of turbulent transport for TCV H-mode pedestals
Contact: Dr Oleg Krutkin, Dr. Benoît Labit
ITER and next step devices are foreseen to operate in the so-called H-mode regime. This regime is characterized by the formation of a transport barrier at the plasma edge called the pedestal. Understanding the turbulent transport in the pedestal is of paramount importance to assess the performance of future fusion reactors since Pfus ∼ pped2 where Pfus is the fusion power and pped is the pedestal plasma pressure. In particular, the pedestal of ITER is expected to operate at much lower collisionality than in most current devices. The TCV tokamak in Lausanne is pursuing a substantial experimental effort to explore H-mode and pedestal physics for various H-mode regimes. The goal of the thesis will be to help to interpretation by calculating the transport inside the pedestal with gyrokinetic simulations with the GENE code. First, both linear and nonlinear local simulations at the top of the pedestal will be envisaged for different pressure profiles and plasma shapes, ranging from low to high collisionalities and from low to high shaping (mainly triangularity). In a second step, global GENE simulations will be executed for entire pedestal region. At the end of the thesis, a new framework for GK analysis will be available to support TCV exploitation.
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Design and Development of a Multi-Stage Depressed Collector for Gyrotrons
Contact: Dr Jérémy GenoudGyrotrons are currently the preferred source for plasma heating in fusion devices. For tokamaks like ITER, DEMO or STEP, several dozen gyrotrons are planned for Electron Cyclotron Resonance Heating (ECRH) and Electron Cyclotron Current Drive (ECCD). Among the key factors for the success of commercial fusion reactors, net electrical efficiency stands out as one of the most crucial. In this context, maximizing the efficiency of gyrotrons (currently limited to 40-50%) is critical to optimize this factor. To address this challenge, a multi-stage deceleration approach, widely used in slow-wave devices for decades with efficiencies exceeding 80%, is being considered. This approach works by recovering a portion of the energy from electrons by separating their trajectories based on kinetic energy and directing them to the appropriate electrode stages. However, implementing this strategy in current fusion gyrotrons presents significant physical and technological challenges.
The objective of this project is to design, develop, build, and test a multi-stage depressed collector (MSDC) based on an innovative strategy. To minimize risks, the project will focus on the development and test of the MSCD on a low-power gyrotron used for spectroscopy. This modular gyrotron will allow the PhD candidate to conduct hands-on experiments.During the design and building phase, the PhD candidate will collaborate with ETH Zurich’s Advanced Manufacturing Laboratory to leverage the advantages of innovative additive manufacturing techniques. During the whole project, the candidate will collaborate with a research group from ETH Zurich.
Open positions in experimental physics in the Basic Plasma Physics group
- Experimental and theoretical investigation of helicon waves in TORPEX
Contact: Prof. Ivo Furno, Dr. Marcelo Baquero
Helicon waves are electromagnetic waves that can propagate in magnetized plasmas at frequencies between the ion and electron cyclotron frequencies. They are very interesting in the context of low temperature plasmas because they can lead to very high ionization efficiency in the “helicon mode” regime. In that case, heating a plasma with helicons can lead to high densities approaching values seen in scrape-off layers and divertors of tokamaks.
While studies of helicon properties have been carried out since at least the 1970s, they have mainly focused on cylindrical geometries. TORPEX, a toroidal basic plasma physics device at SPC, recently underwent an upgrade in which a birdcage antenna was installed that can excite helicon waves. This has enabled studies in a toroidal geometry in a way that was previously not possible and that we have only started to investigate.
We are currently seeking a candidate to fill an open PhD position in experimental physics to pursue experiments and numerical modeling of helicon wave physics in TORPEX. These investigations lie at the intersection of several fields in science and engineering including plasma physics, electronics, control systems and simulations, thus providing a unique opportunity to develop interdisciplinary competences.
Plasma Physics Theory
- Simulation of the plasma dynamics at the tokamak edge
Contact person: Prof P. Ricci
The understanding turbulence in the edge of magnetic confinement device is an outstanding open issue in magnetic fusion. The physics of this region determines the boundary conditions of the whole plasma by controlling the plasma refueling, heat losses, and impurity dynamics. Edge dynamics regulates the heat load on the tokamak vessel; this is considered among the most crucial open problems for ITER and future fusion reactors. Since a few years, a project has been initiated at the SPC with the goal of improving the understanding of edge physics. This effort has significantly advanced our grasp of plasma turbulence in the edge of a relatively simple configuration, the circular limited tokamak, and we are now exploring the physics of diverted configurations. Ph.D. theses are proposed with the goal of advancing the simulation and the understanding of edge turbulence in reactor relevant conditions, in particular to consider improved plasma models and advanced exhaust configurations.
Open positions in experimental physics at the BioPlasmas Lab
A virtual tour of the BioPlasmas Lab can be found here:
https://www.epfl.ch/research/domains/swiss-plasma-center/virtual-tours/
The interest in Cold Atmospheric Plasmas (CAPs) is constantly growing for a wide number of applications, from medical treatments, to sterilization of bacteria, viruses, as well as fungii (plasma-agriculture). The high-energy electron population obtained with CAP results in a complex chemistry featuring a variety of Reactive Oxygen and Nitrogen Species (RONS), which have a key role in affecting the biological sample, but keeping a low ambient temperature during the process, thanks to the low energy of ions and atmospheric gas molecules.
At the BioPlamas Lab of the SPC, this interdisciplinary topic where physics, chemistry, and biology are strongly connected is explored on several projects, with a two-fold challenge: on the one hand, CAPs are developed for industrial applications to have a short-medium term impact on the society, on the other hand, the mechanism underlying the biological effects of CAPs is investigated to increase the current understanding of CAP applications, as well as to fine tune the target process.
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Investigating via active and passive spectroscopy the chemistry of cold atmospheric plasmas for biological applications
Contact person: Prof. Ivo Furno, Dr. Fabio Avino
To shed light on the mechanism underlying CAP effect on biological samples, a key step consists in obtaining a detailed spatial and temporal mapping of the RONS produced in the proximity of a plasma source. To address this challenge, the Bio-plasmas lab is equipped with a variety of active and passive spectroscopic methods, such as a picosecond laser to perform laser induced fluorescence spectroscopy and other laser-based measurements, such as E-FISH. The laser can be coupled to an in-house developed nanosecond-pulse power supply used to power our plasma sources as an alternative to commercial AC power supplies that are also available in the lab. Complementary CAP application to biological samplesare envisaged.
The PhD candidate will be responsible for the experimental activity, including, but not limited to, laser-based measurements, which will advance the current understanding of the RONS generated by our plasma sources. Numerical modelling could complement the Ph.D. activities. Collaborations with other laboratories sharing and complementing the SPC-Bio-plasmas lab expertise will likely be accessible.
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Investigating the underlying mechanisms responsible for Plasma Activated Water biocidal activity
Contact person: Prof. Ivo Furno, Dr. Fabio Avino
The production and application of Plasma Activated Water (PAW) is one of the investigated research topics at the BioPlasmas Lab, as an indirect plasma treatment of non-pathogen E. Coli: deionized water is firstly treated with a dedicated plasma source (surface dielectric barrier discharge), which enriches it with a variety of RONS, and secondly is applied on E. Coli testing its biocidal properties. The main challenge consists in understanding the details of the mechanisms responsible for the biocidal effects of PAW.
Within this framework, we are looking for a Ph.D. to pursue this experimental activity, coupling the know-how in plasma physics of the SPC, with several biological tools (e.g Flow Cytometry, Proteomics, RNA sequencing, single cell fluorescent time-lapse microscopy) that are mostly available either in the Biolab, or in other groups/laboratories on the EPFL campus. The BioPlasmas Lab is fully equipped with all the necessary for standard wet-lab activities as well as a brand-new Nikon time-lapse microscope, PCR, Q-PCR, and a novel device for single cell impedance measurement. This project will follow a previous Ph.D. project oriented on E.coli inactivation mechanism investigation by PAW. Comparisons of PAW inactivation effectiveness with other microorganisms (e.g. gram positive) will be performed during the PhD.
This project will provide the unique opportunity to acquire skills and experience on a topic joining physics, biology and chemistry.
Open positions in superconductivity for fusion
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Applied Superconductivity – R&D on Nb3Sn Superconducting Magnets
Contact Person: Dr. Xabier Sarasola, email: [email protected] .
We are looking for a motivated PhD candidate with a solid background in physics, interested in the R&D program of high-field dipole magnets suitable for constructing superconducting test facilities and accelerator magnets. The magnets are based on an innovative type of two-stage cable made of high Jc, Nb3Sn strands. The challenging project has a potential to open a new avenue towards the next generation of the accelerator-type magnets.
The successful candidate will prepare a short section of the high Jc cable with the support of an industrial partner, and characterize it in the SPC laboratory. The focus of the work is on the design, construction and test of a small prototype coil, retaining basic characteristics of a high field dipole magnet. The student will present his/her work in international conferences and report the results and findings in scientific journals. Experience in applied superconductivity or cryogenics is a valuable asset, though not a mandatory requirement. The place of work is Villigen PSI, close to Zurich.