If you need more information on any proposal, send an e-mail to the corresponding contact person.
If you want to apply for one of those topics, please follow the procedure indicated on this page .
- Study and optimization of electron density profiles, turbulence characteristics and instabilities in the edge and pedestal of TCV plasma
Observations  point to the fact that over all tokamak plasma particle and energy confinement is dominated by transport properties in the plasma edge. At the same time in the so called H-mode regime of plasma confinement, the edge confinement pedestal is very often unstable and there are frequent, large expulsions of plasma particles and energy into the surrounding volume depositing a significant fraction of the plasma particles and energy onto the plasma facing components with the potential to damage these components. The expulsions are referred to as Edge Localised Modes (ELMs). It is planned to operate ITER in the H-mode confinement regime and it is likely that ITER will suffer ELMs. One avenue of current tokamak physics research is to understand the physics of ELMs and explore avenues to quench the ELMs and/or to mitigate their effects. High spatial and temporal resolution measurements of electron density profiles and electron density turbulence in the plasma edge will help elucidate the central role of the plasma edge in tokamak confinement and lead to a better understanding of ELM physics and inter-ELM confinement. A particular goal would be to develop a viable type-II ELM regime, in which target heat loads are significantly reduced while the confinement remains good. As in other tokamaks, this regime is achieved at TCV with high plasma triangularity and high density. We are seeking one or two motivated PhD students to pursue these topics. Part of the work would include further development of a prototype, extremely high resolution, millimeter-wave pulsed reflectometer  and Doppler backscattering (DBS)  system for the characterisation of edge density profiles, turbulence characteristics and poloidal flow velocity in the plasma edge in both standard confinement, or L-mode, and H-mode regimes. An additional system to feature prominently, particularly in the study of H-mode and ELMs, is the Phase Contrast Imaging diagnostic which measures density fluctuations. It is expected that a significant effort be placed in enhancing the existing hardware and optimising its use. Interaction with the groups from the experimental department as a whole will be necessary and collaboration with the SPC theory group is expected.
 O. Sauter et al, Phys. Plasmas 21, 055906 (2014)  P. Molina-Cabrera et al, to be submitted to Rev. Sci. Instrum.  P. Molina-Cabrera et al, Rev. Sci. Instrum. 89, 083503 (2018)
- Fast-ion deuterium alpha (FIDA) Spectroscopy
Contact person:Dr. MER B.P. Duval
Neutral heating beams are often used in thermonuclear devices to heat the plasma above that achievable by passing large currents through the plasma resistance (Ohmic Heating). The fast neutral atoms injected are well above thermal (called fast-ions) and must slow down in the plasma to efficiently heat the thermal plasma. FIDA spectroscopy takes the light emitted from the interaction of the fast ions/atoms within the plasma to analyse the spatial and velocity profiles of these ions from injection to thermalisation. These fast ions can be taken as a proxy for the fast Helium atoms created by particle fusion (the basic process of energy production concerned) and as they slow, they are subject to many interactions with the target plasma that can prematurely eject these fast ions, which could be catastrophic as their energy is used to keep the plasma hot and thus reactive. TCV has recently installed such a fast ion heating beam and preliminary FIDA spectroscopy shows a rich range of physical processes. This thesis will commence with the installation of two multi-chord spectroscopic systems to observe FIDA light. Many experimental probes on the effect of plasma shape and other parameters (density, temperature etc.) will follow. The student will use the FIDASIM program developed by a worldwide group to interpret the spectra together with detailed plasma transport modelling to diagnose the fast ion behaviour. This work will be part of a new and developing group at the SPC looking into fast ion behaviour on the TCV Tokamak.
- Novel Disruption Mitigation System
A critical unresolved issue for tokamak fusion reactors and ITER is the mitigation of disruptions where an established plasma carrying a large current loses stability. On ITER, disruptions could be powerful enough to significantly damage the tokamak structure and must be addressed before the machine can safely operate at high performance and demonstrate that fusion energy can be achieved. Currently, the most promising mitigation approach is “massive material injection” to cool the plasma and radiate the stored energy, spreading it evenly over the vessel to avoid vessel damage and reduce the concurrent electromagnetic forces. Various approaches are being attempted but none has yet met the requirements. The goal of this project is to design, develop, test and calibrate known and novel disruption mitigation systems on the TCV tokamak. Specifically, this will involve the design and development of these concepts (gas valves or other material injection systems), co-ordinating manufacturing and installation of the complete system, performing experiments on the TCV tokamak and then completing an analysis of the data with the aid of existing and extending present models. As this is a high priority program within the EUROfusion community, this research may include travel to other institutes within Europe and collaborating on their experiments and design concepts.
- Power Balance Studies on TCV
A power balance is a fundamental test of all physical systems. Specifically on a Tokamak, where such a balance is challenging to obtain, it remains critical in interpreting the plasma performance and, in particular, the power exhaust routes from the heated plasma back to the machine structure. One main reason that this is challenging is the difficulty in accurately measuring the radiated power that extends from the Infra-red to the X-ray region and can include a strong particle exhaust component. To address this goal, a new diagnostic that incorporates bolometeric measurements and electromagnetic sensitive solid state diodes is being installed on the TCV tokamak. This experimental project will further develop and exploit these new diagnostics aiming to minimize the remaining uncertainty in radiated energy measurements. The TCV plasma is heated both by an Ohmic current (to obtain the Tokamak configuration) and by controlled Neutral Particle beams and high power Gyrotron (microwave) auxiliary heating. This task will involve obtaining an in-depth knowledge of several radiation diagnostics, their exploitation in the challenging Tokamak environment and developing analyses to interpret experimental observations. Furthermore design and modification of the hardware systems, where applicable, will be investigated and implemented through leading specific TCV experiments and calculating power balance over the whole TCV program. There is also scope for collaboration, including travel, with other European groups on their machines.
- Isotope effects for H-mode confinement regime in TCV
Contact person: Dr. B. Labit
During the Pre-Fusion Power Operation Phase (PFPO), ITER will operate in the so-called H-mode regime of good confinement with Hydrogen and/or Helium as the main ion species. Nevertheless, most of the existing scaling used to quantify H-mode efficiency are based on Deuterium plasmas and therefore the extrapolation to Hydrogen or Helium plasma is largely uncertain. From H or He plasmas, compared to D plasmas, the goal of this thesis is to advance the understanding of crucial issues associated with the H-mode physics among which the L-H transition, the confinement with dominant electron heating, the fueling efficiency, the pedestal transport, the first wall and divertor heat loads, etc. The candidate will design and conduct experiments on the TCV device, the tokamak at the EPFL. New analysis tools together with theoretical models will be implemented.
- Development of an imaging neutral particle analyser (I-NPA) for TCV
Contact persons: Duccio Testa, Basil Duval, Alexander Karpushov
TCV is now equipped with a high power (1MW) / high-energy (25keV) Neutral Beam Injection (NBI) system, with a second system being planned to deliver fast neutrals at even higher energy (50keV). The injected fast neutrals then ionize in the plasma, producing supra-thermal ions which, in turns, may undergo charge-exchange neutralization and be expelled from the plasma. These ejected fast neutrals can be measured using a neutral particle analyzers and can then be used as a proxy to determine the fast ion distribution function in some relevant phase-space region.
TCV is currently equipped with a compact NPA, and major improvements will be needed to measure the fast ions produced by the second NBI system, hence the development of a new I-NPA, currently at the stage of conceptual design. This thesis will commence with the completion of the design, procurement, installation and commissioning of the I-NPA system, and will then move onto the analysis of the measurements obtained with this system, and other fast ion diagnostics, towards the development of a multi-diagnostic tomographic reconstruction of the fast ion distribution function. This work will be part of a new and developing group at the SPC looking into fast ion behavior on TCV.
- Thomson scattering data analysis for real-time applications
Contact person: Dr. P. Blanchard
On the TCV tokamak, reliable electron temperature and density profiles are routinely obtained from Thomson Scattering (TS) measurements. In 2013-2014, the TS diagnostic has undergone a substantial upgrade which is opening the road to real-time (RT) applications of such parameters.
In the frame of a PhD, algorithms for RT analysis of TS signals should be first developed and tested along with the implementation of a new DAQ system. The availability of electron temperature and density profiles in RT could then be used for TCV scenario development and actuator control like microwave heating system as well as inputs for RT transport code like RAPTOR.
Real Time Control of Tokamaks
Contact person: Dr Federico Felici
The SPC tokamak TCV is equipped with an advanced real-time control system, based on matlab-simulink and which allows rapid and flexible developments. In addition, we have developed a rapid tokamak transport simulator, RAPTOR, capable of simulating in real-time current density and kinetic profiles. This is a perfect environment for PhD thesis project related to real-time control of tokamaks, including magnetic control, plasma profile control, as well as advanced topics such as scenario control, monitoring and supervision.
Measurement of turbulence and modes driven by and interacting with the high-energy NBI ions in TCV
Contact person: Dr. Duccio Testa
Analysis of NBI-driven magnetic turbulence and modes in TCV, and interaction of MHD instabilities with the slowing-down NBI ions; develop and test mathematical tools for the magnetic turbulence analysis as needed; develop high-frequency magnetic sensors based on LTCC technology.
Contact person: Prof. Ivo Furno
Understanding the interaction of plasma turbulence with suprathermal ions, i.e. ions with energies greater than the quasi-Maxwellian background plasma, is a major challenge for the next generation of magnetic fusion reactors. While experimentally challenging in fusion devices, suprathermal ion measurements are accessible in basic devices with extended diagnostic capabilities and flexible configurations, such as the TORPEX device at SPC.
We are seeking for a Ph.D. candidate to conduct detailed investigations of basic aspects of suprathermal ion-turbulence interaction on TORPEX using a controllable suprathermal ion source and diagnostics, which allow fully time-resolved 3D measurements of the suprathermal ion dynamics. In parallel with the experiments, the Candidate will use state-of-the-art numerical codes to obtain 3D simulations, which will be compared with experimental data and theory predictions. The proposed subject is of fundamental importance for nuclear fusion and crosses the frontier between plasma physics and research in complex systems.
Contact person: Dr. Duccio Testa
Analysis of the Toroidal Alfven Eigenmode (TAE) measurements obtained in JET using the upgraded TAE system, including real-time control applications, MHD spectroscopy, and in preparation of studies of alpha-driven TAEs during the DT experiment planned at JET for 2017-2018.
Note: the upgraded TAE system should become operational around the end of 2014 or early 2015.
Overall data analysis for JET also to include comparison with all fast ion diagnostics and other turbulence diagnostic.
Contact person: Prof L. Villard
The SPC theory group has been active since many years in the field of numerical simulation of magnetized fusion-relevant plasmas by developing codes that are run on some of the currently most powerful High Performance Computing (HPC) platforms. In particular, the realistic description of low frequency turbulence from first principles using gyrokinetic theory, which remains a great simulation challenge, has been one of the group’s main research focus. The loss of heat and particles associated to this turbulence is a key limiting factor in achieving the conditions required in a fusion reactor. The architecture of the most powerful HPC platforms has been evolving towards more heterogenous systems (CPU+GPU or CPU+MIC) and there is therefore the need to adapt our physics application codes to this new type of machines. We are currently looking for a PhD candidate that is seriously motivated to deal with advanced numerical simulations of gyrokinetic turbulence and actively engage in the current effort to adapt our codes to the new generation platforms. The thesis will thus include both physical studies as well as technical aspects. The successful candidate will interact with our group at SPC and other institutions and laboratories.
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.
- Investigation of protection limits in Nb3Sn accelerator magnets
Contact person: Dr. P. Bruzzone
- PhD thesis in Applied Superconductivity on the Investigation of protection limits in Nb3Sn accelerator magnets
- Development of vacuum impregnated winding samples for the experimental assessment of the maximum allowable hot spot temperature.
- Experimental evaluation and modeling of the failure mechanism.
- Development of alternative cable geometries for accelerator magnets.
- Publication of results in scientific journals and at international conferences
The Superconductivity Group of SPC is located in the premises of the Paul Scherrer Institute (PSI) in Villigen.
In 2018, the Advanced Wakefield Experiment (AWAKE) reached a milestone demonstrating that plasma wakefields generated by externally injected proton beams can efficiently accelerate charged particles over 10 m distance, thus fulfilling the objective of the AWAKE Run 1 phase. This first ever proof-of-concept boosted the next phase, AWAKE Run 2. The goal of Run 2 is to accelerate an electron bunch with a narrow relative energy spread and an emittance sufficiently low for applications. In parallel to AWAKE Run 2, high-density plasma, generated by a helicon source in a linear geometry, is under development at CERN in collaboration with the Swiss Plasma Center in Lausanne (Switzerland), the Institute for Plasma Physics in Greifswald (Germany), and the University of Madison in Wisconsin (USA). This development poses formidable challenges from the point of view of plasma physics, technology and diagnostics. We are looking for a Ph.D. student who will participate in this joint endeavor, working partly at the Swiss Plasma Center and partly at CERN on the helicon plasma cell and diagnostics development. Should you be interested or know someone who could be, please send an email to [email protected].