RFX Supervisor: M. Giacomin
Academic supervisor: M. Giacomin
Head of the RFX research group: M. Zuin
Leader of the RFX research program: L. Marrelli
Tipologia: Sperimentale, Modelling, Numerica, Compilativa
Abstract:
Plasma turbulence in the boundary of magnetic confinement fusion devices is typically studied by means of complex three-dimensional two-fluid simulations, where fluid quantities, such as the plasma density, the electron and ion temperatures, the electron and ion parallel velocities, are evolved self-consistently with the electromagnetic field. The GBS code is a state-of-art turbulence code that has been extensively used for more than ten years to investigate boundary turbulence in tokamaks and stellarators. Recently, GBS was extended to simulate reversed field pinch (RFP) configurations, with the aim of investigating plasma turbulence in the boundary of RFX-mod2 (Consorzio RFX, Padua). This extension required the implementation in GBS of new differential operators.
In this project, the student will apply the method of manufactured solutions (MMS) to verify the correct implementation of these new differential operators. The MMS consists in adding “ad-hoc” sources in the model equations to drive the system to a prescribed solution. The system is verified if the difference between the numerical and the prescribed solution scales with the order of accuracy of the numerical scheme used to discretized the operators.
Tesi assegnata a: Elia Martari
RFX Supervisor: Maurizio Giacomin
Academic supervisor: Maurizio Giacomin
Head of the RFX research group: Matteo Zuin
Leader of the RFX research program: Tommaso Bolzonella
Category: Sperimentale, Teorica, Numerica, Modelling
Abstract:
The design of future high-performance magnetic confinement fusion devices requires accurate predictions of the energy confinement time, which is the time taken by the stored energy to leave the confined plasma. This important quantity depends on turbulent transport, whose prediction often requires complex and computationally expensive first-principles nonlinear gyrokinetic simulations, becoming prohibitively expensive when multiple scenarios need to be considered.
For this reason, reduced transport models, which include a simplified physics, are commonly applied in scenario development. A recent reduced transport model has been derived to specifically address turbulent transport in highly shaped electromagnetic regimes in presence of equilibrium flow shear (https://arxiv.org/abs/2404.17453). The core of this model is described by a quasi-linear metric that is evaluated from first-principles linear gyrokinetic simulations. The thesis project aims to optimize this reduced transport model by employing machine learning techniques in order to provide a fast way to compute the quasi-linear metric. In fact, performing linear gyrokinetic simulations still require hundreds of core-hours, therefore limiting the application of this transport model in scenario development. During the project, a large database of linear gyrokinetic simulations covering a multidimensional space of approximately ten features will be used to train a machine learning model, which will replace the need of linear gyrokinetic simulations to evaluate the quasi-linear metric. This new surrogate model will be implemented in the T3D code (https://bitbucket.org/gyrokinetics/t3d/src/main/) for transport simulations and the results of T3D will be compared against a higher fidelity transport model. Additional linear gyrokinetic simulations will be performed with the GS2 code (https://gyrokinetics.gitlab.io/gs2/page/index.html).
Previous experience (if necessary): Basic knowledge of Python
Assigned to: Francesco Erario
Proponente/Relatore RFX: M. La Matina, M. Agostini
Relatore Accademico: M. Agostini
Capogruppo: L. Carraro
Responsabile di Programma: T. Bolzonella
Tipologia: Sperimentale, Teorica, Numerica, Compilativa
Abstract:
Gli ELMs sono instabilità che si verificano nei plasmi confinati in modo H, regime fondamentale per i
futuri reattori a fusione. La tesi si propone di studiare L’evoluzione temporale dei profili elettronici
prima, durante e dopo un ELM.
Il lavoro prevede l’analisi sperimentale dei dati raccolti dal tokamak TCV (Tokamak à Configuration Variable) per plasmi in modo H che presentano ELMs: come principale diagnostica verrà utilizzata la diagnostica spettroscopica Thermal Helium Beam (THB).
Tesi assegnata a: Andea Sanfilippo
Proponente/Relatore RFX: V. Candeloro, I. Mario
Relatore accademico: M. Zuin
Capogruppo RFX: M. Zuin
Responsabile di Programma RFX: D. Marcuzzi
Tipologia: Sperimentale, Teorica, Numerica, Compilativa
Abstract:
Neutral Beam Injectors for fusion applications require energetic neutral beams as auxiliary heating system for fusion reactors. Neutral beams for ITER require up to 1 MeV of energy, hence the production and acceleration of negative ions, due to their high neutralization efficiency compared to positive ion beams. Negative ion sources are based on the inductive coupling of electromagnetic waves to a hydrogen plasma (ICP discharge). To optimize the design of such sources, and particularly of the RF driver (the region where the plasma is generated by coupling of 1 MHz RF waves), the MINION experiment is in operation at Consorzio RFX and will start operate from April 2025 with solid state RF generators. The main diagnostic systems to measure the plasma features are emission spectroscopy and Langmuir probes. The proposed activity consists in: 1) Design and assembly of the Langmuir probe diagnostic systems 2) Characterization of the diagnostic systems 3) Preliminary deployment and test of the diagnostic systems in MINION plasma. The student will improve his/her knowledge of the physics of ICP plasmas and on the diagnostics of cold plasmas. The activity includes simple simulations of the plasma features, of the electrical circuit of the Langmuir probe in RF waves environment, and data analysis.
Competenze necessarie per svolgere con successo la tesi:
Conoscenza base della fisica dei plasmi e nozioni sull’utilizzo delle sonde di Langmuir; concetti base dell’analisi dati.
Tesi assegnata a: Eleonora Maria Valonta
Proponente: M. Dalla Palma (DTT-RFX), A. Zoppoli (DTT-Università di Napoli Federico Secondo)
Capogruppo RFX: A. Rizzolo
Responsabile di Programma: S. Peruzzo (Technology & Engineering Development Program)
Relatore Accademico: to be identified
Tipologia: Sperimentale, Teorica, Numerica, Compilativa
Abstract:
DTT is one of the largest superconducting tokamak under construction with the mission to get scientific and technological proofs of power exhaust in prospect of the first nuclear fusion power plant [1, 2]. The 5.5MA maximum plasma current, 6T toroidal magnetic field at the plasma center, and 2.19m plasma radius make DTT a flexible and compact facility for testing D-shaped plasmas with different configurations of heat load spreading.
The mechanical systems of DTT are designed and integrated analysing interfaces consistently with machine operating states including plasma operation, disruptions, baking, seismic event, and maintenance.
Testing of different divertor concepts shall be guaranteed with flexibility in the divertor region. Only a subset of the alternative configurations, those considered most promising for DEMO, are considered for the design of the first divertor. However, the first divertor is designed to accommodate different magnetic configurations with single null as reference.
In DTT, 54 divertor modules are foreseen, 3 for each 20° sector. Out of these, 4 can be test modules, where advanced divertor configurations can be tested.
In a divertor standard module, the target configuration is based on the solid tungsten (W) monoblock concept. This layout is based on the reference actively water cooled W divertor targets, and relies on proven technologies already qualified for ITER. The W monoblocks are supported by the divertor cassette.
The main components involved in the divertor integration are: in-vessel support pads welded between the vessel inner shell and the toroidal rails (support system), the interface between the divertor cassette and the support system (locking-alignment system), and the toroidal rails which design and position depend on compatibility requirements with the different plasma physics scenarios and with remote handling operations.
The divertor cassette could be electrically isolated with respect to the inboard support pads in order to reduce the electrical current circulating during plasma events thus reducing the electromagnetic loads. The toroidal periodicity of the electrical isolation will include not more than 3 cassettes and will depend on the specific designed solution.
The proposed activity foresees a contribution to the mechanical design of the cassette to vacuum vessel interface with electrical isolation beginning from the selection of the suitable materials. Then, CAD tools and calculation methods will be used to analyse a solution under the machine operating states against design rules and functional and interface requirements.
In particular, the student can apprise: the design of the cassette support system & locking-alignment system; the design of the inboard and outboard toroidal rails; mechanical, electrical, and vacuum compatibility; remote handling interfaces.
References
[1] R. Ambrosino, “DTT – divertor tokamak test facility: A testbed for DEMO,” Fusion Engineering and Design, vol. 167, p. 112330, 2021
[2] R. Martone, R. Albanese, F. Crisanti, A. Pizzuto, P. Martin Eds.. “DTT Divertor Tokamak Test facility Interim Design Report, ENEA (ISBN 978-88-8286-378-4), April 2019 (“Green Book”)”
Tesi assegnata a: Samuele Bovo
Proponente/Relatore RFX: U. Giuliani
Relatore Accademico: G. Zollino
Capogruppo: A. Maistrello
Responsabile di Programma: S. Peruzzo
Tipologia: Modellistica, Teorica, Numerica, Compilativa
Abstract:
The student will use the model COMESE (COsto Medio del Sistema Elettrico – Electricity System Mean Cost) to produce and analyze different energy scenarios. The Italian electricity system will be the object of the analyses, with a long term time horizon compatible with the upgrading of the energy system in the pursuit of decarbonization goals, i.e. the second half of the 21th century. Specifically, the model will be used coupled with an optimization routine, in order to produce optimized system designs able to meet the electricity demand at the least possible system cost.
Each scenario will be designed under the constraint of complete decarbonization and will rely on variable renewable generation and nuclear energy as the main sources of energy. The optimization of the system design under different cost assumptions for the photovoltaic technology and the electrochemical storage technology will allow to assess how, and to what extent, the penetration of solar energy varies as a function of its capital cost and possibly of the capital cost of electrochemical storage.
Tesi assegnata a: Pietro Gaspari
Proponente/Relatore RFX: M. Agostini
Relatore Accademico: G. Zollino
Capogruppo: A. Maistrello
Responsabile di Programma: T. Bolzonella
Tipologia: Modellistica, Teorica, Numerica, Compilativa
Abstract:
EnergyScope è un modello opensource di ottimizzazione per scenari energetici con settore elettrico, termico e dei trasporti sviluppato inizialmente presso l’EPFL di Losanna.
Lo scopo della tesi è quello di confrontare i risultati di EnergyScope con i risultati ottenuti dal modello di ottimizzazione COMESE, modello per scenari energetici sviluppato internamente al Consorzio RFX.
Il primo obiettivo del lavoro è quello di replicare con EnergyScope scenari energetici sviluppati con COMESE per verficare la corrispondenza dei risultati.
Il secondo obiettivo invece è quello di mantenere la separazione delle domande finali in EnergyScope (elettricità, calore bassa temperatura, calore alta temperatura, mobilità) e verificare se la modellazione del sector-coupling porta a differenze sostanziali rispetto agli scenari con solo settore elettrico.
Tesi assegnata a: Riccardo Biondi
Proponente/Relatore RFX: N. Marconato
Relatore accademico: N. Marconato
Capogruppo RFX: M. Brombin
Responsabile di Programma RFX: S. Peruzzo
Tipologia: Sperimentale, Teorica, Numerica, Compilativa
Abstract:
The student will work on the design of a spark protection circuit for the measuring system of currents of the order of picoampere or lower (picoammeter), in high-voltage circuits. The developed circuit will be employed to protect this breakable diagnostic, used to measure the leakage current in a mock-up system for experimental tests on High Voltage (HV) gas insulated components. This activity is part of the R&D for the design of a HV transmission line feeding the Neutral Beam Injector (NBI) of the DTT fusion experiment. The project required analysis of the literature, design of the circuit by means of a SPICE-like software for circuit analyses and finally realization and testing of the physical device.
Competenze necessarie per svolgere con successo la tesi: Good knowledge of electrical engineering. SPICE-like software knowledge is welcome
Tesi assegnata a: Griselda Cibaj
RFX Supervisor: G. Chitarin, S. Denizeau
Academic supervisor: G. Chitarin
Head of the RFX research group: A. Rizzolo
Leader of the RFX research program: D. Marcuzzi
Tipologia: Modelling, Teorica, Numerica, Compilativa
Abstract:
SPIDER is the full-scale prototype of plasma source for the Neutral Beam Injector (NBI) of the experimental nuclear fusion reactor ITER. Operations on SPIDER aiming are high performances compatible with ITER target are ongoing.
During a typical pulse on SPIDER, several negative ion beamlets are extracted from a plasma source through a Plasma Grid, by the voltage applied on a grid located just upstream of the Plasma Grid: the Extraction Grid (EG). Under the effect of this voltage, electrons are also extracted from the source and must be eliminated in order not to damage the accelerator components. To do so, permanent magnets embedded inside the EG deflect the electrons on the grid surface, which results in significant heat loads where these electrons impinge.
For this reason, this component is actively cooled by embedded water channels. The temperature on the EG is measured by a set of recently installed sensors based on the Fiber Bragg Grating (FBG) concept. These FBG sensors consist in a type of sensor inserted along an optical fiber that reflects a specific range of wavelength of the light passing through it. This wavelength range depends on the spatial periodicity of the refractive index in the lattice inside the sensor core. The thermal dilatation of this lattice modifies the refractive index spatial periodicity and therefore the wavelength range of reflected light. This induces a direct correlation between the sensor core temperature and the wavelength of the reflected light.
The thesis activities involve participating to the experimental sessions to monitor and analyze in real time the data obtained by the FBG sensors, in particular during experimental sessions with long pulses.
In parallel, the main objective of the thesis is to develop a set of interdependent simulation models (beam optics model on Opera, transient thermal model on ANSYS Workbench and CFD on ANSYS Fluent) to estimate, from the experimental data, the map of heat loads deposited by the electrons on the EG surface.
If the student is proficient and the activities of the thesis go better than expected, it may be asked to him/her to study more in detail the physical phenomena (plasma drifts, plasma source configuration…) responsible for the particular profile of the heat load.
The following activities are foreseen:
• overview of the literature on Neutral Beam Injectors for fusion and more specifically on the SPIDER experiment,
• participation to SPIDER experiment, real time data analysis,
• elaboration of numerical models, case analysis, physical interpretation
Tesi assegnata a: Leonardo Lucchi
RFX Supervisor: M. Giacomin
Academic supervisor: M. Giacomin
Head of the RFX research group: M. Zuin
Leader of the RFX research program: L. Marrelli
Tipologia: Modelling, Teorica, Numerica, Compilativa
Abstract:
Plasma turbulence plays a critical role in magnetic confinement fusion devices, regulating fusion performance and heat flux to the wall. Plasma turbulence is often investigated by means of complex and challenging three-dimensional simulations. Although significant progress has been made in characterizing turbulence in tokamaks and stellarators, only limited work has been carried out in reversed field pinch, mostly because its complex and self-organized magnetic configuration. Recently, the GBS code has been upgraded to target the simulation of reversed field pinch configurations. Building on this recent upgrade, this project will explore the feasibility of RFX-mod and RFX-mod2 GBS turbulence simulations in reversed field pinch configurations, with particular focus on the recently implemented three-dimensional Poisson’s and Ampère’s solver.
Tesi assegnata a: Tommaso Berteotti
Proponente/Relatore RFX: L. Orlandi, P. Franz
Relatore accademico: L. Piron
Capogruppo RFX: L. Carraro
Responsabile di Programma RFX: L. Marrelli
Abstract:
In magnetic fusion devices, tomography reconstruction is a technique that can be applied to Soft-X-Ray (SXR) data (brilliance) to obtain a spatial distribution of the plasma properties – in particular, the electron temperature. One of the challenges with the current tomographic reconstruction method is its time-intensive nature, requiring significant computational resources. In this context, the development and application of a machine learning model can help expedite the tomographic reconstruction process, enabling its reconstruction in real-time.
The aim of this Thesis project is to analyze SXR data of RFX-mod plasmas (Consorzio RFX, Padova, Italy) and to create a database usable for machine learning. A machine learning procedure will be applied to obtain the coefficients of the Cormack-Bessel expansion, used to mathematically retrieve the 2D emissivity map.
Tesi assegnata a: Edoardo Bucalo
RFX Supervisor: T. Bolzonella, P.Vincenzi, C. De Piccoli
Head of the RFX research group: D. Terranova
Tipologia: Modelling, Teorica, Numerica, Compilativa
Abstract:
The presence of an energetic particle (EP) population strongly characterizes fusion plasmas, which will be dominated by MeV-range alpha particles in burning plasma conditions. Neutral Beam Injection (NBI), primarily used to heat plasmas to fusion temperatures, is another source of EPs that present similarities to the fusion-alpha population. NBI is currently used in most present-day devices and will also be used in the international ITER experiment1, currently being built in Cadarache (FR). This project explores non-Maxwellian distribution functions that characterize NBI energetic particles in tokamaks and their effect on the plasma, such as heating, current-drive, and torque injection. This will be done through numerical modelling, using the state-of-the-art ASCOT2 suite of codes. ASCOT is an orbit-following Monte Carlo code for simulating EPs in tokamaks by solving the Fokker-Planck equation for minority species. The complex ASCOT suite of codes has been recently rewritten3 to fit modern parallelized code standards and has an advanced post-processing Python environment. It can be used to track EP orbits and losses, to simulate the ionization and slowing down of NBI EPs, the generation and slowing down of alpha EPs, and EPs’ acceleration and slowing down due to interaction with Ion-Cyclotron waves in fusion plasmas. It can deal with full 3D machine geometry and non-axisymmetric magnetic field backgrounds. This project will apply the ASCOT code to the ITER-satellite JT-60SA tokamak4 (Naka, JP), starting the first plasma operations with NBI soon. JT-60SA case is particularly relevant for ITER due to the high injection energy of its NBI system, capable of injecting particles with energy up to 500 keV, i.e., the closest to the 1 MeV NBI system foreseen for ITER. Moreover, JT-60SA envisages the use of several injectors (in co-/counter- current or normal injection direction, with low and high injection energy, with or without a vertical tilt of the injection lines) that result in a variety of possible EP distribution functions, each of them with peculiar effects on the plasma. For instance, the modulation of NBI-induced current drive and input torque is possible, leading to unprecedented experimental conditions in the coming campaigns. Thanks to its equipment and flexibility, JT-60SA represents, therefore, the most interesting experiment to study NBI EPs in view of future ITER operations. The proposed project’s success will contribute to the modeling effort in view of the coming JT-60SA experimental campaigns and the study of ITER-relevant EP scenarios. Moreover, it will provide skills in the use of a state-of-the-art parallelized numerical code widely used for EP fusion studies, in the physics of plasma EPs and their non-Maxwellian distribution functions, and in the peculiar characteristics of the NBI-generated EP population with their beneficial effects on fusion-relevant plasmas.
Previous experience (if necessary): fusion plasma physics courses, basic programming skills (Python)
Tesi assegnata a: Tainam Mazouz
RFX Supervisor: R. Cavazzana, M. Fadone
Academic supervisor: M. Zuin
Head of the RFX research group: M. Zuin
Leader of the RFX research program: L. Marrelli
Tipologia: Sperimentale, Teorica, Numerica, Compilativa
Abstract:
The behaviour of the plasmas used for Glow Discharge Conditioning (GDC) of “first wall” components, despite being widely applied in almost every fusion experiment, still lacks the full reproducibility and reliability required for the process. To study and clarify the mechanisms involved in the processes of this type of plasma and its interaction with materials and components, the FRACTAL experiment was set up at Consorzio RFX. The thesis work will primarily focus on measuring discharge characteristics under different operational conditions using Langmuir probes, followed by the analysis of the collected data to clarify the key parameters needed to identify the most stable and effective glow plasma regimes.
Previous experience: good skill in data analysis using interactive programming languages like python, Matlab or IDL are preferred.
Tesi assegnata a: Mirza Rameez
Proponente/Relatore RFX: M. Zuin
Relatore Accademico: M. Giacomin
Capogruppo RFX: M. Zuin
Responsabile di Programma: L. Marrelli
Tipologia: Sperimentale, Teorica, Numerica, Compilativa
Abstract:
The thesis aims at the investigation of the excitation of Langmuir waves in a small-scale experiment where a weakly ionized plasma is produced in the presence of an inhomogeneous magnetic field. The aim is to replicate the observation obtained by means of satellites (such as Parker Solar Probe and Solar Orbiter) of Langmuir waves destabilization inside the so-called magnetic holes (region of space where magnetic field intensity is significantly reduced) within the Solar wind plasmas.
Langmuir waves, which are typically strongly damped in laboratory plasmas due to kinetic effects (Landau damping mechanism), will be induced through the excitation of the two-stream instability by using a suprathermal electron beam propagating in a background plasma. The role of an externally applied spatially inhomogeneous magnetic nozzle in determining the dispersion properties of the waves will be investigated in a variety of experimental conditions also in terms of background gas (He, Ar and H), pressure, and ionization fraction.
Due to the low ionization fraction, the dynamics of the plasma under investigation is dominated by electron-neutral collisions, whose characteristic frequency is order of magnitude lower than those associated with Langmuir waves. This makes the plasma realized in the laboratory a good model for the collisionless plasma of the Solar wind.
The thesis work will include an experimental activity, devoted to the preparation of the device and of the diagnostic system, to data acquisition and analysis, as well as a numerical activity focused on Eulerian simulations of the Vlasov-Poisson equations for the analysis of beam-plasma interaction, the associated generation of electrostatic waves and their propagation in linear and nonlinear regimes.
The experimental activity will be performed inside the laboratories of Consorzio RFX, Area CNR, Padova.
Tesi assegnata a: Oscar Bradman Lemonidis
Proponente/Relatore RFX: P. Vincenzi, C. De Piccoli, T. Bolzonella
Relatore accademico: Prof. Faganello ( Aix- Marseille)
Capogruppo RFX: D. Terranova
Responsabile di Programma RFX: T. Bolzonella
Tipologia: Sperimentale, Teorica, Numerica, Compilativa
Abstract:
Energetic particles (EPs) are the key ingredient of a successful nuclear fusion plasma, where fusion alpha particles will dominate plasma dynamics. In present-day devices and next-step experimental reactors, energetic particles from Neutral Beam Injection (NBI) continue to play a crucial role in heating plasmas to fusion-relevant temperatures. All EPs have in common a non-Maxwellian distribution inside the plasma, which determines physics processes such as the transfer of energy to the thermal population by Coulomb collisions, i.e. the slowing-down process. In the case of NBI, it is also possible to induce plasma current and inject torque to affect plasma rotation. These properties are strongly connected to the EP distribution function that determines the interaction with the background plasma. Ad-hoc numerical models have been developed to solve the Fokker-Planck equation that describes EP dynamics. Consorzio RFX is a leading institute in developing high-energy NBI systems, and robust numerical activity is being carried out to predict the effect of such beams on fusion plasmas.
We propose this master’s thesis to a student interested in understanding the physics of EPs in fusion plasma by performing numerical simulations with state-of-the-art codes. In particular, the student will be guided by intuitive tutorials to familiarize with the ASCOT suite of codes, a Monte-Carlo, orbit-following model widely used in the fusion community to simulate EPs in plasmas. The student will then apply ASCOT to simulate the behaviour of NBI EPs in fusion plasmas, predicting the beam-plasma interaction in international experiments such as the Divertor Tokamak Test (DTT) facility in construction in Italy or the Japanese-European tokamak JT-60SA, which will start the first NBI operations soon. The interest of these tokamaks is the high injection energy of beam particles relevant for reactor plasmas such as ITER. The student will finally discuss how different plasmas and beam characteristics will affect the interplay between EPs and background plasmas in fusion devices.
Competenze necessarie per svolgere con successo la tesi: ASCOT5 has an extensive pre- and post-processing library written in Python. We recommend a basic knowledge of the Python programming language, though knowledge of a similar language can also be sufficient since, initially, we will not require particular programming skills. Fusion plasma physics courses are recommended.
Tesi assegnata a: Tainam Mazouz
Proponente/Relatore RFX: M. Zuin
Relatore Accademico: M. Giacomin
Capogruppo RFX: M. Zuin
Responsabile di Programma: L. Marrelli
Tipologia: Sperimentale, Teorica, Numerica, Compilativa
Abstract:
The thesis aims at the investigation of the excitation of Langmuir waves in a small-scale experiment where a weakly ionized plasma is produced in the presence of an inhomogeneous magnetic field. The aim is to replicate the observation obtained by means of satellites (such as Parker Solar Probe and Solar Orbiter) of Langmuir waves destabilization inside the so-called magnetic holes (region of space where magnetic field intensity is significantly reduced) within the Solar wind plasmas.
Langmuir waves, which are typically strongly damped in laboratory plasmas due to kinetic effects (Landau damping mechanism), will be induced through the excitation of the two-stream instability by using a suprathermal electron beam propagating in a background plasma. The role of an externally applied spatially inhomogeneous magnetic nozzle in determining the dispersion properties of the waves will be investigated in a variety of experimental conditions also in terms of background gas (He, Ar and H), pressure, and ionization fraction.
Due to the low ionization fraction, the dynamics of the plasma under investigation is dominated by electron-neutral collisions, whose characteristic frequency is order of magnitude lower than those associated with Langmuir waves. This makes the plasma realized in the laboratory a good model for the collisionless plasma of the Solar wind.
The thesis work will include an experimental activity, devoted to the preparation of the device and of the diagnostic system, to data acquisition and analysis, as well as a numerical activity focused on Eulerian simulations of the Vlasov-Poisson equations for the analysis of beam-plasma interaction, the associated generation of electrostatic waves and their propagation in linear and nonlinear regimes. The experimental activity will be performed inside the laboratories of Consorzio RFX, Area CNR, Padova
Tesi assegnata a: Oscar Bradman Lemonidis
RFX Supervisor: M. Giacomin
Academic supervisor: M. Giacomin
Head of the RFX research group: M. Zuin
Leader of the RFX research program: L. Marrelli
Tipologia: Modelling, Teorica, Numerica, Compilativa
Abstract:
Plasma turbulence plays a critical role in magnetic confinement fusion devices, regulating fusion performance and heat flux to the wall. Plasma turbulence is often investigated by means of complex and challenging three-dimensional simulations. While significant progress has been achieved in the past years
on understanding plasma turbulence in tokamaks and stellarators, turbulence in the boundary of reversed field pinch (RFP) configurations remain largely unexplored. On the other hand, RFPs provide an ideal environment to investigate the effect of magnetic chaoticity on turbulence, which is an extremely important topic in magnetic confinement fusion. A recent upgrade to the GBS code (https://gbs.epfl.ch/) has enabled the possibility to carry out the first-ever boundary turbulence simulations in RFP configurations. During the internship, which will take place at Consorzio RFX in Padua, the student will perform simulations of a reduced RFX-mod geometry with the aim of assessing the computational
feasibility of full-scale RFX-mod simulations, identifying the main numerical issues and testing possible
solutions, and providing a first insight on plasma turbulence in the reversal region of a RFP configuration.
The simulations will be performed on the largest high performance computing facilities in Europe. During the internship, the student may also collaborate with the GBS development team at EFPL, Lausanne, Switzerland.
Tesi assegnata a: Tommaso Simionato
Proponente/Relatore RFX: L. Pigatto
Relatore accademico: M. Giacomin
Capogruppo RFX: D. Terranova
Responsabile di Programma RFX: T. Bolzonella
Tipologia: Numerica, Teorica, Modellistica, Compilativa
Abstract:
Global stability of a Tokamak plasma, in the framework of ideal MHD, roughly depends on the toroidal current density and pressure gradients. The same ingredients play a crucial role in the performance (confinement, fusion production) of the same plasma, with desirable configurations often being close to stability thresholds. Assessing this proximity to unstable regimes is important during the design of operational points in future experiments.
Auxiliary heating systems, such as Neutral Beam Injectors (NBI), introduce particle populations with different energies with respect to the plasma thermal bulk. These so-called hot particles can trigger instabilities themselves as well as interact with global ideal MHD modes. When non-ideal contributions come into play, extended MHD models need to be used and validity of such models needs to be considered. In this work a drift-kinetic MHD hybrid model will be applied, through the linear stability code MARS-K, to assess the global stability of a NBI heated plasma. In this peculiar case the neutral beams provide most of the plasma pressure and are designed to achieve beam-target fusion. The thesis will start with studying the beam characteristics and evaluating the applicable physics model, implementing then simulations with increasing complexity.
Tesi assegnata a: Maria Chiara Picchini
RFX Supervisor: U. Giuliani
Academic supervisor: G. Zollino
Head of the RFX research group: A. Maistrello
Leader of the RFX research program: S. Peruzzo
Tipologia: Modelling, Teorica, Numerica, Compilativa
Abstract:
The thesis work will focus on the development and use of the model COMESE to produce energy scenarios for the analyses of a decarbonized power system. The renewable potential for solar and wind power generators in the Italian territory will be taken into account in order to define the better exploitable mix of these sources, with a high detail with respect to different generators models for both energy sources. This approach aims at assessing which is the best trade-off between the efficiency of the single generators and their land-occupation, with a total system-costs perspective.
Previous experience: MATLAB basic skills
Tesi assegnata a: Martina Canali
RFX Supervisor: D. Bonfiglio, L. Spinicci
Academic supervisor: M. Passoni – Polimi.
Head of the RFX research group: S. Cappello
Leader of the RFX research program: L. Marrelli
Tipologia: Modelling, Teorica, Numerica, Compilativa
Abstract:
This project aims at a substantial enlargement of the predictive capabilities of the three-dimensional magneto-hydrodynamic (3D MHD) nonlinear code SpeCyl. In continuation of recent PhD work, which led to the modelling of a thin resistive wall at the plasma interface, with self-consistent flow and magnetic field conditions, the candidate will be asked to contribute to the progressive improvement of SpeCyl’s boundary conditions through the implementation of a second passive shell at a finite distance from the plasma. Together with the future further development of control coils, this project is part of a process of increasing realism in the nonlinear modelling of the RFX-mod experiment, which is also useful to effectively anticipate the dynamics in the forthcoming configuration, RFX-mod2.
The candidate will therefore be required to carry out analytical/numerical work to determine and implement the new double-wall boundary conditions, in full consistency with the MHD model already present in the code. The correctness of the implementation will then be verified through a benchmark of the new double-wall module against analytical models of the MHD linear stability theory.
Further numerical development work could be evaluated, if the project timing will allow for it. The final version of the code, produced by the candidate, will be used in predictive modelling studies of MHD dynamics, investigating important plasma instabilities such as quasi-laminar states of the reversed-field pinch configuration.
Previous experience (if necessary): n.a.
Assegnata a: Francesco Galeazzi
RFX Supervisor: M. Veranda, F. Sattin
Academic supervisor: V. Russo (Polimi)
Head of the RFX research group: S. Cappello
Leader of the RFX research program: L. Marrelli
Tipologia: Modelling, Teorica, Numerica, Compilativa
Abstract:
The project involves an implementation of the ion heating model by low-frequency waves, as described in the paper [F. Sattin, D.F. Escande, Physical Review E, vol. 107, art. 065201 (2023)]. The candidate is asked to specialize the model to the geometry of a Reverse Field Pinch device during magnetic reconnections. Numerical quantities involved (amplitude and frequency spectrum of excited Alfvén waves, scale length of the reconnecting layer, …) will be extracted from a database of numerical simulations performed with the visco-resistive nonlinear MHD code SPECYL. The final output is a rate of ion heating, to be compared with expected levels. In particular, numerical plasma configurations will be tailored to published MST data regarding different ion heating in order to reproduce experimental findings/measurements
Tesi assegnata a: Lorenzo Martinelli
RFX Supervisor: B. Segalini
Academic supervisor: M. Giacomin
Head of the RFX research group: M. Zuin
Leader of the RFX research program: D. Marcuzzi
Tipologia: Sperimentale, Teorica, Modellistica, Compilativa
Abstract:
In negative ion sources such as SPIDER, surface processes of negative ion production are enhanced by Caesium evaporation in the plasma chamber. Tracking the Cs particle trajectories and predicting their distribution on the source walls and grids, hence, is a key task to optimise H- extraction and acceleration.
With this thesis work, the student will learn to use a 3D particle tracing Montecarlo code aimed at computing particle trajectories, taking into account many collisional processes, the influence of magnetic and electric fields and plasma interactions. The student will adapt the code to Caesium related processes, and study the influence of the main plasma parameters and source conditions on its distribution on the source surfaces, correlating it to negative ion production.
Tesi assegnata a: Eleonora Degan
Proponente/Relatore RFX: G. Palumbo
Relatore accademico: D. Della Sega
Capogruppo RFX: M. Valente
Responsabile di Programma RFX: L. Marrelli
Tipologia: Sperimentale, Teorica, Numerica, Compilativa
Abstract:
The recently developed Fusion-Fission Hybrid Reactor (FFHR) proposal represents an innovative approach to nuclear fusion, integrating a Reversed Field Pinch (RFP) reactor with sub-critical fission modules. This concept, aimed mainly at tritium breeding, requires a more deepen study of reactor materials due to the implementation of superconducting magnetizing and equilibrium coils. A key challenge is mitigating the high-energy neutron flux from the plasma to prevent performance degradation of superconducting components, while ensuring steady efficient operation of the in-core components.
This study focuses on the selection and optimization of blanket and core materials, beginning with an investigation of the elements reported in the literature for neutron attenuation, taking into account their characteristics and performance.
A numerical model based on a Monte Carlo approach will be developed to assess neutron shielding requirements while balancing thermal and electromagnetic constraints. Through an iterative process of material proposal, simulation, and validation, the research must ensure compliance with shielding, structural and operational limitations.
The outcomes will contribute to enhancing the feasibility of FFHR systems by optimizing neutron shielding strategies for superconducting fusion devices.
Competenze necessarie per svolgere con successo la tesi: Basic understanding of the Reversed Field Pinch (RFP) machine design and its key components. Experience in numerical modeling using Monte Carlo methods and statistical analysis. Proficiency in MATLAB programming language, with a focus on simulation and data processing techniques
Tesi assegnata a: Antonio Rigato
Relatore RFX: D. Abate, L. Marrelli
Relatore Accademico: N. Marconato
Tipologia: Modelling, Teorica, Numerica, Compilativa
Abstract:
The present thesis focuses on the electromagnetic modelling and design of a multi gap solution for the passive stabilizing shell of magnetic confinement fusion experiments in reversed field pinch (RFP) configurations. The modelling activity aims at studying the effects of multiple gaps in the passive stabilizing shell surrounding a RFP plasma, by means of electromagnetic models with different level of complexity. The effect of different number and shape of gaps will be investigated in terms of plasma stability and engineering complexity, by developing dedicated numerical codes based on FEM/BEM approach. The selected multi gap solution will then be analysed in terms of engineering design and manufacturing processes.
Competenze richieste: Elettrotecnica, Elettrotecnica computazionale, conoscenza base di linguaggi di programmazione e ambienti di sviluppo (es.: COMSOL, ANSYS, MATLAB)
Tesi assegnata a: Christian Garlani