Tesi in corso di svolgimento

Tesi di laurea assegnate nel 2023

Tesi Triennali di Fisica

Feasibility study of a 4D emittance measurement for the SPIDER ion source

Relatore RFX: C. Poggi

Relatore accademico: G. Serianni

Capogruppo RFX: M. Zuin

Tipologia: Sperimentale, Teorica,   Numerica, Compilativa

Abstract:

SPIDER is the prototype of ITER heating neutral beams. It aims at producinig up to 50A of negative hydrogen ions, divided in 1280 beamlets, and accelerate them up to 100keV. During its first years of operation, the optics of SPIDER beamlets was investigated using several diagnostics, such as optical cameras and thermography measuring in the position space (namely x and y coordinates), beam emission spectroscopy measuring one component of the particle velocities (vx or vy) and Allison emittance scanner, providing a simultaneous measurement of a position and a velocity component (x and vx). This last diagnostic consists of a slit selecting the beam particles, a pair of metallic plates symmetric and parallel to the slit and then a second slit, aligned with the first one. An electric field is generated between the plates, so that only the particles with a well-defined transverse entrance velocity at the first slit can reach the second one and be collected at the Faraday cup. By moving the detector in front of the beam (in the direction perpendicular to the slit width) and by sweeping the voltage between the plates it is possible to determine the 2D transverse phase-space of the particle beam. This diagnostic provided a valuable insight into the phase-space structure of SPIDER beamlets, being able to identify the tails of the beamlets phase-space distribution.

During SPIDER last campaigns only a few beamlets were operated, allowing an easier investigation of the single beamlet optics. However, in view of future SPIDER multi-beamlet operation, the emittance scanner needs to be redesigned. For this reason, an upgraded version of the scanner is under development, with the goal of performing a direct measurement of x, vx, y and vy coordinates. Two additional metallic plates should be added to measure in the other transverse velocity direction, and a new Faraday cup, adequate to the expected currents. The aim of this thesis is to verify the feasibility of this approach using numerical simulations of a scanner with a double set of parallel plates, to dimension the various components of the detector, and to design and test the new current detector in a dedicated ion source.

Competenze necessarie per svolgere con successo la tesi:

Assegnata a Fabrizio Lovisetti

Design and application of diagnostic systems for an ICP plasma discharge

Proponente/Relatore RFX: I. Mario

Relatore accademico: G. Serianni

Capogruppo RFX: M. Zuin

Responsabile di Programma RFX: V. Toigo

Tipologia: Sperimentale, Teorica, Numerica, Compilativa

Abstract:

Neutral Beam Injectors for fusion applications require the production and acceleration of negative ions. Negative ion sources are based on the inductive coupling of electromagnetic waves to a hydrogen plasma (ICP discharge). To optimise the design of such sources, and particularly of the RF driver (the region where the plasma is generated), the MINION experiment is under design at Consorzio RFX and will start operations in 2023. The main diagnostic systems to measure the plasma features are emission spectroscopy and Langmuir probes.

The proposed activity consists in:

  1. Design of the diagnostic systems
  2. Characterisation 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 might include simple simulations of the plasma features.

Competenze necessarie per svolgere con successo la tesi:

Tesi assegnata a:William Henri Vienne

Setting Up of SPIDER New Interference Filters Diagnostics

Proponente/Relatore RFX: B. Zaniol

Relatore accademico: G. Serianni

Capogruppo RFX: L. Carraro

Responsabile di Programma RFX: V. Toigo

Tipologia: Sperimentale, Teorica, Numerica, Compilativa

Abstract:

SPIDER is the prototype of negative ion source for ITER neutral beams under development at Consorzio RFX, Padova. To help optimising the negative ion production, SPIDER is equipped with a full set of optical diagnostics that analyse the electromagnetic radiation in the wavelength range between 300 nm and 1000 nm, spontaneously emitted by the plasma inside the source. For the restart of SPIDER experimental operations at the beginning of 2024, a new diagnostic based on interference filters and photomultipliers will be added. Aim of the thesis is to assemble this new diagnostic and to perform all the preliminary tests in order to verify its correct functioning and its performances. It will be then coupled to SPIDER and intensity calibrated. The new measurements will be checked and validated by comparison with spectrometer signals.

Tesi assegnata a: Sergio Monopoli

Evaluation of the plasma parameters by means of emission spectroscopy in a new ICP discharge experiment at the Neutral Beam Test Facility

Proponente/Relatore RFX: I. Mario

Relatore Accademico: G. Serianni

Capogruppo: L. Carraro

Responsabile di Programma: D. Marcuzzi

Tipologia: Sperimentale, Teorica, Numerica, Compilativa

Abstract:

Neutral Beam Injectors for fusion applications require the production and acceleration of negative ions. Negative ion sources are based on the inductive coupling of electromagnetic waves to a hydrogen plasma (ICP discharge). To optimise the design of such sources, and particularly of the RF driver (the region where the plasma is generated), the MINION experiment was designed and realised at Consorzio RFX.

The start-up phase of the experiment has already started and first measurements campaign is planned for the end of November 2023.

Within the first MINION campaign, measurements of hydrogen plasma emission with emission spectroscopy system will be performed, with the aim to characterize the plasma parameters in the region of the ion source where the ICP plasma is ignited. The plasma parameters will be evaluated with the assistance of collisional radiative models. Plasma parameter evaluation will be repeated under different operational conditions (e.g. RF power, pressure, plasma electrode bias; possibly magnetic configuration).

The student will directly contribute to data collection and data interpretation. S/He will participate in the design and execution of the experiments.

The student is expected to improve his/her knowledge on ICP plasmas and spectroscopy-based diagnostics techniques.

Tesi assegnata a: Martina Tesser

Plasma velocity during magnetic reconnection

Proponente/Relatore RFX: M. Veranda

Relatore accademico: T. Bolzonella

Capogruppo RFX: S. Cappello

Responsabile di Programma RFX: L. Marrelli

Tipologia: Sperimentale, Teorica, Numerica, Compilativa

Abstract:

Magnetic reconnection is a ubiquitous phenomenon in nature, both in space and in laboratory hot plasmas, where it occurs continuously. It is the change of topology in magnetic field lines confining hot plasmas and, in experiments for the production of energy using nuclear fusion, it is associated with the presence of instabilities of the confining magnetic field, and with a rapid release of the plasma’s magnetic energy, which converts into the kinetic energy of its constituent particles.

This thesis deals with the main models to describe reconnection: the student learns the theory of reconnection using the magnetohydrodynamic model, and then focuses on the behavior of the velocity field. He will analyze the results of the model used to describe plasmas, and will deal with graphic visualization of the velocity field: this will help understanding better the dynamics of magnetic reconnection. The work will take place at the theory and advanced simulation group at Consorzio RFX.

Competenze necessarie per svolgere con successo la tesi: Basic knowledge of plasma physics

Tesi assegnata a: Tommaso Simionato

Tesi Triennali di Ingegneria

Investigation of materials exposed to ultrapure water in experimental fusion reactors

Relatore RFX: C. Cavallini

Relatore accademico: P. Sonato

Capogruppo RFX: A. Rizzolo

Responsabile di Programma RFX: V. Toigo

Abstract:

Water is the most common fluid used to remove the heat produced in a research fusion reactor.

The Neutral Beam Test Facility (NBTF) at Consorzio RFX (Padua, Italy) host two test beds: MITICA, the  1 MeV full-scale prototype of the ITER NBI source, and SPIDER, the low energy 100 keV ITER full-size Ion Source.

SPIDER and MITICA experiments are actively cooled by Ultrapure Water (UPW) to electrically insulate in-vessel components that are polarized to high voltage levels. Water circulating in pipes reacts with inner channel surfaces made of copper, copper alloys and stainless steel, causing a water resistivity degradation. Maintaining high quality water is the most important factor in preventing degradation. . Depending on the material and the water composition, several chemical reactions can occur to form soluble or insoluble compounds. General corrosion of copper and copper alloys in ultrapure water will be experimentally investigated, using metal release test. During the thesis, you will learn how to manage ultrapure water, discover the CuCrZr alloy, test different material exposed to the same environmental condition and take part of the ITER project by working at the NBTF facility!

Competenze necessarie per svolgere con successo la tesi:

Assegnata a Sara Zampieri

Measurement and control of DC current component in the MITICA Acceleration Grid Power Supply inverter system

RFX Supervisor: L. Zanotto

Academic supervisor: P. Bettini

Tipologia: Sperimentale, Teorica, Numerica, Compilativa

Abstract:

The thesis deals with the measurement of the dc current component in the inverters of the MITICA Acceleration Grid Power Supply. After a literature survey on the subject of dc current generation and control on three phase inverter systems supplying power transformers, the student shall analyze the precision of the present current transducers andassessthe use of new transducers or methods to estimate the dc current component supplied by the inverters in different load conditions and transients. The thesiscan be completed by experimental measurements on a dummy load aimed at testing the new transducers or methods and reviewing the operation of the existing dc current controller, with focus on possible strategies for improvement.

Tesi assegnata a: Andrea Magnabosco

Negative Ion Beam profile estimation on STRIKE calorimeter by means of Newton’s Method

Proponente/Relatore RFX: R. Delogu

Relatore accademico: M. Margoni

Capogruppo RFX: G. Taliercio

Responsabile di Programma RFX: V. Toigo

Tipologia: Sperimentale, Teorica, Numerica, Compilativa

Abstract:

STRIKE (Short-Time Retractable Instrumented Kalorimeter Experiment) is an instrumented calorimeter; it has been designed with the main purpose of characterizing the negative ion beam produced in SPIDER (Source for Production of Ion of Deuterium Extracted from Radio Frequency plasma) in terms of beam uniformity and divergence, during short pulse operations. STRIKE is made of 16 1D Carbon Fiber Carbon composite (CFC) tiles, intercepting the whole beam and observed on the rear side by infrared (IR) cameras.

The whole beam consists of 1280 beamlets, 80 for each tile, and the profile of a beamlet can be well approximated by a 2D Gaussian curve. Furthermore, due to the beamlet configuration and the heat transfer condition, some of the beamlets could overlap.The aim of this thesis is to determine, by means of Newton’s method, the parameters (amplitude, Half Width at Half Maximum, position of the Gaussian 2D profile) of all beamlets, in order to have a real-time tool to be used during operation. Moreover, the method will be tested also for overlapping beamlets.

Competenze necessarie per svolgere con successo la tesi: basic programming, English language

Tesi assegnata a
: Eleonora Degan

Analysis and tests on breakdown high-frequency transients on SPIDER’s insulation transformer

Proponente/Relatore RFX: Mattia Dan

Relatore Accademico: Paolo Bettini

Capogruppo: Alberto Maistrello

Responsabile di Programma: Vanni Toigo

Tipologia: Sperimentale, Teorica, Numerica, Compilativa

Abstract:

SPIDER is the test-bed for the negative ion beam source of the ITER Heating Neutral Beam Injectors (NBI). The beam source is polarized up to – 96 kV for the beam acceleration, achieved through an electrostatic grid acceleration system. Similarly, the Ion Source and Extraction Power Supply (ISEPS) is polarized at the acceleration voltage, with an insulating transformer powering the system to ensure proper dc insulation between the primary and secondary circuits. A peculiarity of the high voltage system is the frequent occurrence of arc breakdowns between the acceleration grids due to the short gap required by the beam optics. These breakdowns happen due to the short gap required by the beam optics, leading to high-frequency voltage stresses on the interconnected power supply system. One component that can be subjected to high voltage stresses is ISEPS insulation transformer, in particular in its secondary circuit.

The purpose of this thesis is to analyze the breakdown transient conditions on the SPIDER insulation transformer: the student shall get a good comprehension of the fast transients subsequent to a breakdown, use circuital models to estimate the voltage stresses and conduct tests on the system at reduced medium voltage levels.

Tesi assegnata a: Daniele Fasolo

Caratterizzazione elettromagnetica delle sonde di campo magnetico locale ad alta frequenza per la macchina RFXmod2

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 for the electromagnetic characterization of high frequency pick up coils for magnetic measurements in the RFXmod2 experiment.

Competenze necessarie per svolgere con successo la tesi: Basic concepts of electrical engineering.

Tesi assegnata a: Alessandro Stefani

Categorizzazione di “segnali calcio” nelle piante in risposta a stimoli esterni

Proponente/Relatore RFX: A. Rigoni-Garola, V. Antoni

Relatore accademico: G. Serianni

Capogruppo RFX: C. Taliercio

Responsabile di Programma RFX: S. Peruzzo

Tipologia: Sperimentale, Teorica, Numerica, Compilativa

Abstract:

Lo ione calcio svolge un ruolo di segnalazione chiave nelle piante ed è coinvolto in un’ampia gamma di processi fisiologici quali la crescita, lo sviluppo e la risposta allo stress. Studi recenti hanno dimostrato che il trattamento con acqua attivata dal plasma (PAW) può portare ad un aumento dei livelli di calcio intracellulare nelle piante, che a sua volta attiva varie vie di segnalazione coinvolte nella crescita delle piante e nella tolleranza allo stress. Obiettivo della tesi è organizzare in un unico database i segnali calcio espressi da individui diversi della stessa specie botanica esposti a diverse PAW.  In particolare le diverse PAW corrisponderanno all’esposizione a  due diverse sorgenti di plasma ( torcia e scarica a barriera dielettrica) e per diversi  tempi di attivazione. Il database così ottenuto verrà successivamente analizzato  mediante un algoritmo di tipo machine learning così da poter rilevare le caratteristiche medie dei segnali calcio  che emergono dalla risposta dei singoli individui. L’intero lavoro di tesi sarà svolto in ambiente python e jupyter, mentre gli strumenti utilizzati saranno Pandas per la creazione del database di dati e TensorFlow o Pytorch per la definizione del modello di ML.

Competenze necessarie per svolgere con successo la tesi: Sono consigliate la conoscenza del linguaggio di programmazione python e una certa dimestichezza con l’ambiente GNU-linux

Tesi assegnata a: Ivan Brillo

Analysis of the data acquired by dual directional couplers installed in SPIDER experiment

RFX Supervisor: A. Maistrello

Academic supervisor: M. Margoni

Head of the RFX research group: A. Maistrello

Leader of the RFX research program: V. Toigo

Tipologia: Sperimentale, Teorica, Numerica, Compilativa

Abstract:

SPIDER is one of the experiment of the Neutral Beam Test Facility, dedicated to the development of the Heating Neutral Beam Injector for the ITER reactor [1]. It includes a plasma source and a multi-grid extraction system composed of plasma grid, extraction grid, and grounded grid. The plasma is generated inside the plasma source through a set of eight so-called ‘drivers’, each one including an RF antenna to transfer up to 100 kW to the plasma via inductive coupling. The drivers, connected in pairs, are supplied by a 200 kW tetrode-based RF oscillator operating at 1 MHz ± 100 kHz [2] [3].

During the past experimental campaigns, the voltamperometric output power measurement performed by the RF oscillators has demonstrated low accuracy and dependence on the load impedance. An additional measuring system based on dual directional couplers was therefore introduced and operated for more than 100 pulses.

The aim of the thesis is to analyse the data acquired by the dual directional couplers, to compute the active power delivered to the loads and to compare them with the original measurement method.

References:

Previous experience: Electrical engineering, energy transmission, fast Fourier transform, basic knowledge of Matlab or Python

Tesi assegnata a: Enrico Stura

Integrazione del modello circuitale equivalente dell’esperimento High Voltage Padova Test Facility

Proponente/Relatore RFX: N. Marconato, T. Patton

Relatore Accademico: N. Marconato
Capogruppo: M. Brombin

Responsabile di Programma: D. Marcuzzi

Tipologia: Modelling, Teorica, Numerica, Compilativa

Abstract:

Integrazione del modello circuitale della facility per isolamenti in alta tensione in vuoto HVPTF.

In particolare allo studente è richiesto:

  • L’upgrade del circuito equivalete di HVPTF aggiungendo un blocco RL non lineare per la transizione microscarica-arco;
  • valutare l’effetto delle componenti resistive (R e G) del blocco che modella il cavo di alimentazione;
  • eventualmente l’integrazione con il circuito interno del moltiplicatore di tensione Cockroft Walton;
  • analisi di sensibilità dello shunt HF per generare un diagramma banda-sensibilità, utilizzando parametri realistici ottenuti da una ricerca di mercato per selezionare i migliori componenti (con bassi parametri parassiti) per protezioni e resistori.

Tale proposta di tesi è un’occasione per lo studente di imparare ad usare software per la soluzione numerica di circuiti (PSIM e LTspice) e per conoscere varie applicazioni dell’elettrotecnica ai sistemi di misura e di alta tensione.

Competenze richieste: Teoria dei circuiti

Tesi assegnata a: Emanuele Frasson


The role of nuclear power in zero CO2 emission energy scenarios in Italy

Proponente/Relatore RFX: U. Giuliani

Relatore Accademico: G. Zollino

Capogruppo: A. Maistrello

Responsabile di Programma: S. Peruzzo

Tipologia: Modelling, 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 main sources of energy. The optimization of the system design under different cost assumption for the nuclear technology will allow to assess how, and to what extent, the penetration of nuclear energy varies as a function of its capital cost.

Competenze richieste: Conoscenza base di MATLAB / MATLAB basics

Tesi assegnata a: Aldi Bode

Mechanical and electrical integration of the DTT divertor in the vacuum vessel

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

Integrazione e Avviamento di Nuovi Componenti nell’Impianto di Raffreddamento di NBTF

Proponente/Relatore RFX: C. Cavallini

Capogruppo RFX: M. Valente

Responsabile di Programma: D. Marcuzzi

Relatore Accademico: P. Sonato

Tipologia: Sperimentale, Teorica, Numerica, Compilativa

Abstract:

NBTF (Neutral Beam Test Facility) è  un sito sperimentale localizzato a Padova, presso il Consorzio RFX, il cui scopo principale è la costruzione, prova e ottimizzazione del prototipo a scala reale degli HNB (Heating Neutral Beams) di ITER. NBTF comprende due esperimenti:

  1. SPIDER (Source for Productions of Ions of Deuterium Extracted from a Radio-frequency plasma): si tratta della sorgente a ioni negativi a dimensioni reali con estrazione a bassa tensione di 100 keV.
  2. MITICA (Megavolt ITER Injector and Concept Advancement): è il prototipo a scala reale per l’iniettore di fasci neutri per il riscaldamento di ITER che opera a piena potenza del fascio con tensioni fino a 1 MV.

L’impianto di raffreddamento di NBTF è stato studiato e disegnato per rimuovere fino a 70MW da entrambi gli esperimenti. L’impianto è caratterizzato da tre principali sistemi di raffreddamento:

  1. Circuiti Primari (PCs), che raffreddano direttamente i componenti di SPIDER e MITICA
  2. Circuiti Secondari (SCs) che raffreddano i primari
  3. Circuiti Terziari (TCs) che raffreddano i secondari scambiando calore con l’ambiente.

Acqua ultrapura è utilizzata come mezzo di raffreddamento per isolare componenti posti ad alte tensioni (fino a 1 MW). Fenomeni di corrosione-erosione sono stati osservati nei circuiti primari che raffreddano i sistemi di alimentazione. Nuovi componenti sono stati individuati e acquistati per implementare il monitoraggio e il controllo della conduttività, parametro principale nei circuiti di NBTF per la stima della qualità dell’acqua ultrapura.

Lo studente parteciperà attivamente alla prima installazione, messa in opera, utilizzo e caratterizzazione dei nuovi componenti. Inoltre si occuperà della comparazione dei nuovi risultati con quelli prima raccolti precedentemente alla loro installazione, sia per quanto riguarda il monitoraggio della conduttività sia per quanto riguarda la variazione delle performance idrauliche dell’impianto.

Tesi assegnata a: Alessandra Alberton

The role of photovoltaic power in zero CO2 emission energy scenarios in Italy.

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

Tesi Magistrali di Fisica

Modeling of ion heating by Alfvèn waves during magnetic reconnections in the RFP configuration

Proponente/Relatore RFX: M. Veranda

Relatore Accademico: F. Sattin

Capogruppo RFX: S. Cappello

Responsabile di Programma: 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 Alfvèn 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.  

Tesi assegnata a: Alessio Fabbian

Analysis of locked dynamics in JET

Proponente/Relatore RFX: Lidia Piron

Relatore accademico: L. Piron

Capogruppo RFX: D. Terranova

Responsabile di Programma RFX: T. Bolzonella

Tipologia: Sperimentale, Teorica, Numerica, Compilativa

Abstract:

Locked modes are MHD instabilities which can be present in magnetic fusion devices and are responsible of rotation braking, particle and energy confinement degradation, and can lead to plasma disruptions. Because of these deleterious effects, the dynamics of locked mode (triggering and its evolution) needs to be deeply investigated.

In this Thesis work, experiments performed in Work Package Tokamak Exploitation (WPTE) devices, which suffer from the presence of locked modes, will be analyzed utilizing data from multiple plasma diagnostics.

Competenze necessarie per svolgere con successo la tesi:

Tesi assegnata a: Alessandra Tonel

Investigation on the relation between MHD turbulence and electron acceleration in Reversed Field Pinch plasmas

RFX Supervisor: N. Vianello

Academic supervisor: G. Carraro

Head of the RFX research group: M. Zuin

Leader of the RFX research program: L. Marrelli

Tipologia: Sperimentale, Teorica, Numerica, Compilativa

Abstract:

The thesis will investigate the process of electron acceleration in magnetically confined plasmas and its relation with electrostatic and magnetic turbulence. In particular will perform an experimental investigation on data collected in a Reversed Field Pinch plasmas, data obtained by insertable probes combining Langmuir probes, magnetic pick-up coils and Electron energy analyzer (EEA). The analysis will be performed at different temporal scales to verify eventually if turbulence energy cascade has any influence on the signal collected by the EEA being this proportional to electron energy. Analysis will include advanced statistical tools, including wavelet transform, waiting times and Probability distribution functions. The collected information will be compared to similar statistical analysis performed on the outcome of numerical simulations, based on Vlasov code obtained in condition closed to the explored experimental regime.

Tesi assegnata a: Monia Calcagno

Towards global turbulence simulations of reversed field pinch configurations

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

Development of a Machine Learning Algorithm for Tomography reconstructions in RFX-mod

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

Tesi Magistrali di Ingegneria

Negative Ion Beam profile estimation on STRIKE calorimeter by means of Machine Learning techniques

RFX Supervisor: R. Delogu

Academic Supervisor: N. Marconato

Capogruppo RFX: Taliercio

Responsabile di Programma RFX: V. Toigo

Tipologia: Sperimentale, Teorica, Numerica, Compilativa

Abstract:

STRIKE (Short-Time Retractable Instrumented Kalorimeter Experiment) is an instrumented calorimeter; it has been designed with the main purpose of characterizing the negative ion beam produced in SPIDER (Source for Production of Ion of Deuterium Extracted from Radio Frequency plasma) in terms of beam uniformity and divergence, during short pulse operations. STRIKE is made of 16 1D Carbon Fiber Carbon composite (CFC) tiles, intercepting the whole beam and observed on the rear side by infrared (IR) cameras.The whole beam consists of 1280 beamlets, 80 for each tile, and the profile of a beamlet can be well approximated by a 2D Gaussian curve. Furthermore, due to the beamlet configuration and the heat transfer condition, some of the beamlets could overlap.The aim of this thesis is to determine, by means of machine learning techniques, the parameters (amplitude, Half Width at Half Maximum, position of the Gaussian 2D profile) of all beamlets, in order to have a real-time tool to be used during operation. Moreover, where possible, deconvolution will have to be applied to the overlapping beamlets.

Competenze necessarie per svolgere con successo la tesi: basic programming, English language

Tesi assegnata a: Kenji Urazaki Junior

Investigation on the relation between MHD turbulence and electron acceleration in Reversed Field Pinch plasmas

RFX Supervisor: N. Vianello

Academic supervisor: G. Carraro

Head of the RFX research group: M. Zuin

Leader of the RFX research program: L. Marrelli

Tipologia: Sperimentale, Teorica, Numerica, Compilativa

Abstract:

The thesis will investigate the process of electron acceleration in magnetically confined plasmas and its relation with electrostatic and magnetic turbulence. In particular will perform an experimental investigation on data collected in a Reversed Field Pinch plasmas, data obtained by insertable probes combining Langmuir probes, magnetic pick-up coils and Electron energy analyzer (EEA). The analysis will be performed at different temporal scales to verify eventually if turbulence energy cascade has any influence on the signal collected by the EEA being this proportional to electron energy. Analysis will include advanced statistical tools, including wavelet transform, waiting times and Probability distribution functions. The collected information will be compared to similar statistical analysis performed on the outcome of numerical simulations, based on Vlasov code obtained in condition closed to the explored experimental regime.

Tesi assegnata a: Monia Calcagno

Design and implementation of electronic control unit of a DCCT sensor for beam current measurement of the SPIDER experiment

Proponente/Relatore RFX: N.Marconato

Relatore accademico: N. Marconato

Capogruppo RFX: M. Brombin

Responsabile di Programma RFX: V. Toigo

Tipologia: Sperimentale, Teorica, Numerica, Compilativa

Abstract:

L’esperimento SPIDER (https://www.igi.cnr.it/ricerca/negative-ion-neutral-beam-injection/spider/i-componenti-di-spider/) è in shut-down fino a dicembre 2022 per le riparazioni, le modifiche e i miglioramenti derivanti dall’esperienza fatta nei primi anni di funzionamento dal 2018 ad oggi.

Tra questi upgrades è prevista l’installazione della diagnostica detta “Beamlet Group Current Monitor” (BGCM) per la misura della corrente del fascio di particelle relativa a ciascuno dei 16 gruppi di aperture (beamlet groups) delle griglie di accelerazione. È necessario pertanto progettare un sensore di corrente in grado di misurare la corrente del fascio in uscita dalla griglia di terra per ciascuno dei 16 bealmlet groups. I 16 segnali di corrente derivanti da ciascun sensore daranno la misura della totale corrente di fascio, permettendo inoltre una valutazione dell’uniformità dello stesso.

Principali requisiti del sensore di corrente sono i seguenti:

•           Misura sia della componente DC, sia della componente ad alta frequenza (decine di kHz);

•           Operazione in alto vuoto (10-6 mbar);

•           Resistenza a carichi termici non trascurabili;

•           Elevata risoluzione e precisione in un range di correnti compreso tra 100 mA e 3 A;

•           Immunità a campi magnetici DC esterni;

•           Immunità alla componente a radiofrequenza di 1MHz della corrente del fascio;

•           Immunità a breakdown elettrici

•           Compatibilità meccanica con gli spazi disponibili davanti a ciascun beamlet group.

La tecnologia dei cosiddetti Direct Current Current Transformer (DCCT) è ritenuta essere la più promettente per questo tipo di sensori di corrente, da un punto di vista di sensibilità, robustezza ed immunità ai disturbi. La tesi proposta si pone all’interno delle attività necessarie allo sviluppo di un sensore che adotti questa tecnologia per il caso specifico di SPIDER. Allo studente è richiesto il supporto per la determinazione dei migliori componenti elettronici adatti alla realizzazione del sistema di alimentazione e controllo del sensore stesso e la sua successiva realizzazione. La tesi prevede una prima fase di ricerca per la determinazione delle migliori tecnologie e una seconda fase implementativa, con il supporto di un nostro tecnico elettronico.

Competenze necessarie per svolgere con successo la tesi: Basic concepts of electrical engineering. Fair knowledge of the English language. Electronics and control theory is welcome

Tesi assegnata a: Samuele Bisinella

Optimal use of national renewable resources in a decarbonized power system

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

Optimization of the storage systems fleet in decarbonized energy scenarios

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 an optimized storage systems fleet. Energy storage can be achieved with several technologies; each one characterized by different costs, possibly with relevant differences between rated power costs and rated capacity costs. An optimal storage systems fleet must be designed by taking into account the optimal share for each technology and the optimal storage duration (the ratio between rated capacity and rated power) for each one of them.

Previous experience: MATLAB basic skills

Tesi assegnata a: Simone Boso

Development of an integrated polarization, conditioning and acquisition system for large Langmuir probe arrays in cold plasmas

RFX Supervisor: R. Cavazzana

Academic supervisor: N. Marconato

Head of the RFX research group: M. Brombin

Leader of the RFX research program: D. Marcuzzi

Tipologia: Sperimentale, Teorica, Numerica, Compilativa

Abstract:

Langmuir probes are electrodes immersed in a plasma, used to obtain the measurement of plasma density and temperature from their current-voltage characteristic. The measurement need to be appropriately tuned for the specific situation – e.g. the sensitivity of the current measure spans from µA to hundreds of mA depending on the type of plasma, and the exciting voltage must be appropriately set to obtain usable data, while avoiding possible probe damage. While this constrains can be easily handled in the case of single probe a manually operated, they become quite a challenge for an automated system composed by hundreds of probes. The aim of the thesis to collaborate to the development of the integrated system for the MITICA experiment, facing the problem of probe polarization control, signal conditioning and data acquisition, by integrating state of the art isolated ADC converters, power switching controllers and FPGAs.

Previous experience: basic knowledge of Spice and use of Matlab or Python for data analysis are prefereed.

Tesi assegnata a: Mattia Bevilacqua

RFX-mod2 Pulse Discharge Cleaning: review of the design and modeling

Proponente/Relatore RFX: F. Santoro

Relatore accademico: P. Bettini / N. Marconato
Capogruppo RFX: A. Maistrello

Responsabile di Programma RFX: L. Marrelli

Tipologia: Sperimentale, Teorica, Numerica, Compilativa

Abstract:

The Pulse Discharge Cleaning system (PDC) is part of the RFX-mod2 experiment and is designed to clean the inner wall of the plasma chamber by producing repetitive pulses with a low plasma current value around 50 kA and a toroidal field of about 50 mT. To this purpose, an articulated set of Power Supply system, with different features and current and voltage ratings were designed and manufactured in the early 2000. Now, a revamping of the system is in progress in view of the restarting of the RFX-mod2 experimental campaigns.

The thesis is focused on the understanding of the PDC design and operation; the verification and completion of the electrical models already developed; participation in experimental tests; analysis of relevant results and validation of models against the tests data can be part of the thesis in dependence of the tests schedule.

Competenze necessarie per svolgere con successo la tesi: Basic concepts of electrical engineering and power electronics, MATLAB or Python, Simulink.

Tesi assegnata a: Matteo Faoro

Modelling low-q tokamak equilibria for RFX-mod2 experiment

Proponente/Relatore RFX: D. Abate

Relatore Accademico: A. Cenedese

Capogruppo: M. Brombin

Responsabile di Programma: L.Marrelli  

Tipologia: Modelling, Teorica, Numerica, Compilativa

Abstract:

In RFX-mod2, a variety of divertor configurations will be possible including standard upper single null (USN) but with negative triangularity. The presence of an insertable polarized electrode in the lower part of the machine would allow to investigate both L-mode and H-mode regimes. Moreover, the exploration of improved confinement regime other than H-mode such as negative triangularity tokamak but at low-q regime. This is a unique contribution that can be made in RFX-mod2 thanks to the 192 active saddle coils covering the whole torus and able to actively control the plasma magnetohydrodynamic instabilities.

The thesis aims to define low-q plasma equilibria for the future RFX-mod2 experimental activity. In particular, upper single null plasmas – with both positive and negative triangularity – will be defined in terms of shape conditions and plasma equilibrium parameters. By acting on total plasma current and plasma current density profile, different plasma conditions can be considered including L-mode and H-mode confinement regimes. Then, the coil currents needed to obtain such plasma equilibria are computed within the engineering constraints of the machine.  This study will be carried out by using the IET numerical tool with inputs provided by CHEASE code. The new equilibria will then be verified by free-boundary calculations using the FRIDA code. These will provide also the magnetic fields at the pick-up coil sensors positions which are used to control the plasma position and shape.

Tesi assegnata a: Andrea Corbioli

Thermo-hydraulic design and specification for the construction of the DTT in-vessel coils Progetto termo-idraulico e specifica per la costruzione delle bobine in-vessel di DTT

Proponente: M. Dalla Palma

Capogruppo RFX: A. Rizzolo

Relatore Accademico: P. Sonato

Tipologia: Modelling, Teorica, Numerica, Compilativa

Argomento della tesi:

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, testing, and maintenance.

The DTT in-vessel coil system comprises:

  • vertical stability coils: 2 poloidal field coils located above and below the tokamak’s mid-plane designed for fast vertical stabilization of the plasma;
  • divertor coils: 4 coils located in the divertor region designed for sweeping control on divertor legs and local modification of the plasma configuration;
  • edge localized mode (ELM) coils: 27 coils fixed to the inner-shell of the vacuum vessel designed for active control of edge-localized modes and error fields.

The design if the in-vessel coils has been defined and in particular the same coil conductor will be used for manufacturing all the coils and it will consist of a stainless steel jacket, an inner copper conductor and a techno-polymer insulation.

Steady state and transient thermo-hydraulic analyses of the coil conductor based on analytical and finite element methods in the solid domain are needed applying the electrical current as a time function during the machine operating states. Thermo-mechanical verifications of the coil conductor are needed in the region of the connection with coil feeders and along coil turns/branches applying available electromagnetic loads. The analyses will contribute to the validation of the already carried out preliminary design in order to proceed with the preparation of the technical specification for the procurement of the conductor and of the coils.

A collaboration with IPP Team working on ASDEX-U is ongoing.

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: Gabriele Clerici

Tesi di laurea assegnate nel 2022

 TITOLORELATORE SUPERVISORELAUREANDA/O
Water chemistry definition for power plants cooling circuits and irradiation damage on materialsPiergiorgio SONATOClaudia GASPARRINIFrancesca GENERO
Setup ed utilizzo di un sistema spettrometrico a pozzetto per il monitoraggio
di acqua ed elementi attivati per valutazioni di carattere radioprotezionistico
o
Monitoraggio dell’attivazione del fluido vettore dell’impianto di raffreddamento della Neutral Beam Test Facility mediante sistema spettrometrico a pozzetto al Germanio iperpuro
Francesco LONGO Manuela BATTISTELLASimone COMINELLI
Measurement of electron density in radiofrequency plasmas by means of wave detection Gianluigi SERIANNIMatteo ZUINEmma LUNARDI
Design and specification for the construction of the cryogenic, electrical, and cooling penetrations for the DTT vacuum vesselPiergiorgio SONATO Mauro
DALLA PALMA
Patrick FANCHIN
Study of voltage and current modulation in SPIDER RF generators Paolo
BETTINI
Riccardo CASAGRANDELuca
CONTRO
Measurement of electron density in radiofrequency plasmas by means of wave detection Gianluigi SERIANNI Matteo ZUINEmma LUNARDI
Design of the DTT thermal shieldGennaro CUCCURULLOMauro
DALLA PALMA

Gianluca BARONE
Fabrizio APICELLA
The role of the electric transmission grid in decarbonization process of the Italian power sectorGiuseppe ZOLLINO Chiara BUSTREOStefano GRAZIAN
Caratterizzazione dello scambio termico in giunzioni bullonate in vuotoGiuseppe CHITARIN Andrea RIZZOLOAlessandro ZACCHELLO
Modelling of the propagation of a large negative ion beam Gianluigi SERIANNI Emanuele SARTORI
Valeria CANDELORO
Daniele MUSSINI
Analisi di spark-gaps a sfere per la protezione dalle sovratensioni nell’esperimento MITICA Giuseppe CHITARINTommaso PATTON Daniele APRILELuca DA RE
Analisi della distribuzione di cesio in una sorgente di ioni negativi, per mezzo di una diagnostica spettroscopica di assorbimento Gianluigi SERIANNIMarco BARBISANLuca BALDINI