Centro di Ateneo “Centro Ricerche Fusione”
c/o Consorzio RFX

Ciclo di studi: Tesi di Laurea triennale/magistrale
Corso di Laurea: Fisica
Tipologia: sperimentale
Titolo: Setup ed utilizzo di un sistema spettrometrico a pozzetto perilmonitoraggio di acqua ed elementi attivatiper valutazioni di carattere radioprotezionistico.
oppure
Monitoraggio dell’attivazione delfluido vettore dell’impianto di raffreddamento della Neutral Beam Test Facility mediante sistema spettrometrico a pozzetto al Germanio iperpuro.
Relatore RFX: M. Battistella, S. Dal Bello
Relatore Accademico: Da determinare

Argomento della tesi:

Monitoraggio dipossibilicomponenti attivati ai fini radioprotezionistici mediante sistema spettrometrico al Germanio iperpuro.  Il Consorzio RFX ha acquisito unsistema di monitoraggio per la radioprotezione da impiegare per misure spettrometriche di vario tipo, tra cui: acqua, filtri e resine contenenti prodotti di corrosione attivati, matrici solide attivate e piccoli elementi/campioni degli impianti sperimentali potenzialmente attivati. Il sistema spettrometrico è costituito da un rivelatore al Germanio iperpuro (HpGe di tipo "p") raffreddato con azoto e relativo pozzetto in piombo, da un’elettronica di conteggio digitale multicanale e da un computer con pacchetti software dedicati per:
-l’acquisizione di spettri e loro manipolazione, calibrazioni base e gestione via software dei parametri hardware della catena di acquisizione;
- la calibrazione in efficienza con metodi matematici(Montecarlo) e applicando metodi di sottrazione del fondo per picchi.
L’attività di tesi partirà da un breve corsotenuto dalla ditta fornitrice sull’uso del sistema di misura e proseguirà con lo studio del suo funzionamento e la messa a punto di procedure dettagliate per il setup e la calibrazione del sistema con apposite sorgenti di taratura. Comprenderà inoltre la modellazione e caratterizzazione di alcune geometrie tipiche di possibili campioni da analizzare, secondo le indicazioni dell’Esperto di Radioprotezione e l’esecuzione di misure/test su alcuni campioni (con ogni probabilità non attivati) al fine di testare il sistema.

Data:09/2022
Stato: non assegnata

Ciclo di studi: Laurea Magistrale
Corso di Laurea: Fisica
Tipologia: Analisi dati
Titolo: Effects of microtearing modes on energy confinement properties of Reversed-Field Pinch (RFP) plasmas
Relatore RFX: M. Zuin
Relatore Accademico: M. Zuin

Argomento della tesi:
Within the magnetic spectrum of magnetic fluctuations in the Reversed Field Pinch configuration for the magnetic confinement of thermonuclear plasmas, small scale coherent modes (with wavelengths of the order of the ion Larmor radius) are found to be destabilized by strong pressure gradients during improved confinement regimes.
The thesis work will focus on the (still undetermined) role played by these coherent microtearing modes inmodifying the energy confinement time. The investigation will be based on the analysisof the data coming from highly resolved both in time and space systems of magnetic probes located inside the vacuum vessel of the RFX-mod experiment.
In particular, the isotope effect on the spectral properties of small scale instabilities will be investigated by comparing plasmas produced with Hydrogen and Deuterium as working gases.

Data: 24/05/2022
Stato: non assegnata

Ciclo di studi: Laurea Magistrale
Corso di Laurea: Fisica
Tipologia: Modellistica
Titolo: Real-time modelling of DTT scenarios
Relatore RFX: LidiaPiron
Relatore Accademico: Lidia Piron

Argomento della tesi:
Motivation:
For future large tokamak operations it will be increasingly important tohave a real-time control-oriented simulation code capable of augmenting the diagnostic insight on the plasma with model-based predictions of its state.

Strategy:
The control-oriented 1D transport code RAPTOR will be applied to model the plasma scenarios of the Divertor Tokamak Test (DTT) facility, the brand-new Italian fusion experiment that is under construction in Frascati (Roma).
Through this project, the student will:
-be introduced to the RAPTOR code and the DTT experiment
-develop her/his knowledge on tokamak plasma scenarios
-mature a critical understanding of the potentialities and the limits of control-oriented
predictive modelling.

Framework of the study: Università degli Studi di Padova, Consorzio RFX, ENEA, DTT
Competenze richieste: Ambienti Python,Matlab
Conoscenza degli argomenti trattati nei seguenti corsi della Laurea Magistrale in Fisica:
-Physics of fluids and plasmas
-Physics of nuclearfusion and plasma applications

:15/09/2021
non assegnata

Ciclo di studi: Magistrale
Corso di Laurea: Ingegneria / Fisica
Tipologia: Sperimentale
Titolo: Analysis of locked dynamics in MAST-Upgrade/ JET / AUG
Relatore RFX: Lidia Piron
Relatore Accademico: LidiaPiron

Argomento della tesi:

ThisThesis aims at investigating the dynamics of locked mode behavior, a Magneto-Hydro-Dynamics instability, in plasmas performed
I) In the MAST-Upgrade device, at CCFE, Culham, UK, when exploringa wide range of operational parameters, such as plasmacurrent, density, shapes...
II) In the ASDEX Upgrade device, at IPP institute, Garching, Germany,during Shattered Pellet Injector (SPI) experiments,
III) In the Join European Torus (JET) device, at CCFE,Culham, UK, during Shattered Pellet Injector (SPI) experiments.
Such studies have been performed recently, in 2021/2021, in the frameworkof JET1/Tokamak exploitation WorkPackage (EUROFusion).TheThesis work consists in analyzing statistically magnetic, kinetic signals, Dalpha and Infra-red camera signals.
The candidate should chooseone option (I or II or III), only.
Competenze richieste: Data analysis (Matlab, Python, IDL)

Stato: non assegnata

Cycle of study: Second Cycle Degree
Degree Course: Physics
Type: numerical-modelling/data analysis
Title: Numerical investigations of SPIDER negative ion beam in support of Beam Emission Spectroscopy
RFX Supervisor: Riccardo Agnello, Marco Barbisan, Roberto Pasqualotto
Academic supervisor: Gianluigi Serianni

Description of the thesis:

The negative ion source SPIDER, located at Consorzio RFX (Padova, Italy) is thefull-scale prototype of the source for the Heating Neutral Beam(HNB) Injector for the fusion reactor ITER. SPIDER’s main goals are investigating the extracted negative ion beam and optimizingits performances in terms of current, homogeneity and extraction optics.Multiple diagnostics are routinely employed in SPIDER to measure the extracted negative ion beam. One of these techniques, the Beam Emission Spectroscopy (BES) relies onthe analysis of the emission spectrum of beam particles interacting with the background gas. BES technique is employed to estimatethe beam divergence,one of the crucial parameterfor HNB optimizationin terms of beam extraction optics and transport.
The goal of this thesis isto advance in the understanding of the physics of the extracted beam in SPIDERdevelopingnumerical models to simulate the spectra acquired by the diagnostic BES. These numerical tools arenecessary for a thorough comprehension of collected data.The activities envisaged for this thesis include, on the one hand, the development or exploitation of existing beam optics numerical tools, and, on the other hand, the thorough analysis of BES experimental data collected during the last experimental campaigns. A special attention will be devoted to coupling dedicated numerical tools, from theprocess of negative ion extraction and acceleration, to the interpretation of beam diagnostics data. This step of gathering the multiple physical processes is required to improve the understanding of the overall SPIDER operation. Therefore, this approach will be based on the activity of comparing the outcome of multiple diagnostics. Apart from the formative experience in working as a part of alarge team, this work of thesisin intended to actively contributein the advancement of the physics comprehension of full-scale negative ion sourcesfor fusion.

Required skills: familiarity with Matlab and/or C++ and/or Python and/or IDL or similar.
Date:08/04/2022

Cycle of studies: Second Cycle Degree
Degree course: Physics
Title: Density limit in the RFXmod tokamak
Type: data analsyis, modelling
RFX Supervisor: Paolo Zanca, Fulvio Auriemma
Academic supervisor: Lidia Piron

Description of the thesis:



Status: available

Ciclo di studi: Laurea magistrale
Corso di Laurea: Fisica
Tipologia: sperimentale
Titolo: Caratterizzazione spettroscopica di SPIDER
Relatore RFX: Zaniol Barbara
Relatore Accademico: Matteo Agostini

Descrizione della tesi:

Spider e’ il prototipo della sorgente di ioni negativi che dovra’ costiture parte dei neutral beams di ITER. Per ottimizzare la produzione di ioni negativi, in Spider sono state installate una serie di diagnostiche ottiche, basate sull’analisi della radiazione emessa spontaneamente durante il suo funzionamento. Le grandi dimensioni dell’esperimento hanno reso necessari diversi punti di raccolta della radiazione, per questo sono state previste piu’ di 100 linee di vista. Le diagnostiche ottiche disponibili sono di tipo spettroscopico, dagli spettri si puo’ monitorare il contenuto di impurezze del plasmae con modelli interpretativi appositi, determinarne la densita’ e la temperatura elettronica. La tesi proposta e’ la caratterizzazione spettroscopica di SPIDER al variare delle condizioni sperimentali, con particolare riguardo alle disuniformita’ spaziali.

Competenze richieste: Programmazione di base

Stato: non assegnata

Ciclo di studi:Laurea magistrale
Corso di Laurea: Fisica
Tipologia: sperimentale
Titolo della tesi: Misura delle temperature rotazionale e vibrazionale delle molecole di H2 nelle diverse regioni di SPIDER
Relatore RFX: Zaniol Barbara
Relatore Accademico: Matteo Agostini

Argomento della tesi:

Spider e’ il prototipo della sorgente di ioni negativi che dovra’ costiture parte dei neutral beams di ITER. Per ottimizzare la produzione di ioni negativi, in Spider sono state installate una serie di diagnostiche ottiche, basate sull’analisi della radiazione emessa spontaneamente durante il suofunzionamento. Le diagnostiche ottiche disponibili sono di tipo spettroscopico,edagli spettrimisuratisipossono misurare molte grandezze fisiche utili all’ottimizzazione del funzionamento dell’iniettore. Fra queste le misure di temperatura legate al gas principale: la temperatura rotazionale e vibrazionale delle molecole di H2. La tesi propostaconsiste nella derivazione e nello studio di queste temperature,nelle diverse regioni di SPIDER, al variare delle condizioni sperimentali.
Competenze richieste: Programmazione di base

Ciclo di studi: Laurea Magistrale
Corso di Laurea: Fisica
Tipologia: sperimentale
Titolo della tesi: Studio di tecniche tomografiche per il fascio di ioni negative di SPIDER
Relatore RFX: Margherita Ugoletti,Matteo Agostini
Relatore Accademico: MatteoAgostini

Argomento della tesi:
La luce emessa dal fascio di ioni negativi diSPIDERquando interagisce con il gas di fondo in cui si propaga viene usata per studiare il fascio stesso.Un set di 15 telecamere visibili misurano l’integrale di linea della luce emessa dal fascio, e mediante un’inversione tomografica è possibile ricavare dalle misure integrate una mappa bidimensionale dell’emissione del fascio stesso. Scopo della tesi è sviluppare uno o più metodi per l’inversione daapplicare ai dati sperimentali. Una volta sviluppate le tecniche, si devono applicare ai dati sperimentali raccolti confrontando i risultati anche con l’algoritmo oggi esistente in modo da studiare pregi e difetti delle diverse inversioni.
Competenze richieste: Programmazione di base
Data della proposta:10/11/2021
Stato:non assegnata

Tipo di tesi:Magistrale
Corso di Laurea: Physics
Tipologia: sperimentale-modellistica
Titolo della tesi: 3D plasma-wall interaction in the RFX-mod device
Relatore RFX:Gianluca Spizzo, Lionello Marrelli
Relatore Accademico: Matteo Zuin


Argomento della tesi:

Plasma-wall interactions (PWI) in nuclear fusion devices are often shaped in regular patterns which reflect in detail the complicated 3D structure of the magnetic field in the plasma: pioneering work in the TEXTOR tokamak has shown in the past that a good proxy to compare experiment with 3D field modelling is the connection length to the wall, measured parallel to the magnetic field line, Lc (Schmitz, 2008). In that work, it was shown that the deposition pattern on the wall of TEXTOR was strictly related to the pattern of Lc, so that a careful control of plasma instabilities could reduce the power deposition on the wall. Recent camera images of the PWI pattern on the RFX-mod reversed-field pinch operated by Consorzio RFX (Padova, Italy) have been made available. Topic of the thesis will be to calculate the full, 3D pattern of connection length
(, , )in RFX-mod by means of the guiding-center code ORBIT (White & Chance, 1984) and to relate this map to the images of PWI. Final purpose of the thesis is finding what magnetic instabilities are responsible for most severe energy and particle flux to the wall. This information is important in view of the refurbished RFX-mod2 device which is under realization at Consorzio RFX (Marrelli, 2019).
Competenze richieste: elettromagnetismo/fisica dei plasmi, programmazione (IDL e/o python, fortran non strettamente necessario, ma preferibile).
Data della proposta:10/11/2021
Stato:non assegnata

Tipo di tesi:Laurea Magistrale
Corso di Laurea:Physics
Tipologia:Analisi dati,Modellistica
Titolo della tesi:Comparison of the experimental data with the BIRD model outcomings.
Relatore RFX:Emanuele Spada
Relatore Accademico:Matteo Zuin

Argomento della tesi:
The development oftheneutral particle injector forthe heating of thermonuclear plasmas in theITER experiment, presently under construction, requires a thorough study of the high voltage holding characteristics of anegative ionelectrostatic accelerator. In particular, the basic physical origin of the observed vacuum arcingis still a matter of debate. With the aim to deepen the comprehension of these phenomena, two experimental devices have been realized at ConsorzioRFX: HVPTF (High-Voltage-Padova-Test-Facility) and HVSGTF (High-Voltage-Short-Gap-Test-Facility). The last onewas designed to verify and/or improve a recentfirst-principles theoretical model–BIRDmodel (BreakdownInduced by Rupture of Dielectric layer) which traces the breakdown to the emission of electrons by a dielectric cathodic surface. After familiarizing with the theoretical model, the present thesis focuses on the study of HVSGTF experimental data, in order to compare them with the predictions of the BIRD modelas well asto provide important clues on possible developments.
Competenze richieste: Basic knowledge ofdata anaylsisandprogramming tools (e.g. matlab and/or similar)
Data della proposta:16/06/21
Stato:non assegnata

Tipo di tesi:Laurea Magistrale
Corso di Laurea:Fisica
Tipologia:Modellistica
Titolo della tesi:Peeling-ballooning stability of DTT plasmas with Resonant Magnetic Perturbations
Relatore RFX:Leonardo Pigatto
Relatore Accademico:Tommaso Bolzonella

Argomento della tesi:
The present thesis focuses on studying the optimization of the 3D magnetic boundary in perspective DTT plasmas by means of external magnetic fields from saddle coils. A set of non-axisymmetric coils is presently being developed for the I-DTT tokamak, with the main purpose of Edge Localized Modes (ELMs) mitigation and Error Field (EF) control. ELMs are localMagneto-Hydro-Dynamic (MHD)instabilities that appear in fusion relevant plasmas during the so-calledH-mode operation. This consists in an increased confinement regime triggered when a Tokamak plasma is operated with sufficient auxiliary heating, with respect to a purely ohmic plasma (examples of auxiliary heating can beneutral beam, electron cyclotron,ion cyclotron). The destabilization of ELMs is linked to the pressure (and pressure gradient) in the peripheral region of the plasma, where a transport barrier, responsible for the improved confinement, is formed. Spurious magnetic fields, known as error fields (EFs), are inevitably present in fusion devices and can be associated with either stationary non-symmetric electromagnetic sourcesor with transient phenomena inducing eddy currents in asymmetric geometricalfeatures of a specific machine. Correction of Error Fields (EF) is a task of primary importance for operating fusion devices, in order to maximize performance and avoid undesirable disruption events. The thesis proposes a modeling activity onplasma scenariosforeseen for the operation of the DTT machine, which is being designed for construction in Frascati (Italy). The student will build experience in one of the most challenging topics for operating a modern Tokamak device, the study will be relevant to address design and operation issues for DTT in particular.The thesis will explore the effect of external magnetic perturbation recipes developed for the aforementioned purposes of ELM and EF control, on a selection of perspective DTT operational scenarios.The final goal is to provide useful insight on plasma stability for present integrated modeling and future plasma operations.
Competenze richieste (se necessarie): Ambienti Python e Matlab; Conoscenza degli argomenti trattati nei seguenti corsi della Laurea Magistrale in Fisica:
-Physics of fluids and plasmas
-Physics of nuclear fusion and plasmaapplications
Data della proposta:23/11/2021
Stato:non assegnata

Tipo di tesi:Laurea Magistrale
Corso di Laurea:Fisica
Tipologia:Teorico/Modellistica
Titolo della tesi:Drift-kinetic modeling of Resistive WallMode stability with fast ion anisotropy
Relatore RFX:Leonardo Pigatto
Relatore Accademico:TommasoBolzonella

Argomento della tesi:
Demonstrating the capability of achieving high fusion power density and good confinement properties has been one of the main targets of present day magnetic fusion experiments, and an even more crucial one for the next generation of devices with are under construction or design. A possible way towards substantial performance improvement is operating a thermonuclear fusion device athigh normalized pressure, with a high fraction of non-inductive current drive and exploiting both external and internal transport barriers for confinement.
The so-called Advanced Tokamak (AT) scenarios could represent a viable way for steady-state operation with the aforementioned characteristics. In such plasmas an important fraction of heating and current drive is provided by Neutral Beam Injection (NBI) systems, which also lead to increasing the fraction of high energy ions in the plasma. Under the point of view of stability however, advanced scenarios are challengingto achieve.This thesis will focus on the study of ideal MHD instabilities that cause a global displacement of the plasma column and grow on Aflvén time scales. In presence of a close-fitting resistive wall the mode is slowed down to the time scale of themagnetic field penetration, being then called Resistive Wall Mode. Many experiments over the last decade have been performed (both on Tokamak and Reversed Field Pinch devices) to study RWM physics and tackle the issue of stabilization. Strong evidence suggests that RWMs interact (by exchanging energy) with particle populations within the plasma, this effect can be exploited for stabilization. The thesis work starts with understanding the drift-kinetic MHD model that explains the aforementioned interaction, familiarizing with some of the most common numerical tools, with foreseeable tuning and customization.RFX-mod plasmas canbe the first applicationto focus on in the thesis, studying the effect of NBI fast ions on RWM stability in both Tokamak and RFP plasmas. The problems of modelling mode-particle interaction as well as the fast ion distribution will be addressed. These analyses will stand as base for the extension to more challenging high performance scenarios.Multi-machine modelling and comparisonis foreseeable in the horizon of the thesis, including e.g. JT-60U, TCV, JET.
Competenze richieste (se necessarie):
Ambienti Python e Matlab.
Conoscenza degli argomenti trattati nei seguenti corsi della Laurea Magistrale in Fisica:
-Physics of fluids and plasmas
-Physics of nuclear fusion and plasmaapplications
Data della proposta:23/11/2021
Stato:non assegnata

Thesis level: Master
Corso di Laurea:Physics
Thesis type:Plasma modeling/numerical (to be carried out by internship at CEA- Cadarache)
Title:Simulating edge plasma turbulence for ITER: Improving the numerical resolution of a very anisotropic, poorly conditioned diffusion problem

RFX tutor:P. Innocente
CEA Internal tutors:Hugo Bufferand (CEA, IRFM), hugo.bufferand@cea.fr;
Eric Serre (CNRS, laboratoire M2P2 Aix Marseille University),
eric.serre@univ-amu.fr;
Academic tutor:L. Giudicotti

Thesis description:
To predict heat deposition on plasma-facing components of current tokamaks and future reactors, a major effort is being made to develop codes capable of modelling turbulence in the edge plasma. Many mathematical and numerical problems remain to be overcome in order to be able to simulate plasma in a machine the size of ITER. In particular, calculating the electric potential requires the inversion of a 3D anisotropic Laplacian. The anisotropy is very strong with diffusivity in the direction parallel to the magnetic field several million times greater than diffusivity in the transverse directions. In addition, the boundary condition of Robin type almost degenerated in Neumann conditions makes the problem difficult to invert because very poorly conditioned. Various linear solvers are used to solve the problem: direct solvers which work well but which do not make it possible to go up in resolution,thecomputation time being quickly prohibitive and the parallelization inefficient; iterative solvers, the most promising of which currently use an algebraic-multigrid type pre-conditioner. The subject of the internship will consist in seeking solutions to accelerate the resolution of the Laplacian by mainly following two tracks: building an adapted pre-conditioner by possibly reformulating the problem (play on the geometry, “physical” aggregation of the unknowns of the problem); test the libraries "on the shelf" to solve the problem by looking for a good parallelization of the computation (ex: implementation of multigrid algebraic solver on GPU [AMGX Nvidia]). The internship subject may continue into a PhD thesis.

Date:December the 08th, 2020
Status:not assigned

Thesis level: Master (internship at CEA-Cadarache)
Corso di Laurea: Physics
Thesis type:Plasma modeling/numerical (to be carried out by internship at CEA- Cadarache)
Title:Investigation of second-order terms in gyrokinetic models: impact on guiding-center dynamics

RFX tutor:P. Innocente
CEA Internal tutors:Guido Ciraolo (CEA, IRFM), guido.ciraolo@cea.fr;
Cristel Chandre (CNRS, laboratoire I2M Aix Marseille University),
cristel.chandre@univ-amu.fr;

Academic tutor:L. Giudicotti

Thesis description:
The motion of a charged particle in strong electromagnetic fields is characterized by a fast cyclotron motion around magnetic field lines and slower drifts associated with the motion of the so-called guiding center. Based on the observation that the fast motion is mostly irrelevant for the study of plasma turbulence, reduced kinetic models have been developed in the late 1980s, and numerically investigated in a very active way, starting the early 2000s. Gyrokinetics is nowadays state-of-the-art for the investigation of plasma turbulence. There is not one gyrokinetic model, but a hierarchy of them, depending on the assumptions made for the reduction. The main element behind a gyrokinetic model is its chosen ordering between the various small parameters characterizing, e.g., the background electric and magnetic field inhomogeneities (resp.,ܧandܤ) and the amplitude and the spatial and temporal fluctuations of the perturbing electromagnetic fields (characterized by,߱and∥). The derivation of a proper gyrokinetic model has to be consistent with the chosen ordering from the particle to the guiding center and from the guiding center to the gyrocenter dynamics. The order at which is reduction is carried out sets the limits of investigation of this model. Currently, all of the numerical codes are first or second order inߜ. The overall objective of the internship is to start to assess the importance and impact of second order terms in the gyrokinetic models, depending on the region of interest in the plasma, core versus edge. The proposed strategy is to simplify as much as possible the geometry to isolate the different drifts, and analyze them on simple models to get a clear picture in phase space of the role of the different terms. A first task is to investigate these effects in a slab geometry with a constant and uniform magnetic field. We will investigate the dynamics of charged particles in the guiding-center approximation. In the expansion in the guiding-center theory, the first order is well known, an ExB drift with FLR effects. However, less is known on the second order terms which change the effective potential felt by the guiding-center dynamics. We will look at the dynamics of these guiding centers in phase space. The importance and influence of second order terms will be assessed in the various regimes of the electric and magnetic fields to determine if and when they need to be taken into account in gyrokinetic codes. This will be tested on various electrostatic potentials, ranging from toy models to more realistic ones. A second task, which will be addressed depending on the progress of the work, is to extend the study to more complex magnetic geometries, starting first with straight magnetic field lines (and varying amplitudes along these lines) in order to assess the grad-B drifts. Then, by selecting a specific geometry, we will investigate the impact of curvature drifts on the dynamics of the guiding centers. These investigations will be done with the same electrostatic potentials for a comparison with the ExB
drift effects.

Submission date:December the 08th, 2020
Status:not assigned

Tipo di tesi:Tesi Magistrale
Corso di Laurea:Fisica
Tipologia:modellistica
Titolo della tesi:Working point characterization of folded optical resonator for photo-neutralization of negative ions
Relatore RFX:A. Fassina - alessandro.fassina@igi.cnr.it
Relatore Accademico:G. Serianni

Argomento della tesi:

La fotoneutralizzazione di fasci di ioni negativi è un’interessante alternativa alla neutralizzazione a gas e a plasma (migliore efficienza, possibilità di lavorare con sorgente del fascio a potenziale di terra, ecc.). La maggiore difficoltà tecnologica riguarda la richiesta di potenze ottiche dell’ordine di alcuni MW e la conseguente necessità di una cavità di enhancement, con un fattore di merito nell’incremento della radiazione tra 10^2 e 10^3. Il lavoro riguarderà la caratterizzazione (stabilità, battimenti, perdite) di risonatori ottici o anulari accoppiati a sorgenti FEL (free electron laser), e riguarderà lo studio del carico radiativo sulle ottiche, dello spettro longitudinale e trasverso e il suo impatto sull’efficienza del dispositivo, e un dimensionamento di massima dell’ondulatore e dell’acceleratore per avere una stima di costi ed efficienza.

Data della proposta:14/12/2019
Stato:non assegnata

Magistrale Fusica - Master Thesis in Physics
Thesis type:Experimental/modelling
Thesis title:Diagnostic of fusion plasmas by Thomson scattering of laser light
Academic supervisor:Leonardo Giudicotti
RFX supervisor:Roberto Pasqualotto

Thesis abstract:

Thomson scattering (TS) of laser light is a well known diagnostic technique for the measurement of spatial profiles of electron temperatureTeand electron densityne in fusion plasmas. For the new italian experiment DTT a TS system based on the LIDAR approach is being considered. In LIDAR TS, a laser pulse with time duration of ~150 ns (corresponding to a spatial extension of ~4.5 cm) is sent into the plasma and observed from the back. The spatial profile ofTeandneis determined measuring the time evolution of the scattering light. This technique poses considerable experimental challenges and requires the most advanced solutions in terms of laser and optics technology. In the framework of this activity the student will first achieve a general knowledge in TS diagnostics, by developing advanced modelling techniques of TS systems and working on the integration of state-of-the art lasers, detectors and high speed digitizers in the diagnostic. In addition she/he will be involved in extensive laboratory tests for the complete characterization of TS components such as very high speed MCP-PMT detectors,very high speed digitizers and filter polychromators.
Submission Date:10/10/2020
Status:available
Previous kowledge:Basic plasma physics and programming. Knowledge of laser and solid
state physics are welcome but not mandatory.

Tipo di tesi:Laurea Triennale/Magistrale
Corso di Laurea: (Fisica/Ingegneria)
Tipologia:(sperimentale)
Titolo della tesi:Reconstruction of Negative Ion Beam Heat Flux profile on STRIKE by Neural Networks.
Relatore RFX: Rita Delogu, Gianluigi Serianni
Relatore Accademico: Gianluigi Serianni

Argomento della tesi:

Si propone la ricostruzione del flusso di energia incidente sul calorimetro diagnostico STRIKE mediante l’analisi delle misure termografiche sul retro del calorimetro utilizzando codici di intelligenza artificiale, in particolare le reti neurali. Questo progetto è la prosecuzione e il perfezionamento di un metodo già implementato, per poterlo utilizzare durante le fasi di operazione in
real time di SPIDER.
Competenze richieste: Programmazione di base
Data della proposta: 15/01/2020
Stato:non assegnata

Tipo di tesi:Laurea Triennale/Magistrale
Corso di Laurea: (Fisica/Ingegneria)
Tipologia:(sperimentale)
Titolo della tesi:Commissioning and first operation of Cs Oven for the NIO1 experiment.
Relatore RFX: Rita Delogu, Gianluigi Serianni
Relatore Accademico: Gianluigi Serianni

Argomento della tesi:

Allo scopo di studiare ed ottimizzare la produzione di ioni negativi, il Consorzio RFX e i Laboratori Nazionali di Legnaro (INFN) hanno realizzato una sorgente RF di ioni negativi H-, NIO1 (Negative Ion Optimization 1). NIO1. Per aumentare la produzione di ioni negativi H-è stato montato un forno del cesio per il quale è prevista una attività di commissioning e messa in servizio.
Si propone di seguire il commissioning e le prime operazioni del forno del cesio di NIO1 per verificarne il corretto funzionamento. L’attività di tesi riguarderà anche l’analisi dei dati e la verifica delle performance del forno.
Competenze richieste: Programmazione di base
Data della proposta: 13/01/2020
Stato:non assegnata

Tipo di tesi:Laurea Magistrale
Corso di Laurea:Fisica
Tipologia:Modellistica
Titolo della tesi:DTT NBI fast particle modelling with Monte Carlo ASCOT code
Relatore RFX:Pietro Vincenzi
Relatore Accademico:Tommaso Bolzonella

Argomento della tesi:
The student will simulate and analyse the behaviour of neutral-beam (NB) injected energetic particles (EPs) in tokamak plasma scenarios by means of a numerical Monte Carlo model. The work will contribute to the study of the NB injector capabilities for DTT project (Divertor Test Tokamak), the new Italian large experimental facility now being designed. Fast particles injected by NB are one of the most promising tools to achieve the temperatures needed in fusion-relevant tokamak plasmas. The energetic particles are injected at energies much higher than the target plasma (at least 10 times higher, in our case a NB energy of 400 keV). The injected neutrals are ionized in the plasma (becoming fast ions) and Coulomb collisions allow energy exchange between EPs and plasma ions/electrons during the slowing down process. EPs not only heat the plasma but can drive non-inductive currents and provide torque to the plasma. The student will acquire familiarity with the physics problem of the interaction between NB EPs and plasma, described by the Fokker-Planck equation, and typical methods to evaluate the EPs distribution function (particularly Monte Carlo solvers). ASCOT Monte Carlo code allows to solve EPs orbits (solving the full gyro-motion orbit), taking into account Coulomb collision for the Fokker-Planck equation. It is important to know EPs orbits because the size and shape of these orbits drive different EP losses. The student will prepare and manage the input/output for the Monte Carlo code ASCOT and will be guided in the interpretation and visualization of the simulation results such as orbits, particle losses, heating and current drive in the plasma. The student will use existing tools and may develop further numerical tools such as Matlab/Python scripts for the analysis.

Competenze richieste:basic notions on tokamak plasma physics; basic knowledge of computational programming tools (e.g. matlab and/or similar – e.g. python)
Data della proposta:28/01/2020
Stato:non assegnata

Thesis type:Master Thesis
Graduation course :Physics
Type:experimental/modelling

Tutor:A. Fassina, D. Fiorucci
Academic Relator:L. Giudicotti
Title:Comparative study and modelling of photo neutralizing techniques in fusion NBI injectors

Thesis description:

Today the development of a negative ion beam photoneutralizer is seen as crucial to rise the overall reactor efficiency. The thesis work aims to optimize the design under evaluation at Consorzio RFX of non-resonant optical cavity fed by a pulsed laser and carry on a comparative review of the optical resonator concept, focusing on radiation impact on optics, overall efficiency, thermal management, techniques for optical compensation and so on. Modelling tools will be developed mainly in COMSOL, while optics simulations will require also development of dedicate coding (Python).

Date29/10/19
Status:not assigned

Tipo di tesi:Tesi Magistrale
Corso di Laurea:Fisica
Tipologia:sperimentale
Titolo della tesi:Slideaway and runaway electrons in RFP plasmas

Relatore RFX:A. Fassina - alessandro.fassina@igi.cnr.it
Relatore Accademico:L. Giudicotti

Argomento della tesi:

The presence of non-thermal (NT) particle populations in fusion relevant plasmas has a crucial importance in confinement characterization, instability growth and current drive. Detection and characterization of NT particle in RFX discharges requires an integrated analysis between Thomson Scattering, soft Xray, spectroscopic and density data. In particular, Bayesian inference and Information Geometry techniques will be applied to extract data on electron distribution function. The thesis work should also include an analysis of the links between MHD activity and fast particle population, in particular as far as MHD dynamo is concerned. .

Status:not assigned

Tipo di tesi:Laurea Magistrale
Corso di Laurea:Fisica, Ingegneria
Tipologia:teorica - numerica
Titolo della tesi:Modelling of fast response surface thermocouples for fusion plasma facing components
Relatore RFX:Mauro Dalla Palma, Monica Spolaore
Relatore Accademico:prof. Piergiorgio Sonato

Argomento della tesi:

Thermal measurements are performed on plasma facing components of fusion machines, especially on the divertor to provide coolant calorimetry (coolant temperatures measured at inlet and outlet [i]), local temperatures relevant to the component surface (sensors embedded in the component under the exposed surface [ii]), bulk calorimetry (time variation of temperature observed at the same sensor [iii]), or the power density deposited in each castellated module (temperatures detected at the same time by sensors located at different distances from the heated surface [iv,v]). Signals of these temperature measurements will be used during pulse operation or first wall conditioning for parameters monitoring, protection, and control. Surface eroding thermocouples (or “self-renewing thermocouples”) can be used to instrument plasma facing
components in which the thermojunction is formed in a very thin layer at the surface of the sensor [vi]. This construction leads to a fast thermal time response (10 ms), robust design, and is particularly useful to characterize the surface temperature evolution of the plasma facing component with the carrier body made of the same material as the component. Surface thermocouples also enable a simple computation of the power density applied to the component. Arrays of surface thermocouples proved to be a vital component of the overall diagnostic set and can be installed to measure pulsed heat flux in the divertor of tokamak [vi]. The activity will consist of modelling the signal response of surface eroding thermocouples, developing a sensor design, and integrating the concept in the castellations of the DTT device divertor [vii,viii].

Stato:non assegnata

Tipo di tesi:Laurea magistrale
Corso di Laurea:Fisica
Tipologia:teorica
Titolo della tesi:Non-adiabatic processes during interactions between magnetized particles and low-frequency electromagnetic waves: classical and quantum aspects
Relatore RFX:F. Sattin
Relatore Accademico:L. Salasnich

Argomento della tesi:

A diabatic processes in classical mechanics involve a non-autonomous Hamiltonian H = H(t), featuring an extremely (rigorously, infinitely) slow variation, when compared to all time scales involved. Canonical action variables stay unaltered, to within terms of higher order in dH/dt, and are accordingly called "adiabatic invariants". The existence of these invariants is fundamental in Bohr's development of quantum mechanics, and is extremely important in classical mechanics as well, since constraints the dynamics over manifolds of lower dimension. A textbook example is provided by the magnetic moment of a charged particle in a slowly varying
magnetic field. A slow deformation of H is a necessary but not sufficient condition in order to ensure adiabaticity. There exist instances of systems where a finite but arbitrarily small rate of variation does actually breaks adiabatic invariants up. The reason lies in the existence, in phase space, of topologically distinct regions, separated by one or several separatrices evolving in time.Any transition from one to another of these regions is accompanied by a finite irreversible change of the adiabatic invariants. The student is asked to study a paradigmatic case of this phenomenology: a charged particle in magnetic field, interacting with one or several electromagnetic waves with frequency lower than the particle cyclotron one, in order to avoid resonance conditions. This toy model may be taken as representative of an important class of true physical systems: e.g., it may be used to model the ion heating by Alfvèn waves in the solar corona. Student's tasks will be: to write down the hamiltonian function of such a system; study its topology in the phase space while varying the free parameters; identify the transition from an adiabatic to a diabatic process through the numerical integration of the equations of motion. Once the study of the classical version of the problem is over, the student shall tackle the quantum side, by writing the time-dependent Schrödinger equation down, numerically solving it, and checking the validity (or failure) of the adiabatic theorem.
Competenze richieste:Si tratta di una tesi a carattere teorico/numerico. E' richiesta familiarità con--o disponibilità ad apprendere l'uso di--software per l'analisi numerica (preferibilmente Mathematica).

Stato:non assegnata

Tipo di tesi: Magistrale
Corso di Laurea:  Ingegneria / Fisica

Tipologia: Sperimentale
Titolo della tesi: Characterization of magnetic field errors in MAST-U coil manufacturing

Relatore RFX: Lidia Piron

Relatore Accademico: Lidia Piron

Responsabile di Programma:
Argomento della tesi:

Error fields are spurious magnetic field perturbations that  can degrade the plasma performance in a magnetic fusion devices through various mechanisms, such as rotation braking, fast particles losses and MHD instability onset. The identification of error field sources thus plays a vital role to guarantee  safe and robust plasma operations. In this project, the validation of a 3D electro-magnetic modelling of poloidal field coils again experimental data will be carried to detect error field sources in the coil manufacturing process in the MAST-U device (Culham, Oxfordshire, UK).

Competenze richieste: Data analysis (Matlab, Python, IDL)
Stato: non assegnata

Tipo di tesi: Magistrale
Corso di Laurea:  Ingegneria / Fisica

Tipologia: Sperimentale
Titolo della tesi: Resonant field amplification in JET high pressure scenarios

Relatore RFX: Lidia Piron

Relatore Accademico: Lidia Piron

Argomento della tesi:

In magnetic fusion devices to probe plasma stability, magnetic field perturbations induced by means of external coils are applied in high pressure regimes in the so-called  resonant field amplification technique. Such a technique has been extensively applied in high-beta plasmas performed in the JET tokamak (Culham, Oxfordshire, UK). In this project, data from multiple diagnostics, such as magnetics, Thomson scattering, and equilibrium reconstructions will be analyzed to characterize the plasma amplification process.

Competenze richieste: Data analysis (Matlab, Python, IDL)
Data della proposta:
Stato: non assegnata

Cycle of studies: 2nd (master)
Degree course: Engineering/Physics/Material Sciences
Title of the thesis: Simulation of plasma parameters towards the optimization of first wall components by Glow-Discharge Cleaning
Type: theoretical/modelling
RFX Supervisor: Stefano Ciufo & Ruggero Milazzo
Academic supervisor: Matteo Zuin (Physics) or Emanuele Sartori (Engineering) or Sonato (Material Sciences)

Group Leader (Lorella Carraro)

Description of the thesis: The Glow-Discharge Cleaning (GDC) is one of the most important systems for plasma consistency in fusion reactors, during experimental campaigns. It is usually employed by considering only the current required for sputtering on the first wall materials and with relatively high voltages. The purpose of this thesis is to adapt a Particle-In-Cell (PIC) code in order to simulate plasma-wall interactions from the perspective of the RFX facing Carbon tiles. In particular, energy distribution and impact angles are quantities that must be estimated, depending on boundary conditions, so to serve as input for modeling solid-state phenomena (sputtering, impurity retention/desorption, defect generation, etc.) that determine fusion performance in turn. The importance of this study lies in gaining understating of the physics ruling plasma-wall interactions and the correct application of boundary condition. In this way, GDC operations can be significantly optimized by reduction in the resources required for the operation and in the time required for execution. The candidate's thesis will focus on adapting the PIC code to create a map enclosing energy and angles for different species contained in the plasma and with respect to the facing wall. Results will be analysed to describe plasmas and they will deal with graphic visualization of the abovementioned parameter space with final aim of better understanding the dynamics of plasma-wall interaction. The work will take place at Consorzio RFX.
 
Date: November 24nd, 2022

Tipo di tesi: magistrale
Corso di Laurea: Fisica

Tipologia: Sperimentale/Analisi dati

Titolo della tesi: Analysis and active control of drift-waves in magnetron sputtering plasmas
Proponente/Relatore RFX: M. Zuin

Relatore Accademico: M. Zuin

Altri relatori coinvolti: R. Cavazzana, L. Cordaro
Capogruppo: Zuin

Responsabile di Programma: Peruzzo

Argomento della tesi:

In the magnetron sputtering device, operated at Consorzio RFX, electrostatic drift-waves have been observed to be excited and to propagate in Argon plasmas. A theoretical linear dispersion relation, already on purpose developed, well reproduces the wave dispersion properties.

The main work of the thesis will be devoted to the analysis of the dependence of the spectral properties of these waves on the used working gas. With this aim, a complex diagnostic system made of several Langmuir probes will be realized and measurements will be taken by using Helium, Hydrogen, Nitrogen, Neon and Xenon as working gases, in a variety of pressure conditions. Experimental data will be compared to the prediction of the linear model, which explicitly depends on the ion mass.

In a second phase, a system of active, independently fed, electrodes will be exploited in order to control the spectral properties of the propagating waves, trying to induce a transition from a chaotic to an ordered fluctuation state.  

Competenze richieste (se necessarie):
Data della proposta: 25/01/2023
Stato: non assegnata