Дисертації з теми "Accélérateurs linéaires à induction"
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Alvinerie, Clara-Marie. "Etude numérique et expérimentale de la dynamique des faisceaux d'electrons dans les accélérateurs linéaires à induction." Electronic Thesis or Diss., Normandie, 2023. http://www.theses.fr/2023NORMC291.
Flash radiography allows characterizing the state of a dense object subjected to extreme physical conditions, with displacement velocities of several kilometres per second. These conditions require a specific X-ray source: small size (a few millimetres), brief duration (less than 100 ns), high energy (around 20 MeV) and high current (a few kA). This source is produced using Bremsstrahlung radiation generated by the interaction of an intense and pulsed electron beam with a high atomic number metal target. A velvet cathode emits the beam and an linear induction accelerator (LIA) transports it. The quality of radiography is mainly conditioned by the physical characteristics of the X-ray source, which are closely linked to the properties of the electron beam. The work carried out in this PhD thesis aims to model the beam dynamics in LIAs by integrating its physical characteristics, including some instabilities which degrade the beam. The developed models were validated during the commissioning of the MCH3 accelerator at CEA Valduc in Epure facility.The modelling of beam dynamics is based on the Particle-In-Cell (PIC) code LSP-Slice and the transport code EVOLI (EVOLution of Instabilities). The latter was developed during this thesis and models the size of the beam envelope and its charge centroid, as well as the "temporal" propagation of the beam by its segmentation into discs.In the first place, studies were conducted on the motion of the beam centroid during its transport. In EVOLI, the equations describe the centroid with the influence of space charge. A numerical optimization procedure allowed the simulation to reproduce the results obtained in MCH3 by incorporating the influence of the Earth's magnetic field and the misalignment of various magnetic elements (solenoids and steerers). The application of this new method to other beam transports makes possible to calculate steerer settings for numerical pre-centering of the beam. This method offers the prospect of significant time savings during the experimental beam centering process, which typically requires numerous shots.Afterward the beam modelling contributed to the commissioning of MCH3 accelerator at the end of 2022. With an initial transport attempt, the entire beam charge did not reach the conversion target, despite numerical simulations predicting nominal transport based on the envelope formalism. Experimental measurements revealed significant centroid oscillations due to the Beam Break-Up (BBU) instability. Then, a simplified BBU model was incorporated into EVOLI. By using this numerical model, a new high magnetic field transport was designed, theoretically limiting BBU intensity at the accelerator end by a factor 2.5. This result was experimentally verified by a BBU reduction by a factor 3, enabling a stable and reproducible transport of the entire beam charge to the target. However, this strong magnetic field transport strategy leads to an increase of the Corkscrew motion, which increases with magnetic field strength as shown in the work initiated in this thesis. Therefore, optimizing beam transport is a compromise between the various instabilities within the accelerator. The work of this thesis opens up prospects for considering instabilities to design innovative transports, particularly in the context of multi-pulse machines, which are currently a major development in flash radiography machines
Ruiz, Nicolas. "Etude et réalisation d'un faisceau de positons lents." Paris 6, 2011. http://www.theses.fr/2011PA066643.
Longuevergne, David. "Etude et test d'un module accélérateur supraconducteur pour le projet Spiral2." Paris 11, 2009. http://www.theses.fr/2009PA112304.
The SPIRAL2 project, in its construction phase at GANIL in Caen, will increase the capabilities of the current existing facility SPIRAL. This upgrade consists in the construction~of a production area of rare radioactive isotopes associated to a superconducting linac. The latter can accelerate a 5 mA deuteron beam up to 40 MeV and can handle a wide variety of ions (protons, deuterons, ions with a charge over mass ratio of 1/3) up to 14. 5 MeV/u at 1 mA. The targeted fission rate (~ 1014 fissions/secondes) and accelerating polyvalence is achieved thanks to the superconducting technology. The study, the conception and integration of the superconducting accelerating modules are in charge of the Nuclear Physics Institute of Orsay (IPNO). The PhD work presented here consisted in first testing and characterising mechanically and electromagnetically the superconducting quarter-wave resonator in a qualifying cryostat (- 269°C). Then, a fully-equipped accelerating module has been tested without beam. More specific studies have been carried out on the Q-disease, on microphonics and on the frequency tuning system with moving plunger, a novel system for superconducting cavities. The validation of the accelerating module performances during the PhD period has lead to the fabrication phase launching of the accelerating cavities and their modules
Mainaud, Hélène. "Une nouvelle approche métrologique : l'écartométrie biaxiale : application à l'alignement des accélérateurs linéaires." Université Louis Pasteur (Strasbourg) (1971-2008), 1996. http://www.theses.fr/1996STR13275.
Takorabet, Noureddine. "Optimisation de l'alimentation des convertisseurs électromécaniques linéaires à induction." Vandoeuvre-les-Nancy, INPL, 1996. http://docnum.univ-lorraine.fr/public/INPL_T_1996_TAKORABET_N.pdf.
Gerardin, Frédéric. "Etude de la compensation de charge d'espace dans les lignes basse énergie des accélérateurs d'ions légers de haute intensité." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS001/document.
The study of intense ion beam dynamics in lowenergy beam transport line (LEBT) representsone of the most important challenges inaccelerating sciences. At low energy, it isdominated by the space-charge field created bythe beam itself, which is generally non-linearand can induce halo, emittance growth and beamlosses. But, a ion beam at low energypropagating in a LEBT ionises the residual gas.The particles (ions and electrons) fromionisation are repelled or confined radially bythe space charge field according to their chargesign.Other interactions take place in the LEBT,modifying the beam dynamics and the space chargecompensation time and the space-chargecompensation yield. In order to obtain predictiveand precise results quantitatively, numericalsimulations of beam transport in space-chargecompensation regime with WARP code havebeen realized taking account the most probablephysical interactions. Then, we will discuss theresults with comparisons with experimental dataobtained on the MYRRHA and IFMIF LEBT’s
Peaucelle, Christophe. "La problématique de l'évolution des moments d'une densité de particules soumises à des forces non linéaires." Phd thesis, Grenoble INPG, 2001. http://tel.archives-ouvertes.fr/tel-00001153.
Bramoullé, Céline. "Etude par le code Monte Carlo PENELOPE des faisceaux de rayons X produits par des accélérateurs linéaires d'électrons SL-Elekta." Toulouse 3, 2000. http://www.theses.fr/2000TOU30128.
Valette, Matthieu. "Etudes de dynamique faisceau pour les accélérateurs IFMIF." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS242/document.
As part of the Broader Approach to Fusion concluded between Japan and Europe, the IFMIF (International Fusion Materials Irradiation Facility) project was launched for the study of future fusion materials resisting intense neutron fluxes. A major component of it is the couple of twin high power accelerators (2 × 5 MW) which will produce the neutron flux by bombarding a Lithium target with a deuterium beam at an energy of 40 MeV. Considering these ambitious specifications, a first phase called EVEDA (Engineering Validation and Engineering Design Activity) is ongoing to provide the design and construction of an up to scale prototype accelerator to an energy of 9 MeV in Japan. The work of this thesis belongs to the field of Accelerators Physics. It consists of beam dynamics studies for the prototype accelerator LIPAc, characterized by unprecedented current and power, thereby requiring outstanding beam quality. The characteristics of this accelerator, makes many studies and simulations for all stages of its commissioning required. Concurrently, background studies on core-halo interactions and on the effects of space charge on high current beams will also be conducted. In particular a new definition of the halo of a particle beam, adapted to the study of these accelerators will be proposed and implemented
Peaucelle, Christophe. "La problématique de l'évolution des moments d'une densité de particules soumises à des forces non linéaires." Phd thesis, Grenoble INPG, 2001. http://www.theses.fr/2001INPG0095.
High-power linear accelerators are needed as driver for several projects (spallation neutron sources, hybrid system). This interest brings us to the question of dynamics of high intensity particle beam. Inside intense beam, particles are under non linear forces mainly due to space charge effects. In order to have less heavy and more realistic tools than classical simulation methods (particle-particle interactions, particle-core model), we consider a description of the evolution of a particle density from its statistical parameters, its moments. In a first part, a detailed analysis of the moment problems is shown in a simplified but non restrictive case. To begin with, we develop an original study based on orthogonal polynomial properties which allows us to study one-dimension density moments. We can see that we obtain information about density from only few moments. Such an investigation is essential for a better understanding of moment significance. Then, we apply this description to two-dimension phase space, so that we can precisely estimate where particles are in this phase space. Finally, we enumerate difficulties met and deduce the limits of this method. The second part of this thesis, more experimental, presents beam the measurements of the beam characteristics of accelerator "GENEPI" as a part of hybrid reactor program. Moreover, we show how these specifications yields to beam calibration and validation of theoretical calculations used to design GENEPI
Wang-Gassot, Huimin. "Etudes de la stabilité mécanique des cavités supraconductrices et de la méthode de rigidification par projection thermique de cuivre." Paris 11, 2001. http://www.theses.fr/2001PA112314.
Today's researche in nuclear physics and in particle physics needs high energy or high intensity accelerators; the use of superconducting cavities constitutes a very important technological advance for the design of such facilities, allowing high accelerating gradient with few dissipation. One of the major problems is the frequency shift under Lorentz forces : since the quality factor of the superconducting cavities is much higher than the external factor depending on the beam charge, their bandwidths are very narrow (several Hertz). Even very small mechanical deformations under Lorentz forces could induce a frequency shift which exceeeds the bandwidth when the accelerating gradient becomes very high. The contribution of this thesis consists at first in a numerical analysis of this problem, then in a mechanical study of a new method for stiffening superconducting cavities : a copper coating over their external surface by thermal spray techniques
Serrano, Benjamin. "Validation physique par Monte Carlo de la modulation d'intensité sur l'accélérateur Primus et le système de plan de traitement Helax TMS : application aux tumeurs cancéreuses ORL." Nice, 2006. http://www.theses.fr/2006NICE4015.
The intensity modulated radiation therapy is a technique consisting on the modulation of the irradiation fluence beam. It involves an optimized dose distribution in the patient and minimizes safe tissue irradiation. At the Center Antoine Lacassagne, this technique had been implemented once the acquisition of a multileaf accelerator Primus has been made. Meanwhile, the dose distribution in a heterogeneous phantom, typically of head and neck regions, presents some discrepancies between the calculated and the measured dose. This work aims to explain these discrepancies. In the first part a Monte Carlo simulation of the photon beam for the two nominal potential energies of 6 and 25 MV delivered by the linear electron accelerator have been realized. These investigations were performed with the Monte Carlo radiation transport computer code MCNPX. Some adjustments on the primary electron beam energy and the spot size of the source, given by the manufacturer, have been applied to optimize the adjustment between the ionization chamber and the Monte Carlo simulation on the depth-dose and the dose profile distributions. The second part of this work permits us to check the calculation data given by the treatment planning system in a heterogeneous phantom. The result shows a bad approximation of the material density by the TPS and explains the discrepancies encountered during the implementation of IMRT. We also show the utility of the "collapsed cone" dose calculation algorithm and the non-appropriateness of radiological film in heterogeneous medium. At least the complete accelerator modelling has been achieved and its development for clinical applications will be investigated
Fuhrmann, Celso. "Contribution à l'étude des structures accélératrices bipériodiques à ondes stationnaires pour électrons." Paris 11, 1985. http://www.theses.fr/1985PA112022.
Experimental results on biperiodic standing wave accelerating structures are presented. These structures which are characterized by a high effective shunt impedance, are designed for standing wave, high duty cycle electron accelerators. Two types of structures are studied: the on-axis coupled structure and the coaxial coupled structure. The expressions for the dispersion relation, coupling coefficients, phase and group velocity are derived from a coupled resonator model. An experimental method to eliminate the stopband is put forward. The influence of the coupling slots on the dispersion curves is studied experimentally. The effective shunt impedance and the transit time factor are measured by the field perturbation techniques. Measured parameters are compared with SUPERFISH theoretical calculations. The field perturbation technique is also applied to measure the transverse shunt impedance of the dipole modes which are responsible for the beam breakup phenomenon
Vinatier, Thomas. "Influence des paramètres du laser sur la dynamique des paquets courts d’électrons relativistes dans des accélérateurs linéaires basés sur des canons RF et développement de diagnostics associés." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112195/document.
In several applications, quasi-relativistic sub-ps electron bunches are required: Laser-plasma acceleration, Free electron lasers, Generation of intense THz radiation, Study of ultra-fast phenomena in matter… The short nature of the bunch and the necessity of a high peak current for the applications imply strong space-charge forces leading to a degradation of beam properties, as its transverse emittance and duration. The main difficulty is to characterize, model and take into account these effects. My thesis falls within this context through the study of dynamics and diagnostics related to these short bunches, namely whose rms duration is not directly measurable by an electronic method locating the border at a few tens of picoseconds. The chapter 2 consists in the measurements of several properties of these bunches: charge, transverse emittance and duration. The originality of my work is that I use simple methods, both on the theoretical (analytical at maximum) and technological (using only common elements of electron accelerators) point of view. These methods, more suitable for less extreme bunches, allow however obtaining very good results. I especially developed a method of charge measurement from the measurement of the light intensity emitted by a scintillating screen following the interaction with an electron beam. This method allows precisely measuring charges lower than 100fC. This is better than the capabilities of classical diagnostics (ICT and Faraday Cup) limited to the picocoulomb because of electronic noise. This method is useful since the short bunches are often low-charged to minimize the effects of space-charge forces. It will also be used for detectors calibration, which requires low charges. I also adapt multiparametric methods to measure the transverse emittance and duration of electron bunches. These indirect methods allow determining these properties from the measurement of other more accessible properties: the transverse dimensions for the transverse emittance and the energy spread for the duration. The duration measurement (3-phase method) gives very good results, since it allows determining with accuracy better than 10% rms durations lower than one picosecond. The emittance measurement without taking into account the space-charge forces in the modeling gives mixed results, since the accuracy is from 20% (3-gradients method) to more than 100% (3-screens method). A significant accuracy improvement, up to a factor of 5, can be obtained by taking the space-charge forces into account through a beam envelop equation, which constitutes the originality of my work. The chapter 3 consists in the comparison of the properties of short electron beams, single or longitudinally modulated, generated by three different methods: Injection of a short or longitudinally modulated laser pulse in an RF-gun; Magnetic compression in a chicane; RF-compression in an accelerating structure (Velocity Bunching). I particularly shown that, at equal conditions of charge, the generation of short bunches thanks to a short laser pulse driven an RF-gun is disadvantageous, both from the beam duration and transverse emittance point of view, with respect to a magnetic or RF compression of an already accelerated beam. This is explained by the more important space-charge forces just after the beam emission by the photocathode. It also consists in the development and test of analytical models for longitudinal beam dynamics. I developed a longitudinal transfer matrix for RF-gun, starting from a Kim-like model. This model has been compared with several measurements performed at PITZ and PHIL and shown to be accurate on the energy and temporal aspects, but not on the energy spread aspect. I also developed an analytical model of the velocity bunching phenomenon in travelling wave accelerating structures, starting from a simple model developed by P. Piot
Kenne, Godpromesse. "Méthodes d'identification pour des systèmes non linéaires avec paramètres variant dans le temps : application aux machines tournantes à induction." Paris 11, 2003. http://www.theses.fr/2003PA112146.
This dissertation deals with on-line identification of nonlinear systems with time-varying parameters. The algorithms developed here are potentially useful for the design of the drives that can adjust controller parameters automatically. Another possible application is for the detection of failure. Two approaches have been designed. The first approach is based on the sliding mode observer (SMO). Two identification schemes using this approach have been investigated for electrical parameters and rotor flux estimation of an induction motor. The first and the second scheme are based respectively on the dynamical law and algebraic law which converge in finite time. The simulation and expenmental results have been compared to the results obtained using the recursive least square methods (RLSM). The methods based on the SMO are more robust with respect to parameters uncertainties, measures noises and are more easily implementable than the RLSM method. The second approach is based on the radial basis function neuronal predictor. We proposed parameters estimation scheme using this predictor for a large class of nonlinear systems with time-varying parameters. This method has been combined with high-gain observer to estimate electrical parameters and rotor speed of a three phase induction motor. The method can also be applied to the design of the mot or drives in sensorless control. Real-time implementation results obtained using both approaches show the fast convergence of the estimates to their true values and the robustness of both approaches with respect to time-varying parameters, measures noises, parameters and model uncertainties and sampling effects
Bernier, Nikita. "Study of the photoproduction of 8Li with the reaction ⁹Be(g, p)⁸Li." Master's thesis, Université Laval, 2013. http://hdl.handle.net/20.500.11794/24290.
The TRIUMF laboratory in Vancouver B.C. is a world leader in the production of rare radioactive ion beams. Such beams are fundamental in research for nuclear physics, nuclear astrophysics and solid state science among others. TRIUMF is constructing a 50 MeV, 10 mA superconducting electron linac as part of its ARIEL project. The accelerated electrons will be used to produce RIB through photodisintegration. The electron beam is “converted” into photons by braking radiation of the electrons passing through a high Z material placed immediately before the production target. The initial target to be employed is 9Be, used to produce a 8Li beam. The 9Be is imbedded in a BeO compound manufactured at TRIUMF and designed following specifications of IPN Orsay where the preliminary tests will be conducted while ARIEL is being constructed. Both the power deposition and rare isotope production rates were calculated using the Monte Carlo simulation package FLUKA.
Gillieaux, Olivier. "Modélisation des éléments non linéaires dans la simulation des convertisseurs statiques d'énergie." Toulouse, INPT, 1998. http://www.theses.fr/1998INPT017H.
Chen, Langshi. "Méthode de Krylov itératives avec communication et efficacité énergétique optimisées sur machine hétérogène." Thesis, Lille 1, 2015. http://www.theses.fr/2015LIL10114/document.
Iterative methods are frequently used in extremely large scale linear problems, such solving linear systems or finding eigenvalue/eigenvectors of matrices. As these iterative methods require a substantial computational workload, they are normally deployed on large clusters of distributed memory architectures communicated via MPI. When the problem size scales up, the communication becomes a major bottleneck of reaching a higher scalability because of two reasons: 1) Many of the iterative methods rely on BLAS-2 low level matrix vector kernels that are communication intensive. 2) Data movement (memory access, MPI communication) is much slower than processor's speed. In case of sparse matrix operations such as Sparse Matrix Vector Multiplication (SpMV), the communication even replaces the computation as the dominant time cost. Furthermore, the advent of accelerators/coprocessors like Nvidia's GPU make computation cost more cheaper, while the communication cost remains high in such CPU-coprocessor heterogeneous systems. Thus, the first part of our work focus on the optimization of communication cost of iterative methods on heterogeneous clusters. Besides the communication cost, power wall becomes another bottleneck of future exascale computing in recent time. Researches indicate that a power-aware algorithmic implementation strategy could efficiently reduce the power dissipation of large clusters. We also explore the potential energy saving implementation of iterative methods in our experimentation. Finally, both the communication optimization and energy efficiency implementation would be integrated into a GMRES method, which demands an auto-tuning framework to maximize its performance
Plewa, Jérémie-Marie. "Etude de l'influence des plasmas dans les diodes à électrons pour la radiographie éclair." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30156/document.
Intense X-ray flash radiography is used to take a stop-action picture of a material under extreme conditions like high densification, high temperature and high movement speed. The success of this kind of radiography is based on the quality of the X-ray source which must necessarily be penetrating (some MeV), intense (several rads), short (a few tens of ns) and small (a few mm). The X-ray pulse is generated from the bremsstrahlung radiation emitted during the interaction with a metal target of a focused electron beam of high energy (MeV) and high intensity (kA). This process strongly links the properties of the electron beam to those of the X-ray beam and thus to the quality of the radiography picture. In this context, the thesis is about the electron beam dynamics in the electron diode (i.e. just before electrons move towards the accelerator) as well as about the characterization of the velvet plasma from which electrons are extracted to form the beam. Firstly, the dynamics of the intense electron beam was studied using the LSP code based on the "Particle-In-Cell" method. The simulations were compared to measurements made on the injector of a linear induction accelerator, at the CEA Valduc center on the Epure facility. Based on the developed simulation model, a new single-pulse electron diode was designed, sized and realized during this thesis to increase the intensity of the electron beam from 2.0 kA to 2.6 kA, thus improving the radiographic performances of the facility. In a second step, a model allowing to study the mechanisms involved in the production of the electron beam from the cathode plasma was developed. This latter is a collisional-radiative model (CRM) 0D describing the evolution of the plasma species density of a plasma whose composition is directly related to the molecules and atoms desorbed by the velvet cathode. [...]
Dubois, Jérôme. "Contribution à l'algorithmique et à la programmation efficace des nouvelles architectures parallèles comportant des accélérateurs de calcul dans le domaine de la neutronique et de la radioprotection." Thesis, Lille 1, 2011. http://www.theses.fr/2011LIL10109/document.
In science, simulation is a key process for research or validation. Modern computer technology allows faster numerical experiments, which are cheaper than real models. In the field of neutron simulation, the calculation of eigenvalues is one of the key challenges. The complexity of these problems is such that a lot of computing power may be necessary. The work of this thesis is first the evaluation of new computing hardware such as graphics card or massively multicore chips, and their application to eigenvalue problems for neutron simulation. Then, in order to address the massive parallelism of supercomputers national, we also study the use of asynchronous hybrid methods for solving eigenvalue problems with this very high level of parallelism. Then we experiment the work of this research on several national supercomputers such as the Titane hybrid machine of the Computing Center, Research and Technology (CCRT), the Curie machine of the Very Large Computing Centre (TGCC), currently being installed, and the Hopper machine at the Lawrence Berkeley National Laboratory (LBNL). We also do our experiments on local workstations to illustrate the interest of this research in an everyday use with local computing resources
Hubert-Tremblay, Vincent. "Élaboration des éléments d'une simulation Monte Carlo permettant l'évaluation d'une planification de traitement en radiothérapie externe : compression d'images DICOM à l'aide d'un octree et modélisation de la tête d'un accélérateur linéaire." Thesis, Université Laval, 2006. http://www.theses.ulaval.ca/2006/23953/23953.pdf.
Gong, Jinlin. "Modélisation et conception optimale d’un moteur linéaire à induction pour système de traction ferroviaire." Thesis, Ecole centrale de Lille, 2011. http://www.theses.fr/2011ECLI0016/document.
This thesis focuses on studying the performance of the linear induction motor using the method of finite element analysis, and the optimal design on a time-costly model. The finite element method is used to study the performance of the linear induction motor. Firstly, the 2D finite element model (FEM) is constructed, which allows taking into account the longitudinal end effects. The transverse edge effects are taken into account within 2D model by varying the conductivity of the secondary and by adding the inductance of the winding overhang. Secondly, a coupled model between the magnetic and thermal 3D FEM is built which allows taking into account both the end effects and the temperature influence. Finally, a test bench is realized to validate the models. The comparison between the different models shows the importance of the coupled model. Optimal design using finite element modeling tools is a complex task and also time-costly. The surrogate model-assisted optimization strategies are studied. The direct surrogate model-assisted optimization and the Efficient Global Optimization are compared. A three-level output space-mapping technique is proposed to reduce the computation time. The optimization results show that the proposed algorithm allows saving a substantial computation time compared to the classical two level output space-mapping. Using the 3D FEM, a multi-objective optimization with a progressive improvement of a surrogate model is proposed. The proposed strategy evaluates the FEM in parallel. A 3D Pareto front composed of the finite element model evaluation results is obtained, which allows taking the decision for the engineering design
Bourat, Christophe. "Système de découpage sous-harmonique d'un faisceau d'électrons pour injecteur d'accélérateur linéaire." Paris 11, 1988. http://www.theses.fr/1988PA112018.
The need of a 100 % duty cycle electron accelerator for use in nuclear physics, has led in 1981 the CEN Saclay Linear Accelerator Group, to study a machine using the existing linac associated with a pulse stretcher ring. The production of electron bunches at the ring RF frequency (600 MHz) requires the design of a new injector including a chopping beam system with a deflecting electromagnetic cavity and a collimator. A comparison between four transverse magnetic modes, led to choose a TM110 parallelepipedic chopper. The construction of a prototype and of a vacuum-tight cavity followed by microwave measurements has permitted to solve several mechanical problems and to specify the cavity electrical properties. In a first step1the beam line, including - focusing, offset deflection coils, chopping with a rectangular collimator - has been studied, for zero intensity beam current, on the basis of a matrix model. An experimental 40 keV beam line, has been assembled to measure the bunch length. The method was based on a spectral analysis of the signal delivered by a large band, 50 ohms adapted beam collector. The bunch shape in the time domain was reconstructed by inverse Fourier transform. The beam dynamics has been studied with a 3D space charge model which has been introduced into the PARMELA tracking code. Simulations showed that a 150 keV, 2A beam could be chopped with the same deflecting lay-out
Garolfi, Luca. "Accélérateur linéaire d'électrons à fort gradient en bande S pour ThomX." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS007/document.
The ThomX source should provide quasi-monochromatic high-quality X-rays (range 45-90 keV). The framework of the thesis is the electron beam linac energy upgrade from 50 MeV to 70 MeV necessary to achieve X-rays of 90 keV. For this purpose, the development of a compact high-gradient S-band electron accelerating structure is needed. It implies a research and development (R&D) activity at LAL in partnership with a French company (PMB-Alcen) in the High-Gradient (HG) technology of accelerating structures. The LAL-PMB-Alcen collaboration aims at the fabrication of a normal-conducting HG S-band structure by tackling the technological aspects that limit the achievement of high-gradient acceleration mostly due to vacuum RF breakdown and pulsed heating fatigue. Basically, the electromagnetic and thermal design of the HG S-band accelerating section has been performed at LAL. Meanwhile, PMB-Alcen was in charge to perform the fabrication, tuning and low power tests of prototypes and the final accelerating section. In this work, a fully coupled electromagnetic-thermal-structural finite element analysis on the THOMX RF gun has been performed with Ansys workbench. The HG accelerating section final regular cell dimensions and the power coupler design have been optimized. In particular, the electromagnetic simulation techniques and outcomes have been applied to constant impedance (CI) TW prototypes and also to a constant gradient (CG) final accelerating section. This allowed to verify the geometry choice, validate the fabrication procedure and check the fulfilment of the normal operating conditions. Moreover, a coupled thermo-mechanical study on a CI copper prototype has been performed. The water cooling system has been simulated to validate the capability to extract the heat generated by the dissipated power on the walls of the structure and guarantee a uniform temperature distribution along the section. Also, vacuum simulations have been performed on a 16-cells CI copper prototype and also on the final CG accelerating section. In addition, the main steps for the fabrication of the RF gun at LAL and a 7-cells aluminium prototype at PMB-Alcen have been presented. RF low power tests on the prototype have been performed in order to validate the 3D geometry design and the machining process. Taking into account the experimental results, mechanical problems and technological constraints have been tackled and some solutions have been proposed for the future copper prototype fabrication. Finally, beam dynamics simulations of the ThomX linac has been carried out by ASTRA code. The aim is to reduce as much as possible the energy spread and the transverse emittance to preserve the spectral purity of the produced X-rays, at the electron-photon interaction point. A model as close as possible to the characteristics of the real components, such as RF gun, TW section and solenoids has been considered. Important results came out from these simulations regarding laser parameters (spot size and duration), the maximum magnetic field of solenoids for high space charge effect compensation, dephasing between the RF and laser in the gun and effect of the travelling wave electromagnetic field on the particle dynamics. Different options for the parameter settings of machine operation and a new configuration of the solenoids position have been proposed. An optimization of the beam dynamics properties has been obtained by using a genetic algorithm and the ultimate performances of the electron beam have been highlighted
Bensafa, Imad Khaled. "Mesure de l'asymétrie de spin de faisceau en diffusion Compton virtuelle polarisée sur le proton." Clermont-Ferrand 2, 2006. http://tel.archives-ouvertes.fr/docs/00/08/34/67/PDF/bensafa.pdf.
Zhang, Lei. "Contribution to robust and adaptive control and observation of linear induction machine : High order sliding mode approach." Thesis, Bourgogne Franche-Comté, 2018. http://www.theses.fr/2018UBFCA010.
Dynamic end effects play an important role in the Linear Induction Machine (LIM) control. They increase significantly the nonlinearity of the machine model and generate several difficulties to control and observe states with good performances. This thesis addresses three distinctissues: LIM robust control, LIM speed and flux estimation and observer-based robust control using higher order sliding mode theory.In the first part, to achieve speed and flux tracking,Super Twisting Controller (STC), Adaptive Super Twisting Controller (ASTC), and Adaptive Twisting Controller (ATC) were proposed and implemented into LIM system with great performance, i.e. finite time convergence and robustness properties. Among them, STC ensures continuous control with finite time convergence of the error to zero despite disturbances, under the assumption that their bounds are known. ATC and ASTC can deal with unknown bounded disturbance thanks to their adaptive properties.In the second part, a novel simplified LIM model was proposed and its observability has been proved. Then, Second Order Sliding Mode Observer (SOSMO) and Adaptive High Order Sliding Mode Observer (HOSMO) were proposed to estimate LIM speed, only by using the measured stator voltages and stator currents. SOSMO observer is based on the super twisting algorithm and its stability has been proved with Lyapunov’s theory, which can guarantee finite time convergence with less chattering. Adaptive HOSMO strategy combines speed adaptive algorithm and HOSMO method together to estimate rotor fluxes and speed simultaneously.In the third part, the LIM is viewed as two second order subsystems. Moreover, only the speed and the flux are supposed to be measured. Based on that two differentcontrollers based on HOSMO were presented in order to achieve flux and speed tracking. In both controllers, the idea of active disturbance rejection control is applied. Hence, the HOSMO is used to estimate the derivatives of the flux and the speed, as well as the disturbance. Then, in order to deal with the uncertainty in the measured variables, two different SM controllers are proposed. Firstly, the TC is applied in the LIM. However, the control signal in this case is discontinuous. Then, in order to provide a continuous control signal, the TC is replaced with STC. The stability and convergence of proposed TC-HOSMO and STC-HOSMO approaches were given and simulation validated their performances
Moreau, Stéphanie. "Conception d'un algorithme de reconstruction de vertex pour les données de CMS - Etude de détecteurs gazeux (MSGC) et silicium à micropistes." Phd thesis, Université Louis Pasteur - Strasbourg I, 2002. http://tel.archives-ouvertes.fr/tel-00392517.
L'étude des détecteurs gazeux à micropistes (MSGC) a porté sur les derniers tests sous un faisceau de haute intensité avant leur remplacement dans le trajectographe de CMS. Ces tests ont permis de montrer un nombre faible de pistes perdues ainsi qu'un rapport signal sur bruit stable. Ce test a donc prouvé que les MSGC répondaient aux exigences pour être intégrées au trajectographe de CMS.
La contribution suivante a consisté en l'étude de détecteurs silicium à micropistes et de son électronique associée sous un faisceau de type "25 ns". Ces tests ont indiqués un bon fonctionnement de l'électronique de contrôle et du système d'acquisition. Le rapport signal sur bruit, le delai et l'efficacité de reconstruction ont aussi été étudiés.
La dernière étude a porté sur la conception d'un algorithme de reconstruction consacré à la recherche de vertex secondaires dans la cadre du projet ORCA. Cet algorithme itératif a pour but d'être utilisé pour l'identification de jets contenant des quarks b. Cette partie analyse aussi les performances de reconstruction de vertex primaires (avec et sans empilement)
Leste, Jérémy. "Mise en œuvre et apports cliniques d'un modèle Monte-Carlo d'un accélérateur linéaire de radiothérapie externe." Thesis, Toulouse 3, 2020. http://www.theses.fr/2020TOU30242.
The validation of radiotherapy treatment is based on the calculation of absorbed dose. The algorithms used in the clinic routinely are fast but limited in some cases. In these situations, the Monte-Carlo (MC) calculation remains the reference. However, it is complex to set up, and requires significant computing resources. In this context, this thesis work consisted of developing a MC double calculation solution adapted to clinical cases, and to study its possible application and contribution. To that end we have developped a package named GAMMORA (GAte Monte carlo MOdel for Radiotherapy Application). It includes the MC modeling of the TrueBeam (Varian) implemented on the GATE platform, as well as a python script to automatically generate the simulation macros for all types of treatments (electrons, VMAT, SRS, SBRT, VMAT-SBRT) from the patient's DICOM data. The model has already been validated for simple photon beam applications (X-RTE). We completed it by integrating the modeling of the electron beams (e-RTE) and those of complex clinical cases. By parallelizing the simulations on a high-performance computing cluster (CALMIP), we achieved reasonable calculation times with a statistical uncertainty always less than 2% in the areas of interest (from 10 min for the e-RTE to 3 h for the X -RTE). To avoid the use of large phase space files (PHSP), we created and validated a deep learning particle generator (GAN) based on the manufacturer's PHSP. For the e-RTE, the applicators were modeled for simple and complex fields. The simulations were validated by comparing them to the reference measurements made in water for the energies 6, 9, 12, and 18 MeV. We also compared the performance of GAMMORA and the clinical algorithm (eMC) with measurements (radiochromic films) for a complex phantom with heterogeneity (bone and lung) and surface irregularity. GAMMORA's results were better or equivalent to eMC's in almost all configurations. The clinical case study also showed significant differences in dose distributions between the two algorithms (particularly in high density regions). An interplay effect (IE) study was then performed. First, measurements were taken using a quality control phantom (Octavius 4D) placed on a programmable 3D motion platform. It was a question of qualitatively evaluating the IE for a few configurations. Then, these configurations and 75 others were simulated using GAMMORA to study the IE extensively by modifying different physical parameters (period, amplitude and shape of motion, dose per fraction or safety margins). An adapted methodology allowed us to isolate the IE from the blurring. The results show that the IE alone induced statistically significant differences between the predicted dose distribution and the one delivered. [...]
Lambert, Guillaume. "Harmoniques cohérentes du Laser à Electrons Libres générées à partir d'harmoniques produites dans les gaz sur le prototype de l'accélérateur SCSS." Phd thesis, Université Paris Sud - Paris XI, 2008. http://tel.archives-ouvertes.fr/tel-00267686.
Debbou, Mustapha. "Modélisation et commande d'un système innovant pour la propulsion navale." Thesis, Toulouse, INPT, 2014. http://www.theses.fr/2014INPT0028.
This study focuses on the benefits that can be induced by the use of the Double Fed Induction Machine (DFIM) operating in motor mode for marine propulsion systems. It can be achieved by the additional degree of freedom it provides, firstly, by exploiting the natural structural redundancy, and secondly, by the alytical redundancy introduced by applied control strategies. The first part of this thesis presents the modeling of a propeller architected mainly around the DFIM and its load such as a propeller with three fixed and symmetrical blades. Several control strategies have been introduced to control the system, in fact, linear and nonlinear control laws type associated with various modulators have been validated and applied to the propulsion structure. The objective was to evaluate the influence of these techniques for two major design criteria, namely, losses in power converters, and noise and vibration noise. Naval propulsion as any embedded system has requirements for the quality of service not only in performance but also reliability and availability. Indeed, the systems designed for these types of applications must ensure and guarantee continuity of service in response to the failures in system components. The use of MADA in propulsion systems provides a natural structural and analytical redundancies which ensure system service continuity in the presence of a fault in this structure. Two faults are considered in this study, a power semiconductor fault in the power converter and a speed sensor / position failure. Control strategies proposed, the propeller modeling established and reconfigurations adopted following settings have been validated by simulation and experimentally on the real laboratory or industrial benches developed in the context of this study
Egberts, Jan. "IFMIF-LIPAc Beam Diagnostics. Profiling and Loss Monitoring Systems." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00772158.
Cheymol, Benjamin. "Développement des instruments de mesures des profiles transversaux et d'emittance pour l'accélérateur linéaire LINAC4 au CERN." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2011. http://tel.archives-ouvertes.fr/tel-00877031.
Blanco, Oscar. "Dynamique des faisceaux dans la section finale de focalisation du futur collisionneur linéaire." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112108/document.
The exploration of new physics in the “Tera electron-Volt” (TeV) scale with precision measurements requires lepton colliders providing high luminosities to obtain enough statistics for the particle interaction analysis. In order to achieve design luminosity values, linear colliders feature nanometer beam spot sizes at the Interaction Point (IP).Three main issues to achieve the beam size demagnification in the Final Focus Section (FFS) of the accelerator are the chromaticity correction, the synchrotron radiation effects and the correction of the lattice errors.This thesis considers two aspects for linear colliders: push the limits of linear colliders design, in particular the chromaticity correction and the radiation effects at 3 TeV, and the instrumentation and experimental work on beam stabilization in a test facility.A new chromaticity correction scheme, called non-interleaved, is proposed to the local and non-local chromaticity corrections for CLIC. This lattice is designed and diagnosed, where the main issue in the current state of lattice design is the non-zero second order dispersion in the Final Doublet (FD) region where a strong sextupole is used to correct the remaining geometrical components.The radiation effect can be evaluated by tracking particles through the lattice or by analytical approximations during the design stage of the lattices. In order to include both, radiation and optic parameters, during the design optimization process, two particular radiation phenomena are reviewed: the Oide effect and the radiation caused by bending magnets .The analytical result of the radiation in bending magnets in was generalized to the case with non-zero alpha and non-zero dispersion at the IP, required during the design and luminosity optimization process. The closed solution for one dipole and one dipole with a drift is compared with the tracking code PLACET, resulting in the improvement of the tracking code results.The Oide effect sets a limit on the vertical beamsize due to the radiation in the final quadrupole. Only for CLIC 3 TeV this limit is significant, therefore two possibilities are explored to mitigate its contribution to beam size: double the length and reduce the QD0 gradient, or the integration of a pair of octupoles before and after QD0.Part of the requirements of the FFS for new linear accelerators are tested in The Accelerator Test Facility (ATF). The beam size reduction using the local chromaticity correction is explored by an extension of the original design, called ATF2 with two goals: achieve 37 nm of vertical beam size at the IP, and the stabilization of the IP beam position at the level of few nanometres. Since 2014 beam size of 44 nm are achieved as a regular basis at charges of about 0.1 × 10^10 particules per bunch.A set of three cavities (IPA, IPB and IPC), two upstream and one downstream of the nominal IP and on top of separate blocks of piezo-electric movers, were installed and are used to measure the beam trajectory in the IP region, thus providing enough information to reconstruct the bunch position and angle at the IP. These will be used to for beam stabilization and could detect beam drift/jitter beyond the tolerable margin and undetected optics mismatch affecting the beam size measurements. The specifications required of 1 nm resolution over 10 μm dynamic range at 1.0 × 10 10 particules per bunch with the ATF2 nominal optics have not been yet achieved.The minimum resolution achieved is just below 50 nm at 0.4 × 10^10 particules per bunch with a set of electronics impossing a noise limit on resolution of 10 nm per cavity. The dynamic range is 10 μm at 10 dB attenuation and 0.4 × 10^10 particules per bunch, indicating the need to upgrade theelectronics. The integration to the ATF tuning instruments is ongoing. Nonetheless, feedback has been tested resulting in reduction of beam jitterdown to 67 nm, compatible with resolution