Ultrashort, nearly monochromatic hard X-ray pulses enrich the understanding of the dynamics and function of matter, e.g., the motion of atomic structures associated with ultrafast phase transitions, structural dynamics and (bio)chemical reactions. Inverse Compton backscattering of intense laser pulses from relativistic electrons not only allows for the generation of bright X-ray pulses which can be used in a pumpprobe experiment, but also for the investigation of the electron beam dynamics at the interaction point. The focus of this PhD work lies on the detailed understanding of the kinematics during the interaction of the relativistic electron bunch and the laser pulse in order to quantify the influence of various experiment parameters on the emitted X-ray radiation. The experiment was conducted at the ELBE center for high power radiation sources using the ELBE superconducting linear accelerator and the DRACO Ti:sapphire laser system. The combination of both these state-of-the-art apparatuses guaranteed the control and stability of the interacting beam parameters throughout the measurement. The emitted X-ray spectra were detected with a pixelated detector of 1024 by 256 elements (each 26μm by 26μm) to achieve an unprecedented spatial and energy resolution for a full characterization of the emitted spectrum to reveal parameter influences and correlations of both interacting beams. In this work the influence of the electron beam energy, electron beam emittance, the laser bandwidth and the energy-anglecorrelation on the spectra of the backscattered X-rays is quantified. A rigorous statistical analysis comparing experimental data to ab-initio 3D simulations enabled, e.g., the extraction of the angular distribution of electrons with 1.5% accuracy and, in total, provides predictive capability for the future high brightness hard X-ray source PHOENIX (Photon electron collider for Narrow bandwidth Intense X-rays) and potential all optical gamma-ray sources. The results will serve as a milestone and starting point for the scaling of the Xray flux based on available interaction parameters of an ultrashort bright X-ray source at the ELBE center for high power radiation sources. The knowledge of the spatial and spectral distribution of photons from an inverse Compton scattering source is essential in designing future experiments as well as for tailoring the X-ray spectral properties to an experimental need.

RésuméLa diffraction et la diffusion de rayons X sont utilisées dans de nombreux domaines de la physique, de la médecine et de la technologie. Des faisceaux de haute brillance sont néanmoins requis pour améliorer les performances de ces techniques. L’utilisation de la diffusion Compton d’un laser sur un faisceau d’électrons présente un grand intérêt pour la production de rayons X. Ce processus permet l’emploi d’un anneau de stockage d’électrons compacts et d’un résonateur optique pour accroître la puissance laser. Avec un tel système, un taux de collision laser-électron supérieur au méga Hertz est envisageable permettant d’atteindre un flux de rayons X de l’ordre de 10¹³ photons/s. Dans le premier chapitre, je décris les motivations pour le développement d’une source de rayons X basée sur la diffusion Compton et utilisant un résonateur optique. Je détermine aussi les performances que l’on peut attendre de ce type de sources ainsi que l’état de l’art actuel dans ce domaine. Dans le deuxième chapitre, je décris le comportement et les propriétés des résonateurs optiques en régime impulsionnel. J’introduis la notion de phase CEP (‘carrier envelope phase’) et je montre la nécessité de contrôler à la fois la fréquence de répétition de l’oscillateur laser et cette phase CEP. Le chapitre 3 est consacré aux oscillateurs fibrés à blocage de mode. Je montre les performances du laser que j’ai construit en utilisant le phénomène de rotation de polarisation non-linéaire.La méthode d’asservissement laser-résonateur optique ‘tilt locking’ est introduite au chapitre 4. Je décris tout d’abord les études de simulations et le montage expérimental qui ont permis de tester la méthode en régime impulsionnel. Je donne ensuite les résultats expérimentaux qui démontrent la faisabilité de la méthode ‘tilt locking’ en régime impulsionnel. J’effectue aussi une comparaison expérimentale des performances de la méthode ‘tilt locking’ avec la méthode classique ‘Pound-Drever-Hall’. Je termine le chapitre en indiquant une difficulté expérimentale de la méthode pour générer plusieurs signaux d’erreurs.Je décris la conception du système optique de la machine Compton TTX de l’université Tsinghua dans le chapitre 5. Les performances attendues pour cette machine sont des flux de rayons X compris entre 10¹º et 10¹³ photons/s. / X-ray diffraction and scattering, X-ray spectroscopy, and X-ray crystallography are widely used in the life sciences, material science, and medical diagnosis. High-quality and high-brightness X-rays are a strong requirement to improve applications. Inverse Compton scattering (ICS) X-ray source has attracted great interests worldwide lately. To significantly enhance the average X-ray photon flux, a compact electron storage-ring combined with a high finesse optical enhancement cavity (OEC) can be utilized. In such a system, the collision rate between the electron beam and the laser pulse is greatly increased to the MHz range, enabling a photon flux up to 10¹³ph/s.In the first chapter, I describe the motivation behind the development of OEC based on ICS X-ray source. The characteristics of this kind of X-ray source are summarized, compared to those of the conventional low-repetition-rate Terawatt laser system based on ICS X-ray source. The latest progress and research status of OEC based on ICS X-ray source are presented. Pulsed-laser injected high-finesse OEC stacking theory and properties are discussed in Chapter 2. Not only does the OEC based on ICS X-ray source require the laser pulse repetition rate to be matched to the free spectral range (FSR) of the cavity, where both also have to match the electron storage-ring circulation frequency. In addition, we have to match the phase shift of the laser repetition rate to the phase offset introduced by the dispersion of the cavity mirrors, since our cavity finesse design value is quite high. The stacking theory is analyzed in the frequency domain. Cavity properties, including cavity mirror dispersion, finesse, and FSR, are discussed in detail. A laser frequency comb and OEC coupling is analyzed also. The laser source development is presented in Chapter 3. We constructed a mode-locked fiber laser based on nonlinear polarization rotation. The locking model, locking techniques, and the theory, simulations and experimental tests of tilt locking (TL) in the pulsed laser injected high-finesse OEC are discussed in Chapter 4. We succeeded in locking a pulsed laser to a high-finesse cavity with the TL technique. The experimental results show that the TL and the Pound–Drever–Hall techniques have the same performance: stable locking, high sensitivity, and the same power coupling rate for picosecond laser pulse case, while the test results for full spectrum TL locking show that it is uneasy to align the split-photodiode to the beam waist.Based on the above experimental study and tests, we design the OEC system for Tsinghua University X-ray project in Chapter 5. The expected X-ray flux is 10¹º to 10¹³ ph/s. We detail every subsystem requirement.

X-ray diffraction and scattering, X-ray spectroscopy, and X-ray crystallography are widely used in the life sciences, material science, and medical diagnosis. High-quality and high-brightness X-rays are a strong requirement to improve applications. Inverse Compton scattering (ICS) X-ray source has attracted great interests worldwide lately. To significantly enhance the average X-ray photon flux, a compact electron storage-ring combined with a high finesse optical enhancement cavity (OEC) can be utilized. In such a system, the collision rate between the electron beam and the laser pulse is greatly increased to the MHz range, enabling a photon flux up to 10¹³ph/s.In the first chapter, I describe the motivation behind the development of OEC based on ICS X-ray source. The characteristics of this kind of X-ray source are summarized, compared to those of the conventional low-repetition-rate Terawatt laser system based on ICS X-ray source. The latest progress and research status of OEC based on ICS X-ray source are presented. Pulsed-laser injected high-finesse OEC stacking theory and properties are discussed in Chapter 2. Not only does the OEC based on ICS X-ray source require the laser pulse repetition rate to be matched to the free spectral range (FSR) of the cavity, where both also have to match the electron storage-ring circulation frequency. In addition, we have to match the phase shift of the laser repetition rate to the phase offset introduced by the dispersion of the cavity mirrors, since our cavity finesse design value is quite high. The stacking theory is analyzed in the frequency domain. Cavity properties, including cavity mirror dispersion, finesse, and FSR, are discussed in detail. A laser frequency comb and OEC coupling is analyzed also. The laser source development is presented in Chapter 3. We constructed a mode-locked fiber laser based on nonlinear polarization rotation. The locking model, locking techniques, and the theory, simulations and experimental tests of tilt locking (TL) in the pulsed laser injected high-finesse OEC are discussed in Chapter 4. We succeeded in locking a pulsed laser to a high-finesse cavity with the TL technique. The experimental results show that the TL and the Pound-Drever-Hall techniques have the same performance: stable locking, high sensitivity, and the same power coupling rate for picosecond laser pulse case, while the test results for full spectrum TL locking show that it is uneasy to align the split-photodiode to the beam waist.Based on the above experimental study and tests, we design the OEC system for Tsinghua University X-ray project in Chapter 5. The expected X-ray flux is 10¹º to 10¹³ ph/s. We detail every subsystem requirement.

X-ray diffraction and scattering, X-ray spectroscopy, and X-ray crystallography are widely used in the life sciences, material science, and medical diagnosis. High-quality and high-brightness X-rays are a strong requirement to improve applications. Inverse Compton scattering (ICS) X-ray source has attracted great interests worldwide lately. To significantly enhance the average X-ray photon flux, a compact electron storage-ring combined with a high finesse optical enhancement cavity (OEC) can be utilized. In such a system, the collision rate between the electron beam and the laser pulse is greatly increased to the MHz range, enabling a photon flux up to 10¹³ph/s.In the first chapter, I describe the motivation behind the development of OEC based on ICS X-ray source. The characteristics of this kind of X-ray source are summarized, compared to those of the conventional low-repetition-rate Terawatt laser system based on ICS X-ray source. The latest progress and research status of OEC based on ICS X-ray source are presented. Pulsed-laser injected high-finesse OEC stacking theory and properties are discussed in Chapter 2. Not only does the OEC based on ICS X-ray source require the laser pulse repetition rate to be matched to the free spectral range (FSR) of the cavity, where both also have to match the electron storage-ring circulation frequency. In addition, we have to match the phase shift of the laser repetition rate to the phase offset introduced by the dispersion of the cavity mirrors, since our cavity finesse design value is quite high. The stacking theory is analyzed in the frequency domain. Cavity properties, including cavity mirror dispersion, finesse, and FSR, are discussed in detail. A laser frequency comb and OEC coupling is analyzed also. The laser source development is presented in Chapter 3. We constructed a mode-locked fiber laser based on nonlinear polarization rotation. The locking model, locking techniques, and the theory, simulations and experimental tests of tilt locking (TL) in the pulsed laser injected high-finesse OEC are discussed in Chapter 4. We succeeded in locking a pulsed laser to a high-finesse cavity with the TL technique. The experimental results show that the TL and the Pound-Drever-Hall techniques have the same performance: stable locking, high sensitivity, and the same power coupling rate for picosecond laser pulse case, while the test results for full spectrum TL locking show that it is uneasy to align the split-photodiode to the beam waist.Based on the above experimental study and tests, we design the OEC system for Tsinghua University X-ray project in Chapter 5. The expected X-ray flux is 10¹º to 10¹³ ph/s. We detail every subsystem requirement.

La diffusion Compton inverse est l’interaction entre un photon et un électron de haute énergie. Il en résulte l’émission d’un nouveau photon d’énergie supérieure à celle du photon incident suivant la trajectoire de l’électron. Ces propriétés rendent possible la création d’une source de rayonnement X hautement directive, monochromatique accordable dans une large gamme spectrale. Il suffit d’accélérer les électrons sur quelques mètres pour leur faire gagner l’énergie minimale requise. Les photons proviennent d’une chaîne laser fortement amplifiée. Une telle source est donc relativement compacte, peu couteuse à mettre en oeuvre et facilement accessible aux utilisateurs. Elle est particulièrement adaptée aux besoins des musées ou des hôpitaux pour des applications comme l’analyse d’oeuvres historiques ou la radiothérapie. L’objectif de cette thèse est de mettre en oeuvre une source de rayonnement X par diffusion Compton inverse en bout de ligne de l’accélérateur ELSA (Electrons et Laser, Sources X et applications). L’installation ELSA comprend un accélérateur linéaire d’électrons appartenant à la Direction des Applications Militaires du Commissariat à l’Energie Atomique à Bruyères-le-Châtel (CEA DAM). Le but est de produire des impulsions de rayonnement X ultra-courtes dans une gamme énergétique allant de 10 à 100 keV. Elle servira notamment à la caractérisation de détecteurs à réponse ultra-rapide développés à la DAM. Un système optique destiné à augmenter le flux de rayonnement X produit a été développé. Il consiste à replier la trajectoire du laser pour empiler les impulsions au point d’interaction. Dans le même but, une mise à niveau de l’installation à été réalisée afin d’augmenter l’énergie des électrons de 18 à 30 MeV. Les résultats expérimentaux ont enfin été comparés aux résultats obtenus à l’aide de simulations PIC 3D. / X-ray sources based on inverse Compton scattering process produce tunable near-monochromatic and highly directive X-rays. Recent advances in laser and accelerator technologies make the development of such very compact hard X-ray sources possible. These sources are particularly attractive in several applications such as medical imaging, cancer therapy or culture-heritage study, currently performed in size-limited infrastructures. The main objective of this thesis is the development of an inverse Compton scattering source on the ELSA linac of CEA at Bruyères-le-Châtel as a calibration tool for ultra-fast detectors.A non-resonant cavity was designed to multiply the number of emitted X-ray photons. The laser optical path is folded to pile-up laser pulses at the interaction point, thus increasing the interaction probability. Another way of optimizing the X-ray yield consists in increasing the electron bunch density at the interaction point, which is strongly dependent on the electron energy. A facility up-grade was performed to increase the electron energy up to 30 MeV. The X-ray output gain obtained thanks to this system was measured and compared with calculated expectations and 3D PIC simulations.

En astronomie gamma, les systèmes binaires sont des objets stellaires impliquant une étoile massive et un objet compact, le plus léger des deux en orbite autour de l’autre. Ils émettent de façon régulière à haute et très haute énergie (E > 100 GeV) et peuvent être détectés par le réseau de télescopes H.E.S.S.. Malgré leur faible nombre, ils présentent une grande diversité de comportement et sont caractérisés par une modulation de flux dépendant de la position de l’objet compact. 2 systèmes binaires sont étudiés : LS 5039 et PSR B1259–63, en effet un jeu de données conséquent est disponible puisque ces sources sont observées maintenant depuis plus de 10 ans. En 2012, le cinquième télescope de plus grande taille a commencé ses observations et permet ainsi de faire la connexion avec le domaine du GeV.Une modélisation de ces deux systèmes binaires dans le cas d’une diffusion anisotrope inverse Compton dans le régime de Klein–Nishina sera aussi proposée avec une prise en compte du disque circumstellaire pour PSR B1259¡63. Les données recueillies lors d’une observation peuvent être détériorées par une atmosphère dégradée, affectant ainsi le flux de photons ° collectés. Un coefficient traduisant la qualité de l’atmosphère est donc nécessaire. De plus les gerbes peuvent être déformées à cause de laprésence du champ magnétique terrestre, les études de ces phénomènes sont donc nécessaires pour essayer de corriger ces effets. / Binary systems in gamma astronomy are stellar objects involving a massive star with a compact object, the lightest in orbit around the other. They emit regularly at high energy and very high energy (E > 100 GeV) for detection by H.E.S.S. telescopes. Despite their low relative number, they are all characterized by a modulation of gamma photon flux which depends on the position of the lightest object. We will focus more on 2 binary systems : LS 5039 and PSR B1259–63, we have a susbstantial data, H.E.S.S. telescopes have regularly observed these objects for more than 10 years. In 2012, a fifth telescope much larger size, began observations and enables to get events at lower energy and then make the connection with other experiments such as Fermi-LAT. A modelling of these two binary systems in anisotropic inverse Compton in Klein–Nishina regime are also presented and the circumstellar disk is taken into account for PSR B1259–63. Data taken by theH.E.S.S. telescopes can be improved. During observations, atmosphere can be degraded and thus affecting the flux of gamma photons collected. It’s therefore important to know the transparency coefficient of the atmosphere during an analysis. Furthermore, the electromagnetic air showers are more distorted because of the Earth’s magnetic field, a study of these phenomenas is necessary to correct these effects.