No description available.

Proton sources driven by high-power lasers are a promising addition to the portfolio of conventional proton accelerators. Regarding particle cancer therapy, where tumours are irradiated with protons or ions, the novel accelerator technology can be particularly beneficial for translational research - the research branch in which results of basic research are transferred to new approaches for the prevention, diagnosis and treatment of cancer. The overarching aim in the thesis at hand was a translational pilot study to irradiate tumours on mice’s ears with laser-accelerated protons while achieving the quality level of conventional proton accelerators. This is the only way to compare the radiobiological data of the novel accelerator technology with those of the established ones. To enable such experiments a predetermined dose distribution according to the radiobiological model’s requirements must be delivered to a sample volume. Ergo, the laser-driven protons have to be transported and shaped after their initial acceleration. Intense laser-driven proton pulses, inherently broadband and highly divergent, pose a challenge to established beamline concepts on the path to application-adapted irradiation field formation, particularly for 3D. This work demonstrates the successful implementation of a highly efficient and tuneable pulsed dual solenoid setup to generate a homogeneous (laterally and in depth) volumetric dose distribution using only a single dose pulse from the broad laser-driven proton spectrum. The experiments using the ALBUS-2S beamline were conducted at the titanium:sapphire high-power laser Draco PW at the Helmholtz-Zentrum Dresden–Rossendorf. The beamline and its model were characterised and verified via independent methods, leading to first experimental studies providing volumetrically homogeneous dose distributions to detector targets as well as tumour and normal tissue in proof-of-concept studies. To perform the mouse pilot study, a new solenoid with cooling capacities was designed, characterised and implemented in the course of this thesis. The combination of the new solenoid and an overall performance improvement of the laser-proton accelerator, enabled the successful conduction of the mouse model study. The results show that laser-accelerated protons induce a comparable tumour growth delay as protons from conventional accelerators. This outcome and the demonstration of the flawless interaction between laser-proton accelerator, beam transport, dosimetry and biology qualify the laser-based accelerator technology for complex studies in translational cancer research. Looking into the future, their unique extremely high intensity renders them of particular interest for the investigation into the ultra-high dose rate regime. There, the so-called FLASH effect shows fewer side effects in normal tissue while maintaining the same effect in the tumour when the target dose is administered in milliseconds rather than minutes, as currently common. The ALBUS-2S setup at Draco PW already provides all necessary conditions to realise irradiation times of around ten nanoseconds in preclinical studies. This significantly expands the parameter space for investigating the FLASH effect and is presented as a proof-of-concept in this thesis.

Proton sources driven by high-power lasers are a promising addition to the portfolio of conventional proton accelerators. Regarding particle cancer therapy, where tumours are irradiated with protons or ions, the novel accelerator technology can be particularly beneficial for translational research - the research branch in which results of basic research are transferred to new approaches for the prevention, diagnosis and treatment of cancer. The overarching aim in the thesis at hand was a translational pilot study to irradiate tumours on mice’s ears with laser-accelerated protons while achieving the quality level of conventional proton accelerators. This is the only way to compare the radiobiological data of the novel accelerator technology with those of the established ones. To enable such experiments a predetermined dose distribution according to the radiobiological model’s requirements must be delivered to a sample volume. Ergo, the laser-driven protons have to be transported and shaped after their initial acceleration. Intense laser-driven proton pulses, inherently broadband and highly divergent, pose a challenge to established beamline concepts on the path to application-adapted irradiation field formation, particularly for 3D. This work demonstrates the successful implementation of a highly efficient and tuneable pulsed dual solenoid setup to generate a homogeneous (laterally and in depth) volumetric dose distribution using only a single dose pulse from the broad laser-driven proton spectrum. The experiments using the ALBUS-2S beamline were conducted at the titanium:sapphire high-power laser Draco PW at the Helmholtz-Zentrum Dresden–Rossendorf. The beamline and its model were characterised and verified via independent methods, leading to first experimental studies providing volumetrically homogeneous dose distributions to detector targets as well as tumour and normal tissue in proof-of-concept studies. To perform the mouse pilot study, a new solenoid with cooling capacities was designed, characterised and implemented in the course of this thesis. The combination of the new solenoid and an overall performance improvement of the laser-proton accelerator, enabled the successful conduction of the mouse model study. The results show that laser-accelerated protons induce a comparable tumour growth delay as protons from conventional accelerators. This outcome and the demonstration of the flawless interaction between laser-proton accelerator, beam transport, dosimetry and biology qualify the laser-based accelerator technology for complex studies in translational cancer research. Looking into the future, their unique extremely high intensity renders them of particular interest for the investigation into the ultra-high dose rate regime. There, the so-called FLASH effect shows fewer side effects in normal tissue while maintaining the same effect in the tumour when the target dose is administered in milliseconds rather than minutes, as currently common. The ALBUS-2S setup at Draco PW already provides all necessary conditions to realise irradiation times of around ten nanoseconds in preclinical studies. This significantly expands the parameter space for investigating the FLASH effect and is presented as a proof-of-concept in this thesis. / Protonenquellen, die von Hochleistungslasern getrieben werden, sind eine vielversprechende Ergänzung zu herkömmlichen Protonenbeschleunigern. Im Hinblick auf die Partikeltherapie von Krebserkrankungen, bei der Tumoren mit Protonen oder Ionen bestrahlt werden, kann die neuartige Beschleunigertechnologie vor allem der translationalen Forschung von Nutzen sein, in der die Ergebnisse der Grundlagenforschung in neue Ansätze zur Vorsorge, Diagnose und Behandlung von Krebserkrankungen übertragen werden. Übergeordnetes Ziel der vorliegenden Arbeit war eine translationale Pilotstudie zur Bestrahlung von Tumoren an Mäuseohren mit laserbeschleunigten Protonen bei gleichzeitiger Erfüllung des Qualitätsniveaus konventioneller Protonenbeschleuniger. Mit den Ergebnissen ist ein Vergleich der strahlenbiologischen Daten der neuen und der etablierten Beschleunigertechnologie möglich. Um dieses Experiment zu realisieren, muss eine vorher festgelegte Strahlendosis, die den Anforderungen des radiobiologischen Modells entspricht, an ein Probenvolumen abgegeben werden. Die lasergetriebenen Protonenpulse müssen dafür nach ihrer Beschleunigung transportiert und geformt werden. Intensive lasergetriebene Protonenpulse sind von Natur aus breitbandig und stark divergent. Sie stellen eine Herausforderung für etablierte Beamline-Konzepte auf dem Weg zu einer anwendungsangepassten Bestrahlungsfeldbildung dar, insbesondere bei einer räumlichen Anwendung. Diese Arbeit zeigt die erfolgreiche Implementierung eines hocheffizienten und abstimmbaren gepulsten Zwei-Solenoid-Aufbaus zur Erzeugung einer homogenen (lateral und in der Tiefe) volumetrischen Dosisverteilung mit einem einzigen Dosispuls aus dem breiten lasergetriebenen Protonenspektrum. Die Experimente an der ALBUS-2S3 Beamline wurden am Titan:Saphir-Hochleistungslaser Draco4 PW am Helmholtz-Zentrum Dresden– Rossendorf durchgeführt. Die Beamline und ihr Modell wurden experimentell charakterisiert und mit unabhängigen Methoden verifiziert. Es konnten erste experimentelle Studien durchgeführt werden, bei denen volumetrisch homogene Dosisverteilungen auf Detektorziele sowie Tumor- und Normalgewebe in Proof-of-Concept Studien appliziert wurden. Für die Durchführung der Maus-Pilotstudie wurde im Rahmen dieser Arbeit ein neuer kühlbarer Solenoid entworfen, charakterisiert und implementiert. Zusammen mit einer allgemeinen Leistungsverbesserung des Laser-Protonen Beschleunigers wurde die Pilotstudie erfolgreich abgeschlossen. Sie zeigt, dass laserbeschleunigte Protonen eine vergleichbare Verzögerung des Tumorwachstums bewirken wie Protonen aus konventionellen Beschleunigern. Dieses Ergebnis und der Nachweis des einwandfreien Zusammenspiels von Laser- Protonen-Beschleuniger, Strahltransport, Dosimetrie und Biologie qualifizieren die laserbasierte Beschleunigertechnologie für komplexe Studien in der translationalen Krebsforschung. Mit Blick auf die Zukunft sind sie aufgrund ihrer einzigartigen, extrem hohen Intensität besonders interessant für die Untersuchung im Bereich ultrahoher Dosisleistungen. Dort zeigt der so genannte FLASH-Effekt weniger Nebenwirkungen im gesunden Normalgewebe bei gleicher Wirkung im Tumor. Die Zieldosis wird dabei innerhalb von Millisekunden verabreicht und nicht, wie derzeit üblich, innerhalb von Minuten. Der ALBUS-2S-Aufbau bei Draco PW bietet bereits alle notwendigen Voraussetzungen, um in präklinischen Studien Bestrahlungszeiten von etwa zehn Nanosekunden zu realisieren. Dies erweitert den Parameterraum für die Untersuchung des FLASH-Effekts erheblich und wird in dieser Arbeit auch als Proof-of-Concept vorgestellt.

Rapid progress in ultra-intense laser technology has resulted in intensity levels surpassing 1022 W/cm2, reaching the highest possible density of electromagnetic energy amongst all controlled sources available in the laboratory. During recent decades, fast growth in available intensity has stimulated numerous studies based on the use of high intensity lasers as a unique tool for the initiation of nonlinear behavior in various basic systems: first molecules and atoms, then plasma resulting from the ionization of gases and solids, and, finally, pure vacuum. Apart from their fundamental importance, these studies reveal various mechanisms for the conversion of a laser pulse's energy into other forms, opening up new possibilities for generating beams of energetic particles and radiation with tailored properties. In particular, the cheapness and compactness of laser based sources of energetic protons are expected to make a revolution in medicine and industry.   In this thesis we study nonlinear phenomena in the process of laser radiation interacting with plasmas of ionized targets. We develop advanced numerical tools and use them for the simulation of laser-plasma interactions in various configurations relating to both current and proposed experiments. Phenomenological analysis of numerical results helps us to reveal several new effects, understand the physics behind them and develop related theoretical models capable of making general conclusions and predictions. We develop target designs to use studied effects for charged particle acceleration and for the generation of attosecond pulses of unprecedented intensity. Finally, we analyze prospects for experimental activity at the upcoming international high intensity laser facilities and uncover a basic effect of anomalous radiative trapping, which opens up new possibilities for fundamental science.

The generation of high current multi-MeV protons and ions by irradiation of short pulse high intense laser on an ultra-thin target has been observed and subjected great interest in recent. When ultra-thin overdense target is irradiated by focused ultraintense laser pulse, hot electrons are generated by various mechanisms and they generate energetic ion beams. In TNSA, a quasi-electrostatic field is produced on the target rear surface when the the laser pulse interacts with overdense target, driving hot electrons go torward the target rear surface. However, this mechanism results in a range of field gradients leading to a broad proton energy distribution typically. To overcome the issue, an alternative accelration mechanism has been presented to achieve the quasi-monoenergetic proton acceleration and the mechanism is called Radiation Pressure Acceleration. In the RPA, the radiation pressure push electrons into the target smoothly and setting up an electrostatic field by the laser pressure. In this thesis, we study two alternative experimental methods for the quasi-monoenergetic proton acceleration and find experimental feasibility of the presented methods from other research groups. / text

No description available.

No description available.

Experimental results and simulations of imploding fusion concepts have identified the Rayleigh-Taylor (RT) instability as one of the largest inhibitors to achieving fusion. Understanding the origin and development of the RT instability will allow for the development of mitigating measures to dampen the instability growth, thus improving the chance that fusion concepts such as inertial confinement fusion (ICF) are successful. A study of 1D and 2D simulations are presented for investigating RT instability growth in deceleration stage of imploding geometries. Two cases of laser-driven implosion geometry, Cartesian and cylindrical, are used to study late stage deceleration-phase RT instability development on the interior surface of imploding targets. FLASH's hydrodynamic (HD) and magnetohydrodynamic (MHD) modeling capabilities are used for different laser and target parameters in order to study the RT instability and the impact of externally applied magnetic fields on their evolution. Several simulation regimes have been identified that provide novel insight into the impact that a seeded magnetic field can have on RT instability growth and the conditions under which magnetic field stabilization of the RT instability is observable. Finally, future work and recommendations are made. / Master of Science / The direction for the future of renewable energy is uncertain at this time; however, it is known that the future of human energy consumption must be green in order to be sustainable. Fusion energy presents an opportunity for an unlimited clean renewable energy source that has yet to be realized. Fusion is achieved only by overcoming the earthly limitations presented by trying to replicate conditions at the interior of stellar structures. The pressures, temperature, and densities seen in the interior of stars are not easily reproduced, and thus human technology must be developed to reach these difficult stellar conditions in order to harvest fusion energy. There are two main branches of developmental technology geared towards achieving the difficult conditions controlled nuclear fusion presents, magnetic confinement fusion (MCF) and inertial confinement fusion (ICF)[17]. Yet in both approaches barriers exist which have thwarted the efforts toward reaching fusion ignition which must be addressed through scientific discovery. Successfully reaching ignition is only the first step in the ultimate pursuit of a self sustaining fusion reactor. This work will focus on the experimental ICF configuration, and on one such inhibitor toward achieving ignition, the Rayleigh-Taylor (RT) instability. The RT instability develops on the surfaces of the fusion fuel capsules, targets, and causes nonuniform compression of the target. This nonuniform compression of the target leads to lower pressures and densities through the material mixing of fusion fuel and the capsule shell, which ultimately leads to challenges with reaching fusion ignition. The work presented here was performed utilizing the University of Chicago's FLASH code, which is a state-of-the-art open source radiation magneto-hydrodynamic (MHD) code used for plasma and astrophysics computational modeling [11]. Simulations of the RT instability are performed using FLASH in planar and cylindrical geometries to explore fundamental Rayleigh-Taylor instability evolution for these two different geometries. These geometries provide easier access for experimental diagnostics to probe RT dynamics. Additionally, the impact of externally applied magnetic fields are explored in an effort to examine if and how the detrimental instability can be controlled.

La problématique de génération de champs magnétiques quasi-statiques intenses constitue un défi pour la physique de l’interaction laser-plasma. Proposé il y a 30 ans, l’utilisation de cibles "boucles" irradiées par laser se distinguent par leur design compact ne nécessitant aucune génération de courant pulsé en plus de la puissance laser et ont dévoilé récemment leur grand potentiel.Ce travail de thèse s’attache à la caractérisation des phénomènes physiques et au développement de cette technique. On a ainsi montré la génération de forts champs magnétiques quasi-statiques par interaction laser-matière (500 J, durée laser de 1 ns et intensité ~10^17 W/cm^2) atteignant une amplitude de plusieurs centaines de Teslas pendant 2 à 3 ns. L'évolution temporelle et la distribution spatiale des champs magnétiques ont été mesurés par trois diagnostics indépendants : sondes B-dot, rotation de Faraday et défléctométrie de protons. La caractérisation des mécanismes physiques sous-jacents ont aussi fait appel à des diagnostics de rayonnements X de la région irradiée par laser ainsi qu’à des mesures d’ombroscopie optique du fil de la boucle en expansion.Une application de ces champs au guidage magnétique d’électrons relativistes dans la matière dense a permis d'ouvrir de nouvelles perspectives au transport de hautes densités d’énergies dans la matière. En effet, en laissant suffisamment de temps pour que le champ magnétique pénètre dans la cible dense, une amélioration d’un facteur 5 de la densité d’énergie portée par les électrons après 50 µm de propagation a été mise en évidence.En outre, des décharges de courants intenses consécutives à l'irradiation par impulsion laser courtes (50 J, durée laser < 1 ps et intensité ~10^19 W/cm^2) ont été observées. Une imagerie protonique de la décharge a permis de mesurer la propagation d’une onde électromagnétique à des vitesses proches de la vitesse de la lumière. Cette onde d’une durée de ~ 40 ps a été utilisée comme lentille électromagnétique pour focaliser et sélectionner sur une bande étroite d'énergie un faisceau de protons de plusieurs MeV (jusqu’à 12 MeV) passant dans la boucle.Les résultats de ces différentes mesures et applications expérimentales ont été par ailleurs confrontées à des simulations et à des modèles analytiques.Les applications de cette thèse se déploient sur des aspects comme :- la fusion par confinement inertiel, en guidant des faisceaux d'électrons relativistes jusqu'au cœur de la capsule de combustible, tout en confinant les particules qui y déposent leur énergie ainsi que celles créées par les réactions de fusion nucléaire;- l'astrophysique et la planétologie de laboratoire, en générant des sources secondaires de particules énergétiques ou de rayonnement afin de porter la matière dense a de très hautes températures (matière tiède et dense), ou en magnétisant des plasmas pour reproduire des phénomènes astrophysiques à plus petite échelle au laboratoire;- et enfin le contrôle de faisceaux de particules chargées dans le vide pour le développement de sources laser dans le cadre d'applications s'effectuant à distance de la source notamment en science, dans l'industrie, ou même en médecine. / The problem of strong quasi-static magnetic field generation is a challenge in laser-plasma interaction physics. Proposed 30 years ago, the use of the laser-driven capacitor-coil scheme, which stands out for its compact design while not needing any additional pulsed power source besides the laser power, only recently demonstrated its potential.This thesis work aims at characterizing the underlying physics and at developing this scheme. We demonstrated the generation of strong quasi-static magnetic fields by laser (500 J, 1 ns-duration and ~10^17 W/cm^2 intensity) of several hundreds of Teslas and duration of 2-3 ns. The B-field space- and time-evolutions were characterized using three independent diagnostics: B-dot probes, Faraday rotation and proton-deflectometry). The characterization of the underlying physical processes involved also X-ray diagnostics of the laser-irradiated zone and optical shadowgraphy of the coil rod expansion.A novel application of externally applied magnetic fields to guide relativistic electron beam in dense matter has been carried out and the obtained results set the ground for improved high-energy-density transport in matter. Indeed, allowing sufficient time for the dense target magnetization, a factor 5 improvement of the electron energy-density flux at 50µm-depth was evidenced.Besides, the generation of high discharge currents consecutive to short laser pulse irradiation (50 J, <1 ps-duration and ~10^19 W/cm^2 intensity) was also pointed out. Proton imaging of the discharge permitted to measure the propagation of an electromagnetic wave at a velocity close to the speed of light. This wave, of ~40ps-duration, was used as an electromagnetic lens to focalize and energy-select a narrow energy range within a multi-MeV proton beam (up to 12 MeV) passing through the coil.All-above experimental measurements and application results were thoroughly compared to both computer simulations and analytic modeling.The applications of this thesis work in a near future will concern:- inertial confinement fusion, by guiding relativistic electron beams up to the dense core nuclear fuel, and by confining particles depositing their energy in it, or even those resulting from the fusion reactions;- laboratory planetology and astrophysics, by generating secondary sources of energetic particles and radiation to reach the warm-dense-matter state or by magnetizing plasmas to reproduce astrophysical phenomena in scaled experiments;- and finally, the control of charged particle beams in vacuum, useful in particular for the development of laser-driven sources for distant applications in science, industry or even medecine.

Physics at extreme conditions is not a young field; there have been decades of developments that have allowed us to generate high-pressure and high-temperature conditions in a vast array of materials. Conventionally, these extreme conditions were generated using static compression techniques; compressing a material in a diamond anvil cell which could then be heated or cooled, with structural information deduced using synchrotron radiation. These techniques are still invaluable for extreme conditions research although the pressures and temperatures that are accessible to them are limited by the strength of the diamond anvil cells and their ability to withstand extreme temperatures. The necessity for access to pressure-temperature states that are beyond the scope of the conventional diamond anvil cell is driven by the need to characterise extreme environments such as planetary interiors. It was long believed that materials in high pressure-temperature states would exhibit relatively simple, high-symmetry crystal structures, but recent research has proven that, conversely, there is an abundance of complex structural behaviour at these extreme conditions. One means of attaining pressure-temperature states beyond those accessible using static compression techniques is to impart a large amount of energy into a material in a comparatively short period of time (milliseconds to nanoseconds); this is known as dynamic compression. Dynamic compression can be generated using impact techniques or, alternatively, via laser ablation. Access to the most extreme conditions is commonly achieved by generating a shockwave which compresses the sample with the fastest achievable compression wave. Not only does this type of compression facilitate access to the most extreme states, it also allows us to explore the physics of impact phenomena and other such situations involving rapid energy transfer. Dynamic compression occurs on short timescales and, as such, there is a considerable challenge in implementing diagnostics to study the behaviour of compressed materials. Furthermore, because complexity is commonplace in extreme conditions, it is vital that any diagnostics should be able to provide data of high enough quality that this complexity may be resolved. The advent of 4th generation light sources (x-ray free electron lasers) has afforded us the opportunity to obtain extraordinarily high quality data on dynamic compression timescales. In the interest of refining analytical techniques when utilising this novel technology, materials exhibiting complex crystal structures should be investigated. Antimony is an element which is known, under static compression, to transform from a Peierls-distorted rhombohedral phase (R-3m) to an incommensurately modulated host-guest structure (I'4=mcm(00γ)000s), a structure with an incredibly high level of complexity. The complexity of this host-guest phase, and the relatively low pressure at which it forms, makes antimony an ideal candidate for testing the resolution achievable using these 4th generation light sources. Furthermore, it is interesting to observe whether such a complex phase can form on the short timescales of dynamic compression. In this work antimony is both statically and dynamically compressed and the results of both experiments are compared. A static phase diagram is constructed for antimony up to 31 GPa and 835 K, confirming the location of a previously theorised triple point and suggesting the location of an additional triple point. Three solid phases are characterised and data are found to agree with the pre-existing static compression studies. The nature of the host-guest phase is investigated and the guest 'chains' are found to remain intact even at the highest temperatures and pressures, a result which has not previously been observed in high pressure-temperature host-guest structures. Dynamic data from shock-compression experiments at pressures up to 59.3 GPa are plotted alongside the static data and contrasting phase behaviour is discussed. Four solid phases are identified along with one liquid phase. Observation of the host-guest phase in shock-compressed antimony confirms that highly complex crystal structures are able to form on the nanosecond timescale.