Generation of monoenergetic ion beams with a laser accelerator

Die vorliegende Arbeit beschäftigt sich mit der Erzeugung monoenergetischer Protonen- und Ionenstrahlen mittels laserbasierter Teilchenbeschleuniger. Eine Methode wurde entwickelt, welche es erlaubt, die bei relativistischen Laser-Plasma-Wechelswirkungen auf Festköpertargets auftretenden Raumladungseffekte gezielt mit einer punktartigen Teilchenquelle zu kombinieren. Durch diese einzigartige Interaktionsgeometrie konnten zum ersten Mal Protonenstrahlen mit einem intrinsisch schmalen Energiespektrum mit einem wenige Mikrometer großen Laserbeschleuniger generiert werden. Der experimentelle Aufbau wurde im Verlauf der vergangenen drei Jahre konsequent im Hinblick auf Reproduzierbarkeit und die maximal erzielten Teilchenenergien verbessert. Der daraus resultierende Grad an Verlässlichkeit erlaubte die Bestimmung der ersten Energie-Skalierungsgesetze speziell für monoenergetische Protonenstrahlen. Darüber hinaus konnte die Interaktionsgeometrie auf verschiedene Targetmaterialien übertragen werden, was die Erzeugung monoenergetischer Kohlenstoffstrahlen ermöglichte. Die experimentelle Arbeit wurde von der parallelen Entwicklung eines komplexen theoretischen Modells unterstützt, welches die Beobachtungen vollständig erklärt und in hervorragender Übereinstimmung mit zahlreichen numerischen Simulationen ist. Die hier vorgestellten Ergebnisse weisen weit über die Grenzen der vorliegenden Arbeit hinaus: Die Möglichkeit, zuverlässig monoenergetische Ionenstrahlen mittels kompakter, laserbasierte Teilchenbeschleuniger zu erzeugen ist, in Verbindung mit den einzigartigen Eigenschaften laserproduzierter Teilchenstrahlen, von fundamentaler Bedeutung für die Grundlagenforschung, für die Materialwissenschaften und potenzielle medizinische Anwendungen und wird maßgeblich zur Entwicklung einer neuen Generation von Beschleunigern beitragen.A method for the generation of monoenergetic proton and ion beams from a laser-based particle accelerator is presented. This method utilizes the unique space-charge effects occurring during relativistic laser-plasma interactions on solid targets in combination with a dot-like particle source. Due to this unique interaction geometry, MeV proton beams with an intrinsically narrow energy spectrum were obtained, for the first time, from a micrometer-scale laser accelerator. Over the past three years, the acceleration scheme has been consistently improved to enhance both the maximum particle energy and the reliability of the setup. The achieved degree of reliability allowed to derive the first scaling laws specifically for monoenergetic proton beams. Furthermore, the acceleration scheme was expanded on other target materials, enabling the generation of monoenergetic carbon beams. The experimental work was strongly supported by the parallel development of a complex theoretical model, which fully accounts for the observations and is in excellent agreement with numerical simulations. The presented results have an extraordinarily broad scope way beyond the current thesis: The availability of monoenergetic ion beams from a compact laser-plasma beam source in conjunction with the unique properties of laser-produced particle beams addresses a number of outstanding applications in fundamental research, material science and medical physics, and will help to shape a new generation of accelerators

MIT-Portugal Program

Thesis (S.M. in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 197-205).As the world turns increasingly towards knowledge economies, the integration of innovation, higher education (HE) and research policies continues to gain importance. In 2006, the Portuguese government and MIT launched the MIT-Portugal Program (MPP) as an integrative, university-centered innovation strategy that aims at reorienting Portuguese engineering education and research around the issues of innovation, entrepreneurship and technology management, serving as an incubator to establish missing links between universities and industry. The program was conceived as a targeted response to Portugal's specific innovation challenges. These challenges derive both from the country's specific socio-economic trajectory as well as general European reform pressure, and include for example the creation of strong graduate programs in engineering and science to address a critical lack in human resources, greater internationalization of Portuguese education and research, the achievement of critical research mass and international competitiveness in some designated key areas, and a greater involvement of external stakeholders and particularly industry in the universities. This thesis provides a real-time assessment of the MIT-Portugal Program one year prior to the completion of its current 5- year funding cycle. The thesis finds that MPP indeed represents an apposite, effective and comprehensive policy response to Portugal's imminent innovation challenges. The concerted combination of multiple policy tools has yielded important and visible successes, most notably in the creation of strong and international education programs, an unprecedented degree of networking and collaboration among Portuguese researchers and institutions, and the re-orientation of engineering education around innovation and industry needs. Secondly, the assessment has revealed significant opportunities for program improvement as well as some persistent barriers to implementation, in particular in the domains of industry linkages, program outreach and communication, and certain systemic and legal challenges that frame MPP's operation within the Portuguese system. Based on the thesis findings, thirdly, a continuation of the program beyond the current cycle is strongly recommended in order to extract the maximum benefit from the collaboration, to strengthen sustainable long-term bonds between the participating institutions, to include the lessons from the first period, and to ensure the retention and dissemination of the program achievements throughout the system. While such a renewal is highly uncertain due to the current economic constraints on Portugal and Europe as well as the substantial degree of politicization surrounding the Program, MPP should be viewed as a long-term strategic investment with great spillover potential into the Portuguese higher education and innovation system that is worth harnessing and expanding. Finally, the thesis argues that MPP does in fact provide a generalizable framework that could serve as a model strategy for other catching-up countries facing similar challenges.by Sebastian M. Pfotenhauer.S.M.in Technology and Polic

A cascaded laser acceleration scheme for the generation of spectrally controlled proton beams

We present a novel, cascaded acceleration scheme for the generation of spectrally controlled ion beams using a laser-based accelerator in a 'double-stage' setup. An MeV proton beam produced during a relativistic laser–plasma interaction on a thin foil target is spectrally shaped by a secondary laser–plasma interaction on a separate foil, reliably creating well-separated quasi-monoenergetic features in the energy spectrum. The observed modulations are fully explained by a one-dimensional (1D) model supported by numerical simulations. These findings demonstrate that laser acceleration can, in principle, be applied in an additive manner.Deutsche Forschungsgemeinschaft (DFG contract no. TR18)Deutsche Forschungsgemeinschaft (contract no. 03ZIK052)European Union (Laserlab Europe

Circular economy inspired imaginaries for sustainable innovations

In this chapter, Narayan and Tidström draw on the concept of imaginaries to show how Circular Economy (CE) can facilitate values that enable sustainable innovation. Innovation is key for sustainability, however, understanding and implementing sustainable innovation is challenging, and identifying the kind of actions that could direct sustainable innovations is important. The findings of this study indicate that CE-inspired imaginaries enable collaboration and by relating such imaginaries to common and shared social and cultural values, intermediaries could motivate actors into taking actions that contribute to sustainable innovation.fi=vertaisarvioitu|en=peerReviewed