Simulation and measurement of the dynamics of ultra-short electron bunch profiles for the generation of coherent THz radiation

The shape of an electron bunch has a tremendous impact on its emission of synchrotron radiation. Especially the formation of sub-structures can increase the yield in the THz region. This thesis investigates the micro-bunching instability, a mechanism where structures form due to self-interaction of the electrons with their own wake-field. The methods include simulation and measurements. On the simulation side, the thesis describes the optimization of simulation algorithms to increase numerical stability as well as computational performance. On the experimental side, an optimized monitor for single-shot bunch profile measurements was designed to allow continuous bunch profile measurements with high signal-to-noise ratio and a sub-ps resolution at 2.7 MHz repetition rate

Techno-socio-economic energy system optimization: A pareto-based approach

To meet the 1.5 °C goal of the Paris agreement, a rapid transition of energy supply is needed. Not only fossil based thermal power plants have to be replaced, but also 89 % of the global heat supply. While this parallel transition might be challenging, it also offers the chance to lift the potential of mutual benefits, i.e., the electricity sector can benefit from the integration as the sector coupling can provide flexibility. In this context, automatic optimisation routines can aid finding solutions that are not just feasible but also meet other demands, such as affordability. However, different stakeholders often have deviating, sometimes even contradicting demands for qualities of energy systems. Even affordability might be read in different ways. Also, we find ourselves in a situation where physics and regulations might not overlap. This contribution presents an approach designed to explore the space of optimal solutions, facilitating informed decisions, including the weighting of various design goals, late in the planning process. The contribution also gives examples, where the energy system model has to deviate from the actual physical system. The Energetisches Nachbarschaftsquartier (ENaQ) serves as a case study for this approach. Its boundary conditions are shortly outlined and example results are assessed

MTRESS 3.0 -- Modell Template for Residential Energy Supply Systems

MTRESS is a tool that facilitates the creation of models of residential energy supply systems by providing a template with meaningful presets. This model can then be used to linearly optimise the operation of the energy system. Version~3.0 enables multiple locations belonging to one energy system to be defined. Furthermore, it adds hydrogen as an energy carrier with the possibility to convert power to gas using electrolysis and to store gas at different pressure levels. Additionally, we reworked the Python API, giving more flexibility to the user.Comment: 14 pages, 2 figure

Multikriterielle Bewertung und Optimierung: Anwendungsbeispiele sektrorengekoppelter Energiesysteme

Auslegung und Betrieb von Energieversorgungsl¨ osungen befinden sich in einer starken wechselseitigen Abh¨ angigkeit: Fur die Auslegung m ¨ ussen Annahmen ¨ uber den sp ¨ ¨ ateren Betrieb gemacht werden, durch die Auslegung werden Betriebsweisen erm¨ oglicht oder verbaut. Gleichzeitig befindetAuslegung und Betrieb von Energieversorgungsl¨ osungen befinden sich in einer starken wechselseitigen Abhängigkeit: Fur die Auslegung müssen Annahmen über den späteren Betrieb gemacht werden, durch die Auslegung werden Betriebsweisen ermöglicht oder verbaut. Gleichzeitig befindet sich die Energieversorgung in einem Zielkonflikt verschiedener Indikatoren wie Emissionen, CAPEX, OPEX oder Systemdienlichkeit. Wie sieht beispielsweise eine Anlagenkombination aus, die mit möglichst geringen Investitionskosten möglichst flexibel einsetzbar ist? Dieser Beitrag stellt eine Methodik zur multikriteriellen Optimierung von sektrorengekoppelten Energiesystemen vor und gibt Anwendungsbeispiele aus den Bereichen Wohnungsbau und Sanierung von Betriebsarealen. sich die Energieversorgung in einem Zielkonflikt verschiedener Indikatoren wie Emissionen, CAPEX, OPEX oder Systemdienlichkeit. Wie sieht beispielsweise eine Anlagenkombination aus, die mit m¨ oglichst geringen Investitionskosten m¨ oglichst flexibel einsetzbar ist? Dieser Beitrag stellt eine Methodik zur multikriteriellen Optimierung von sektrorengekoppelten Energiesystemen vor und gibt Anwendungsbeispiele aus den Bereichen Wohnungsbau und Sanierung von Betriebsarealen

A Monte-Carlo assessment of the effects of long-term changes on residential energy supply systems

Space heating accounts for approximately one third of the global final energy consumption in both the residential and the commercial building sub-sectors. Including hot water, the 2010 IPCC report on buildings attributes 53% of the total final energy demand of the worldwide building sector to the demand for low temperature heat. At the same time, according to the IEA, the share of renewable energy supply in 2019 only met 11% of the global heat demand, leading to a domination of fossil fuels in this sector, contributing 40% (13.3 Gt) of global CO2 emissions. While these facts underline the need for fast changes, in particular integrating the sectors of heat and electricity, decisions should also include long foresight: Once installed, such systems typically operate for decades. This contribution presents a risk analyses of long-term changes on the national scale on different energy supply systems at the district scale. For example, the effect on changing capacity of renewable electricity generation on the CO2 emissions caused by the residential energy demand is assessed. To evaluate the uncertain characteristic of the future, a probabilistic scenario space is spanned instead of working with distinct scenarios. This space is then sampled using the Monto Carlo method, resulting in probability density functions for previously defined key performance indicators

Wirtschaftlichkeitsanalyse zur Identifizierung eines pareto-optimalen Wärmeversorgungssystems in verschiedenen Wetterregionen in Deutschland

Die Wärmewende hat im Jahr 2022 durch steigende Energiepreise und verschärfte Regulatorik einen neuen Schub bekommen. Auf der Suche nach alternativen Wärmeversorgungssystemen spielt neben dem hohen Anteil an erneuerbarer Wärme auch die Wirtschaftlichkeit eine wichtige Rolle. Aufgrund verschiedener Wetterbedingungen können unterschiedliche Heizbedarfe und Wärmeerzeugungspotenziale vorliegen und damit unterschiedliche Energieversorgungssysteme eingesetzt werden. Diese Studie untersucht, wie groß Vorteile individueller Lösungen im Vergleich zu Lösungen sind, die unabhängig von der Betrachtung des Standorts ausgelegt werden. Ein komplementäres Ziel der vorliegenden Studie besteht darin, die Übertragbarkeit der Modellierungen für das Projekt ENaQ (Energetisches Nachbarschaftsquartier Fliegerhorst Oldenburg) auf andere Regionen in Deutschland zu testen. Für drei Wetterregionen (kalt, warm und mild) werden die ökonomischen Kosten möglicher Kombinationen eines Bündels an Technologien gerechnet und miteinander verglichen. Die Modellierung und Bewertung der verschiedenen Energieversorgungssysteme geschieht auf der Basis des Modell Template for Residential Energy Supply Systems (MTRESS), das im Rahmen des Forschungsprojektes ENaQ entwickelt wurde. Für die vorliegende Studie wurde folgende Vorauswahl für die Technologien getroffen: a) Wärmepumpen und BHKW (exergetisch effiziente Wärmeerzeuger) b) Gaskessel und P2H (Wärmeerzeuger mit geringen Investitionskosten), c) PV und Solarthermie (Quellen für lokale erneuerbare Energie), sowie d) Wärmespeicher und Batterien

On the Perturbation of Synchrotron Motion in the Micro-Bunching Instability

The self-interaction of short electron bunches with their own radiation field can have a significant impact on the longitudinal beam dynamics in a storage ring. While higher bunch currents increase the power of the emitted CSR which can be provided to dedicated experiments, it simultaneously amplifies the strength of the self-interaction. Eventually, this leads to the formation of dynamically changing micro-structures within the bunch and thus fluctuating CSR emission, a phenomenon that is generally known as micro-bunching or micro-wave instability. The underlying longitudinal dynamics can be simulated by solving the VFP equation, where the CSR self-interaction can be added as a perturbation to the Hamiltonian. In this contribution, we focus on the perturbation of the synchrotron motion that is caused by introducing this additional wake field. Therefore, we adopt the perspective of a single particle and eventually comment on its implications for collective motion. We explicitly show how the shape of the parallel plates CSR wake potential breaks homogeneity in the longitudinal phase space and propose a quadrupole-like mode as potential seeding mechanism of the micro-bunching instability. Moreover, we consider synchrotron motion above the instability threshold and thereby motivate an approach to control of the occurring micro-bunching dynamics. Using dynamically adjusted RF amplitude modulations we can directly address the continuous CSR-induced perturbation at the timescale of its occurrence, which allows for substantial control over the longitudinal charge distribution. While the approach is not limited to this particular application, we demonstrate how this can significantly mitigate the micro-bunching dynamics directly above the instability threshold. The gained insights are supported and verified using the VFP solver Inovesa and put into context with measurements at KARA

Continuous bunch-by-bunch spectroscopic investigation of the micro-bunching instability

Electron accelerators and synchrotrons can be operated to provide short emission pulses due to longitudinally compressed or sub-structured electron bunches. Above a threshold current, the high charge density leads to the micro-bunching instability and the formation of sub-structures on the bunch shape. These time-varying sub-structures on bunches of picoseconds-long duration lead to bursts of coherent synchrotron radiation in the terahertz frequency range. Therefore, the spectral information in this range contains valuable information about the bunch length, shape and sub-structures. Based on the KAPTURE readout system, a 4-channel single-shot THz spectrometer capable of recording 500 million spectra per second and streaming readout is presented. First measurements of time-resolved spectra are compared to simulation results of the Inovesa Vlasov-Fokker-Planck solver. The presented results lead to a better understanding of the bursting dynamics especially above the micro-bunching instability threshold.Comment: 12 pages, 11 figure