Leiden University Student Repository

Tabaksblat, Mark 2023

Designing effective microwave excitation of the TECH plasma reactor

Bachelor thesis | Natuurkunde (BSc)

closed access

The goal of this thesis is to design a setup which can be used as a prototype for the TECH reactor. The TECH reactor is a cylinder with rounded edges, in which a microwave plasma will be formed....Show moreThe goal of this thesis is to design a setup which can be used as a prototype for the TECH reactor. The TECH reactor is a cylinder with rounded edges, in which a microwave plasma will be formed. The cavity should resonate with the right eigenmode at a constant frequency of 2.45 GHz, and the excitation structure should produce a reflection coefficient of smaller than 0.8, enabling a tuning device to maximize power transfer. These conditions must hold for a broad range of conductivities of the plasma. Firstly, the effect of a resonance frequency tuning ring inside the cavity was researched, in order to keep the right eigenmode at a constant frequency of 2.45 GHz. Secondly, the excitation structure was optimized to ensure that at the relevant plasma conductivities, the reflections from the setup were minimized. Later simulations yielded that for almost all conductivities of the plasma, the setup was sufficiently impedance matched to the waveguide to enable an auto tuning device to prevent reflections. Thirdly, unexpected eigenmodes of the cavity were discovered. Therefore, adjustments were made to the cavity such that the resonance frequencies of other modes would not be close to 2.45 GHz, to prevent the excitation of these modes. This thesis continued the work of De Man [3]. In the end, the simulations yielded promising results and the setup is almost fully designed. Soon, experiments with the electric field in the cavity can be carried out, which form an important step towards being able to measure plasma breakdown.Show less

Tuinstra, Willemijn 2019

Conscience & Connections. Marcellus Franckheim (1587-1644) and his contacts in the Habsburg World at the eve of the Thirty Years War.

Master thesis | History (MA)

open access

The Dutch glassmaker’s son and rector of the Latin school in Zutphen, Marcellus Franckheim (Zutphen 1587- Dunkirk 1644), converted from Calvinism to Catholicism in 1614 and became secretary to...Show moreThe Dutch glassmaker’s son and rector of the Latin school in Zutphen, Marcellus Franckheim (Zutphen 1587- Dunkirk 1644), converted from Calvinism to Catholicism in 1614 and became secretary to Cardinal Melchior Khlesl at the court of the Habsburg Emperor Matthias. He ended his life as councillor to the Spanish King Philip IV in the admiralty of the Flanders fleet. By analysing Franckheim’s surviving correspondence and publications, this thesis shows that while Franckheim’s life on first sight seems full of unexpected moves and change, there is a remarkable continuity in his faith, his contacts and his opinions. It also shows that the Dutch Gomarist-Arminian controversy during the Twelve Years Truce directly influenced his decision to convert and that a group of engaged Zutphen Catholic citizens connected him to the Counter-Reformation world of the Habsburg courts in Europe. Using Marcellus Franckheim as an exemplary case, this thesis addresses the broader question of how Dutch Catholics in the early seventeenth century, both in the Low Countries and in exile, participated in local and transnational networks to promote and consolidate their faith. It also provides insight in the interconnectedness of the political and religious conflicts in the Low Countries and the Holy Roman Empire, in particular with regard to the ways in which individuals felt involved and tried to influence these events.Show less

Tempelman, Wouter 2012

Sahagun and the world where new meets old; a literary and pictographic analysis of the ethnographic documents written in sixteenth century Mexico.

Master thesis | Archaeology (MA/MSc)

open access

When Sahagún came to New Spain he encountered the indigenous population who were in the process of converting to Christianity. He arrived with a group of fellow Franciscan friars with the mission...Show moreWhen Sahagún came to New Spain he encountered the indigenous population who were in the process of converting to Christianity. He arrived with a group of fellow Franciscan friars with the mission to establish a new Christian utopia where a thousand year peace would reign. Sahagún was ordered to write down all that he could find about Nahua culture which resulted in the Historia general. In this manuscript there are various rituals and deities described in full detail and they are said to be idolatrous. Sahagún would take his students from his college in Tlatelolco and gather pictographic information from Tepepulco in order to copy it into the Primeros Memoriales. In this manuscript it is clear that European elements are incorporated in pre-colonial drawings. The Nahua population proved difficult in adopting the Christian faith and kept holding on to traditional beliefs, often mixing old rituals with Christian rituals. This was something Sahagún became upset about, knowing that the traditional rituals were actually in honour of Satan and his demons that needed to be combated. When Sahagún reached old age he was of strong conviction that the mission to establish the utopia had failed and he suggested that Christianity should move on to other parts of the world where conversion would be more successful.Show less