"The development of Retarding Potential Analyzers (RPAs) capable of measuring high-density stationary and flowing plasmas is presented. These new plasma diagnostics address the limitations of existing RPAs and can operate in plasmas with electron densities in excess of 1x1018 m-3. Such plasmas can be produced by high-powered Hall Thrusters, Pulsed Plasma Thrusters (PPTs), and other plasma sources. The Single-Channel micro-Retarding Potential Analyzer (SC-microRPA) developed has a minimum channel diameter of 200 microns, electrode spacing on the sub-millimeter scale and can operate in plasmas with densities of up to 1x1017 m-3. The electrode series consists of 100 micron thick molybdenum electrodes and Teflon insulating spacers. The alignment process of the channel, as well as the design and fabrication of the stainless steel outer housing, the Delrin insulating tube, and all other microRPA components are detailed. To expand the applicability of the SC-microRPA to densities above 1x1018 m-3 a low transparency Microchannel Plate (MCP) has been incorporated in the design of a Multi-Channel micro-Retarding Potential Analyzer (MC-microRPA). The current collection theory for the SC-microRPA and the MC-microRPA is also derived. The theory is applicable to microRPAs with arbitrary channel length to diameter ratios and accounts for the reduction of ion flux due to the microchannel plate in the case of the MC-microRPA, due to absorption of ions by channel walls, and due to the applied potential. Current-voltage curves are obtained for incoming plasma flows that range from near-stationary to hypersonic, with temperatures in the range of 0.1 to 10 eV, and densities in the range of 1x1015 m-3 to 1x1021 m-3. The SC-microRPA current collection theory is validated by comparisons with the classical RPA theory and particle-in-cell simulations. Determination of unknown plasma properties is based on a fuzzy-logic approach that uses the generated current-voltage curves as lookup tables."

This study examines the processes behind two of Moderna museets complementary projects: The Museum of Wishes and The Second Museum of Wishes. The purpose of this study is to, by using these projects, examine the connection between collections and collectors, and to examine the relationship between museums, complements of the collection and representation. The aim is to compare the projects and find out if there were different reasons, methods or other significant factors that might have affected the processes. I intend to explain how these projects can be understood as a practice of complementary collecting by relating them both to collection theory and representation. My theoretical framework primarily consist of Susan Pearce’s research. I have chosen to incorporate her concepts of the poetics of collecting, the politics of collecting and the importance of earlier collected experience in my comparative study of the projects. In addition, I have also incorporated research about categories with the intention of relating it to Pearce. By studying literature that discusses the historical aspect of the projects, as well as articles, catalogues and documents that were contemporary with the projects, I have been able to compare the backgrounds as well as ideologies that might have influenced the projects. The result of this study shows that although there were many differences between the methods and processes, the art works that were collected during the projects can both be interpreted as a physical changing of the collection, a changing of the structure of the collection and a changing of the identity of the museum. What the museum gathered during the projects didn’t just represent what the organizer thought the museum needed, but can also be understood as a way of changing the standard of the collection in order to be able to compete with other museums or gathering more knowledge. This study is a two years master’s thesis in Museums and Cultural and Heritage Studies.