Development of an integrated polarization, conditioning and acquisition system for large Langmuir probe arrays in cold plasmas

Plasma physics and its related technological applications are a major research field of growing interest. Covering a broad range of aspects, from the most theoretical ones to the smallest practical case, the progress achieved up until now has been made possible due to both theoretical understanding, supported by the use of numerical simulation, and from the ability to direct measurements, carried out as accurately as possible, of plasma properties. One of the main driving forces that keeps pushing the research on plasmas and their properties, is the field of the long sought nuclear fusion as a source of clean, sustainable and practically unlimited energy. The constant evolution of the analog and digital electronics has enabled the design and realization of plasma diagnostic systems of increasing precision, resolution and quality. Thus the number of simultaneous measurements being needed to be processed increased as well, resulting in new challenging requirements. Nevertheless due to the nature of the plasma itself, which displays property rather different form the usually known states of matter, like temperatures ranging from thousands to million of degrees, plasma diagnostic is always a challenging field, which very rarely falls in the category of routine application. Among the diagnostic system, one of the simplest and basic method to measure plasma properties is through the use of electrostatic probes, also known as Langumuir probes. Even if at first glance it could appear a simple textbook exercise, transforming this technique into a practical and reliable system for routine plasma diagnostic is far from a trivial task. The purpose of the thesis work is the design and test of two critical parts of an integrated signal conditioning and data acquisition system capable of retrieving information such as the plasma density, the ion and electron saturation current and the electron temperature from large arrays of Langmuir probes.