VALIDATION OF KALMAN FILTER METHOD FOR VERTICAL POSITION AND SPEED ESTIMATION IN THE TCV TOKAMAK

openConvalida del metodo del filtro di Kalman su sistema state-space linearizzato da simulatore Forward Grad Shafranov Evolutive (FGE). Design delle matrici di covarianza per la stima della posizione, della velocità del plasma, dalla stima delle correnti di attive e di vessel e delle constraints. Simulazione di diversi shots di TCV.Validation of the Kalman filter method on state-space system linearized by Forward Grad Shafranov Evolutive simulator (FGE). Design of covariance matrices for position and plasma velocity estimation, from estimations of active and vessel currents and constraints. Simulation of several shots of TCV

Strategies to reduce photobleaching, dark state transitions and phototoxicity in subdiffraction optical microscopy

In all subdiffraction fluorescence microscopy techniques, the theoretically infinite attainable resolution is, in practice, limited by the photobleaching of fluorophores. Repetitive scans of the sample required for e.g. three dimensional recordings, increase photobleaching, dark state transitions and, in case of living cells, phototoxicity. To advance such experiments all possibilities to reduce the photobleaching must be explored. In this thesis, various chemical and physical approaches to tackle photobleaching are studied within the context of stimulated emission depletion (STED) microscopy, which is the first and most prominent method for subdiffraction imaging. The STED setup constructed for this purpose allows for the fast adaptation to new fluorescent dyes, and relies on a novel adaptive spectral and phase filter technique. Furthermore, the optical setup facilitates a gentle exposure strategy, in which the time that the dye is irradiated is significantly reduced. Three-dimensional images can therefore be recorded, and the palette of applicable dyes can be expanded to the blue-green regime by the so far unemployed coumarin derivatives, which are known to be prone to photobleaching. The label itself is another vantage point from which photobleaching limitations in subdiffraction microscopy can be circumvented. For the first time, light-driven modulation of the fluorescence from Mn-doped ZnSe quantum nanocrystals has been established through excited-state absorption (ESA). This enables a new type of far-field fluorescence microscopy with diffraction-unlimited resolution based on quantum dots, which are well known for their superior photostability. The correct sample embedding in the refractive index matching is also of high importance, if spherical aberrations and light scattering are to be minimized to optimize the fluorescence collection. For this purpose, an embedding medium, 2,2´-thiodiethanol (TDE) is introduced, which, by being miscible with water at any ratio, allows for refractive index matching up to that of immersion oil and making high resolution recordings deep within the sample feasible