LaserTron - Lasers give CT a new face

Abstract:

The intention of the Lasertron consortium was to develop the basic principles of a locally-excited laser-driven high-current electron source as one of the key-components for future X-ray devices. These devices will find application especially in Computed Tomography (CT), where high-power X-ray sources are needed, combining high brightness and high modulation capability. The advantages for CTs are an increase of temporal and spatial resolution of the 3-D images and simultaneously a decrease of dose rate for patients. The project comprised on the one hand the analysis of applicable electron emission mechanisms, such as photo-electrical emission with wavelengths from IR to UV and plasma-based electron emission. Both realized by Laser radiation. Emission currents of more than 1 A where produced with a plasma cathode, based on a Laser-induced discharge plasma and grid controlled electron emission. Circuit times less than 1 µs and temporal modulation strongly connected to Laser-burst duration were measured. X-ray imaging verified high brightness and low emittance of the electron beam. On the other hand ultrafast Lasers were investigated and developed with pulse durations from fs to ps, repetition rates in the MHz regime and (as the main part) average output powers of multiple 100 W. Additionally, suitable optics where designed, manufactured and tested with special regard to damage threshold and dispersion.