High performance ceramic discharge chambers

The work presented focuses on the development of one of the critical components of a stationary Plasma Hall Effect Thruster, the discharge chamber or accelerating channel. A global approach is being performed. It has been initiated by analyzing the various discharge chamber configurations adopted by different applications using HET, leading to a detailed assessment of the applicable requirements for HET discharge chambers. Scaling up and down being one of the major targets of the activity, a complete discussion of the requirements of such a component has been done and also how those requirements are affected by the currently envisaged up and down scaling of the current HET technology. The limitations of the current chamber manufacturing technology has also been reviewed together with an assessment of alternative technologies that can be appropriate candidate for up and down scaling issues. From an experimental point of view, different up and down scaled (5KW / 90 W) HET units have been selected as target for closely studying and manufacturing the corresponding chambers. Some numerical simulations of the contained plasma and the resulting thermal situation along those particular ceramic components have been performed and closely discussed. Starting from the current state-of-the-art technology based on hot-pressing and final machining of BN-SiO₂ materials, the manufacturing steps have being optimized and some novel compositions with enhanced properties have also being developed. Finally, a complete characterization of the produced materials has been performed focusing on the ion sputtering behaviour of the different material compositions being studied. A laboratory experimentation procedure capable of detecting behaviour differences is being set-up, and here a reported some of the preliminary results.