Improvement of the E-field triggered surface breakdown of dielectric anodes in vacuum ion diodes

To improve the dielectric flashover in adsorbates at the surface of dielectric inserts of vacuum diode anodes, start electrons are implemented by several means. The first method is to trap a layer of electrons at the structured surface (grooves) by means of auxiliary electrodes. A second method uses the idea that a low gap semiconducting surface layer spends electrons into the adsorbates, if the electric field passes a critical value. Experiments with a pinch reflex diode at the 1.2 TW pulse generator `Kalif´ will be reported. On the basis of the latter method anode inserts are tested, which are woven from glassfiber. The weak conductivity of glass and the ability to trap a desired amount of adsorbates (H<sub>2</sub>,He, N<sub>2</sub> for example) makes it possible to form proper plasmas and to do it without hydrocarbon. One of the results of the current investigation is that the micro inhomogeneity of the ion beam could be reduced drastically. A first full-scale test in a B<sub>Θ</sub>-diode at the PPL `Kalif´ is presented.