Model of the vacuum diode with adsorbate anode operation

For experiments with divertor materials under ITER disruption conditions a proton beam with pulse duration longer than 10 – 20 µs and energy density attributed to the emitting surface of more than 20 mJ/cm² is needed The most simple version of such a proton source is a vacuum diode, operating in a bipolar flow regime. The emitter of electrons is a plasma formed at the cathode due to an explosive emission. A plasma formed at the anode surface as a result of desorbtion and ionization of adsorbates by electrons is a source of ions. In order to understand the experimental results obtained in the test diode investigation and to predict real scale diode parameters model of the diode with adsorbate anode operation was developed The results of calculations showed that such diode is able to produce ion beam with 5nergy density attributed to the anode surface of more than 20 mJ/cm². The whole pulse duration of the ion beam can be large than 20 µ. But effective part of the pulse when power density exceeds needed level is around 10 µs. The model can be used also for analyzing of the vacuum breakdown effects in vacuum diodes operating in long pulse mode.