A new method of electron seeding used for accurate testing of multipactor transients

When testing components for multipactor discharge breakdown it is important to have available sufficient "seed" electrons to initiate the discharge. This is especially important for the multicarrier situation where the addition of all carriers give repetitive short term high peak voltage transients. Standard electron generation processes such as Beta emitting radioactive sources or cold emission from Tungsten needles have serious limitations as far as "seeding" electron rate production is concerned Thus, a new concept in generating "seed" electrons based on the photo-electric effect has been developed in the ESTEC laboratories of the European Space Agency. A measure of the effectiveness of such a "seeding" source can be determined by the time it takes a Multipactor discharge to occur after the microwave signal has reached the required discharge threshold. The difference between the time at which the microwave power reaches its maximum (the signal turns "ON") and the onset of detected multipactor indicates the delay time of the multipactor discharge. This principally depends on the availability of "seed" electrons at the device under test. By the large reductions in this delay time measurement, it has been demonstrated that the electrons produced by the photoelectric phenomena allow a more controlled test scenario to be established.