Objective
The multipactor effect is an important failure mechanism in many modern rf systems operating at or close to vacuum conditions. The phenomenon manifests itself as avalanche-like increase of free electrons, which is caused by secondary electron emission from the device walls when hit by energetic electrons being accelerated by the rf field. Multipactor breakdown is becoming an increasingly severe problem in different rf applications such as space-borne communication, rf accelerators, and high power microwave generators. This development is the result of the increasing microwave power along with the tendency to fabricate microwave devices as compact as possible.
The multipactor effect has been investigated both theoretically and experimentally during almost 70 years. However there still exist fundamental questions, for instance, the transition from multipactor to corona discharges and multipactor discharges on dielectric materials, which are poorly understood. In addition, the present technical development tends to give rise to new situations for which the established theory is not applicable. Consequently, multipactor theory is in urgent need to be developed further, both by analytical and numerical means.
At present, most works on the multipactor effect consider only relatively simple geometry (e.g. plane parallel models or rectangular waveguides) and monochromatic rf fields. This situation is rapidly becoming acutely unsatisfactory since the telecommunication industry increasingly tends to involve e.g. multi-carrier operation and devices with more complicated geometrical configurations and materials, in particular dielectric materials.
The work within the proposed project will involve theoretical studies based on both analytical and numerical methods and the predictions will also be compared with experimental results. One of the main objectives of the proposed project is a detailed investigation of multipactor discharges on the surface of dielectric materials. A basic study will be carried out of single-sided multipactor discharges together with an investigation of different mechanisms responsible for dielectric evaporation stimulated by the multipactor. The aim is to be able to calculate the threshold power for multipactor discharges to occur on a dielectric plate irradiated by powerful microwaves. The theoretical predictions will be compared with experimental data also obtained within the project. Particular attention will be given to calculation of the power deposited on dielectric surfaces by multipacting electrons and to estimates of the rate of dielectric evaporation including the subsequent transition to a corona discharge.
In addition to the basic study of the multipactor, the second part of the project will involve detailed numerical simulations of multipactor discharges inside a particular micro strip line containing dielectric materials. These simulations will be carried out using a special code developed within the project.
Topic(s)
Call for proposal
Data not availableFunding Scheme
Data not availableCoordinator
412 96 Göteborg
Sweden