Charging effect, aging and storage conditions impact on SEY of Dielectric Materials for Flight Hardware - Archive ouverte HAL
Communication Dans Un Congrès Année : 2022

Charging effect, aging and storage conditions impact on SEY of Dielectric Materials for Flight Hardware

Résumé

It is widely assumed that the multipactor threshold of RF space equipment does not evolve between qualification and flight. While the threshold of a fully metallic RF component may be somewhat stable under controlled storage conditions, flight hardware that contains dielectric piece parts in its critical areas is harder to stabilise. Non-optimal storage conditions over long periods of time, contamination and charging effect have a sensible impact on the threshold. In the framework of ESA project EVEREST [1], it was clearly demonstrated that the that surface aging during the storage period of RF hardware can have a direct impact on the multipactor threshold of flight hardware. Particle-in-cell software can make realistic predictions of the Multipactor threshold of a given device based on the TEEY curve of its materials. However, when it comes to dielectrics, the dependencies of TEEY with ageing and charge are not fully understood. For that reason, the last release of the ECSS-E-ST-20-01C [2] recommends very high security margins for thresholds in the presence of dielectric (up to 12dB). After manufacturing, space hardware is exposed to a specific atmosphere, in that moment a layer of hydrocarbon contamination begins forming over the surface. The composition of this layer depends on the surface reactivity, the atmosphere, the temperature and the humidity. Moreover, manipulation of the materials induces a specific charge distribution that is different for each component and depends on the type of dielectric and the specific process that the material underwent. Consequently, the surface composition and charge distribution of the materials in the hardware evolves from the manufacturing, through storage to the operational environment. These evolutions affect the TEEY of the material, which in turn have an impact on the Multipactor threshold. In the framework of the ESA TRP activity “Impact of Storage Conditions and Aging Effect on RF Breakdown” a study was started in order to test and analyse how aging affects the TEEY properties of a group of relevant materials in the most common storage conditions for space equipment. In particular, three dielectrics (Teflon, Alumina and Ferrite) are stored in four different conditions (ambient atmosphere, ISO-8 clean room, Nitrogen atmosphere and moist atmosphere). The evolution of the TEEY and the surface chemical composition of the three materials is monitored during a storage period longer than two years. In order to correlate the TEEY to the multipactor threshold, dedicated RF components have been developed and two multipactor test campaigns, one on virgin samples and one at the end of the storage cycle are performed on selected samples. So far, it has been observed that the TEEY and the surface composition have evolved significantly for all storage conditions during the aging process. Moreover, it has been found that electric charging has a very significant effect. Indeed, the evolution of the charging state of the samples (trapped charges) affects the EEY parameters in such manner that can screen potential effect of contamination and storage on the electron emission properties for certain type of materials. The goal of our contribution is to present and analyse the results and its consequences. Challenges related to the Guidelines can be deduced for long time material storage of critical RF equipment.
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Dates et versions

hal-03931072 , version 1 (09-01-2023)

Identifiants

  • HAL Id : hal-03931072 , version 1

Citer

Mohamed Belhaj, Sarah Dadouch, Juan-Antonio Duran-Venegas, J. Sinigaglia, Philippe Mader, et al.. Charging effect, aging and storage conditions impact on SEY of Dielectric Materials for Flight Hardware. MULCOPIM 2022, Oct 2022, Valence, Spain. ⟨hal-03931072⟩

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