The objectives are to:

• investigate the damage mechanisms of coatings and relevant substrates due to irradiation of ions, protons and electrons.

• define a network of accelerator facilities (protons, He+ and electrons) suitable for performing such testing

• develop protocols/guidelines for validation/qualification testing of coated optical components for space

• develop radiation robust coated optical components in a relevant test case (e.g. a science mission instrument) on which to apply the developed test procedures.

 

 

Optical coated elements are mainly optimized for their optical characteristics, such as transparency or reflectivity in a desired spectral region. However, for space missions in the near future it is fundamental to ensure the sustainability of these optical elements in the harsh conditions of the relevant space environment, preventing the occurrence of any critical radiation induced optical degradation of their performances. In fact, optical performances of the components strongly affect the data outcomes, and their degradation can lead to a misinterpretation of the scientific data due to an uncontrolled change of the instrument response. In extreme scenarios, the failure of a component can affect the operational capacity of the whole instrument.

 

Electrons, protons and ions are considered among the principle causes of potential damage to optical coatings. The clear definition of testing procedures to assess the robustness of optical components against the operational environment is pivotal to prevent in-flight failures. The definition of tests and the development of consequent guidelines based on the results will be applied to test the optical components to be realized within the project in view of their potential application to a space science mission. The operational environment of this mission will be in fact characterized by unprecedented levels of irradiations of protons and electrons. It is therefore considered as a valuable test case.

 

 

The following activities will be carried out within the project:

• Simulations of irradiation and implantation profiles in different substrate materials and coatings. Protons, He+ and electrons will be considered

• Identification of a network of potential facilities capable to cover all relevant energies/ions species. Define the methodology for irradiation

• Definition of a test plan according to simulation results

• Fabrication of single and bilayer coatings, to make specific relevant tests defined in the plan. Single and bi-layer film will be metals and dielectrics or a combination of both. Different representative substrates will be used.

• Irradiation tests and analysis of results: the samples will be analyzed prior to and after irradiation, comparing their performances with witness samples not irradiated. Optical characterization and morphological / structural investigations will be performed.

• The definition and writing of guidelines for the test and qualification of optical coatings for use in the space radiation environment: indication of facilities, methods, flux rates etc.

• Fabrication of a set of coatings designed and realized to be robust against the radiation environment requirements for a science mission. Optical filters will be taken as a relevant example (i.e. critical components in relation to their long term stability when exposed to ions and electrons).

• The relevant radiation test environment will be defined based on the results and testing/qualification of components developed in according to the defined guidelines carried out.