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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - GREST (Getting Ready for EST)

Teaser

Summary

GREST aims to take the European Solar Telescope (EST) to the next level of development by undertaking activities to improve the performance of current state-of-the-art instrumentation to the level expected for EST. Legal, industrial and socio-economic issues are also addressed, as key questions for the attainment of EST.

The improvement of current state-of-the-art instrumentation is fundamental to accurately detect the weak imprints that solar magnetic fields leave on the detected radiation at the smallest spatial scales. Magnetic fields are responsible for the heating of the outer layers of the solar atmosphere and are the ultimate cause of explosive events. Though these phenomena are clearly detectable at large scales, their onset and evolution is determined by what happens at small scales on the Sun itself.

The developments addressed with GREST go beyond any existing state-of-the-art devices in all aspects required for a large-aperture solar telescope. Increasing the telescope diameter has a direct impact on the rest of the elements of the telescope and in particular of the instruments. GREST goes in this direction and designs, tests or prototypes of critical instrument elements are foreseen. The results of these studies are expected to have a large impact not only for EST, but also for other large infrastructures. The developments boosted by GREST will be of natural interest for other infrastructures, positioning European industry in the forefront of instrumental novelty.

Currently, the technologies to be tested are not available for the next generation of solar telescopes, and GREST could put Europe on a privileged position to generate knowledge, science and technology. This will raise the competitiveness level of the Community, opening new markets and opportunities.

The overall objectives of GREST are the following:
-Boost and evaluation of new generation detectors
-Development of a capacitance-stabilised Fabry-Perot Interferometer (FPI)
-New techniques for 2D solar spectro-polarimetry
-Development of large format liquid-crystal modulators
-Evaluation of the performance of the EST-MCAO deformable mirrors
-Strategic work for industrial, financial and legal issues related to the future construction and operation of EST.

Work performed

The main achievements reached during the first 18 months of the project are:

-Detectors: A detector platform has been developed for a large-format prototype detector based on sCMOS technology. Complementarily, a feasibility study for the development of a new, high speed polarimetric camera based on the detector/amplifier structure DEPFET has been addressed. For these devices, in-situ storage of the image information gathered inside of four independent images registers inside the sensor material is envisaged; such a device will allow for much higher modulation speeds as conventional polarimeters based on standard imaging detectors.
As a third branch of detector development and evaluation, a forerunner large field-of-view wavefront sensor.

-FPI: Work has been focused on the development of an innovative digital control of FPIs. In particular: a) definition of the technical requirements on sensing and actuator components of the FPI; b) electronic control system and opto-mechanical designs of a 50-mm FPI prototype; and c) realisation of the breadboard of the customised capacitance-stabilised electronic control system.

-2D spectropolarimetry: A number of options have been studied for a 2D solar spectro-polarimetry, based on either a microlens array or an image slicer.
Different configurations of the prototype image-slicer increase the field-of-view of a single exposure by increasing the length and number of output slits produced by the image slicer. The next step will address the design of an IFU that meets the requirements of the selected option.
Concerning the microlens array, the concept has been modified and extended to a design with polarimetric capabilities. In the adopted solution, the full spatio-spectral image formed after the spectrograph is split-up into six beams, each representing one polarimetric modulation state.

-Large modulators: A first round of liquid-crystal variable retarders has been fabricated. based on different concepts: Anti-Parallel Aligned Nematic, Parallel Aligned Nematic (Pi Cell) and ferroelectric cells. The units have been tested to study their homogeneity, response to applied voltage, response time, optical quality and dependence of all these parameters with size.
Adaptive optics: A specific simulation software to model the behaviour of tilted DMs in different conditions has been developed to study the performance of the MCAO system of EST. Using the new software, the analysis and the characterisation of the spatial response of tilted DMs have been performed under different scenarios.

In addition to that, two main strategic tasks have been addressed: a) evaluation of the expertise and size of the scientific community in the field of solar physics in each country; and b) analysis of legal and governance models as well funding schemes for a large infrastructure like EST.

Final results

The achievement of EST, is only possible through the international collaboration, driven by the research excellence, the collaboration between public and private sector and the support of national governments. In order to bring together the necessary efforts of the participating countries, the Consortium envisaged an initial plan of activities to carry out within the framework of GREST, which has gradually have a clear impact on the progress of EST, but also a socio-economic impact at both regional as national level. This impact goes beyond the project itself, creating new jobs, establishing new partnerships with industry and attracting non-European partners.

-The total budget of the EST construction design is around 11 Mâ‚¬, and will be partly funded by EC under the H2020 framework. The Consortium is negotiating with all the European countries involved in EST their yearly contribution to the project.

-EST has attracted a good number of partners but as a transnational project, but its doors should remain open to others. Thus, in an attempt to raise the interest on EST by non-European partners, South Korean and Japanese institutions have been contacted and informed about the EST progress.

-Thanks to the technological capabilities acquired IAC has recently launched the IACTEC, a space for technological and business cooperation, designed to generate technological products with high added value with a clear market interest. GREST team collaborates actively with this initiative where it is expected to hire and train highly qualified personnel, exploiting the synergies with the industrial sector.

-The EST Project Office will be soon established in Tenerife (Spain) thanks to the support to the national and regional funding. The objective of the Office is to accomplish the preliminary design of the telescope fulfilling the scientific requirements. The IAC will start the recruitment process early 2017 of around 20 persons between technical and administrative staff.
-Thanks to the on-going projects (SOLARNET, GREST), the Consortium is acquiring a better knowledge of the expertise and capacities of the European industrial sector, and in particular of those companies that would participate in the construction of EST.