Reference number of the aid programme:___SA.52864(2019/X)_National Centre for Nuclear Research Purpose of public aid:_art. 26 The project concerns investments in strategic research infrastructure, i.e. the construction of a laser on free electrons POLFEL placed on the Polish Roadmap for Research Infrastructure (PMDIB). The infrastructure will consist of a free electron laser (FEL), a photocathode testing laboratory, research lines and laboratories necessary for the operation of apparatus and a laboratory for users of research lines. The project will be implemented by a 8-entity consortium of scientific units and universities, the leader of which will be the National Centre for Nuclear Research (NCBJ). The POLFEL infrastructure will have an operational structure focused, stationary, located on the premises of the NCBJ in Otwock. The POLFEL laser will be the first in the country and one of several sources in the world of cohesive electromagnetic radiation with tuning wavelengths in several ranges from THz to VUV, emitted in pulses ranging from femtoseconds to picoseconds, with high impulse power (or a row of gigawatts) or high average power (a row of tens of watts). The project will be implemented over a period of 4 years (01.01.2019-31.12.2022), broken down into 4 simultaneously implemented tasks corresponding to the construction of basic infrastructure modules. The POLFEL infrastructure will be owned by NCBJ. It was assumed that in 40 % of the working time the infrastructure would be earmarked for economic use, i.e. it would be made available commercially to interested third parties. The remaining 60 % of the working time will be used for non-economic use (R & D projects carried out by members of the consortium).