Secondary Electron Emission (SEM) Grid for the FAIR Proton Linac

New SEM-Grid has been developed for FAIR Proton Linac, the instrument consists of 2 harps fixed together in an orthogonal way. This SEM-Grid will provide higher resolution and accuracy measurements as each harp consists of 64 tungsten wires 100 micro-meter in diameter and 0.5 mm pitch. Each wire is fixed to a ceramic PCB with an innovative dynamic stretching system, this system assures wire straightness under typical thermal expansion due to beam heat deposition. Electric field distribution has been performed, 3 main parameters have been optimized, wires distribution, quantity of polarization electrodes and distance between electrodes and wires. The design and production of the SEM-Grids have been performed by the company Proactive R&D; that has count on the expertise of ESS-Bilbao to define safe operation limits and signal estimation by means of a code developed specifically for this type of calculations. Preliminary validations of the first prototypes shown good values of electric field behaviour signal. After additional beam test validations to be performed on June 2022, final series of the SEM-Grid will be produced and installed on FAIR proton LINAC.