Speaker
Description
GyM [1] is a linear plasma device (LPD) operating at Istituto per la Scienza e Tecnologia dei Plasmi, CNR, Milan, with the aim of studying the plasma-material interaction (PMI) for magnetic confinement nuclear fusion applications. GyM is part of the portfolio of the EUROfusion facilities and one of the LPDs of the EU Contracting Party involved in the IEA Technology Collaboration Programme on Plasma-Wall Interaction.
This contribution reviews the upgrade of GyM, named “BiGyM”, currently underway as part of the NEFERTARI project [2] funded by Next Generation EU, which is due to conclude at the end of April 2026. The aim of the upgrade is to extend the accessible parameter space from plasma densities of 10$^{16}$–10$^{17}$ m$^{-3}$ and ion fluxes of 10$^{20}$–10$^{21}$ m$^{-2}$s$^{-1}$, suitable for reproducing ion and charge-exchange neutral fluxes impinging on the main chamber wall of tokamaks, such as ITER, towards 10$^{18}$–10$^{19}$ m$^{-3}$ and 10$^{22}$–10$^{23}$ m$^{-2}$s$^{-1}$, which are more representative of divertor conditions. This is being achieved by installing two helicon plasma sources, each delivering 10 kW of power via 13.56 MHz RF birdcage antennas [3]. In addition, a new sample exposure system has been developed to reproduce the operating conditions of ITER divertor plasma-facing components by heating the samples up to 1500 K and applying a negative bias voltage down to –300 V, thereby enabling precise control over the energy of the incident ions. Finally, GyM’s PMI diagnostic capabilities are also being enhanced through the implementation of a picosecond laser-induced breakdown spectroscopy (ps-LIBS) for in situ characterization of material composition changes and hydrogen isotope retention. Procurement was completed in February 2026, and the upgrade phase has recently begun. The GyM vessel has been disassembled and the layout rearranged to accommodate the new sectors for the two helicon birdcage antennas. First vacuum tests have been successfully completed, and the BiGyM magnetic configuration has also been implemented. The new pumping system is now being achieved. First plasma is expected by June, with PMI experiments planned later in 2026.
[1] A. Uccello, et al., Front. Phys. 11, 1108175 (2023)
[2] L. Marrelli, et al., manuscript submitted to Nucl. Fusion
[3] Ph. Guittienne, et al., Plasma Sources Sci. Technol. 30, 075023 (2021)