Interaction of a Ne-H2 SOL-like plasma with graphite

Abstract

Neon was recently introduced in tokamak plasmas to enhance the radiative properties of the scrape off layer (SOL). We have studied on SPISA (Surface Plasma Interaction Simulation Apparatus) the interaction of a Nez.sbnd;H2 mixed plasma (electronic density ∼ 5 × 1018m−3, Te ≈ 20 eV) with a graphite 5890PT sample. The subsequent thermodesorption of the sample shows that the total amount of implanted neon depends on the ratio of partial pressures of neon and hydrogen more than on ionic densities, bombarding energies or total fluences. The thermodesorption spectra are shown to be in good agreement with a diffusion model with an activation energy of 0.35 ± 0.07 eV and a pre-exponential factor D0 = 3 × 10−17m2s−1. These results are in agreement with Tore Supra results on neon desorption from the walls after plasma shots.