Comparison of the scrape-off layer two-point model for deuterium and helium plasmas in JET ITER-like wall low-confinement plasma conditions

Abstract

The hydrogenic two-point model (H-2PM), an analytical model for the scrape-off layer that predicts a common electron and ion temperature and density along a flux tube from a target temperature and density, is adapted to a single-species helium (He) model, preserving the 2PM assumptions and analytical nature. Across a range of densities and heating powers, the predicted $T_e$ is within $20\mathrm{eV}$ of upstream measurements by high-resolution Thomson scattering (HRTS) for low-confinement He plasmas performed in JET ITER-like wall (JET-ILW). For high-recycling conditions, He-2PM predictions of $n_e$ were within 10% of the Li-beam diagnostic measurements, excluding the near-SOL, when assuming $Z_{\mathrm{eff}}=1$, suggesting the divertor SOL was not fully ionised in the JET-ILW He plasmas.