Erosion in the DIII-D divertor by neon-detached plasmas

We report the first measurements of erosion of divertor materials by plasmas detached by neon injection. Neon injection cooled the plasma edge by radiation, reduced the temperature and increased the density of the divertor plasma, and reduced the peak heat flux onto the divertor plate, while maintaining good H-mode energy confinement and purity of core plasma. The rate of carbon erosion at the outer strike point was very high (∼15 nm/s), in contrast to the absence of erosion from plasmas detached by deuterium injection observed in previous experiments. The erosion rate for tungsten and vanadium remained low for neon-detached plasma. A likely cause of the high net carbon erosion rate is physical sputtering by neon, chemically enhanced by the formation of hydrocarbons.