Ion temperature measurements in the tokamak scrape-off layer

The ion temperature is a particularly important but rarely measured plasma boundary quantity. In this work we introduce a new electric probe, the segmented tunnel probe (STP), which measures ion temperature, electron temperature, and parallel ion current density simultaneously and with high temporal resolution. The probe was built and tested in the CASTOR tokamak. The STP was operated in a Mach-probe arrangement in a DC mode, providing bi-directional measurements with the temporal resolution of 1 μs. Therefore, it has significant potential to be employed in the research of transient phenomena in tokamaks (e.g. turbulence, fluctuations and ELMs). We present radial profiles of the plasma parameters in the CASTOR tokamak measured by the STP, using calibrations from particle-in-cell simulations.