Helium Ion Observation during 3rd Harmonic Ion Cyclotron Heating in Large Helical Device

In higher harmonic ion cyclotron resonance heating using the fast wave, a helium resonance layer appears near the plasma core. It is very important to detect the helium ions to investigate the confinement of α particles, which are produced by a nuclear reaction in ITER or a fusion reactor. In Large Helical Device (LHD), we attempt to observe the charge-exchange helium particles using a compact neutral particle analyzer (CNPA). Helium acceleration below 5 keV can be confirmed by comparing the signal ratio of helium in adjusted plate voltages of the CNPA to that of hydrogen. Successful helium measurement in LHD will lead to the development of α particle measurement

First Monte-Carlo modelling of global beryllium migration in ITER using ERO2.0

ERO2.0 is a recently developed Monte‐Carlo code for modelling global erosion and redeposition in fusion devices. We report here on the code's application to ITER for studying the erosion of the beryllium (Be) first wall armour under burning plasma steady state diverted conditions. An important goal of the study is to provide synthetic signals for the design of two key diagnostics: the main chamber visible spectroscopy and the laser in‐vessel viewing systems. The simulations are performed using toroidally symmetric plasma backgrounds obtained by combining SOLPS simulations extended to the wall using the OSM‐EIRENE‐DIVIMP edge code package. These are then further combined with a shadowing model using magnetic field line tracing to provide a three‐dimensional correction for the flux patterns. The resulting plasma wetted area, which amounts to ∼10% of the total first wall area, is in excellent agreement with shadowing calculations obtained with the SMITER field line tracing code. The simulations reveal that the main Be erosion zones are located in regions intersected by the secondary separatrix, in particular the upper Be panels, which are close to the secondary X‐point. For the particular high‐density Q = 10 background plasma case studied here, ∼80% of the eroded Be is found to re‐deposit on main chamber surfaces. The rest migrates in almost equal parts to the inner and outer divertor and is deposited close to the strike lines