Effect of magnetic configuration on the neutral particle transport in compact helical system edge region

Neutral particle behavior in compact helical system (CHS) was studied with the Monte Carlo simulation code DEGAS. By shifting the magnetic axis position, magnetic configuration of CHS device changes from the material limiter to the magnetic divertor. We estimated Hα emission from excited hydrogen atoms and dissociated molecules with a collisional radiation model, and compared experimental observations to study the change of recycling condition. With the comparison of simulation result with Hα detector signal, the change of recycling source by the magnetic axis shift was qualitatively confirmed.