Impurity Behavior in JIPP T-II Tokamak Plasma

Resonance lines from oxygen and iron ions in JIPP T-II tokamak plasma are measured before and during the rise of the electron density. Spatial profiles of volume emissivities of OVII, FeXII and FeXVI are obtained. The comparison of experimental and computational results is made by using a one-dimensional impurity transport code. The code assumes oxygen influx by the desorption due to charge-exchanged hydrogen neutrals hitting the wall and iron influx by self-recycling. The increment of oxygen influx results in the increments of oxygen line intensities during the rise of electron density due to gas puffing, and the enhanced ionization process due to the increased electron density results in the outward movement of the peak position of volume emissivity of OVII. It is surmised that the diffusion of oxygen ions is dominated by anomalous diffusion while diffusion of iron ions is affected by both the neoclassical and anomalous diffusions.