Z Sub eff Measurements and Low-Z Impurity Transport for NBI (Neutral Beam Injection) and ICRF (Ion Cyclotron Resonance Frequency) Heated Plasma in JIPP T-IIU Tokamak

摘要

A visible bremsstrahlung detector array system for Z sub eff measurements and a charge exchange recombination spectroscopy (CXRS) system for fully ionized impurity profile measurements were installed on JIPP TII-U to study impurity transport for Neutral Beam Injection (NBI) and Ion Cyclotron Resonance Frequency (ICRF) heated plasma. More impurities are sputtered by ICRF heating than by NBI and/or ohmic heatings. The carbon contribution to Z sub eff is 80 to 90 percent for NBI heated plasmas, and 60 percent for NBI + ICRF heated plasmas. With a carbon coating of vacuum vessel, the Z sub eff value decreases 2.4 to 1.7 and the carbon contribution to Z sub eff increases up to 80 to 90 percent. The diffusion coefficient D sub a = 1.0 m(2)/s and the convective velocity v sub a(a) = 13 m/s is obtained at the plasma edge for carbon impurity from the radial profile and time evolution of fully ionized carbon after the ICRF pulse is turned on.