Poloidal Magnetic-Field Measurement System In Jt-60

A diagnostic system using a helium beam for local poloidal magnetic field measurements (Zeeman polarimeter system) has been constructed. The Zeeman spectrum of the helium 3(1)P-2(1)S line was observed in JT-60. The intensity and energy of the neutral helium beam were up to 0.6 A and 200 keV, respectively. Resolution of the Zeeman polarimeter was 0.01 nm which was realized by using a Littrow-type spectrometer. Photon counting efficiency was 0.065. Moreover, an in situ wavelength calibration could be done, using an Ar laser, within an error of 0.001 nm.