AbstractThe spectrum and the level of fluctuation have been evaluated from the phase data obtained with a reflectometer during the period without phase runaway on the JFT-2M tokamak. The estimated fluctuation level is about 1% in OH mode (at ra < 0.8), about 4% in L mode (at ra ≈ 0.8) and about 10% in H mode (ra > 0.9), while the measured position changes according to the density profile.