抄録
The experiments of CDU of VIBES were conducted as scheduled. The first one was executed while running the VIBES system and the second without running the system. G-jitter acceleration was measured by two sets of tri-axial accelerometers on board the VIBES and the CDU . Diffusion of OH- was measured by color of phenolphtalein by using the fact that phenolphtalein turns color between pH 8 and pH 10. Measured diffusion showed a more than 20% faster rate com pared to theoretically calculated one. This means that the apparent diffusion coefficient of OH- was D*~2D in thefirst experiment and D*~3D in the second, where Dis diffusion coefficient of OH-. Measured g-jitter by the accelerometer on-board the CDU showed a stronger g-jitter level in thesecond experiment than that in the first. This corresponds that the diffusion in the second was larger
than that in the first. This suggests that there exist some convection in the liquid due to g-jitter. With regards to measuring natural convection due to residual gravity, this failed because we could not obtained clear distribution of color. The measured flow from the distribution of color, however, was opposite to that predicted.
