[en] An enhancement of line average electron density was observed in the CASTOR tokamak when lower-hybrid power was launched into ohmic plasma. A broadening of the density radial profile was also found. Such behavior of density in lower hybrid current drive (LHCD) discharges can be attributed to an improvement of particle confinement. The dependence was investigated of the global particle confinement time on the plasma density and the position in the plasma. A simple model was used to evaluate the total number of particles in the plasma volume. The global particle confinement improved by a factor of 2-2.5 during LHCD. Further improvement of the global particle confinement was found in the plasma closer to the optimum. (author) 5 figs., 5 refs