We developed a multi-channel H alpha array system to measure two-dimensional (2D) radial profiles of H alpha emissivity in the central cell of the tandem mirror GAMMA 10/PDX. It consists of a 2D optical collection system, which contains twelve channels of lenses, H alpha filters, and bundled optical fibers in vertical and horizontal directions. To study H alpha emission behavior and its fluctuation in the hot-ion mode plasma experiments with additional plasma heating application, we used the modified Phillips-Tikhonov tomography method. After applying the fast Fourier transform analysis to the 2D Ha emissivity profiles, we could successfully obtain the 2D fluctuation images for the first time. These results are useful for the detailed study of fluctuations in magnetically confined plasma. (C) 2020 The Japan Society of Plasma Science and Nuclear Fusion Research