Abstract: An efficient total-variation-diminishing radiation magnetohydrodynamics code FOI-1a has been developed. Calculations with FOI have been performed with in the parameters range of Yang accelerator and PTS facility. Numerical results demonstrate that for light array the radiation at peak is dominated by shock heating, while for massive array by shock heating together with adiabatic compression. The ratio of shock heating to adiabatic compression decreases with increasing of array mass. Precursor plasma produced by ablation weakens shock heating and hence has a negative effect on peak radiation. However, precursor plasma has another stabilization effect on magnetic-Rayleigh-Taylor instability, so there should be an optimum ablation rate that maximizes the peak radiation.