The spontaneous outspread of surface-wave plasma (SWP) towards the edge of large-scale quartz window is studied using a time-stepping seff-consistent model. The performances of three different types of slot-antenna arrays are compared,and the electron density distributions for each array at different stages are presented.The results show that slotting along both x and y directions can be helpful to the outspread and can thus enhance the uniformity of SWP.Meanwhile,when we use such an array,the absorption rate of input microwave power can reach more than 83%.