Cylindrical and planar surface corona discharge TEA $CO_2$ laser systems are designed and fabricated, and their output energies are investigated and compared with that of the triple discharge TEA $CO_2$ laser. The case of the planar surface corona discharge type is larger in output energy and more stable in laser operation than the case of the cylindrical surface corona discharge type, but these types are superior to the triple discharge type in output energy and stability of laser operation. The maximum output energies of these two surface corona discharge types are about five times and four times, respectively, of that of the triple discharge type. It is found that the optimal gas mixing ratio varies with the type of surface corona discharge. In the case of the planar type, its ratio is $CO_2:N_2$:He=1:1:3.5, and the maximum output energy is about 400mJ.
