Two capillary discharge devices with different current waveforms were used to excite Ar plasma columns up to 35 cm in length in 3.2 mm diameter channel. The Ne-like Ar lasers at 46.9 nm, 69.8nm and 72.6 nm were obtained with one capillary discharge device with current amplitude of 12-17 kA and a half period of 110 ns. The lasers at 69.8nm and 72.6 nm in Ne-like Ar ions were achieved with low current of 12 kA. The experimental results with different initial pressure show that the 69.8 nm and 72.6 nm lasers can be realized with lower pressure than the pressure of 46.9 nm laser. In addition, the saturated soft x-ray laser at 46.9 nm was generated with the initial pressure of 22 Pa and peak current of 17 kA. The gain coefficient is 0.58 cm-1. On the other capillary discharge device, the highly saturated soft x-ray laser at 46.9 nm was realized with the current amplitude of 27 kA and a half period of 170 ns. The gain coefficient of 1.0 cm-1 has been achieved with the initial pressure of 60 Pa.