A chirped pulse amplification laser with zigzag slab Nd:glass amplifiers dedicated to x-ray laser research is described. The laser provides a 1.6 ps duration pulse with \sim 7\text{\hspace{0.17em} J} energy at a repetition rate of 0.1\mathrm{Hz} . In the power amplifier system, laser light is amplified in a two-step manner: The first step is image-relayed multipass amplification up to \sim 1\text{\hspace{0.17em} J} with a 10\mathrm{mm}\times 10\mathrm{mm} beam. The second step is double-pass amplification up to >10\text{\hspace{0.17em} J} with a 10\mathrm{mm}\times 90\mathrm{mm} beam. By using this laser system, the saturated amplification of the Ni-like Ag laser at a wavelength of 13.9\mathrm{nm} has been successfully demonstrated.