[en] The idea of using a multi-Z (e.g., carbon, oxygen) thin plasma column as a medium for soft x-ray lasing action is presented. A plasma confined by a strong magnetic field is first heated by a CO₂-laser, and then cools rapidly by radiation losses. This leads to a level population inversion of hydrogen-like carbon or oxygen ions. Two computational models are presented. One uses given electron temperature, T/sub e/(t), evolutions. The other uses T/sub e/(t) calculated from an energy balance equation ith CO₂-laser beam power as a parameter. According to calculations, a total gain of G > 100 is expected for 3 → 2 and G > 10 for 4 → 2 transitions (lambda = 182 A and lambda = 135 A, respectively) for CVI ions using a CO₂-laser beam with power approx. 5 x 10¹⁰ W for plasma column heating