On a capillary discharge setup lasing in Ne-like Ar at 46.9nm, the ablation of c apillary wall was investigated for polythene and alumina material at both of inh erent 2—5kA-pre-pulse of setup and separate pre-pulse of 20A by measuring soft x ray emission from the capillary discharged. For inherent pre-pulse and polythe ne capillary, the ablation is too large to create uniform plasma columns and it is impossible to obtain lasing. In the case of 20A-pre-pulse and alumina capilla ry, the ablation decreased remarkably and the laser spike pulse was distinguishe d on an x-ray diode because the uniform Z-Pinch plasma column had formed.