Fig. 1

Deformation profile of the launcher wall with dual-direction perturbations (\(\delta _1\) = +0.172 mm, \(\delta _2\) = –0.172 mm) superimposed on the mean radius (\(R_0\) = 19 mm). The amplitudes over 24 mm along z, providing both axial and radial variation of the inner-wall perturbations.