X‐ray emission from pinch plasma devices with pinch currents ranging from 200 to 400 kA operated with pure high‐Zgases are investigated with temporal spatial and spectral resolution. If operated using elementsZ<18 (e.g., nitrogen or neon)K‐shell emission is observed from column‐like volumes several 100 &mgr;m in diameter and several mm in length (bulk or column mode). ForZ≳18 (e.g., krypton or xenon) emission withh&ngr;≳1 keV is only observed from micropinches. For argon (Z=18) both modes of operation can be observed. The occurrence of a specific mode depends on the initial gas pressure. In this paper the transition regime between column and micropinches is investigated with particular regard to argon. A criterion is proposed to decide whether column mode or micropinch mode is expected. ©1995 American Institute of Physics.