A wall stabilized arc is described which incorporates new design features in order to increase the versatility of this source for quantitative spectroscopic measurements, extending its useful range to lower pressures and to the study of molecular gases. Spectral measurements of different arc portions can be made radially and compared with measurements along the arc axis. It was thus established that in end‐on measurements of argon arcs an essentially homogeneous plasma is viewed by the spectrometer.