Abstract
The electron energy distribution in a hot cathode low pressure discharge is measured by a probe and by means of an electrostatic energy analyser. Probe data indicate a non-maxwellian primary group and two maxwellian electron groups of lower energy, but the analyser spectra show no maxwellian groups. It is found that the probe potential can modify the number and energy distribution of electrons incident on the probe, and this effect is Suggested as an explanation of the Langmuir paradox.