Determination of average electron energy from the volt-ampere characteristic of the Langmuir probe

It is shown theoretically that the volt-ampere characteristic of a Langmuir probe can be used to determine the average electron energy $<\epsilon>$ in very wide limits of variation of the electron energy distribution function. The required segment of the volt-ampere characteristic lies within the limits $\left(0, \frac{1}{3}<\epsilon>\right)$, and the maximum error in the determination of $<\epsilon>$, due to the deviation of the electron energy distribution function from Maxwellian, does not exceed 50%.