For the purpose of reception of the initial data for calculation and designing plasmatron a direct current for heating of the helium, wide experimental researches of intensity of electric field Е along an arch burning in a vortical stream of gas are spent. Sizes Е were defined by a method of measurement of potentials of the neutral sections isolated from each other. Dependences Е on diameter of the channel, a current of an arch and helium expenses are defined. Results of experiments are generalised in критериальной to the form. The obtained data has allowed to calculate volt-ampernye of the characteristic and geometrical parametres plasmatron for heating of helium to temperature 4700 K.