With the purpose of deriving input datas for account and the designings of plasmatrons of a direct current for heating helium, are held broad experimental researches of an electric field strength along an arc, burning in a vortex flow of gas. With usage of the numerical methods the method of application of account of heat losses in the cathode, anode with allowance for of driving heat source is designed. Heat losses in members of a plasmatron subject to inten-sive heating are determined experimentally. The conditions of chilling are determined.