The effect of discharge voltage of a discharge tube were investigated.The discharge voltage (700,800,900,1000,1100,1200) volt were applied under pressure of helium gas was (7Pa) and the inter electrode distance was (130mm). The measurements were achieved without and with parallel magnetic field of (25 mT). The electron temperature calculated from Id – Vd characteristics curves of double Langmuir probe. Results of electron temperature indicated that the behavior of electron temperature decreased with increasing the discharge voltage with and without the magnetic field.But their values at (B=0) was smaller than the corresponding values at (B=25 mT)
