A microwave plasma stream source with variable ion energy operated under low magnetic field electron cyclotron resonance conditions has been developed. A two mode resonant cavity (TE111, E010) was used. It was established that overdense plasma creation (TE111) and high energy in-phase space localized electron plasma oscillations (E010) in a decreased magnetic field lead to the potential for ion energy variation from 10 to 300 eV (up to 1 A of ion current, and a plasma cross section of 75 cm2, hydrogen) by varying the TE111, E010 power, the value of the magnetic field, and pressure. The threshold level of E010-mode power was also determined. An application of this CERA-V source to hydrogenation of semiconductor devices without deterioration of surface layers by ions and fast atoms is under investigation. © 1996 American Vacuum Society.