Optical titanium dioxide film is deposited with the ion beam assistant twin magnetron MF reactive sputtering equipment. The variation of reactive plasma is monitored by Langmuir probe and the I-V curve is also tested simultaneously. The results demonstrate that the assistant ion beam plays an important role in enhancement of electrical charge density in the plasma region. With the increase of ion beam power assistance, the electron density increases and both minus floating potential and reactive sputtering voltage decrease. The plus potential on the surface of the substrate increases during the variation from electron-rich to ion-rich state. The substrate steps into the plasma electric neutrality state when the ion beam assistance power supply is 109 W.

twin magnetron  /  MF sputtering  /  ion beam  /  plasma