Plasma confinement in a mirror magnetic field was applied to the electron cyclotron resonance (ECR) plasma enhanced de sputtering discharge sustained at pressures below 10(-2) Pa. Ion current densities up to 12 mA/cm(2), plasma densities about 10(11) cm(-3) and electron temperatures about 25 eV were measured by a Langmuir probe. The cathode current was maximum when the ECR zone was close to the cathode z(ECR)<10 cm (measured from the center of the cathode). A mirror ratio MR greater than or equal to 3 was necessary for sustaining the discharge at simultaneously large microwave powers and cathode voltages. An application of the system studied to the ion assisted deposition of metallic and compound thin films with a controlled crystal structure is proposed.