Characteristics of an electron cyclotron resonance (ECR) plasma source at a frequenccy of 2.45GHz were briefly described. The experiments showed that both plasma ion density and electron temperature in the charge chamber depended on the magnetic field

microwave power and gas pressure. It was found that the microwave breakdown occurred easily at the static magnetic field of 87.5mT. However

the highest plasma density was obtained at about 93mT. The microwave introducing window consisted of three dielectric plates of quartz

aluminum and BN

which allow better impedance matching with the plasma. The source can operate at gas pressure of 0.l-1Pa. The power reflection coefficient is about 1%. Plasma ion density of 5.8 × 1011cm-3 and electron temperature of 3-12eV have been obtained at the microwave power of 200-700W. The lifetime of the source is more than 300h.