AN OPTIMIZED AND SIMPLIFIED COMPACT ECR ION-SOURCE FOR GASEOUS SPECIES

This paper describes an optimal design of a simple and compact ECR ion source of coaxial shape which belongs to the antenna type ion sources at 2.45 GHz. Avoidance of dielectric pieces in the microwave plasma a nd careful dimensioning of the antenna as well as the use of a radiall y magnetized split ring rare earth magnet allowing the localization of the ECR zone near the fire end of the antenna are the main characteri stics of this design. A 30 mm in diameter ion beam with current densit y of 2.3 +/- 0.1 mA/cm(2) over a 18 mm diameter was produced under a m ass flow rate of 1 seem, a microwave power of 75 W and an extraction v oltage of 1 kV. It was observed that, according to the mass flow rate and amount of microwave power, a high energy tail or peak in the energ y distribution was present or not in the extracted beam. An outstandin g feature of this source was its ability to be operated without any mi crowave tuning element and without a cooling circuitry.