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 and careful dimensioning of the antenna as well as the use of a radially magnetized split ring rare earth magnet allowing the localization of the ECR zone near the fire end of the antenna are the main characteristics of this design. A 30 mm in diameter ion beam with current density of 2.3 +/- 0.1 mA/cm(2) over a 18 mm diameter was produced under a mass flow rate of 1 seem, a microwave power of 75 W and an extraction voltage 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 energy distribution was present or not in the extracted beam. An outstanding feature of this source was its ability to be operated without any microwave tuning element and without a cooling circuitry.