Modified distributed electron cyclotron resonance ion source for the production of large diameter ion beams

Abstract

The work presented in this article concerns the conception and the study of a multiantenna electron cyclotron resonance (ECR) ion source at 2.45 GHz dedicated to the surface treatment of large area materials. In this original device, a microwave plasma is created in a 20 cm in diameter ionization chamber. The 15 cm in diameter extracted ion beam has a current density of about 1 mA/cm2. The applicator is an N-way coaxial power divider in which the N=20 antennas are individually magnetized by internal SmCo bars in order to produce ECR zones in their vicinity. Moreover, the microwave plasma is confined by a multicusp magnetic structure surrounding the ionization chamber. The choice of the source geometry has been guided by the study of some theoretical considerations such as the characteristic diffusion length, the minimum breakdown field, and the penetration depth of the wave into the plasma. Simulations both of the electromagnetic field and the static magnetic field distribution have been carried out in order to validate the final choice of the source geometry. A full characterization of the ECR plasma and of the extracted ion beam was made with different experimental techniques. These results allow us to localize the plasma creation zones inside the ionization chamber. A 120 mA singly charged argon ion beam with a profile homogeneity better than ±5% over 10 cm was obtained 5 cm downstream the extraction system with a 300 W microwave power and a neutral argon pressure of 10−3 mbar in the ionizing chamber.

Landau damping in a bounded magnetized plasma column

“…Electron-cyclotron resonance (ECR) in plasma is of considerable interest for a variety of industrial applications including the usage of high-density plasma source for plasma processing and material surface modification. [19][20][21][22] Takahashi et al [23] and Kaneko et al [24] experimentally studied the propagation and damping mechanism of the left-handed polarized wave near the electron-cyclotron resonance. They have demonstrated that the absorption of the left-handed polarized wave near the ECR point in a magnetized inhomogeneous plasma results from polarization reversal in the axial direction.…”