| R. Gobin*, P-Y. Beauvais, K. Benmeziane, O. Delferrière, R. Ferdinand, F. Harrault,
Commissariat à l’Energie Atomique, CEA-Saclay, DSM/DAPNIA, Gif sur Yvette Cedex, France
J. D. Sherman, LANL, Los Alamos, N.M. 87 545, USA |
H- ions have now been observed in currents extracted from the Saclay microwave proton source. A pulsed, 90 degree dipole magnet has been installed 14.8 cm downstream from an ion beam extraction system designed to operate up to -10 kV. The plasma chamber can be biased by a negative or positive HV power supply and the
diagnostics are grounded. The dipole analyzer was
equipped with an electrostatic-shielded Faraday cup that properly suppresses secondary electron emission. The dipole magnet was calibrated with a 6.4 keV proton-ion beam. The microwave source magnetic field was configured to establish two ECR zones in the plasma chamber. However, the magnetic field is much reduced from 875 G at the emission aperture. The measured hydrogen ion fractions show a large amount of H2 +. First
measurements at negative extraction potential (–3.2 to – 9.0 keV) give electron to H- ratios ranging from 13/1 to 27/1. The derived H- currents are 1-2 mA. Ion source operation with He gas showed no peak for the H- dipole magnet calibrated current. Future experiments are to
optimize the plasma and extraction system for maximum H- beam production.
This Work is supported by European Commission
under contract HPRI-CT-2001-50021 |
