First plasma analysis of the CEA/Saclay ECR hydrogen negative ion source

Reliable high intensity H− ion source development is now part of the CEA/Saclay work in the field of high intensity linear accelerators. A 2.45 GHz electron cyclotron resonance (ECR) H− ion source and test bench have been built. This new source has been designed taking into account our experience on the French high intensity ECR proton source. For H− ion production, the high-energy electrons created in the ECR zone are trapped by a dipole magnetic filter. A rectangular 210 mm long plasma chamber and an intermediate iron shield are used to minimize the magnetic field in the extraction region. A second magnetic dipole separates electrons and negative ions in a 10 kV extraction system. To reduce the electron/H− ratio, the plasma electrode is biased by a power supply. The first helium plasma allowed us to verify the satisfactory electron separator behavior. Pulsed hydrogen plasma is currently produced. The first plasma characterization is under progress as a function of ion source parameters by using Langmuir...