Basic plasma investigations on the Frankfurt high intensity proton source with an electrostatic 127° cylinder spectrometer

For the International Fusion Materials Irradiation Facility, a new volume source has been developed and tested in 1999. The plasma generation is performed by means of a filament-driven arc discharge. Besides, a solenoid for the plasma confinement, the ion source is equipped with a filter magnet to control the electron energy in the plasma. Using a 127° cylinder spectrometer, the energy distributions of H+, H2+, H3+ and electrons as a function of different discharge parameters were measured. Based on these investigations, fundamental plasma parameters are derived, such as plasma-wall potential, electron and ion temperatures. Furthermore, with the knowledge of the electron-energy distributions, it is possible to verify the mechanism of the proton generation in the hydrogen plasma. This paper summarizes the results of basic plasma investigations. The goal of these investigations was to get a better understanding of the plasma physics within the proton source. In addition, it was an aim to gain insight into the trend of experimental results and to be able to improve the ion source performance.