Determination of electron temperature in partial space-charge-compensated high-perveance ion beams

Summary

For heavy-ion inertial-fusion drivers, high-perveance ion beams are required. Space-charge compensation is enhancing the current limit of low-energy beam transport lines (LEBT). The knowledge of the temperature of the compensating electrons and the charge density of the electrons on axis is needed for the calculation of beam transport under the influence of space-charge compensation. A low-energy beam transport line (typically 9 keV, 3 mA DC, He⁺) has been set up and the radial density distribution of the beam ions was measured. Using this data in a one-dimensional numerical simulation, a multiplicity of possible states of the compensated beam can be calculated. Comparing the results of the simulation with measured beam potentials, it is possible to determine the electron temperature as well as the electron density on axis. First experimental results are presented together with the fundamental theory.