Derivation of scaling laws for intense light ion beam divergence with the KALIF–HELIA accelerator

A short description of a new accelerator called KALIF–HELIA is given, that is presently under construction at the Forschungszentrum Karlsruhe. This High Energy Linear Induction Accelerator couples a self-magnetically insulated transmission line with the induction linac technology: the 1 MV pulses from 6 induction cells are added in a “magnetically insulated voltage adder” (MIVA) delivering for 50 ns a pulse of 6 MV and 400 kA to a matched load. This technology is considered in all light ion beam driven reactor concepts as a low cost alternative for the production of energy by inertial fusion (IFE). The pulses delivered by these generators are coupled to diodes that generate the intense light ion beams. Focusing of these beams is presently insufficient and requires scaling to IFE conditions. However, the available scaling laws for beam divergence are not in agreement with the few results from experiments performed at high power levels. Therefore, a verification and improvement of these scaling laws is necessary in order to extrapolate more reliably to beams needed for IFE conditions. e start-up phase – foreseen for end 1997 – KALIF–HELIA will be operated first in negative polarity generating an electron beam. The subsequent operation of the accelerator in positive polarity will allow the verification of the voltage dependence in the divergence scaling laws for proton beams and acceleration voltages up to 6 MV. In a second step, the predicted influence of the ion mass on the beam divergence will be investigated by accelerating Li+ ions instead of protons.