A two-beam radio-frequency quadrupole (RFQ) for funnelling of ion beams at low energies

In a heavy ion inertial fusion (HIIF) driver the strongest current limitations are space charge forces in the low energy part of the linac. For this reason the required high current and small emittance ion beam will be reached by several funnelling stages where two identically bunched ion beams are combined into a single beam with twice the frequency, current and brightness. For the first funnelling stage a new two-beam radio-frequency quadrupole (RFQ) could be used where two beams are bunched and accelerated in a single r.f. cavity. The r.f. structure development and the experimental set-up for beam funnelling with He+ will be presented.