Hybrid Quadrupole Lens for the Focusing Channel of the DARIA Complex

The results of synthesis and electromagnetic calculation of a hybrid quadrupole lens for a proton linear accelerator of the DARIA compact neutron source are presented. The lens includes a permanent magnet quadrupole with a fixed magnetic field gradient and an auxiliary electromagnetic quadrupole excited by a pulsed current. The permanent magnet quadrupole is made of a radiation resistant rare-earth magnet and the electromagnetic quadrupole is designed to compensate for permanent magnet magnetization losses resulting from radiation degradation as neutron fluence accumulates during accelerator operation. A hybrid quadrupole lens can be applied for fast adjustment of the focusing channel as well as for transporting the accelerated ion beams with different ion mass-to-charge ratios.