iThemba LABS, Somerset West, South Africa
Using a Belmont-Pabot spiral inflector for axial beam injection presents difficulties when matching the beam emittance to the cyclotron acceptance. For an electrostatic inflector one of the potential solutions to this problem is to use transverse electric field gradients to influence and optimise the optics. Here we extend this approach to magnetic spiral inflectors. It is demonstrated that the gradient of the magnetic field along the central trajectory can be controlled by an appropriate permanent magnet inflector design, and that these gradients have a large influence on the optics. The transverse gradients are numerically optimised and the performance compared to an optimised electrostatic spiral inflector. A faster numerical method for accurately determining the electric field of an electrostatic inflector is also presented.
