UCLA

MEMS electromagnets occupy a unique niche in the design space of magnetic devices: they are small enough that length-scaling enables Tesla-scale field intensity and kTesla-scale field gradient, but large enough that power dissipation does not exceed practical power density limits for conductive cooling. This work demonstrates the first application of MEMS electromagnets to charged particle beam optics. Particle beam optics are an important component in beam transport systems for medical and scientific instruments such as Hadron therapy for cancer treatment and free electron lasers for high energy coherent light production. These MEMS devices promise smaller and higher performance instruments using the performance scaling that results from reducing the electromagnet gap. This work demonstrated a MEMS multi-pole Ni₈₀Fe₂₀-yoke electromagnet with a 600 &mum pole-pole gap producing a 24-mT dipole field at 3 A, steering a 34-keV electron beam in two dimensions without measurable hysteresis. The same multi-pole electromagnet producing a 220-T/m quadrupole field gradient at 4.7 A was used to focus a 34-keV electron beam. The spatial distribution of the quadrupole field was characterized using a novel electron beam-probe method. Simulations project that 4-pole electromagnets with 100 &mum pole-pole gap electromagnets and a 200 &mum thick Co ₅₇Ni$13Fe₃₀ yoke will produce 850 mT dipole fields and 20,000 T/m quadrupole field gradients, exceeding all published quadrupole optics by more than an order of magnitude.