The University of Melbourne’s TURBO (Technology for Ultra Rapid Beam Operation) project aims to improve charged particle therapy by developing large momentum acceptance beamlines to reduce the energy layer switching time, increasing the efficiency of delivery systems for cancer treatment. Previously, a closed-dispersion arc has been designed utilizing non-linear magnets built as Halbach arrays, which achieves up to ±42% rigidity acceptance in a beamline with an overall bend of 30°. Here – considering the technological complexity of these non-linear magnet arrays – we present a design methodology for compact large momentum acceptance beamlines based on separate-function magnets. We find parameters representing clinical beam quality requirements and perform a multi-objective optimization to investigate trade-offs between them. The separate-function approach provides an alternative for a full-scale beamline that relies on simpler, commercially available technology.

In charged particle therapy, high energy layer switching times prolong beam delivery time, limiting treatment efficiency and accuracy. The TURBO (Technology for Ultra-Rapid Beam Operation) project aims to build a low-energy (0.5-3 MeV) demonstrator beamline for proton therapy with a large momentum acceptance (±42%), enabling rapid delivery over the full clinical energy range, alleviating this bottleneck. Novel beam diagnostic instrumentation is required to monitor key parameters of the beamline constructed for the University of Melbourne’s Pelletron accelerator, which operates at low energies and high current densities. We develop a pepper-pot mask-based method to measure beam phase space distribution and quantify the emittance, and a multi-layer Faraday cup (MLFC) to measure energy distribution. This work now enables the completion of the beam shaping section, and integration of a fixed-field, closed-dispersion beam transport section, key next steps toward assessing TURBO’s potential to shorten beam delivery times.

Permanent magnet Halbach arrays can be used for beam steering and focusing for synchrotron light sources, Fixed Field Accelerators, and plasma accelerators. Conventional implementations require many custom wedge-shaped magnets with tailored geometries and magnetisation angles, preventing material reuse. We present a method for constructing Halbach arrays from many identical rectangular magnets, each rotated in the transverse plane to approximate the optimal configuration. Although this introduces gaps and reduces magnetic efficiency compared with custom-wedge designs, it simplifies fabrication, lowers costs, and enables the magnets to be redeployed for future applications. A prototype array based on this approach has been built for Project TURBO at the University of Melbourne, and measurements confirm that the magnetic field quality meets the requirements of the planned beamline. Construction of the full arrays for TURBO will soon commence, and the reusability of the magnets is expected to provide long term flexibility for subsequent accelerator projects.

The University of Melbourne’s TURBO (Technology for Ultra Rapid Beam Operation) project aims to improve charged particle therapy by developing large momentum acceptance beamlines to reduce the energy layer switching time, increasing the efficiency of delivery systems for cancer treatment. Previously, a closed-dispersion arc has been designed utilizing non-linear magnets built as Halbach arrays, which achieves up to ±42% rigidity acceptance in a beamline with an overall bend of 30°. Here – considering the technological complexity of these non-linear magnet arrays – we present a design methodology for compact large momentum acceptance beamlines based on separate-function magnets. We find parameters representing clinical beam quality requirements and perform a multi-objective optimization to investigate trade-offs between them. The separate-function approach provides an alternative for a full-scale beamline that relies on simpler, commercially available technology.