Statistical Error Analysis of a Beam Delivery System for Laser-driven Proton Therapy

摘要: Laser-driven proton accelerators (LPAs), owing to their compact layout and ultrahigh accelerating gradients, are promising candidates for future proton radiotherapy systems. A key challenge for their clinical application is to maintain beam delivery accuracy at the isocenter under both source-related beam fluctuations and element errors. In this work, we present a systematic error analysis of the beam delivery system of the Compact Laser Plasma Accelerator (CLAPA II) for proton therapy. Based on TraceWin simulations, input beam error (IBE) scans, segmented element error (EE) sensitivity analysis and end-to-end statistical error analysis are carried out to quantify the effects of mismatch, centroid and pointing jitter, magnet misalignment, tilt, and field errors on beam transmission, orbit deviation, and beam size. The results show that entrance Twiss mismatch has only a weak effect on the beam transmission. In contrast, entrance centroid and pointing jitter dominate the terminal orbit stability and particle survival. The response to element errors is strongly section dependent: In the beam collection section, solenoid tilts mainly drive orbit distortion, whereas field errors mainly affect the beam size. In the energy selection section, dipole field errors mainly affect orbit distortion, beam size, and energy selection efficiency. In the beam shaping section, magnet misalignments mainly determine beam position, while field errors dominate beam size stability. Orbit correction can effectively suppress orbit distortion and improve beam transmission efficiency. Overall, the error effects remain controllable, indicating robustness of the CLAPA II beam delivery system and supporting subsequent beam commissioning and system optimization.