Proton therapy is globally recognized as one of the most advanced radiotherapy technologies for oncology. Owing to its unique Bragg Peak dose distribution, it enables precise targeted ablation of tumor lesions, delivering maximum destruction of cancer cells while minimizing radiation exposure to surrounding healthy tissues and organs. It significantly reduces side effects and improves patient cure rates and quality of life, becoming the preferred treatment for pediatric tumors, skull-base tumors, lung cancer, liver cancer and other deep-seated solid tumors. The high‑voltage pulse power supply serves as the core power component of proton therapy accelerator systems, providing high‑amplitude, narrow-width, high-current pulsed outputs for the RF accelerating cavities, deflection magnets, focusing magnets, stripping magnets and kicker magnets of cyclotrons and synchrotrons. It performs critical functions including synchronized energy injection for proton acceleration, beam deflection/focusing control, and fast beam extraction & stripping. Its pulse waveform quality, amplitude accuracy, trigger synchronization and dose control precision directly determine proton energy stability, beam quality, target dose uniformity, and ultimately the clinical efficacy and medical safety of the entire proton therapy system.

Due to strict medical requirements and accelerator operational characteristics, proton therapy imposes far more rigorous specifications than conventional industrial or standard accelerator power supplies: 1.Narrow high-current pulses with ultra-low waveform distortion: Output ranges from several kV to tens of kV, pulse width from hundreds of ns to several μs, and peak current up to several kA. Rise/fall edges must be controlled within tens of ns, pulse top droop ≤0.5%, overshoot ≤0.3%, with no oscillation or tailing. Conventional pulse supplies suffer from topology and parasitic limitations, causing energy dispersion, beam degradation and inaccurate dose delivery. 2.Ultra-high synchronization accuracy: Dozens to hundreds of pulse power supplies must operate synchronously with trigger accuracy ≤10 ns. Minor timing deviations induce acceleration desynchronization, beam loss or failed extraction, interrupting treatment and compromising dose safety. 3.Clinical-grade dose precision & long-term stability: Absolute dose error ≤±2%, uniformity ≤±1%, corresponding to pulse amplitude accuracy ≤±0.5% and pulse-to-pulse consistency ≤±0.2%. Long-term drift during 24/7 continuous operation ≤±0.3%, with no irreversible performance degradation throughout the full lifecycle to guarantee repeatable therapeutic dosing. 4.Medical safety redundancy & regulatory compliance: As Class III medical devices, systems require MTBF ≥100,000 hours, full redundant backup with seamless failover, multi-level safety interlocks, compliance with IEC 60601-1, GB 9706.21 and full NMPA registration certification. 5.High electromagnetic compatibility in complex accelerator environments: Intensive RF, magnet power and pulsed equipment generate severe EMI; fast nanosecond pulses must be suppressed to avoid interfering with sensitive beam diagnostics and clinical measurement systems, meeting strict medical EMC limits. 6.Intelligent control & full data traceability: Full real-time parameter logging, long-term secure storage, seamless interfacing with Treatment Planning Systems (TPS) and accelerator control for automatic pulse adjustment and fully traceable clinical records.

This methodology establishes a full-process technical framework covering narrow high-current pulse topology, waveform optimization, high-precision synchronous triggering, dose stability assurance and medical-grade safety design. It supports cyclotrons, synchrotrons, fixed treatment rooms and gantry-based proton therapy systems, delivering standardized design principles for domestic core component localization and performance upgrading. Targeting narrow pulses, nanosecond synchronization and high dose accuracy, the general architecture adopts all-solid-state modular Marx generator topology combined with distributed fiber-optic synchronous triggering and low-parasitic layout, supported by fully digital closed-loop pulse calibration algorithms. It overcomes traditional limitations of linear modulators, rigid switches and vacuum tubes in achieving fast edges, high current, stability and long service life. The Marx topology eliminates high-voltage transformers; multi-stage capacitors charge in parallel and discharge in series to directly generate high-amplitude high-current pulses without transformer-induced edge distortion or resonance. All-solid-state wide-bandgap switches deliver faster switching, higher repetition frequency and maintenance-free long-term operation suitable for 24/7 clinical service. Six core design principles are defined.

1.Optimized wide-bandgap power devices with parallel current sharing: Third‑generation GaN HEMTs or SiC MOSFETs provide switching rise time ≤10 ns with low parasitic capacitance. Multi-device parallel configuration per Marx stage ensures switching synchronization ≤5 ns and current sharing deviation ≤±2%, enabling extremely high peak current while preventing single-device overload.

2.Symmetric modular Marx unit design: All stages adopt identical standardized modules with matched energy storage capacitors, switches, charging circuits and drivers. Uniform parasitic parameters guarantee synchronous discharge and eliminate waveform distortion caused by component mismatch. Output amplitude scales by stage count; peak current expands via parallel modules with excellent interchangeability for rapid maintenance.

3.Precision isolated constant-current charging: Each stage integrates an independent high-frequency isolated DC-DC charger with charging accuracy ≤±0.2%. Closed-loop voltage compensation corrects temperature drift and aging, maintaining stable inter-pulse amplitude during continuous operation to secure dose repeatability.

4.Ultra-low parasitic discharge layout for nanosecond waveform fidelity: A 3D stacked busbar structure with ultra-thin high-insulation dielectric cancels reverse magnetic flux, reducing total loop inductance below 1 nH to minimize edge degradation, oscillation and top droop. Symmetric equal-length discharge paths ensure uniform timing across all stages. Impedance-matched output transmission eliminates reflection and pulse tailing at accelerator loads.

5.Active digital waveform compensation: FPGA-based real-time droop control dynamically adjusts Marx switching sequences or injects corrective current to suppress pulse top droop ≤0.3%. Active clamping limits overshoot ≤0.2%; fast residual charge discharge ensures symmetric falling edges and eliminates beam tail loss.

6.Double-layer galvanic isolation and high-voltage insulation: Full electrical isolation between Marx stages and between high/low voltage sides with insulation margin ≥2× maximum output voltage. Fiber-optically isolated drivers eliminate high-voltage interference; optimized field grading suppresses partial discharge and corona for long-term operational reliability.

Nanosecond system-wide synchronization is critical for clinical beam stability. A centralized synchronous controller with distributed fiber transmission and local fine delay compensation achieves overall trigger accuracy ≤5 ns. The master FPGA utilizes an oven-controlled crystal oscillator with stability ≤±0.1 ppm to generate global clock and unified trigger signals distributed via equal-length single-mode fiber links (delay stability ≤10 ps/m). Each local unit integrates high-resolution programmable delay chips with tuning step ≤100 ps to compensate device-level timing differences. Real-time online calibration continuously adjusts delays throughout the equipment lifecycle to maintain synchronization stability.

Dose accuracy and long-term stability are guaranteed through full-link closed-loop optimization: High-speed ≥1 GSPS ADCs sample every pulse for amplitude, width and droop; FPGA digital calibration adjusts charging and switching in real time, achieving amplitude precision ≤±0.3% and pulse-to-pulse consistency ≤±0.1%. Multi-dimensional adaptive compensation corrects temperature drift, component aging, input fluctuation and environmental variation, keeping long-term system drift ≤±0.2%. Double-layer magnetic & electromagnetic shielding attenuates external EMI by more than 60 dB while containing internal pulse radiation; multi-stage EMI filtering ensures stable output in harsh clinical accelerator environments.

Medical-grade safety and regulatory compliance follow strict Class III medical device requirements: Redundant hot-standby architecture enables seamless 1 ms failover with no dose interruption during treatment; core control, drive, charging and synchronization circuits adopt dual redundant design to eliminate single-point failure risks. Six hierarchical safety interlocks comply with IEC 60601-1 and GB 9706.21: ultra-fast hardware over-current/over-voltage protection (<100 ns response), software threshold monitoring, dose excess interlock, treatment room door safety, accelerator beam interlock, and independent manual emergency shutdown. Full medical EMC compliance meets GB/T 18268.1 with highest immunity levels and controlled emission to protect sensitive clinical equipment. Full lifecycle traceability stores all pulse parameters, treatment logs and fault records for over 10 years with non-tamperable secure storage, supporting full regulatory audit and seamless hospital information system integration.

In summary, this integrated methodology resolves critical bottlenecks of conventional pulse power technology, unifying nanosecond fast edges, high-current output, ultra-high synchronization and clinical dose precision. The all-solid-state Marx architecture achieves pulse droop ≤0.3%; fiber-optic synchronization delivers system timing ≤5 ns; fully digital closed-loop control ensures amplitude accuracy ≤±0.3%; and comprehensive medical safety design satisfies Class III device certification requirements. Widely applicable to proton and heavy-ion therapy accelerators, it provides core independent controllable technology for domestic advanced radiotherapy equipment localization and clinical performance improvement.