Neutron detectors are core sensing components in nuclear technology applications, nuclear radiation monitoring, neutron scattering experiments, nuclear energy development, geological exploration, safety inspection, national defense and military industries. Featuring high detection efficiency, high sensitivity and excellent energy resolution for neutrons, they are widely applied in reactor neutron flux monitoring, spallation neutron source neutron scattering tests, non-destructive testing of nuclear materials, homeland security radioactive monitoring, petroleum logging and neutron imaging, serving as key equipment for neutron detection and nuclear radiation measurement. The high-voltage bias power supply is an essential supporting component of neutron detector systems. It delivers high-precision and high-stability high-voltage bias to various neutron detectors such as ³He proportional counters, BF₃ proportional counters, boron ionization chambers, scintillator neutron detectors and semiconductor neutron detectors. The output range is typically 0~3000V, while large-area neutron detectors require 0~5000V. Its anti-interference capability, long-term operational reliability, output voltage stability and environmental adaptability directly determine the detector’s efficiency, counting stability, energy resolution and service life. Neutron detectors often operate under harsh conditions with strong electromagnetic interference, nuclear radiation, wide temperature fluctuations, humidity, salt fog and vibration, imposing extreme requirements on power supplies for interference resistance and long-term reliability. On one hand, detectors work in intense electromagnetic and nuclear radiation environments such as nuclear reactors, spallation neutron sources and accelerators; meanwhile, detector output signals are nanoampere-level weak currents highly susceptible to power supply noise, requiring ultra-low output noise and superior immunity. On the other hand, neutron detection systems run 24/7 all year round with a service life exceeding 10 years; field, underground and offshore applications additionally demand resistance to wide temperature ranges, high humidity, salt fog and shock vibration. Traditional high-voltage power supplies suffer from poor interference immunity, radiation-induced failure, insufficient long-term stability and weak environmental adaptability, failing to meet such harsh operating conditions. The design strictly complies with standards including GB/T 7167-2015 Methods for Performance Test of Proportional Counters, GB/T 8995-2008 Radiation Measuring Instruments with Ionization Chambers, GB/T 12727-2017 Qualification of Electrical Equipment for Nuclear Power Plant Safety Systems, and the GB/T 17626 EMC series, fully matching the core requirements of neutron detectors for high immunity, high reliability and long service life. Targeting the key application demands and technical challenges of high-voltage bias power supplies for neutron detectors, this methodology establishes a full-process universal technical framework covering high anti-interference topology design, full-dimensional EMC optimization, nuclear radiation adaptability design, harsh environment protection and long-term reliability design. It meets the high-voltage bias demands of all types of neutron detectors and provides standardized design criteria for the engineering application and performance improvement of domestic neutron detection technologies. Focusing on core challenges including strong interference resistance, long-term high reliability and harsh environment adaptability, this methodology adopts a main architecture of fully isolated modular topology, all-metal sealed shielding structure, dual hardware-and-software anti-interference design and full-environment protection, combined with long-life derating and redundant protection mechanisms. It eliminates traditional drawbacks such as poor immunity, insufficient long-term reliability and weak environmental adaptability, enabling stable operation under strong electromagnetic interference, intense nuclear radiation and extreme conditions to fully satisfy all operating scenarios of neutron detectors. The design follows five core principles: 1. Fully Isolated Modular Topology Design Enhance interference immunity and reliability fundamentally with a quasi-resonant flyback inverter topology featuring simple structure, fewer components and excellent input-output isolation, supporting 0~5000V high-voltage output compatible with all neutron detector bias requirements. Quasi-resonant operation achieves zero-voltage switching for power devices, greatly reducing switching loss and noise to minimize EMI at the source. Dual electrical isolation is implemented between input and output with isolation withstand voltage ≥ twice the maximum output voltage; optical isolation is adopted between control and power circuits to eliminate ground potential coupling and interference paths. For multi-channel detection systems, single-channel modular design is applied with independent inverter, boost, rectifier, filter, closed-loop control and protection for each detector. Full electrical, physical and electromagnetic shielding between modules eliminates crosstalk; single-module faults do not affect the entire system, improving redundancy and allowing flexible channel configuration. Symmetrical voltage-doubling rectification reduces output ripple by over 60% compared with single-ended circuits while lowering voltage stress on rectifiers and capacitors. SiC Schottky diodes eliminate reverse recovery spikes and EMI while offering excellent radiation resistance and high-temperature performance suitable for nuclear radiation scenarios. An irradiation-hardened FPGA+MCU serves as the main controller for high-precision closed-loop regulation, data acquisition and anti-interference algorithms implemented via hardware logic to avoid software failure. Independent isolated power supplies for control circuits prevent noise coupling from power stages. 2. Full-Dimensional EMC and Anti-Interference Design A four-level anti-interference solution—conductive suppression, radiation shielding, grounding optimization and software algorithms—ensures stable power operation without affecting weak detector signals: • Conductive suppression: Five-stage EMI filtering including surge suppression with varistors and gas discharge tubes, common-mode filtering with high-permeability nanocrystalline cores, differential-mode filtering, π-type bus filtering and multi-stage RC low-pass high-voltage output filtering. Double-layer shielded coaxial cables are used for outputs; all control and communication signals adopt optical isolation. • Radiation shielding: Three-layer shielding including thick sealed aluminum alloy enclosures (≥3mm wall thickness, ≥120dB shielding effectiveness) with additional permalloy inner layers for strong magnetic fields; fully welded housing with shielded connectors for continuous shielding; independent metal shielding cavities for each module; local shielding for power devices and secondary shielding for noise-sensitive analog circuits. • Grounding optimization: Combined single-point, partitioned and floating grounding with a unique system protective ground; separated power, analog, digital and shield grounds connected in star topology to eliminate ground loops; floating high-voltage output aligned with detector signal ground to guarantee signal-to-noise ratio. • Software anti-interference: FPGA-based digital filtering including sliding average, median and amplitude limiting filters; adaptive PID control; triple redundancy watchdog and error recovery against single-event upset; fault debouncing to prevent false protection caused by transient interference. 3. Nuclear Radiation Environment Adaptability Design A three-level radiation-hardening solution—component selection, circuit reinforcement and structural shielding—ensures long-term stable operation under intense ionizing radiation: • Radiation-resistant component selection: Industrial or military-grade hardened semiconductors with total dose tolerance ≥100krad(Si) for reactors and ≥50krad(Si) for spallation neutron sources; single-event effect LET threshold ≥60MeV·cm²/mg. Passive components adopt radiation-resistant metal-film resistors, polystyrene ceramic capacitors and radiation-hardened magnetic materials; electrolytic capacitors are excluded. All components undergo strict radiation screening and aging tests. • Circuit hardening: Triple modular redundancy for control logic; Hamming EDAC error correction for registers and memory; triple backup and refresh for configuration data; fast single-event latch-up protection with response ≤100ns to cut power instantly; dual redundant critical circuits with hot standby. • Structural shielding: Thickened aluminum alloy housing optimized via Monte Carlo simulation to reduce total radiation dose by over 50%; local high-density shielding with lead/tungsten alloy for sensitive core circuits; optimized component layout placing radiation-sensitive parts in well-shielded zones away from exterior radiation. 4. Harsh Environment Protection and Adaptability Design A full environmental protection solution with three-proof treatment, wide-temperature design and shock-vibration resistance ensures reliability in field, underground, offshore and industrial sites: • Three-proof protection: Fully sealed IP65+ enclosure with silicone sealing and waterproof connectors; PCB coated with ≥50μm conformal coating for moisture, salt fog and mold resistance; anodized, chromed or powder-coated metal structures for corrosion resistance in marine and high-humidity environments. • Wide-temperature adaptability: All components support −40℃~+85℃ operation; full-range temperature compensation dynamically adjusts reference voltage and control parameters to maintain output accuracy within ±0.2% across the entire temperature range; adaptive thermal management adjusts fan speed for low/high-temperature stability with optional fanless conduction cooling. • Shock and vibration resistance: Reinforced integrated thick aluminum housing with stiffeners; heavy components such as transformers fully potted with high-thermal-conductivity epoxy; multi-point fixed PCB layout with mounting spacing ≤100mm; anti-loosening locked connectors qualified per GB/T 2423 for 10g~50g impact and 5g~10g random vibration for vehicle-mounted, airborne, underground and offshore applications. 5. Long-Term Reliability and Full Lifecycle Design Meeting the 10+ year continuous operation requirement with ultra-derating design, redundancy, full lifecycle health management and comprehensive protection: • Ultra-derating design: Components follow 80% of Grade I derating per GJB/Z 35-93 with voltage stress ≤50%, current stress ≤40% and temperature stress ≤70% of rated values to slow aging. Long-life polypropylene high-voltage capacitors (≥100,000 hours), high-stability metal-film resistors (≤10ppm/year drift) and reliable SiC power devices are adopted; fanless mechanical-structure-free designs are optional for critical scenarios. • Redundancy: Dual redundant AC input with seamless switching; redundant control power supplies; dual hardware-and-software overvoltage/overcurrent protection; hot standby dual-power parallel operation for zero interruption in key applications. • Comprehensive protection: Full protection including input over/undervoltage, overcurrent, output overvoltage, short circuit, overtemperature, high-voltage arcing and ESD with hardware response ≤1μs; soft start and slow high-voltage shutdown to prevent surge damage; safety interlock interfaces linked with reactor and detector systems. • Full lifecycle health management: Real-time full-parameter monitoring with over 10 years of data storage for traceability; health assessment and remaining life prediction for predictive maintenance; regular self-calibration with low-drift references to correct aging errors and maintain precision throughout the service life. This methodology forms a complete technical system covering high anti-interference topology, full-dimensional EMC, nuclear radiation adaptability and long-term reliability for neutron detector high-voltage bias power supplies, thoroughly solving traditional weaknesses including poor immunity, radiation failure, insufficient stability and weak environmental tolerance. The four-level anti-interference design delivers superior EMC performance for strong electromagnetic environments; the three-level radiation hardening ensures reliable operation under nuclear radiation; full-environment protection adapts to extreme conditions; ultra-derating and lifecycle management achieve over 10 years of continuous service. Widely applicable to nuclear reactor monitoring, spallation neutron sources, neutron imaging, geological exploration and safety inspection, it provides core technical support for the engineering promotion and performance upgrade of domestic neutron detection technologies.