Nuclide identifiers are portable radiation detection devices for rapid nuclide classification and dose-rate measurement. Featuring compact size, light weight, fast field deployment and high recognition accuracy, they are widely applied in environmental radiation monitoring, nuclear emergency response, customs & border security, homeland defense, nuclear facility inspection, geological exploration and field radioactive surveys, serving as core equipment for nuclear safety supervision, radioactive pollution prevention and anti-nuclear-terrorism missions. The high-voltage bias power supply is an essential critical component, providing stable high-voltage bias for scintillators, photomultiplier tubes (PMT), silicon drift detectors (SDD), CdZnTe (CZT) and other sensing units. It supports detector operating bias and realizes conversion & amplification from radiation signals to electrical pulses. Its voltage stability, noise performance, power consumption, and wide-temperature adaptability directly determine the device’s energy resolution, nuclide identification accuracy, detection sensitivity, battery runtime and overall field applicability.
Portable field operation imposes far stricter requirements than conventional laboratory high‑voltage power supplies: 1.Ultra-low power consumption & high efficiency: Battery-driven handheld units require over 8 hours continuous runtime. Standby static power ≤10 mW, overall efficiency ≥85% and high efficiency maintained across 10%–100% load range. Traditional high-voltage supplies consume hundreds of milliwatts at idle and suffer poor light-load efficiency. 2.Extreme wide-temperature resilience: Operating range −40 ℃ ~ +85 ℃, storage −55 ℃ ~ +125 ℃; output drift ≤±0.5% across full temperature range with reliable cold startup. Conventional designs often fail at ultra-low temperatures or experience severe drift at high temperatures. 3.Miniaturization & lightweight integration: Volume ＜10 cm³, weight ＜20 g for direct integration inside detector modules. Traditional discrete high‑voltage circuits cannot meet handheld size limits. 4.Ultra-low ripple & high stability: Ripple peak-to-peak ＜0.05%; long-term stability ≤±0.1%/year; short-term stability ≤±0.05%/8 h. Even minor drift changes detector gain, degrading energy resolution and causing misidentification. 5.Wide adjustable output voltage: Continuously tunable from zero to rated voltage covering hundreds to thousands of volts to support PMT, CZT, SDD and various scintillators; adjustment accuracy ≤0.1% for temperature & aging gain compensation. 6.High reliability & strong immunity: Robust against EMI, radiation, vibration and shock; comprehensive protection against overvoltage, overcurrent, overtemperature and short-circuit for stable operation in harsh nuclear emergency sites. 7.Low startup voltage & battery compatibility: Stable operation from 2.5 V to 12 V input, compatible with single/dual lithium batteries (2.7 V–8.4 V) during discharge fluctuations.
This methodology establishes a full-process technical framework covering low-power topology, full-range efficiency optimization, wide-temperature adaptation, ultra-miniature integration and low-noise high-stability output. It supports handheld nuclide identifiers, environmental radiation monitors and personal dose alarms, providing standardized design guidelines for domestic core-component localization. Targeting low-power battery operation, wide-temperature performance and extreme miniaturization, the universal architecture adopts flyback isolation topology + Cockcroft-Walton voltage multiplier + fully digital low-power control, combined with compact integration and adaptive temperature compensation algorithms. It eliminates traditional bottlenecks of high idle power, bulky size and poor extreme-temperature performance. The flyback topology delivers simple structure, minimal components, high voltage ratio and galvanic isolation, while the multiplier stage achieves high output without excessive transformer turns, reducing size and parasitic parameters. Seven core design principles are defined.
1.Optimized low-power flyback design: High-frequency compact ferrite cores achieve high step-up ratio from low battery voltage to kV-level output. Interleaved multi-strand Litz winding minimizes skin-effect loss and leakage inductance; vacuum epoxy potting enhances insulation, vibration resistance and thermal stability. MnZn ferrite maintains stable permeability and saturation flux across −40 ℃ ~ +85 ℃ to prevent core saturation at extreme temperatures.
2.Advanced symmetric Cockcroft-Walton multiplier: Reduces ripple by over 50% compared with single-ended topologies; divides voltage stress evenly across stages to simplify high-voltage insulation. Low-leakage high-speed rectifier diodes (SiC Schottky or fast-recovery HV diodes) ensure negligible reverse current at high temperatures. Low-ESR low-temperature-coefficient ceramic/film capacitors stabilize ripple and accuracy under full temperature variation.
3.Fully digital low-power control architecture: Ultra-low-power MCU with static current ＜1 μA supports multi-mode operation: PFM mode improves light-load efficiency by dynamically reducing switching frequency; standby mode disables power stages with idle power ＜1 mW; sleep mode cuts nearly all circuits with consumption ＜10 μA. High-precision 16-bit ADC digital PID regulation achieves tuning accuracy ≤0.1%; serial digital configuration enables remote calibration and flexible voltage setting for different detectors.
4.Wide input battery adaptive design: Stable startup and operation from 2.5 V to 12 V; integrated under-voltage lockout prevents deep battery discharge and protects lithium cells.
5.Ultra-miniature high-density integration: Full SMD multi-layer PCB layout shortens power loops and reduces parasitics, achieving overall volume ＜10 cm³ and weight ＜20 g for embedded detector integration.
6.Galvanic isolation & safety protection: Transformer isolation with dielectric strength over twice the maximum output voltage ensures operator safety. Dual hardware/software protection covers over/under voltage, overcurrent, short-circuit and overtemperature; instantaneous short-circuit shutdown with automatic recovery safeguards detectors and batteries.
7.Low-noise EMC design: Soft switching reduces dv/dt and di/dt to suppress EMI at the source; multi-stage input/output filtering and metallic shielding contain radiation interference, ensuring undisturbed weak-signal acquisition by detectors.
Full-link low-power & efficiency optimization ensures long battery runtime: Flyback minimizes component count and fixed losses; low-leakage multiplier eliminates unnecessary power dissipation; PFM adaptive frequency control maintains efficiency ≥80% from 10% to 100% load; ultra-low-power auxiliary circuits and high-value sampling resistors reduce static consumption in standby and sleep modes.
Wide-temperature adaptation guarantees reliable field performance from −40 ℃ to +85 ℃: All components selected for −55 ℃ ~ +125 ℃ rating; adaptive temperature-compensation algorithms correct drift caused by core characteristics, semiconductors and passive components; cold-start assist ensures reliable ignition at −40 ℃; uniform thermal layout prevents hotspots; high-temperature stable potting and insulation eliminate condensation or dielectric breakdown under thermal cycling.
High-stability low-noise output secures accurate nuclide identification: High-resolution ADC + precision metal-foil resistors and low-drift bandgap references ensure long-term stability; multi-stage LC and π-type filtering suppress ripple below 0.05%; aging compensation continuously corrects long-term drift to maintain consistent detector gain over years of operation.
In summary, this integrated design solves key traditional limitations: excessive power consumption, large size, poor low/high-temperature performance and low light-load efficiency. The proposed solution achieves static power ＜10 mW, efficiency ≥85 %, stable full-temperature operation, and ultra-compact volume under 10 cm³. It is widely applicable to handheld nuclide analyzers, environmental radiation monitors, personal dose alarms and portable gamma spectrometers, delivering core independent technologies for domestic substitution and performance upgrading of China’s radiation detection equipment.