Deep-space exploration represents the core strategic development direction of the global aerospace industry. From interplanetary transfer and asteroid sample return to outer solar system exploration and interstellar medium research, missions featuring long cruising distances and large orbit maneuvers make electric propulsion the primary propulsion for deep-space probes. Among electric thrusters, ion thrusters deliver ultra-high specific impulse of 3,000–5,000 seconds, ultra-low thrust noise and high-precision thrust control, establishing them as the preferred solution for long-range deep-space missions. The high-voltage acceleration power supply acts as the critical power-processing unit of the ion propulsion system, converting spacecraft bus power into thousands of volts of high-voltage DC for ion acceleration. Its energy efficiency, input voltage adaptability and in-orbit reliability directly determine the probe’s power budget, thermal management pressure, mission lifespan and ultimate exploration objectives. In deep-space missions, high-voltage acceleration power supplies face extreme operating conditions far beyond low-Earth orbit platforms. As solar distance increases, solar array output and bus voltage degrade significantly. For Mars missions, bus fluctuation ranges reach 50%–180% of nominal values; for Jupiter and outer solar system missions, variations may exceed 20%–250%. Meanwhile, ion thrusters require 1,200 V–3,000 V acceleration voltage, creating voltage boost ratios above 100:1 from the standard 28 V spacecraft bus. Additionally, deep-space missions feature 8–15 years of maintenance-free in-orbit operation under high vacuum, −55 ℃–+125 ℃ wide temperature cycling and intense particle radiation, imposing stringent reliability and redundancy requirements. This methodology establishes a full-process technical framework covering topological design, full-chain efficiency optimization, space environmental adaptability, and in-orbit monitoring & protection, applicable to ion thruster high-voltage power supplies for all deep-space missions and providing standardized design criteria for domestic electric propulsion localization and performance upgrading. Addressing ultra-wide input ranges and extreme boost ratios, a three-stage isolated architecture is adopted: synchronous boost pre-regulation + full-bridge LLC resonant isolation + symmetric Cockcroft-Walton voltage multiplication. Function separation resolves wide-input stabilization, isolated high boosting and precision high-voltage output simultaneously, overcoming limitations of conventional single/two-stage designs. Stage 1 — Synchronous boost pre-regulation stabilizes severely fluctuating input into a fixed intermediate bus, eliminating input interference with soft-switching performance. Peak current mode control ensures fast dynamic response; synchronous rectification minimizes conduction loss. Integrated surge limiting, EMI filtering and parallel redundant power switches guarantee compatibility with spacecraft power quality and prevent single-point failures. Stage 2 — Full-bridge LLC resonant isolation provides galvanic isolation and secondary boosting while maintaining full-range soft switching. Optimized resonant parameters ensure ZVS for primary switches and ZCS for secondary rectifiers across 10%–100% load. Operating frequency is optimized between 100 kHz–200 kHz to balance power density and loss. Planar/matrix transformers reduce leakage inductance and high-frequency winding loss, while isolated feedback enables precise high-voltage regulation. Stage 3 — Symmetric voltage multiplication delivers extreme high boost ratios with minimized ripple and device stress. The symmetric Cockcroft-Walton structure reduces ripple by over 50% and divides voltage stress evenly across cascaded stages, simplifying high-voltage insulation. Fast-recovery SiC rectifiers and radiation-resistant low-temperature-coefficient high-voltage film capacitors ensure long-term stability; multi-stage π-filtering further suppresses output ripple for accurate ion beam acceleration. Full-link efficiency optimization is implemented across four dimensions: Topology-level optimization maintains soft switching throughout all operating conditions via pre-regulated fixed intermediate voltage, maximizing ZVS/ZCS coverage and eliminating hard-switching loss. Three-stage voltage division avoids excessive single-stage boost ratios and degraded transformer performance. Device-level optimization employs full wide-bandgap semiconductors: SiC MOSFETs reduce switching loss by over 60% and support high-temperature parallel operation; SiC Schottky rectifiers eliminate reverse recovery loss, cutting rectifier loss by more than 80%. Low-loss aerospace-grade magnetic components and low-ESR capacitors further reduce parasitic dissipation. Magnetic design optimizes core materials (Mn-Zn ferrite, nanocrystalline, amorphous alloy) for minimal high-frequency specific loss. Integrated resonant magnetics reduce component count; interleaved Litz-wire windings mitigate skin/proximity effects and lower transformer leakage inductance. Digital control optimization integrates burst-mode operation for light-load efficiency, dynamic dead-time adjustment to minimize body-diode conduction, and adaptive frequency tuning to maintain optimal resonant operating points under all mission conditions. Long-term space reliability engineering adopts a three-layer protection system: Radiation hardening implements component screening, triple modular redundancy for control circuits, parallel power redundancy, and localized alloy shielding against high-energy particles, ensuring total-dose and single-event resilience matching 8–15 year mission requirements. Thermal vacuum design utilizes full conduction cooling with auxiliary radiation heat dissipation. All heat-generating components bond to high-thermal-conductivity substrates connected directly to the probe’s radiator; uniform layout eliminates hotspots; high-emissivity thermal coatings enhance deep-space radiation cooling, maintaining stable operation within −55 ℃–+125 ℃. Mechanical vibration resistance adopts monolithic milled aluminum housings with reinforced structures; heavy magnetic components are thermally conductive epoxy potted; multi-point PCB fixing and aerospace anti-loosing connectors ensure structural integrity during launch vibration and shock. In-orbit monitoring and multi-level protection guarantee operational safety: Full parameter telemetry collects voltage, current, temperature and fault status via standard spacecraft buses for real-time monitoring, historical data storage and traceable fault analysis. Four-tier redundant protection includes sub-1 μs hardware overvoltage/overcurrent/short-circuit shutdown, software threshold guarding, propulsion-system interlock safety, and fault isolation to prevent single-point mission failure. Intelligent auto-recovery restores operation after transient space disturbances, ensuring uninterrupted deep-space thrust capability. In summary, this integrated framework resolves core difficulties of ultra-wide input adaptability, extreme boost ratios, high efficiency and long-duration reliability. The three-stage topology achieves stable operation across full mission bus fluctuation; comprehensive optimization realizes system efficiency above 95%; full environmental hardening supports 8–15 years of maintenance-free deep-space operation. Widely applicable to Mars exploration, asteroid missions and outer solar system probes, it delivers foundational domestic technical support for high-performance ion propulsion and deep-space exploration breakthroughs.