Pulse Modulation Technology for High Voltage Power Supplies in Neutron Accelerators
In neutron accelerator systems, high-voltage pulse modulators perform dual functions of energy temporal distribution and power waveform conversion. This paper investigates key pulse control technologies for enhancing beam stability and neutron yield.
1. Core Requirements
Neutron accelerators demand pulse modulators with:
1. High peak power: 50MW-level instantaneous power for electron gun emission and target bombardment.
2. Sub-microsecond rise time: ≤200ns edge control ensures beam phase synchronization accuracy <0.5°.
3. Dynamic stability: Voltage fluctuation coefficient ≤±0.1% at 10³Hz repetition rate.
2. Technical Innovations
Marx Generator Optimization
Distributed capacitor banks with magnetic isolation reduce inter-stage losses from 15% to 3.5%. Hybrid thyratron-IGBT switches enable 20-150kV adjustable output.
Pulse Forming Network (PFN)
Asymmetric PFN topology with variable inductance compensation reduces flat-top ripple from ±5% to ±0.8%, decreasing neutron yield deviation to 2.3% in tungsten targets.
Intelligent Control System
FPGA-based timing control implements four operational modes:
Pre-ionization: Gradient voltage injection
Main pulse: Parallel module current balancing
Trailing edge suppression: Active charge recovery
Safety interval: Dielectric recovery monitoring
3. Design Challenges & Solutions
EMI Mitigation
Coaxial shielding and common-mode chokes reduce radiation noise by 40dB at 100kV. Gate drive shaping limits IGBT di/dt below 5kA/μs.
Thermal Management
3D liquid cooling with phase-change materials maintains 40℃ at 10kW. Graphene thermal pads reduce IGBT junction temperature fluctuation from ±15℃ to ±3℃.
Reliability Enhancement
Dual-loop redundancy control monitors gate charge and insulation loss, extending MTBF to 50,000 hours.
4. Applications & Trends
Optimized modulators in compact neutron sources achieve 14MeV neutron flux density of 5×10¹²n/(cm²·s) with 1.2% energy spread. Future superconducting energy storage may boost efficiency to 95%, while digital twin models enable adaptive pulse optimization.
