Pulse Energy Control of Coating-Oriented High-Voltage Pulsed Power Supplies
As the core energy source for physical vapor deposition (PVD) and plasma coating, the pulse energy stability of high-voltage pulsed power supplies directly determines coating quality and process repeatability. This paper systematically elaborates key technologies for microsecond-level pulse energy control from plasma dynamics, pulse modulation, and multi-parameter coupling perspectives.
1. Quantitative Relationship Between Pulse Parameters and Coating Properties
Pulse energy density (E=∫V(t)I(t)dt) fluctuations directly affect coating stress and lattice defect density. Experiments show that when pulse voltage (20-100kV) fluctuations exceed ±0.5%, TiN coating microhardness deviation increases from ±5HV to ±30HV. Bipolar pulse superposition (positive width 5-50μs, negative width 1-10μs) compensates target arcing, stabilizing Al₂O₃ surface roughness at 0.8±0.05μm. For HiPIMS processes, pulses with >100kV/μs rise rates increase ionization rates from 5% (DC) to 80%.
2. Closed-Loop Energy Control Under Dynamic Loads
Target impedance variations (ΔZ/Z≈10^3) during coating cause pulse distortion. Magnetic switch-IGBT hybrid modulation enables adaptive pulse current tracking (1MHz bandwidth), maintaining <±0.3% energy fluctuation under 100A load steps. Combined with real-time plasma spectroscopy (10kHz sampling), PID-fuzzy algorithms adjust pulse frequency (1-500Hz), improving CrN thickness uniformity from ±15% to ±3%.
3. Multi-Physics Interference Suppression
Power-frequency magnetic interference (≤50μT) induces pulse front oscillations (>5%), addressed by coaxial sandwich shielding (permalloy/nanocrystalline/copper mesh) achieving 60dB attenuation. Target thermal radiation (300-600℃) reduces cable insulation resistance, countered by boron nitride-cooled sleeves maintaining >10^14Ω. Vibration-induced contact potentials (5-2000Hz, 0.5Grms) are suppressed to <1mV via air-floated isolation platforms.
4. Pulse Energy Adaptation for Special Coating Processes
Multilayer deposition requires asymmetric bipolar pulses (80kV/100μs positive, 20kV/20μs negative), achieved through magnetically coupled resonant circuits (ns switching), reducing Ti/TiN interface oxygen content to 0.3at%. Nanoparticle composite coatings demand precise inter-pulse intervals (1-10ms), realized via Marx-Bank/inductor topologies with >95% energy efficiency. For asymmetric large-area coatings (aspect ratio>10:1), multi-channel phase-adjusted supplies (<10ns sync error) optimize edge-center thickness ratio from 1:1.8 to 1:1.1.
5. Intelligent Energy Control Systems
Deep learning models analyzing plasma impedance spectra (0.1-10MHz) predict optimal pulse parameters. In DLC coating, this reduces process optimization from 72 hours to 2 hours, stabilizing sp³ content at 85±2%. Digital twins enable real-time energy distribution optimization through multi-physics simulations (EM-thermal-fluid), tripling thermal shock cycles for turbine blade MCrAlY coatings.
Conclusion
Precision pulse energy control is advancing surface engineering toward atomic-scale manufacturing. Future breakthroughs require ultrafast pulse modulation (ps-level), multi-target discharge coordination, and quantum sensing feedback to enable cross-scale functional thin film engineering.
