A coaxial solid state nonlinear pulse forming line with an exponentially tapered ferrite composite core

Area of Science:

• Electromagnetics and Microwave Engineering
• Materials Science for RF Applications

Background:

• Optimization of size, weight, and power (SWaP) is critical for high-power microwave (HPM) systems.
• Solid-state HPM sources, like nonlinear transmission lines (NLTLs), offer advantages over traditional vacuum devices.
• Nonlinear pulse forming line (NPFL) systems integrate pulse formation, reducing SWaP but posing load-matching challenges.

Purpose of the Study:

• To develop a tapered NPFL that addresses load-matching issues in compact HPM systems.
• To characterize the performance of an exponentially tapered composite ferrite core NPFL.
• To investigate the tunability of HPM generation through magnetic biasing.

Main Methods:

• Fabrication of an exponentially tapered NPFL using a composite ferrite core (60% nickel zinc ferrite in PDMS) with a barium strontium titanate shell.
• Characterization of core magnetic properties via magnetization curves and ferromagnetic resonance measurements.
• Evaluation of pulse forming characteristics and HPM generation under varying charging voltages and magnetic biases.

Main Results:

• Pulse rise time (10%-90%) improved from ~6 ns to 1.8 ns with increased charging voltage (5 kV to 15 kV).
• Unbiased HPM generation centered at ~850 MHz with a 125 MHz bandwidth.
• Magnetic biases of 15 and 25 kA/m shifted the center frequency to ~500 MHz, enhancing modulation depth.

Conclusions:

• The tapered NPFL design effectively reduces pulse rise time and offers tunable HPM generation.
• The composite ferrite core NPFL presents a viable solution for compact, efficient HPM systems.
• Further research can explore advanced material compositions and bias configurations for enhanced performance.