Study on a Novel Receiver Protector Using Ultra-Compact Magnet-Free Klystron Scheme

The development of modern receiver protection technology mainly focuses on addressing the challenge posed by pulsed high-power microwave (HPM). This study pioneers a novel magnet-free dual-cavity klystron configuration that serves as the receiver protector for radar systems. Unlike traditional vacuum electronic devices, which require external focusing magnets, the proposed magnet-free klystron structure significantly improves structural compactness and manufacturing consistency, while substantially reducing production costs. This study demonstrates a representative prototype with dimensions of 54 mm (L) <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times 35$</tex-math> </inline-formula> mm (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Phi $</tex-math> </inline-formula>), incorporating a 1 kV/50 mA electron gun configuration. The proposed device operates at a center frequency of 5.8 GHz in C-band. The innovative design achieves multiple performance enhancements, including complete spike-leakage suppression, sub-microsecond recovery characteristics, and the capacity to handle short pulses of power reaching 15kW (350 W for long pulses). 3-D particle-in-cell (PIC) simulations confirmed that the flat leakage power was maintained below 15.2W without transient spikes, achieving a −150-ns response time and a −180-ns recovery time. This breakthrough provides a viable technical pathway for next-generation RF front-door protection.