Impact of Distortion on the Multipactor Threshold for Dual Carrier Digitally Modulated Signals

Multipactor under digitally modulated signals is a field of growing interest in the space industry. The need to operate with higher powers arises from the industry demand to increase data throughput, enabled by advances in space-born amplifiers. However, this often leads to signal distortion, which may alter the multipactor threshold measured in laboratory conditions. This work aims to characterize, through the combination of experimental tests and numerical simulations, how distortion affects the multipactor performance of microwave devices excited by modulated signals. To this end, several dual carrier modulated signals with different distortion levels are digitally created, simulated, and tested on the same multipactor sample. When the simulation configuration matches the laboratory conditions, an excellent degree of accuracy is reported. However, simulations also demonstrate that the nonzero time response of the sensors may play a crucial role in determining the measured threshold, suggesting that laboratory detectors may struggle to detect short-lived events. Numerical predictions also reveal how the thresholds linked to these events are affected by the degree of signal distortion.