Theoretical and Experimental Analysis of Detuning Mechanism for the SLED

A coupled mode theory (CMT) model based on odd–even mode decomposition is proposed to analyze the transient characteristics of detuning in the Stanford Linear Accelerator Energy Doubler (SLED). The primary objective of this analysis is to predict the detuning required to achieve low-distortion and low-loss mode switching in SLED pulse compression systems. The CMT calculations indicate that detuning the resonant cavity causes the output pulse of the SLED to exhibit a beat envelope at a frequency corresponding to the detuning frequency, resulting in pulse distortion. Numerical results show that waveform distortion and energy transmission efficiency are influenced by the resonant cavity’s$Q$-factor, coupling coefficient, and degree of detuning. Specifically, for fixed resonant cavity parameters, higher detuning leads to reduced distortion and improved energy transmission efficiency. A SLED system operating at 2.458 GHz was designed, using a choke piston to achieve stable tuning over a broad range of 86 MHz. Both simulation and experimental results demonstrate good agreement with the CMT model predictions. Experimental tests show that the designed SLED can switch to a low-loss, low-distortion noncompression mode with a detuning of 3 MHz.