Uncertainty Analysis of Electron Density Decay Diagnostics in Double-Gaussian Plasma via Microwave Transmission

Diagnosing the electron density decay on the right side of the peak in double-Gaussian distributed plasma remains a significant challenge for conventional microwave diagnostics. This study proposes a novel diagnostic framework using microwave transmission to characterize this region. A mathematical model is established to link the slope of the transmission coefficient curve to the decay rate of the electron density gradient. Furthermore, an uncertainty quantification approach is introduced by accounting for variations in collision frequency, enabling the estimation of confidence and prediction intervals for the decay rate. The proposed method enhances the accuracy and robustness of microwave-based diagnostics for complex plasma environments, offering a new strategy for electron density retrieval beyond traditional cut-off frequency techniques.