A Method for Diagnosing Electron Density of a High-Enthalpy Plasma Wind Tunnel

To overcome the challenges associated with diagnosing electron density distributions in high-temperature plasma environments, a novel diagnostic method is proposed that integrates Langmuir probe measurements with hydrogen cyanide (HCN) laser interferometry. This technique is applied to the experimental apparatus for plasma-electromagnetic science of near-space hypersonic targets (EAPEHT). The Langmuir probe is used to measure the radial electron temperature, from which the electron density profile is derived based on the ion saturation current. Simultaneously, the HCN laser interferometer provides line-averaged electron density measurements, which are employed to calibrate and refine the probe-based results. Compared with conventional Langmuir probe techniques, the proposed method enhances diagnostic accuracy while reducing the number of required spatial measurements. Experimental results indicate strong agreement with traditional probe diagnostics, with relative deviations within the range of 10%–20%. Furthermore, the radial electron density distribution exhibits a Gaussian profile, validating the reliability and effectiveness of the proposed diagnostic approach.