The high-speed plasma flow generated by a shock tube is widely used in studies of spacecraft communication blackout and related fields. Effective diagnosis of plasma parameters such as electron density is an important prerequisite for carrying out such research. To address the rapid variation and wide dynamic range of electron density in shock-tube plasma, a transient dual electrostatic probe diagnostic study for wide-dynamic-range plasma was carried out by employing a capacitive compensation circuit and dual-channel adaptive data acquisition to suppress displacement current and enable synchronous measurement of weak and strong signals. A 500 kHz triangular sweeping bias was applied to reconstruct instantaneous I-V characteristics, and a segmented data-processing strategy was further adopted to determine electron density in different density regimes, so as to improve the applicability of the diagnostic method over a wide dynamic range.
Experimental results of shock-tube plasma diagnostics show that the system achieves highly transient measurements with a time resolution of 1 μs and wide-dynamic-range measurements spanning four orders of magnitude in electron density, from 10⁹cm^-3 to 10¹³cm^-3. The system also successfully captures the variation of electron density from 10⁹cm^-3 to 10¹³cm^-3 within a time scale of tens of microseconds, indicating that the plasma in shock-tube region II rapidly evolves from initial ionization to a quasi-steady state within this time scale. The complete establishment process of the plasma in region II is clearly resolved, demonstrating that the proposed method is capable of diagnosing the rapid evolution of shock-tube plasma over both microsecond time scales and four orders of magnitude in electron density. The repeatability error of the experiments is less than 5%, demonstrating that the proposed dual electrostatic probe diagnostic method has good reliability and stability. Comparison with numerical simulation results based on a multi-species chemically non-equilibrium flow model shows that the experimental results are generally consistent with the numerical results in terms of electron density magnitude and overall variation trend, indicating that the measured electron density is physically reasonable. In addition, the experimental results are consistent with the numerical simulation in revealing the characteristic rapid establishment behavior of the shock-tube plasma, which further supports the validity of the present diagnostic method. This work can provide an experimental basis for studying the formation and evolution of shock-tube plasma, and can also provide parameter diagnostic support for ground-based simulation studies related to spacecraft reentry communication.