Qualification and Diagnostics development for the European Shock-Tube for High-Enthalpy Research

Abstract:

The ESTHER shock tube is a new state-of-the-art facility at Instituto Superior Técnico to support future ESA planetary exploration missions. The facility recreates the re-entry plasma conditions sustained by a hypersonic velocity atmospheric entry.

These shock wave velocities are in the range of 4 to 14 km/s range. A high-pressure combustion chamber using a mixture of He:H2:O2 ignited by a high-power Nd:YAG laser acts as the driver. A qualification campaign was carried out with 100 shots and evaluating the effects of air:fuel ratio, filling pressure, inert gas dilution and ignition mode. These parameters directly affect the produced shockwave velocity and should be effectively controlled.

Alongside the driver qualification the development of different diagnostics is presented, namely the VUV spectroscopy system and a compact reflectometer/interferometer for space applications. Technical requirements and architecture of a reflectometry/interferometry equipment tailored for both ground-test facilities (shock-tubes and plasma wind-tunnels) and flight experiments are proposed.

A simulation of electromagnetic environment for the RAM-C flight experiment, obtained using a CFD code coupled to an electromagnetic propagation code is presented, outlining the adequacy of such a diagnostic for improving verification and validation for high-speed entry plasma flows.