Plasma and Flowfield Induced Effects on Re-Entry Vehicles for L-Band at Near-Broadside Aspect Angles. Volume I. Experimental Measurements Program Summary and Aerothermal Data Analysis

摘要

A laboratory measurements program has been performed in the Calspan 96 inchhypersonic shock tunnel which has provided a data base on the effects of the ionized flow field about a reentry vehicle on RF energy propagation. The measurements, performed under laminar flow conditions, provide data on plasma induced phase shift and attenuation of incident (uplink) RF signals for three aspect angles around broadside of the test vehicle, as well as measurements of reflection coefficient of an open ended waveguide antenna and mutual coupling between antennas on the vehicle. Vehicle orientations included combinations of pitch and yaw so as to include the effects of crossflow on the measurements The experiments were performed at an L band frequency, under freestream test conditions of 14,000 ft/sec at an equivalent density altitude of 140 kft. Surface distributions of pressure and heat transfer were measured, as well as profiles of the electron number density through the ionized flow field by means of thin-wire electrostatic probes.