Double Langmuir Probes for Hypervelocity Wakes

Double Langmuir probes have been used to measure the ionization intensity in the wake of a hypervelocity projectile; subsidiary experiments to check the validity of the results are described. The spectral characteristic of the fluctuating part of the probe signal has been examined. Because of theoretical and experimental difficulties the results can at most be regarded as giving a qualitative picture of the turbulent structure of the wake. They do show, however, the predominant part played by eddies of roughly the wake diameter, agreeing on the average with the results of Clay et al. [1].