Applications of electric probes away from the ideal limit

Throughout plasma physics, approximations are made during analysis as a means of making problems tractable.  Making sense of those approximations and their limitations in the face of laboratory realities is often vexing to the plasma newcomer.   One reason that Noah Hershkowitz's many contributions to plasma science are so impactful and enduring is his pragmatic approach and accessible presentation.  An example of these qualities can be seen in his book chapter* "How Langmuir Probes Work."  In this article, he describes numerous practical considerations in implementing and interpreting electric probes of various types in a variety of plasma environments.  Through this article, he showed that the many non-ideal cases that arise when dealing with probes can be broken down and considered in a systematic way to understand and exploit their capabilities.  Examples from the three decades since this article was published will be used to highlight the impact of his career beyond his own research results, through his pedagogical skill and the understanding and confidence he inspired in others.

*Noah Hershkowitz, "How Langmuir Probes work," in Plasma Diagnostics, D. L.  Flamm and O. Auciello, eds., Academic Press (1989).