Martin J. Greenwald is a 🏷️#physicist who spent 43 years at the 📝MIT Plasma Science and Fusion Center as a researcher and served as senior scientist and deputy director until stepping back from those roles in 2022 and becoming a visiting scientist. He is the author of the 📝Greenwald limit, the empirical density ceiling that carries his name and is used across the field to predict the behavior of 📝tokamaks far larger than the machines it was derived from.
Greenwald identified the density scaling during studies for the Compact Ignition Tokamak in the late 1980s. He went on to chair the experimental program committee for 📝Alcator C-Mod from 1993 through the 2010s, setting what the high-field 📝plasma experiment actually ran for two decades and producing much of the operating record that later underwrote 📝SPARC's performance projections. He helped develop the tokamak concept that became SPARC alongside 📝Dennis Whyte and MIT students, led the SPARC physics group, and wrote "Status of the SPARC physics basis," the framing paper of the 2020 Journal of Plasma Physics collection in which the machine's physics case was published for peer review before construction.
Marty is why SPARC could be argued rather than asserted. He set two decades of Alcator C-Mod's experimental program, and then framed the physics basis we submitted to the field for refereeing before we cut metal.