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The continuous emanation of radon due to trace amounts of uranium and thoriumin detector materials introduces radon to the active detection volume oflow-background rare event search detectors. $^{222}$Rn produces a particularlyproblematic background in the physics region of interest by the ``naked'' betadecay of its $^{214}$Pb daughter nucleus. While charcoal-based adsorption trapsare expected to be effective for radon reduction in auxiliary circulation loopsthat service the warm components of current {ton-scale} detectors at slow flowrates $(0.5-2\;SLPM)$, radon reduction in the entire circulation loop at highflow rates $\mathcal{O}({100s\;SLPM})$ is necessary to reach high sensitivityin future generation experiments. In this article we explore radon dynamicswith a charcoal-based radon reduction system in the main circulation loop oftime projection chamber detectors. We find that even for perfect radon traps,circulation speeds of $2,000\;SLPM$ are needed to reduce radon concentration ina 10\,ton detector by 90\%. This is faster by a factor of four than the highestcirculation speeds currently achieved in dark matter detectors. We further findthat the effectiveness of vacuum swing adsorption systems, which have beenemployed very successfully at reducing atmospheric radon levels in clean-rooms,is limited by the intrinsic radon activity of the charcoal adsorbent inultra-low radon environments. Adsorbents with significantly lower intrinsicradon activity than in currently available activated charcoals would benecessary to build effective vacuum swing adsorption systems operated at roomtemperature for rare event search experiments. If such VSA systems are cooledto about $190\,K$, this requirement relaxes drastically.

Performance Study of Charcoal-based Radon Reduction Systems for Ultraclean Rare Event Detectors