Like microseconds..................
Storage up to weeks was successful in a vacuum containment, shielded to minimize light, suppress electron discharges, alpha, or neutron exposure sourced within the lab. Cosmic ray remain a low probability, random trigger source, a roll-of-the-dice event. Small yield is tolerable.
Critics of P & F argued that a sustained 1watt fusion excess energy would equal a dose of 10e12 neutrons generated per second. Given that potential for generating a hazardous exposure, limiting the bulk quantity stored seems prudent until, or if a safe storage is devised.
PS:
This lineage of research dates over three decades, initiated to seek a method to reduce the work function of electrodes within a thermionic-to-electric conversion device. One finding lead to another, following down a series of Alice’s Rabbit Holes.
The TOF Mass Spectrometry results with Rydberg Hydrogen are where the results diverged from prediction. The data indicated the cluster fragments possessed too much energy—the implied target density was too high. New science often begins with “That’s odd—What the h€((?”