Time-resolved temperature measurements in hypervelocity dust impact

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• We address energy partitioning in dust grain impacts.
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• We present time-resolved temperature and power measurements from a dust–impact-generated cloud.
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• Thermal radiation is found to be a non-negligible sink for energy in the cloud.

We present time-resolved temperature measurements of the debris cloud generated by hypervelocity dust impact. Micron- and submicron-sized iron grains were accelerated to speeds of 1–32 km/s using the 3 MV electrostatic dust accelerator at the Colorado Center for Lunar Dust and Atmospheric Studies, and impacted on a tungsten target. The resulting light flashes were analyzed by an array of photomultiplier tubes equipped with narrowband interference filters to determine the blackbody temperature and radiant power of the impact-generated cloud as a function of time. We find time-averaged temperatures in the range of 2500–5000 K, increasing with velocity over the range studied; initial temperatures up to approximately twice the time averaged temperature persisting on short timescales (<1μs) compared to the 20μs duration of the flash; and that the temperature falls in a manner consistent with radiative cooling.