Science Seminars

Time-Resolved Temperature Measurements in Hypervelocity Dust Impact

Speaker: Andrew Collette
Date: Thursday, May 10, 2012
Time: 4:00 PM to 5:00 PM
Location: SPSC-N248

Seminar Abstract:

One effect of meteoroid impact on planetary surfaces, for impacting bodies of sufficient mass and speed, is a brief flash of light in the visible or infrared range. In addition to the basics physics questions relating to the impact process, observation of light flash provides a remote diagnostic for impact events and subsequent surface modification. For example, in the case of the Moon, impact-generated light has been observed associated with both Leonid and Perseid meteoroids.

I will discuss experimental studies of the visible light flash generated by hypervelocity dust grain impacts on solid surfaces. Micron-sized iron grains were launched at speeds from 1 to 40 km/sec from the 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 of the impact-generated cloud. We find time-averaged temperatures in the range 2500-5000K, increasing with velocity over the range studied, and initial temperatures up to roughly twice the time averaged temperature persisting on short timescales (1us) compared to the 20-40us length of the flash. Cooling of the cloud is also observed on the 10us timescale.