Title: Granular electrostatic formations with peeled tape

Author (Table Talk): Mary Pat Reiter, Rutgers University

Abstract:

Phenomena ranging from coal dust explosions[1,2] and volcanic lightning[3] to failures of extraterrestrial rovers[4], and the growth of planetesimals[5] are all associated with electrostatics in constituent grains. These interactions can lead to intriguing granular shapes such as Razorbacks[6] which are the formation of spikes in grains flowing down a pile. Following the release of images from the Mars Rover that appeared to show strands or strings in front of the lens, theories began to arise suggesting that they may be electrostatically connected dust particles. We aimed to investigate the formation of granular projections and propose a mechanism that may explain this behavior. Leveraging the electrostatic properties of Scotch tape, we exposed small beds of grains to different geometries of peeled tape. We identified and characterized several shapes including single file tendrils up to ten grains long. We suggest that the two poles of each grain become oppositely charged in the line of grains, linking them together. Though preliminary, we anticipate that our findings can provide a potential explanation and a method for further investigation. [1] Glor. J. Electrostat. 16, 175-191 (1985). [2] Jamesa et al. Hist. Technol. (1999). [3] James, et al. J. Geophys. Res. 105, 16641-16649 (2000). [4] Li et. al. Springer International Publishing, Cham, (2017). [5] Steinpilz, et al. Nat. Phys. 16, 225-229 (2020). [6] Shinbrot et al. Phys. Rev. Lett. 96, 178002 (2006).