A high-speed camera system for observing the streamer to leader transitions in lightning
Abstract
To enhance current DoD research, an ultrahigh-speed camera system is proposed to study thunderstorm and lightning processes within our atmosphere. The system, called the Quadnocular Lightning (QL) Imager, is composed of four Vision Research Phantom ultrahigh-speed cameras (TMX-5010) mounted together inside waterproof housing, which is placed on a remotely controlled adjustable mount for pointing. The four ultrahigh-speed cameras, along with a standard Watec camera used to facilitate pointing, will all simultaneously view the same patch of sky through heated windows. Each ultrahigh-speed camera will be operated with a different ultranarrow bandpass filter (< 2 nm FWHM) to identify the lightning streamer and leader discharge processes and to infer the electric fields in the streamer zones and the leader channel temperatures. Specifically, to measure streamer breakdown processes, two cameras will use ultra-narrow bandpass filter to view two nitrogen fluorescent lines in the violet range (e.g., the 399.7 nm of 2PN2 and 391.4 nm of 1NN2+ lines). The relative intensities of these two lines, which are from different band systems, will be used to determine the electric field strengths in the emission regions, providing important information about the discharges (Liu et al. 2006, 2009b; Ihaddadene and Celestin 2015). To measure the hot leader channels and space leaders, two other ultrahighspeed cameras will use ultra-narrow bandpass filters to measure two emission lines at longer wavelengths (e.g., the 568.0 nm N II and 594.2 nm N II lines). The relative intensities of these two emission lines will be used to infer the leader channel temperatures using standard spectroscopic techniques for lightning (Salanave et al. 1962; Prucitt 1963; Uman 1966; Orville 1968; Warner et al. 2011). The simultaneous measurements from the four cameras will provide important information about the poorly understood streamer-to-leader transition process, in which streamers heat the air and create a hot leader channel. Streamer-to-leader transitions are important for understanding lightning initiation, propagation and attachment processes.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 05, 2025
- Source ID
- FA95502410041
Entities
People
- J. R. Dwyer
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- University System of New Hampshire