Observation of sprite streamer head's spectra at 10,000 fps

Spatially and temporally resolved sprite streamer head spectra were observed for the first time using a slitless spectrograph at 10,000 fps. The spectra consist of the N-2 first positive (1PG) emission. Blue emissions, including the N2 second positive (2PG) and the N-2(+) first negative (1NG) emissions, were not observed presumably due to atmospheric attenuation along a long line of sight. The rotational temperature derived from the spectra indicates a kinetic temperature of 200-300 K with an upper limit of 400 K. Using a simple kinetic model, we estimate the peak electric field in the streamer head to be larger than 1-2Ek.