Emerging and expanding streamer head in low-pressure air

This research was funded by the Academy of Sciences of the Czech Republic under project M100431201. TH was supported by the European Science Foundation Research Networking Programme TEA-IS (ex-change Grant No. 4219). ZB was supported by the Czech Science Foundation, project No. 15-04023S. FJGV was supported by the Spanish Ministry of Science and Innovation (MINECO) under project ESP2017-86263-C4-4-R. TH is grateful for the support of project LM2018097 funded by the Ministry of Education, Youth and Sports of the Czech Republic.