The images above are hydrogen flames. They can burn with very little fuel in tiny gaps and often break up into fractal patterns like the ones above. A team of researchers have been researching hydrogen flames to improve the safety of hydrogen powered devices. More from Phys.org:
The study, published in the latest edition of the journal Physical Review Letters, details the results from experiments which have demonstrated that hydrogen flames can survive in more extreme conditions than previously thought. In this research, led by Fernando Veiga, Eduardo Fernández-Tarrazo and Mario Sánchez Sanz, from the UC3M Department of Thermal and Fluids Engineering, Daniel Martínez Ruiz from the Universidad Politécnica de Madrid (UPM), Mike Kuznetsov from the Karlsruhe Institute of Technology (Germany) and Joachim Grune from Pro-Science GmbH (Germany) have likewise participated.
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