An experimental study of breakdown and pre-breakdown phenomena in liquid nitrogen (LN2) is performed in this paper, in order to provide useful knowledge for the design of high voltage superconducting systems. A metallic tape subjected to pulsed heating is used as electrode, in order to properly simulate the operating conditions of a quenching superconducting apparatus. Measurements of breakdown voltages between the tape and a plane electrode tied to high voltage show the strong influence of tape polarity, LN2 temperature, and delay between heating and voltage application. Various measurements obtained with either a high-speed camera or an intensified camera allow to characterize the sequence of pre-breakdown events (i.e. liquid boiling, vapor bubble development, and streamer propagation) leading to breakdown.

R. Chassagnoux, O. Lesaint, N. Bonifaci, O. Gallot-Lavallée, P. Legendre, C. Creusot, A. Girodet