ABSTRACT
This chapter shows that the current is imposed on the leader head from the 'outside', while the field is adjusted to it to allow the ionization to compensate for any electron losses. However, the structure of a streamer zone in a negative leader has little in common with that of a positive one. The leader development in the initial stage is accompanied by a continuous charge incorporation into the gap. Its amount may exceed several times the active electrode charge; hence, the initial field distribution in the gap is greatly violated. The problem of the leader origin appears to be more ambiguous than that of the streamer origin, since a leader arises in a field distorted by the initial corona charge, creating a reverse field at the active electrode. Indirect evidence for a uniform field distribution in the streamer zone is provided by streamer velocity measurements—they all move uniformly.
