  Planet formation and migration in accretion discs is a very active topic.
Among the many aspects related to that question, dead zones are of particular
importance as they can influence both the formation and the migration of
planetary embryos. The ionisation level in the disc is the key element in
determining the existence and the location of the dead zone. This has been
studied either within the Standard Accretion Disc (SAD) framework or using
parametric discs. In this paper, we extend this study to the case of Jet
Emitting Discs (JED), the structure of which strongly differ from SADs because
of the new energy balance and angular momentum extraction imposed by the jets.
We make use of the (r,z) density distributions provided by self-similar
accretion-ejection models, along with the JED thermal structure derived in a
previous paper, to create maps of the ionisation structure of JEDs. We compare
the ionisation rates we obtain to the critical value required to trigger the
magneto-rotational instability. It is found that JEDs have a much higher
ionisation degree than SADs which renders very unlikely the presence of a dead
zone in these discs. As JEDs are believed to occupy the inner regions of
accretion discs, the extension of the dead zones published in the literature
should be re-considered for systems in which a jet is present. Moreover, since
JEDs require large scale magnetic fields close to equipartition, our findings
raise again the question of magnetic field advection in circumstellar accretion
discs.
