title: Theory of a stationary current-free double layer in a collisionless plasma.
abstract: Current-free double layers can develop in a collisionless, inertia-controlled plasma with two electron populations, expanding in a convergent-divergent nozzle. The double layer characteristics depend on whether they develop at the nozzle divergent side, convergent side, or throat. The divergent-geometry double layer describes faithfully the Hairapetian-Stenzel experiment [Phys. Rev. Lett. 65, 175 (1990)10.1103/PhysRevLett.65.175], whereas the two other types correspond with those studied in self-similar expansions and wall-collection models of similar plasmas.
authors.affiliation: Universidad Politécnica de Madrid, Madrid 28040, Spain. eduardo.ahedo@upm.es
authors.forename: Eduardo
authors.initials: E
authors.lastname: Ahedo
authors.forename: Manuel
authors.initials: M
authors.lastname: Martínez Sánchez