title: Space-charge effects in the current-filamentation or Weibel instability.
abstract: We consider how an unmagnetized plasma responds to an incoming flux of energetic electrons. We assume a return current is present and allow for the incoming electrons to have a different transverse temperature than the return current. To analyze this configuration we present a nonrelativistic theory of the current-filamentation or Weibel instability for rigorously current-neutral and nonseparable distribution functions, f(0)(p(x), p(y), p(z)) is not equal to f(x)(p(x))f(y)(p(y))f(z)(p(z)). We find that such distribution functions lead to lower growth rates because of space-charge forces that arise when the forward-going electrons pinch to a lesser degree than the colder, backward-flowing electrons. We verify the growth rate, range of unstable wave numbers, and the formation of the density filaments using particle-in-cell simulations.
authors.affiliation: Department of Electrical Engineering, University of California, Los Angeles, 90095, USA.
authors.forename: M
authors.initials: M
authors.lastname: Tzoufras
authors.forename: C
authors.initials: C
authors.lastname: Ren
authors.forename: F S
authors.initials: FS
authors.lastname: Tsung
authors.forename: J W
authors.initials: JW
authors.lastname: Tonge
authors.forename: W B
authors.initials: WB
authors.lastname: Mori
authors.forename: M
authors.initials: M
authors.lastname: Fiore
authors.forename: R A
authors.initials: RA
authors.lastname: Fonseca
authors.forename: L O
authors.initials: LO
authors.lastname: Silva