Physical Review Letters
https://journals.aps.org/prl/abstract/10.1103/
PhysRevLett.99.155004
Exact Solution for the Generalized Bohm Criterion in a
Two-Ion-Species Plasma Dongsoo Lee, Lutfi Oksuz, and Noah Hershkowitz
Dongsoo Lee1,
Lutfi Oksuz1,2,
and
Noah
Hershkowitz1,*
1 Department of Engineering Physics, University of
Wisconsin at Madison, Madison, Wisconsin 53706, USA
2 Department of Physics, Suleyman Demirel
Universitesi, Isparta 32260, Turkey
* Author to whom all correspondence should be
addressed. hershkowitz@engr.wisc.edu
Phys. Rev. Lett. 99, 155004 – Published 10 October 2007
Abstract
For a weakly collisional two-ion species plasma, it is
shown that the minimum phase velocity of ion acoustic waves (IAWs)
at the sheath-presheath boundary is equal to twice the phase
velocity in the bulk plasma. This condition provides a
theoretical basis for the experimental results that each ion
species leaves the plasma with a drift velocity equal to the
IAW phase velocity in the bulk plasma [D. Lee et al.,
Appl. Phys. Lett.
91, 041505 (2007)]. It is shown that this result is
a consequence of the generalized Bohm criterion and fluid
expressions for the IAW phase velocities.
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