M. Wendt et al., AMPLITUDE COLLAPSE OF NONLINEAR DOUBLE-LAYER OSCILLATIONS, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics, 57(4), 1998, pp. 4638-4644
The negative differential resistance of a double layer can give rise t
o large amplitude oscillations in the potential drop over the double l
ayer. Such oscillations are investigated in a triple-plasma machine fo
r weak nonlinearity, implying approximately harmonic oscillations at l
ow frequencies (omega much less than omega(pi)). The amplitude of the
potential oscillations can approach the dc potential drop over the dou
ble layer. The oscillation exists within a certain interval of dc drop
s and vanishes outside this interval. An interesting nonlinear phenome
non that we call amplitude collapse is observed. The amplitude does no
t always decrease smoothly from its maximum value to zero when the dc
drop is increased, but there is a sudden jump to vanishing amplitudes.
For a decreasing dc voltage the corresponding sharp amplitude increas
e occurs at a lower voltage. This phenomenon, which is not predicted b
y the classical van der Pol equation, is shown to follow from the gene
ralized van der Pol equation that describes the actual system, by usin
g asymptotic solutions for weak nonlinearity.