  A kinky and clumpy ringlet shares orbit with the moon Pan in the center of
the 320-km wide Encke gap in Saturn's rings (Porco et al., 2005). The ringlet
is mainly composed of micron-sized particles (Showalter, 1991, Hedman et al.,
2011), implying that these particles may be significantly perturbed by
non-gravitational forces, which can limit their lifetimes. We establish a
kinetic model considering the birth, evolution, and death of dust in the Encke
central ringlet allowing to evaluate the ringlet optical depth. First, we
investigate the generation of dust by micrometeorite impacts (the
`impact-ejecta' process) on putative, yet undetected embedded moonlets. Taking
into account the orbital evolution under the influence of the relevant
perturbation forces, the dominant loss mechanisms are collisions with ring
particles in the gap edges, the putative moonlets in the gap, or erosion by
sputtering in Saturn's plasma environment. However, our results show that this
impact-ejecta process alone can only sustain a ringlet of optical depth 3-4
orders of magnitude smaller than the observed values. Consequently, other
processes must be taken into account. For example, mutual collisions among
putative moonlets should produce dust at about the same rate, while further
disruption of ejecta, as proposed by Dikarev (1999), should increase the total
amount of particles. Furthermore, observations show an azimuthal asymmetry of
the material in the Encke gap ringlets (Ferrari and Brahic 1997, M.
Srem\v{c}evi\'c, private communication). We investigate the scenario proposed
by Hedman et al. (2013) that for the Encke central ringlet, the observed
asymmetry is mainly due to the combined action of plasma drag and Pan's gravity
causing a focusing of dust in the region leading Pan's orbit (Hedman et al.
2013).
