WR140 is a colliding wind binary system consisting of a carbon-rich Wolf-Rayet (WC) star
and an O-type star companion, known for its periodic dust formation. The dust structure
takes on a three-dimensional shape, with its components exhibiting multiple
velocities. Various fine-structure lines, such as [S IV] and [Ne III], are to occur in
high-energy environments within the colliding wind region. In this study, we investigate
the physical conditions of the dust region of WR 140 using the James Webb Space
Telescope (JWST) Mid-Infrared Instrument (MIRI) Medium-Resolution Spectrometer, which,
for the first time, offers exceptional sensitivity and spatial resolution to isolate the
dust and the WR star. We report the surprising detection of spatially resolved [Ne V]
lines at 14.3 and 24.3 μm and analyze the three-dimensional electron density
distribution derived from the [Ne V] line ratio. Compared to hydrodynamic simulation, an
increase in the line ratio has been observed for the first time in the regions where the
newly formed dust arc is located. This enhancement indicates a higher electron density
in the colliding winds, which is essential for dust formation.