  TianQin is a proposed geocentric space-based gravitational wave observatory
mission, which requires time-delay interferometry (TDI) to cancel laser
frequency noise. With high demands for precision, solar-wind plasma environment
at $\sim 10^5$ km above the Earth may constitute a non-negligible noise source
to laser interferometric measurements between satellites, as charged particles
perturb the refractivity along light paths. In this paper, we first assess the
plasma noises along single links from space-weather models and numerical
orbits, and analyze the time and frequency domain characteristics.
Particularly, to capture the plasma noise in the entire measurement band of
$10^{-4} - 1$ Hz, we have performed additional space-weather
magnetohydrodynamic simulations in finer spatial and temporal resolutions and
utilized Kolmogorov spectra in high-frequency data generation. Then we evaluate
the residual plasma noises of the first- and second-generation TDI
combinations. Both analytical and numerical estimations have shown that under
normal solar conditions the plasma noise after TDI is less than the secondary
noise requirement. Moreover, TDI is shown to exhibit moderate suppression on
the plasma noise below $\sim 10^{-2}$ Hz due to noise correlation between
different arms, when compared with the secondary noise before and after TDI.
