Interstellar neutral gas atoms penetrate the heliopause and reach 1~au, where
they are detected by IBEX. The flow of neutral interstellar helium through the
perturbed interstellar plasma in the outer heliosheath (OHS) results in
creation of the secondary population of interstellar He atoms, the so-called
Warm Breeze, due to charge exchange with perturbed ions. The secondary
population brings the imprint of the OHS conditions to the IBEX-Lo instrument.
Based on a global simulation of the heliosphere with measurement-based
parameters and detailed kinetic simulation of the filtration of He in the OHS,
we find the number density of interstellar He$^+$ population at $(8.98\pm
0.12)\times 10^{-3}$~cm$^{-3}$. With this, we obtain the absolute density of
interstellar H$^+$ $5.4\times 10^{-2}$~cm$^{-3}$ and electrons $6.3\times
10^{-2}$~cm$^{-3}$, and ionization degrees of H 0.26 and He 0.37. The results
agree with estimates of the Very Local Interstellar Matter parameters obtained
from fitting the observed spectra of diffuse interstellar EUV and soft X-Ray
background.
