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 .