The increase in the total ionization produced by high‐energy &agr; particles in Ar/C2F6mixtures, which have conduction and insulation properties appropriate for use in diffuse discharge switching applications by addition of low ionization energy additives has been quantitatively studied. The energy to produce an electron‐positive ion pair (ip)Win C2F6was found to be 34.7 eV/ip; this rather high value is attributed to the large cross section for electron impact‐induced dissociation of C2F6. TheWvalues of Ar/C2F6mixtures have also been measured and are reported; they increase with increasing C2F6content. TheWvalues of Ar/C2F6binary gas mixtures have been found to decrease by addition of C2H2or 2‐C4H8. Quantitative measurements of theWvalues of the ternary gas mixtures are reported. The amounts of C2H2or 2‐C4H8in Ar/C2F6, which maximize the increase in total ionization have been estimated; some of these ternary gas mixtures may be useful for diffuse discharge switches sustained by external electron beams. The experimental results on theWvalues for the binary and ternary gas mixtures studied have been modeled and good agreement has been found between the experimental and the calculated results. From an analysis of the data it has been found that the &agr;‐particle energy is partitioned between C2F6and Ar approximately in the ratio 4.2:1. It has also been found that at the argon pressures employed, the probability of deexcitation of excited argon atoms by C2F6(or C2H2or 2‐C4H8) molecules is more than three orders of magnitude larger than the probability of radiative deexcitation of the excited argon atoms.